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  • Ultrastructure  (1,615)
  • nitrogen  (794)
  • 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
  • Bacteria
  • Springer  (2,576)
  • Lagos (Nigeria)  (6)
  • Istituto Nazionale di Geofisica e Vulcanologia  (5)
  • American Chemical Society
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  • 1
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24208 | 19325 | 2018-05-19 06:39:34 | 24208 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: The microbial load of four different fish species from five different market locations in Ibadan metropolis were determined using standard microbiological procedures. The bacteria count of fish sampled from Ojo market was the highest while the bacteria count of the fish sample from Bodija market was the lowest. There was no significant difference (p〈0.05) in the microbial load of the fish sampled from various market locations in Ibadan metropolis. Similarly, there was no significant difference (p〉0.05) in the microbial load on various fish species sold in Ibadan metropolis. The isolated bacteria from the study were: E. coli, Salmonella spp, Klebsiella spp, Staphylococcus aureus, Aerosomonas spp, Pseudomonas spp, Vibrio spp, Serratia spp, Chromobacterium spp, Enterobacteria spp and Shigella spp. The fungi count of fish sampled from Omi markets was the highest while the fungi count of the fish sampled from Ojo market was the lowest. The following fungi were however isolated from the study: Aspergillus flavus, Penicillium spp, Fusarium oxysporum, Trrichoderma spp and Ceotrichium albidium. The study shows that reheating may be necessary to destroy or inactivate micro-organisms in smoked fish before consumption.
    Description: Includes: 2 tables and 2 figures.;Also includes: 17 refernces.
    Keywords: Fisheries ; Nigeria ; Ibadan ; Bacteria ; Fungi ; Market ; Fish species ; freshwater environment ; Microbial contamination ; Microorganisms ; Bacteria ; Freshwater fish ; Cured products ; Sample contamination ; Fungi ; Public health ; Quality assurance ; Disinfection
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 223-227
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  • 2
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24166 | 19325 | 2018-05-13 18:40:22 | 24166 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Probiotics are a promising feed additive to stimulate animal growth and secure a low disease response in aquaculture industry where there are high stocking densities in shrimp and fish production. Fermented locust beans (Parkia biglobosa) are known to be rich in protein and used as food condiment. Probiotic bacteria were isolated from this locally available food material. Culture and characterizations of isolates were carried out. Sugar fermentation patterns were determined by using an API 50 CHL system and incubation were performed anaerobically at 37~'C. MRS broth culture grown at 37~'C overnight was added to 9ml of MRS Agar and the bacteria were incubated at 37~'C for 24 and 48 hrs. Discrete and single colony of lactobacillus was isolated using colony morphology and biochemical tests. The most significant viable taxa isolated was Lactobacillus fermentum at a pH range of (3.0-8.0), while the least viable taxa isolated was Leuconostoc mesenteroides ssp. Microscopically they were Grampositive, rod shaped, non- motile, catalase negative and absence of Endospore.
    Description: Includes: 2 tables and 2 plates.;Also includes: 15 references.
    Keywords: Aquaculture ; Nigeria ; Lagos ; Locust bean ; Probiotics ; Lactobacillus ; Probiotics ; freshwater environment ; Feed ; Additives ; Aquaculture ; Microorganisms ; Bacteria ; Disease resistance ; Fermented products ; Fish culture ; Shrimp culture
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 60-63
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  • 3
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24224 | 19325 | 2018-05-19 07:11:26 | 24224 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Jabi Lake is a natural water body in Abuja Federal Capital Territory (FCT). It was expanded for commercial fishing following relocation of Nigeria's headquarters to Abuja in 1993. Quantitative analysis of microbiological status of water and fish from the Lake was carried out. Samples were collected from the dam site, open water, middle lake and inlet. Result reveal that total coliform count which are indicators of pollution are high (2.0 x 103 cfu/ml, 1.1 x 103 cfu/ml, 1.0 x 103 cfu/ml and 1.1 x 103 cfu/ml for dam site, open water, middle lake, and inlet respectively). Total viable count too is high (9.2 x 103 cfu/ml, 4.9 x 103 cfu/ml, 4.6 x 103 cfu/ml and 4.9 x 103 cfu/ml for dam site, open water, middle lake and inlet respectively). There are no coliform bacteria in the muscle of the fish. High bacterial load is an indication of biological pollution and these calls for restraint on the side of those who are using the lake as site for refuse dump.
    Description: Includes: 10 references.
    Keywords: Fisheries ; Pollution ; Nigeria ; Jabi Lake ; Jabi lake ; Water ; Fish ; Bacteria ; freshwater environment ; Microbiology ; Fish ; Pollution ; Water pollution ; Lake fisheries ; Fishery surveys ; Bacteria ; Baseline studies ; Water sampling ; Microbial contamination ; Muscles ; Freshwater fish ; Pollution surveys ; Water analysis ; Freshwater pollution
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 284-286
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  • 4
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24185 | 19325 | 2018-05-16 14:41:02 | 24185 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Bacteria has been implicated in food poisoning, and smoked fish is not an exception.Generally, fish is highly susceptible to spoilage; therefore this study evaluated the bacteria load in smoked fish from three major locations in Shiroro area of Niger State namely; Gwada, Kuta and Zumba.The smoked fish samples collected from these locations were smeared at both the gills and head regions of the fishes. The bacteria samples identified were Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis, Pseudomonas aeruginosa, and Samonella typhi, which were common to all the three locations sampled, while only Streptococcus feacaliswas only was found to be present in both Kuta and Zumba location.The frequency of occurrence of these 68 bacteria samples isolated ranges from 8 - 20%, with Bacillius subtilis having the highest occurrence and Pseudomonas aeruginosa have the least occurrence. Out of the total 68 samples, 14 skin samples (20.6%) and 5 gills samples (7.4%) exceeded the acceptable limits of total mesophilic aerobic counts which were 10〈sup〉6〈/sup〉 - 10〈sup〉7〈/sup〉 cfu/g. In the case of total coliform counts, 12 skin samples (17.6%) and 7 gills samples (10.3%) exceeded the acceptable limit which is 4.0 x 102, while in the case of Staphylococcus aureus, 4 skin samples (5.9%) and 2 gills samples (2.9%) exceeded the acceptable limit which is 103 cfu/g. Similarly 3 skin samples (4.4%) and 1 gill sample (1.5%) exceeded the acceptable limit of Salmonella typhi which is 104 cfu/g.
    Description: Includes: 4 tables.;Also includes: 21 references.
    Keywords: Fisheries ; Health ; Escherichia coli ; Bacillus subtilis ; Staphylococcus aureus ; Staphylococcus epidermis ; Pseeudomonas aeruginosa ; Nigeria ; Shiroro L. ; Bacteria ; Smoked (Clarias spp) fish ; Location and recommended values ; brackishwater environment ; freshwater environment ; marine environment ; Bacteria ; Food poisoning ; Cured products ; Fish ; Fish spoilage ; Acceptability ; Lake fisheries ; Gills ; Brain ; Evaluation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 140-144
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  • 5
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24222 | 19325 | 2018-05-19 07:06:04 | 24222 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: A total of 2,800 tilapia (Oreochromis niloticus) were stocked in seven duplicates 5 by 4 m2 earthen ponds in NIFFR Integrated Farm, New-Bussa, Niger-State. Raw and sterilized poultry manure of 0.13 to 0.52 kg/m3 concentrations were used to fertilize the ponds with the unfertilized ponds serving as control. The following bacteria were isolated from the cow dung manure; Escherichia coli, E. co1iOl57:H7, Aeromonas hydrophila,Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus. The fish samples from the 0.13 and 0.26 kg/m3 sterilized manure fertilized ponds had zero count in the muscles while samples from other ponds had pathogens in their fish muscles. The study revealed that fish samples from sterilized manures were better in terms of microbial safety for fish productions hence sterilized manure are recommended for use in fish production to ensure the microbial safety of the fish, handlers and that of the consumers.
    Description: includes: 13 references.
    Keywords: Aquaculture ; Oreochromis niloticus ; Escherichia coli ; Aeromonas hydrophila ; Samonela typhi ; Shigella dysenteriae ; Staphylococcus aureus ; Nigeria ; Niger State ; Catfish ; Pathogens ; Microbial quality ; Raw and sterilized manue ; freshwater environment ; Bacteria ; Freshwater fish ; Fish culture ; Fish ponds ; Manure ; Microorganisms ; Freshwater aquaculture ; Aquaculture products ; Food fish ; Quality assurance ; Muscles ; Microbial contamination
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 278-280
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  • 6
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24596 | 19325 | 2018-05-20 16:13:09 | 24596 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Sixty apparently healthy Heterobranchus bidorsalis and Clarias anguillaris from NIFFR were cultured and 30 each from Monai and wara villages as wild environments were obtained for the studies. The total bacterial load varied from 2.2 x l05 to 1.08 x l08 and 2.27 x 105 to 6.3 x l08 CFU/g of the skin of C. anguillaris and H.bidorsalis in the culture respectively, while the load varied from 1.77 x 105 to 1.17 x l08 and 2.27 x 105 to 9.0 x l07 CFU/g in the wild respectively. Eleven bacterial general species were identified which include: Bacillus species B.firmus, Pseudomonas species, P. aeruginosa, Escherichia coli, Klebsiella aerogenes, K. ozaenae, Staphylococcus aureus, Streptococcus species, S.faecalis, and Aeromonas species. The aims of this investigation is to compare the type and the load of bacteria isolates on the skin of catfish in both culture and wild environment.
    Description: Includes: 7 references.
    Keywords: Aquaculture ; Fisheries ; Clarias anguillaris ; Heterobranchus bidorsalis ; Nigeria ; Kainji L. ; Comparative study ; Bacteria ; Skin ; Clarias ; Heterobranchus ; Kainji Lake ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 119-122
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  • 7
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gosselin, K. M., Nelson, R. K., Spivak, A. C., Sylva, S. P., Van Mooy, B. A. S., Aeppli, C., Sharpless, C. M., O’Neil, G. W., Arrington, E. C., Reddy, C. M., & Valentine, D. L. Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum. ACS Omega, 6(35), (2021): 22803–22810, https://doi.org/10.1021/acsomega.1c03196.
    Description: The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
    Description: This work was funded with grants from the National Science Foundation grants OCE-1333148, OCE-1333162, and OCE-1756254 and the Woods Hole Oceanographic Institution (IR&D). GCxGC analysis made possible by WHOI’s Investment in Science Fund.
    Keywords: Lipids ; Alkyls ; Bacteria ; Genetics ; Chromatography
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
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    Springer Nature | Springer
    Publication Date: 2024-04-05
    Description: This open access book offers a comprehensive overview of the role and potential of microorganisms in the degradation and preservation of cultural materials (e.g. stone, metals, graphic documents, textiles, paintings, glass, etc.). Microorganisms are a major cause of deterioration in cultural artefacts, both in the case of outdoor monuments and archaeological finds. This book covers the microorganisms involved in biodeterioration and control methods used to reduce their impact on cultural artefacts. Additionally, the reader will learn more about how microorganisms can be used for the preservation and protection of cultural artefacts through bio-based and eco-friendly materials. New avenues for developing methods and materials for the conservation of cultural artefacts are discussed, together with concrete advances in terms of sustainability, effectiveness and toxicity, making the book essential reading for anyone interested in microbiology and the preservation of cultural heritage.
    Keywords: Microbiology ; Cultural Heritage ; Microbial Ecology ; Microbial Genetics and Genomics ; Enzymology ; Applied Microbiology ; Microbial Genetics ; Industrial Microbiology ; Open Access ; Restoration ; Conservation ; Biodeterioration ; Bioweathering ; Bioremediation ; Biocleaning ; Biotechnology ; Green Chemistry ; Fungi ; Bacteria ; Artwork ; Antimicrobial protection ; Biocides ; Microbiology (non-medical) ; Cultural studies ; Social & cultural history ; Ecological science, the Biosphere ; Genetics (non-medical) ; Biochemistry ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSG Microbiology (non-medical) ; thema EDItEUR::J Society and Social Sciences::JB Society and culture: general::JBC Cultural and media studies::JBCC Cultural studies ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAF Ecological science, the Biosphere ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSB Biochemistry
    Language: English
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  • 9
    Publication Date: 2017-04-04
    Description: Balanced information and education are fundamental prerequisites for risk prevention and preparedness. Among others, children embody our best chance to implant appropriate behaviors that will be recalled during hazardous situations and to involve adults according to a knowledge chain reaction. In this work, scientists challenge their communication skills to built a set of hands-on and learn-by-play based laboratory activities, for primary and secondary schools, addressing three major issues: (1) the location of earthquakes and volcanoes on Earth; (2) earthquakes and eruptions mechanisms; (3) earthquakes unpredictability. Students are asked to place volcanoes and earthquakes epicenters (issue 1) on a wooden plate puzzle according to Plate dynamics. To addresses eruption mechanisms (issue 2) and related hazard, we use backing soda forced blowing out from a volcano vent and suggest that a pyroclastic flow is fast, it can spread over a large area and raise high up to the stratosphere. Earthquake mechanisms (issue 2) are discussed describing the energy buildup, release, and transfer, using a wooden sticks bendand- break analogy. The display of acoustic waves caused by the breakage in different situations allows understanding of both the rupture energy and the wave attenuation. Earthquakes occurrence (issue 3) is addressed using steadily pulled blocks sliding on a frictional surface, where pins simulate asperities. These activities were tested, involving thousands of students. Discussions with students and teachers and the analysis of the answers to specific questionnaires gave us confidence that we proposed proper tools to raise risk awareness
    Description: Published
    Description: 89-93
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: Seismic and volcanic hazards, Outreach, Education ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 10
    Publication Date: 2020-02-24
    Description: In 2011 a research project on volcanic risk assessment at La Réunion Island (Project Aléa, Institute de Physique du Globe de Paris, France) was conducted in order to determine more efficient strategies to manage future volcanic crises. The project included the evaluation of volcanic scenarios through field and historical data analysis, as well as a survey on volcanic risk perception in resident population. A clear scientific information and an effective communication with public play a crucial role in risk mitigation strategies. In particular, the evaluation of the public perception during both volcanic crises and dormant periods is an important element in developing actions focused on specific social and cultural contexts. A questionnaire was developed based on the ones used in similar researches conducted on Italian active volcanoes. Items were designed to measure variables connected with personal perception of hazard and risk, trust in mitigation actions and in information received about these aspects. In addition, specific items related to the peculiarities of La Réunion Island environment were included. A total of 2,000 questionnaires were distributed taking into account factors such as the proximity to the volcano and the involvement of communities in recent volcanic emergencies. Main results coming out from this survey, if on the one hand show an adequate residents’ perception of natural hazards, on the other hand highlight their poor knowledge of the island’ active volcano, a similar lacking knowledge of emergency plan for volcanic crises, but also a high confidence in scientists to provide accurate and reliable information on volcanic risk and hazards in contrast with Local Authorities. Remarkable findings of this study assess some key elements that should be considered by the institutions in charge for defining policies aimed to volcanic risk mitigation and management of future volcanic crises.
    Description: Unpublished
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: reserved
    Keywords: risk perception, volcanic hazards ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 11
    Publication Date: 2017-04-04
    Description: This book is one out of 8 IAEG XII Congress volumes, and deals with education and the professional ethics, which scientists, regulators, and practitioners of engineering geology inevitably have to face through the purposes, methods, limitations, and findings of their works. This volume presents contributions on the professional responsibilities of engineering geologists; the interaction of engineering geologists with other professionals; recognition of the engineering geological profession and its particular contribution to society, culture, and economy; and implications for the education of engineering geologists at tertiary level and in further education schemes. Issues treated in this volume are: the position of engineering geology within the geo-engineering profession; professional ethics and communication; resource use and re-use; managing risk in a litigious world; engineering and geological responsibility; and engineering geology at tertiary level. The Engineering Geology for Society and Territory volumes of the IAEG XII Congress held in Torino from September 15-19, 2014, analyze the dynamic role of engineering geology in our changing world and build on the four main themes of the congress: Environment, processes, issues, and approaches.
    Description: Published
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5A. Energia e georisorse
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: open
    Keywords: Geoethics ; Geoeducation ; Professional Ethics ; Engineering Geology ; Communication ; Society ; Risks management ; Georesources ; Geological responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 12
    Publication Date: 2017-04-04
    Description: The defence against natural hazards involves many actors with different roles: geoscientists, decision makers, local authorities, mass media, citizens. A proper management of georisks requires that each role is well-defined and governed by shared operational protocols, especially during the emergency phase, so that overlapping and misunderstanding don’t jeopardize population safety and economic activities. To achieve good results in this direction, it is necessary to undertake a careful evaluation of the limits and expectations of each component of society and the respect of legitimate aspirations and prerogatives. An effective defence system against natural hazards should be planned rationally and based on scientific data, in order to avoid alarmism among citizens, misleading sensationalism by media, careless decisions by politicians, as well as approximation in managing different phases of the risk cycle. Taking into consideration geoethical aspects related to natural hazards can be helpful to make geoscientists aware of their responsibilities towards society and to clarify the role they can play in the interaction with other actors, aiming at more efficacious actions for georisk mitigation.
    Description: Published
    Description: 59-62
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 4V. Vulcani e ambiente
    Description: 4A. Clima e Oceani
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: restricted
    Keywords: Geoethics ; Natural hazards ; Risks ; Society ; Responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 13
    Publication Date: 2020-02-24
    Description: The communication process between the geoscientists and native communities in risk areas can significantly affect disaster prevention and land use planning. In Peru, the problem of disaster prevention is a fundamental policy due to unfamiliarity and deficiency of the associate information on the population. It is possible that talk of disaster prevention it will be an unlikely ideal in a country where most towns have settled on unplanned projects by the constant change and the lack of interest from the authorities in such topics. However, it is anachronistic that the rural communities and towns continue to live without a plan to enable them to improve their quality of life. The correct use of geoscience information in the mass media can help in this work. The characteristics of the enterprise in Peru require more training by professionals in the geosciences and support communication specialists. In this paper, we analyze the problem of communication for disaster prevention in Peru, with the aim of contributing to the articulation of a disaster prevention strategy.
    Description: Published
    Description: 81-83
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: reserved
    Keywords: Communication process ; Disaster prevention ; Risk management ; Peru ; Geoethics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 14
    Publication Date: 2020-10-26
    Description: One of the main objectives of the ITACA (ITalian ACcelerometric Archive) strong motion database, promoted by the Italian Department of Civil Protection, was to improve the characterization of the recording sites from a geological and geophysical point of view and to provide their seismic classification according to the seismic norms pertinent to Italy, namely the Eurocode 8 and the National Technical Norms for Constructions. A standard format to summarize the available information for the recording stations was first produced, in terms of a technical report dynamically linked to the database, i.e., some of the relevant information is automatically updated when the corresponding fields of the database are modified. Then, an important activity of collection, qualification and synthesis of available data was carried out, especially for stations that recorded the strongest earthquakes in Italy in the last 40 years, and for which a relevant number of studies have been published. In spite of this activity, among the more than 700 strong motion stations present in the ITACA database, only a limited number of them could be characterized by quantitative information on subsurface soil properties. For this reason, a dual seismic site classification criterion was implemented, either based on the standard Vs,30 scheme, or, in the absence of such information, based on an expert opinion supported by shallow geology maps, mostly at 1:100,000 scale, and when available on the H/V ratios calculated on recordings. Owing to the relevance in the Italian geographic and morphological context, a special care was also given to the topographic classification of stations, based on suitable criteria developed within a GIS environment.
    Description: Published
    Description: 1779-1796
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: ITACA database ; Strong motion station ; General characterization ; Site classification ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
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    Springer
    Publication Date: 2017-04-04
    Description: Previous research works proved the existence of a synchronization between speech and holds in adults and in 9 year old children with a rich linguistic vocabulary and advanced language skills. When and how does this synchrony develop during child language acquisition? Could it be observed also in children younger than 9? The present work aims to answer the above questions reporting on the analysis of narrations produced by three different age groups of Italian children (9, 5 and 3 year olds). Measurements are provided on the amount of synchronization between speech pauses and holds in the three different groups, as a function of the duration of the narrations. The results show that, as far as the reported data concerns, in children, as in adults, holds and speech pauses are to a certain extent synchronized and play similar functions, suggesting that they may be considered as a multi-determined phenomenon exploited by the speaker under the guidance of a unified planning process to satisfy a communicative intention. In addition, considering the role that speech pauses play in communication, we speculate on the possibility that holds may serve to similar purposes supporting the hypothesis that gestures as speech are an expressive resource that can take on different functions depending on the communicative demand. While speech pauses are likely to play the role of signalling mental activation processes aimed at replacing the “old spoken content” of the communicative plan with a new one, holds may signal mental activation processes aimed at replacing the “old visible bodily action” with new ones reflecting the representational and/or propositional contribution of gestures to the new communicative plan.
    Description: Published
    Description: 252-272
    Description: 5.9. Formazione e informazione
    Description: restricted
    Keywords: Speech pauses, holds, synchrony, child narrations ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 16
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: This is the first volume of an international scientific journal that is dedicated to issues of geoethics and geological culture. Its goal is to inform the Italian and international scientific communities about what emerged at the GeoItalia 2011 conference, attended by not only Italian geoscientists. At this conference, the geoscientists questioned their role in society and the responsibilities that they have to assume as scholars of the planet Earth and experts of the territory. They highlighted the need for rediscovery of the cultural values of geology as a science that can contribute to the construction of correct social knowledge, and the need to be aware that geoethics cannot exist without a real awareness among geoscientists of the cultural value of the Earth sciences.
    Description: Published
    Description: 331
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geoetica ; Geological Culture ; Earth Sciences ; Philosophy ; Education ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: Prof. Giulio Giorello is amongst the most prominent philosophers of science in Italy and in the world. He is currently Professor of the Philosophy of Science at the University of Milan, Director of the Series ‘Science and Ideas’ (Raffaele Cortina Books Editor), and Literary Journalist of the cultural pages of the Corriere della Sera, one of the most important of the Italian newspapers. In this keynote presentation, in interview form, he talks about the value that the Earth sciences have had through history, framing this group of disciplines in ethical and epistemological terms, and highlighting some important elements that have to be considered in geological activities.
    Description: Published
    Description: 343-346
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Giulio Giorello ; Earth Sciences ; Interview ; Philosophy ; Epistemology ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: The international debate in the field of geoethics focuses on some of the most important environmental emergencies, while highlighting the great responsibilities of geoscientists, whatever field they work in, and the important social, cultural and economic repercussions that their choices can have on society. The GeoItalia 2009 and 2011 conferences that were held in Rimini and Turin, respectively, and were organized by the Italian Federation of Earth Science, were two important moments for the promotion of geoethics in Italy. They were devoted to the highlighting of how, and with what tools and contents, can the geosciences contribute to the cultural renewal of society. They also covered the active roles of geoscientists in the dissemination of scientific information, contributing in this way to the correct construction of social knowledge. Geology is culture, and as such it can help to dispel misconceptions and cultural stereotypes that concern natural phenomena, disasters, resources, and land management. Geological culture consists of methods, goals, values, history, ways of thinking about nature, and specific sensitivity for approaching problems and their solutions. So geology has to fix referenced values, as indispensable prerequisites for geoethics. Together, geological culture and geoethics can strengthen the bond that joins people to their territory, and can help to find solutions and answers to some important challenges in the coming years regarding natural risks, resources, and climate change. Starting from these considerations, we stress the importance of establishing an ethical criterion for Earth scientists, to focus attention on the issue of the responsibility of geoscientists, and the need to more clearly define their scientific identity and the value of their specificities.
    Description: Published
    Description: 335-341
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Education ; History of science ; Public issues ; General (Philosophy of Earth sciences) ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 19
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: Franco Ferrarotti, Professor emeritus at ‘La Sapienza’ University of Rome; since winning the first Chair in this discipline in Italy in 1961, he has been considered the Father of Italian Sociology. An independent Member of Italian Parliament in the third government (1958-1963), a member of the New York Academy of Sciences, and a ‘visiting Professor’ at many universities in Europe, North America, Russia, Japan and Latin America. Franco Ferrarotti has taught and still teaches in Europe and America, and he has received many awards throughout his career. In this interview, he talks about the social aspects and consequences of Earth sciences studies.
    Description: Published
    Description: 347-348
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Social aspects ; Geologists activity ; Scientific information ; Society ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 20
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: We argue here that the introduction of an ethical code of conduct that follows the example of the Hippocratic Oath of physicians will help geologists to acquire binding awareness of their professional and social responsibilities. The ethical behavior and obligations of modern geologists involve, but are not limited to, the following issues: correct land/ environment use and management; respect of truth and science; and protection of the Earth systems, on both the local and global scales, and therefore, of our well-being. We believe that for geoligists, the explicit acceptance of an ethical code will help to promote: (i) an awareness of their social role, expertise and sense of belonging to a professional community; (ii) an understanding of the expectations of citizens and society; and (iii) cultural growth, with better use of research and implementation of scientific and professional skills. All this should enhance the public recognition of the social mission of geologists, which is essential for the well-being of society. Therefore, we suggest that like in the majority of medical schools, ethical training should be a part of the university curriculum for students in geology.
    Description: Published
    Description: 365-369
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Hippocratic Oath ; Geologists ; Social responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 21
    Publication Date: 2022-05-26
    Description: © The Authors 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Functional & Integrative Genomics 10 (2010): 97-110, doi:10.1007/s10142-009-0142-y.
    Description: Bacteria of the genus Shewanella can thrive in different environments and demonstrate significant variability in their metabolic and ecophysiological capabilities including cold and salt tolerance. Genomic characteristics underlying this variability across species are largely unknown. In this study, we address the problem by a comparison of the physiological, metabolic, and genomic characteristics of 19 sequenced Shewanella species. We have employed two novel approaches based on association of a phenotypic trait with the number of the trait-specific protein families (Pfam domains) and on the conservation of synteny (order in the genome) of the trait-related genes. Our first approach is top-down and involves experimental evaluation and quantification of the species’ cold tolerance followed by identification of the correlated Pfam domains and genes with a conserved synteny. The second, a bottom-up approach, predicts novel phenotypes of the species by calculating profiles of each Pfam domain among their genomes and following pair-wise correlation of the profiles and their network clustering. Using the first approach, we find a link between cold and salt tolerance of the species and the presence in the genome of a Na+/H+ antiporter gene cluster. Other cold-tolerance-related genes include peptidases, chemotaxis sensory transducer proteins, a cysteine exporter, and helicases. Using the bottom-up approach, we found several novel phenotypes in the newly sequenced Shewanella species, including degradation of aromatic compounds by an aerobic hybrid pathway in Shewanella woodyi, degradation of ethanolamine by Shewanella benthica, and propanediol degradation by Shewanella putrefaciens CN32 and Shewanella sp. W3-18-1.
    Description: This research was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research under the Genomics: GTL Program via the Shewanella Federation consortium.
    Keywords: Phenotypic trait ; Bacteria ; Molecular mechanisms of cold tolerance ; Shewanella ; Protein families
    Repository Name: Woods Hole Open Access Server
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  • 22
    Publication Date: 2017-04-04
    Description: Red Pompeian paintings, very famous for their deep intensity, are currently suffering from darkening. The origins of this darkening degradation are not clearly identified yet and remain a major issue for curators. In the specific case of cinnabar (HgS)-based red pigment, a photoinduced conversion into black metacinnabar is usually suspected. This work is focused on the blackening of red cinnabar paintings coated on a sparry calcite mortar. Different samples exhibiting different levels of degradation were selected upon visual observations and analyzed by synchrotron-based microanalytical techniques. Atomic and molecular compositions of the different debased regions revealed two possible degradation mechanisms. On one hand, micro X-ray fluorescence elemental maps show peculiar distributions of chlorine and sulfur. On the other hand, X-ray absorption spectroscopy performed at both Cl and S K-edges confirms the presence of characteristic degradation products: (i) Hg- Cl compounds (e.g., corderoite, calomel, and terlinguaite), which may result from the reaction with exogenous NaCl, in gray areas; (ii) gypsum, produced by the calcite sulfation, in black coatings. Metacinnabar is never detected. Finally, a cross section was analyzed to map the in-depth alteration gradient. Reduced and oxidized sulfur distributions reveal that the sulfated black coating consists of a 5-ím-thick layer covering intact cinnabar.
    Description: Published
    Description: 7484-7492
    Description: reserved
    Keywords: Microspectroscopy Analysis ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 23
    ISSN: 1570-7458
    Keywords: EPG ; stylectomy ; phloem amino acids ; nitrogen ; aphid-plant interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of nitrogen deficiency in hydroponically grown barley seedlings (Hordeum vulgare L.) on the development and reproduction of the aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) were investigated. Plant growth was significantly reduced in seedlings grown without nitrogen. Aphid intrinsic rate of increase (r m) was also significantly lower on these plants compared with that on plants grown with 8 mol m−3 nitrogen. Phloem sap was collected from seedling stems by aphid stylectomy and amino acids quantified by HPLC. There was a significant reduction in the concentration of non-essential amino acids as a group, but not of essential amino acids. Electrical penetration graphs (EPG) indicated that aphids reached the phloem more quickly and fed for longer on plants grown with nitrogen. This is the first reported study in which this combination of techniques has been used to understand the interactions of an aphid and plant under different environmental conditions.
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  • 24
    ISSN: 1572-8862
    Keywords: acetylene ion ; complex ; hydrogen ; nitrogen ; argon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The complexes formed by the positive acetylene ion with the hydrogen molecule, the nitrogen molecule, and the argon atom are investigated with ab initio calculations using the 6-311G** and the 6-31+G(2df,2pd) basis sets. MP2/6-311G** energies and optimum geometries are obtained, as well as single-point MP3, MP4, and QCISD(T) energies with the MP2/6-311G** optimized geometries. Single-point calculations are performed with the 6-31+G(2df,2pd) basis set at MP2/6-311G** optimized geometries.
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  • 25
    ISSN: 1433-4909
    Keywords: Key words Extreme thermophile ; Thermosipho ; Thermotogales ; Deep-sea hydrothermal vent ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel barophilic, extremely thermophilic bacterium was isolated from a deep-sea hydrothermal vent chimney at the Iheya Basin, in the Okinawa area, Japan. The cells were found to be rod shaped and surrounded by a sheath-like outer structure; the organism did not possess flagella and was not motile. Growth was observed between 45° and 80°C (optimum, 72°C, 45 min doubling time), pH 5.3 and 9.3 (optimum, pH 7.2–7.6), 6.6 and 79 g/l sea salts (optimum, 40 g/l), and 0.1 and 60 MPa (optimum, 20 MPa). Strain IHB1 was found to be a strictly anaerobic chemoorganotroph capable of utilizing yeast extract and proteinaceous substrates such as peptone and tryptone. Elemental sulfur or thiosulfate acted as electron acceptors improving growth. The isolate was able to utilize casein as a sole carbon and energy source in the presence of thiosulfate. The G + C content of the genomic DNA was 31.4 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA–DNA hybridization analysis indicated that the isolate is closely related to Thermosipho africanus; however, it represents a species distinct from the previously described members of the genus Thermosipho. On the basis of the physiological and molecular properties, we propose that the new isolate represents a new species, which we name Thermosipho japonicus sp. nov. (type strain: IHB1; JCM10495).
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  • 26
    ISSN: 1432-0789
    Keywords: Keywords Aggregate stability ; Bacteria ; Burnt soil ; Compost ; Fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The restoration of soil microbial activities is a basic step in the reclamation of burnt soils. For this reason, the ability of municipal solid waste compost to accelerate the re-establishment of bacterial and fungal populations, as well as to re-establish physical properties in a burnt soil, was evaluated in a field experiment. Four treatments were performed by adding different doses of compost (0, 0.5, 1 and 2 kg compost m–2 soil) to a burnt Calcic Rodoxeralf soil, and the changes in microbial populations, salt content, aggregate stability and bulk density were evaluated for 1 year. Initially, the addition of compost had a negative effect on soil microbial populations, but 3 months after compost addition, the number of viable fungal propagules increased in all the amended soils. This positive effect lasted until the end of the experiment. From 30 days onwards, all the amended soils showed a greater total number of bacterial cell forming units than the unamended burnt soil. Organic amendment increased the percentage of 2- to 4-mm aggregates, although the effect on the stability of the 0.2- to 2-mm aggregates and on bulk density was less noticeable.
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  • 27
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    Journal of comparative physiology 186 (2000), S. 347-357 
    ISSN: 1432-1351
    Keywords: Key words Crustacean ; Sensorimotor ; Ultrastructure ; Multilamellar sheath ; Myelinated axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.
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  • 28
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    Nutrient cycling in agroecosystems 56 (2000), S. 139-152 
    ISSN: 1573-0867
    Keywords: nitrogen ; N leaching ; liquid manure ; catch crops ; N mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Results are presented from five years (1990–1995) of a field leaching experiment on a sandy soil in south-west Sweden. The aim was to study N leaching, change in soil organic N and N mineralization in cropping systems with continuous use of liquid manure (two application rates) and catch crops. N leaching from drains, N uptake in crops and mineral N in the soil were measured. Simulation models were used to calculate the N budget and N mineralization in the soil and to make predictions of improved fertilization strategies in relation to manure applications and changing the time for incorporation of catch crops. In treatments without catch crops, a normal and a double application of manure increased average N leaching by 15 and 34%, respectively, compared to treatment with commercial fertilizer. Catch crops reduced N leaching by, on average, 60% in treatments with a normal application of manure and commercial fertilizer, but only by 35% in the treatment with double the normal application rate of manure. Incorporation of catch crops in spring increased simulated net N mineralization during the crop vegetation period, and also during early autumn. In conclusion, manured systems resulted in larger N leaching than those receiving commercial fertilizer, mainly due to larger applications of mineral N in spring. More careful adaptation of commercial N fertilization with respect to the amounts of NH4-N applied with manure could, according to the simulations, reduce N leaching. Under-sown ryegrass catch crops effectively reduced N leaching in manured systems. Incorporating catch crop residues in late autumn instead of spring might be preferable with respect to N availability in the soil for the next crop, and would not increase N leaching.
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  • 29
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    Landscape ecology 15 (2000), S. 187-199 
    ISSN: 1572-9761
    Keywords: BOD5 ; catchment ; empirical model ; land use change ; land use scenarios ; nitrogen ; phosphorus ; runoff ; SO4
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Due largely to unprecedented land-use changes in the Porijõgi River catchment (southern Estonia) losses of nutrients and organic matter have decreased significantly. During the period 1987–1997 abandoned lands increased from 1.7 to 10.5% and arable lands decreased from 41.8 to 23.9%. At the same time, the runoff of total-N, total-P, SO4 and organic matter (after BOD5) decreased from 25.9 to 5.1, 0.32 to 0.13, 78 to 48, and 7.4 to 3.5 kg ha−1 yr−1, respectively. The most significant decreases occurred in agricultural subcatchments while the changes were insignificant in the forested upper course catchment. A simple empirical model which incorporates land-use pattern, fertilization intensity, soil parameters and water discharge accurately described the variations of total-N and total-P runoff in both the whole catchment and its agricultural subcatchments (R 2 varies from 0.95–0.99 for N to 0.49–0.93 for P). In small agricultural subcatchments the rate of fertilization is found the most important factor for nitrogen runoff, whereas in larger mosaic watersheds land use pattern plays the main role. Seven alternative scenarios compiled on the base of the empirical model allow to forecast potential nitrogen and phosphorus losses from the catchment. This information can be used in further landscape and regional planning of the whole region.
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  • 30
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    Plasma chemistry and plasma processing 20 (2000), S. 87-110 
    ISSN: 1572-8986
    Keywords: striations ; nitrogen ; spherical discharge ; spatially inhomogeneous Boltzmann equation ; electron velocity distribution function ; dc glow discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Recent observations of spherical striations in large-volume nitrogen dcdischarges with a central anode have stimulated investigations of thenonlocal electron kinetics in these striations by solving the spatiallyinhomogeneous Boltzmann equation adapted to spherical geometry. Becausethe radial course of the electric potential is largely unknown in thisdischarge, different models concerning its radial course have been developedand used. These models are based on the measured radii of the striationsand the assumption that the potential drop between successive striationsdoes not change. As a consequence, with decreasing distance between thestriations the electric field strongly increases toward the centralanode. It has been found that spherical striations are only obtained ifthe electric field is strongly modulated. In this case, a highly nonlocalbehavior of the velocity distribution function and strongly modulatedradial courses of the macroscopic quantities have been obtained.
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  • 31
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    Journal of chemical ecology 26 (2000), S. 1749-1763 
    ISSN: 1573-1561
    Keywords: Conversion factor ; free amino acids ; fruits ; Kjeldahl ; nitrogen ; nutrition ; protein ; pulp ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Protein content of plant tissues is usually estimated by multiplying total nitrogen by a conversion factor of 6.25. This technique assumes that all nitrogen originates from protein. When applied to fruit pulp, it overestimates protein content because pulp typically contains free amino acids and many nitrogenous secondary metabolites. At issue is the extent of error and, consequently, what the conversion factor between nitrogen and protein should be. We calculated a conversion factor based on pulp samples from 18 species collected in the southeastern United States. We also report a new and simple method of estimating protein and free amino acids in fruit pulp. Because previous studies have found high variation in protein and secondary metabolite content among fruit species, use of a single conversion factor for all species will generate error. In an attempt to reduce such error, we calculated protein contents and conversion factors separately for two common fruit types: lipid-rich/carbohydrate-poor and lipid-poor/carbohydrate-rich. We found no difference between these types of fruit and hence combined results in calculating an average conversion factor of 5.64. Use of an accurate conversion factor is important in estimating protein consumption by wild animals and in formulating diets of captive animals. It can also reveal whether loss of body mass in captive animals on fruit diets is due to insufficient protein consumption, secondary metabolite toxicity, or an imbalance of amino acids.
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  • 32
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    Mycorrhiza 10 (2000), S. 15-21 
    ISSN: 1432-1890
    Keywords: Anthoceros punctatus ; Arbuscular mycorrhiza ; Bryophytes ; Glomus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Glomus claroideum (Schenck & Smith emend. Walker & Vestberg) were investigated for ability to form arbuscular mycorrhiza-like symbioses with the hornwort Anthoceros punctatus (L.). Spores were transferred to a cellulose acetate filter on water agar and a small portion of an Anthoceros thallus was placed directly upon the spores. Light-microscope observations 20 days after inoculation revealed branched hyphae growing within the thallus. After 45 days, arbuscules and vesicles were studied by light- and electron-microscopy. After 60 days in water agar culture, the colonised Anthoceros thalli were transferred to a low-nutrient medium agar. Hyphae spread in the agar and newly formed spores were observed 5 weeks after the transfer. After 4 months, about 1000 spores were formed in each Petri dish. This is the first report of an experimentally established arbuscular mycorrhiza-like symbiosis between an identified fungus belonging to the Glomales and a bryophyte.
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  • 33
    ISSN: 1615-6102
    Keywords: Arabidopsis thaliana ; Cryopreservation ; Dehydration ; Thermal analysis ; Sucrose ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Arabidopsis thaliana suspension cells were preserved in liquid nitrogen for over three years, using embedding of cells in calcium-alginate prior to subculture in sucrose-enriched medium, air-drying, and direct quenching in liquid nitrogen. Survival of cells reached 34%, yielding regrowth at the surface of all cryopreserved beads in less than 7 days. Following pretreatment and dehydration, the water content dropped from 2300% to 34% with respect to dry weight. Differential scanning calorimetry showed that glass transition occurred on cooling, followed by a slight crystallization event on rewarming. The survival of cells was independent of the cooling rate. The tolerance of the acute dehydration step increased progressively with sucrose pretreatment duration, indicating the requirement for adaptative cellular alterations. Ultrastructural studies revealed several changes in cells after sucrose pretreatment prolonged from 1 to 7 days: reversal of the initially plasmolyzed state, microvacuolation, numerous autophagic structures, scarcity of ribosomes, increase in number and size of starch grains. No cell division seemed to occur during this period. After air-drying and after a freeze-thaw cycle, followed by 24 h rehydration, regenerating cells had recovered a high level of ultrastructural organization and contained numerous polysomes suggesting an intense metabolic activity. Trehalose, a cryoprotective disaccharide not considered to be a metabolic substrate, yielded only 70% regrowth after freezing. Biochemical analysis showed that soluble sugars accumulated during the pretreatment, essentially sucrose or trehalose; the monosaccharide content also increased. In the light of these results, the action of sucrose in inducing freezing tolerance is discussed.
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  • 34
    ISSN: 1615-6102
    Keywords: Beta vulgaris ; Cyst nematodes ; Histology ; Resistance mechanism ; Syncytium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using susceptible and resistant sugar beet lines, comparative analyses of root histology and ultrastructure were made during invasion by nematodes and the induction and formation of specific feeding structures (syncytia).The resistant line carried the resistance geneHs1pro−1.Nematodes were able to invade and induce functional syncytia in roots of resistant and susceptible lines. However, syncytia in resistant roots were smaller and less hypertrophied. The vacuolar system of syncytia in susceptible plants contained many small vacuoles. In resistant plants vacuoles were larger but less numerous. Smooth endoplasmic reticulum prevailed in syncytial protoplasts of susceptible plants, whereas almost only rough endoplasmic reticulum occurred in syncytia in resistant plants. The most conspicuous and hitherto undescribed trait of syncytia in resistant roots was the initial appearance of loose, and later compact, aggregations of the endomembrane system which composed most of the endoplasmicreticulum system of syncytia at later stages. Syncytia in resistant plants usually degraded before the nematodes reached their adult stage. The appearance of membrane aggregations and the other resistance-specific features are discussed in relation to their possible effects on syncytium function and role in nematode resistance.
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  • 35
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    Protoplasma 211 (2000), S. 94-102 
    ISSN: 1615-6102
    Keywords: Androgenesis ; Embryogenesis ; Microspore culture ; Pollen ; Ultrastructure ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have made a detailed cytological examination of the development of wheat embryoids, monitoring their initial divisions from two to ten cells by both light and electron microscopy. According to our observations the first embryogenic division is symmetrical. After the androgenesis induction treatment, there is a decrease in ribosome population with cells that have inactive nucleoli made up almost exclusively of a dense fibrillar component. This population is restored after initial embryogenic divisions. During the initial divisions the embryogenic pollen grains do not appear to change in size and the pollen wall remains intact. The exine undergoes no modification but the intine thickens, and we have observed that the thickness of the intine can be used as a cytological marker of androgenesis. The walls separating the cells obtained after embryogenic division contained numerous plasmodesmata. The beginnings of embryo polarization and cell differentiation could be made out in the very early pollen embryoids.
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  • 36
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    Journal of applied phycology 12 (2000), S. 331-339 
    ISSN: 1573-5176
    Keywords: algal biomass ; algal uptake ; ammonia stripping ; biological nutrient removal ; high rate algal ponds ; nitrogen ; nutrients ; nitrification ; urban wastewater treatment ; waste stabilisation ponds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two experimental high rate algal ponds (HRAPs) (1.5m2, 570 L per unit), each with a secondaryclarifier for algal biomass separation (0.025 m2,without recirculation), were fed with urban wastewaterfor a one-year period (June 1993 to July 1994). TheHRAPs were installed on the roof of the Department ofHydraulic, Coastal and Environmental Engineering ofthe Technical University of Catalonia, Barcelona,Spain (lat. 41° 24′ 42″ N; long. 2° 7′42″ E). Nitrogen removal efficiency and changes intotal nitrogen, total organic nitrogen,NH4 +-N, and oxidized nitrogen underdifferent hydraulic retention times (HRTs) werecompared. HRAP A was always operated at a higherHRT than HRAP B. Both HRAPs were subjected to thesame environmental conditions of solar radiation, airtemperature and influent water quality. Grab samplesof influent, effluent of the HRAP (mixed liquor) andfinal effluent from the clarifiers were taken once aweek. The annual average nitrogen removal was 73% forHRAP A, and 57% for HRAP B. Higher removal in HRAP Awas due to a lower inorganic nitrogen concentration inits effluent. Significant differences (p〉 0.05) inthe relative proportions of nitrogen forms between thetwo HRAPs were observed only in autumn and winter.This was mainly because HRAP B did not achieve a highlevel of NH4 +-N removal by stripping andalgal uptake, as observed in HRAP A. NH4 +-Nstripping was the most important mechanism fornitrogen removal (mean efficiency of 47% and 32% inHRAP A and B, respectively) followed by algal uptake,and subsequent algal separation in the clarifiers(mean efficiency of 26% and 25% in HRAP A and Brespectively). The conclusion of this study is thatHRT determines both the nitrogen removal efficiencyand the distribution of nitrogen forms in the effluentof a HRAP. The nitrogen removal level can becontrolled through suitable HRT operating strategies.By operating at a HRT of 4 days in spring and summer,and 10 days in autumn and winter, nitrogenconcentration in the effluent of a HRAP system can bereduced to less than 15 mg L-1 N.
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  • 37
    ISSN: 1573-143X
    Keywords: nitrogen ; organic matter ; shrimp culture ; sulphur cycle bacteria ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 38
    ISSN: 1573-1642
    Keywords: nitrogen ; phosphorus ; macroalgae ; estuary ; anthropogenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Our objective was to begin to investigate sources, sinks, and flux rates of nitrogen (N) and phosphorus (P) in Famosa Slough, a small (12 ha) highly modified urban estuary in San Diego, California, U.S.A. The hydrology of Famosa Slough has been modified by culverts that dampen tidal influence and seasonal runoff from two urban watersheds, each of which has been implicated as a nutrient source that generates nuisance algal blooms. In 1995 and 1996, the ranges of nutrients measured in the water column were extremely wide; upper values exceeded those in other estuaries identified as eutrophic. Average dissolved inorganic nitrogen ranged from 2 to 250 μM, while dissolved inorganic phosphorus ranged from 〈1 to 15 μM. Nutrient content of the water changed rapidly both spatially and temporally depending on the tides and rainfall. While tidal water dominated this system, especially in the dry season, our results indicate that Famosa Slough's small watershed, not the larger watershed of the San Diego River, was the major source of nutrients during rainfall. Sediment nutrients were also high (∼3 mg N g dry wt−1 and 0.600 mg P g dry wt−1). Short-term flux studies suggest that the large accumulations of opportunistic green macroalgae commonly found in this estuary, and possibly the sediments, may act as a large and rapid sink for nutrients during times of high nutrient supply. We suggest that small, shallow estuaries in urban settings may have more complex and rapid nutrient dynamics than those found in larger systems.
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  • 39
    ISSN: 1573-8469
    Keywords: carbon ; cellulose ; cover crop ; damping-off ; discriminant analysis ; lignin ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Stages of oat–vetch cover crop decomposition were characterized over time in terms of carbon and nitrogen cycling, microbial activity and damping-off pathogen dynamics in organically and conventionally managed soils in a field and a controlled incubation experiment. A measurement of relative growth consisting of radial growth of a fungal colony over non-sterilized soil divided by that over sterilized soil was used as an assay of suppressiveness. No differences in relative growth of Pythium aphanidermatum and Rhizoctonia solani were detected between organic and conventionally managed soils amended with cover crop residue. Significant effects of cover crop decomposition stage on the relative growth of both pathogens were obtained. Relative growth of P. aphanidermatum was highest just after incorporation and decreased 3 weeks after incorporation. Relative growth of R. solani was highest about 20 days after incorporation, and decreased 2 weeks later in the organic system, but continued to increase in the conventional system. In both experiments, the N or C content, C:N ratio or dry weight of retrieved debris were significantly correlated with relative growth of P. aphanidermatum. Relative growth of R. solani was significantly correlated with the C:N ratio of soil or the C or N content of debris. Microbial activity was not consistently associated with relative growth of either pathogen.
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  • 40
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    Wetlands ecology and management 8 (2000), S. 197-207 
    ISSN: 1572-9834
    Keywords: benthic invertebrates ; mitigation ; nitrogen ; organic matter ; pedogenesis ; phosphorus ; plant productivity ; restoration and rehabilitation ; salt marsh ; wetland creation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of wetland soil characteristics andbenthic invertebrate communities were evaluated increated Spartina alterniflorasalt marshes inNorth Carolina ranging in age from 1 to 25 years-old.A combination of measurements from different-agecreated marshes as well as periodic measurements overtime on two marshes were used to (1) document rates ofwetland pedogenesis, especially soil organic matter,and, (2) explore relationships between soil andbenthic invertebrate community development. Soilmacro-organic matter (MOM, the living and dead rootand rhizome mat), organic C and N increased and bulkdensity decreased during the 25 years following marshestablishment. The most dramatic changes in bulkdensity, MOM, C and N occurred within the upper 10 cmof the soil with lesser changes below this depth.Created marshes were sinks for organic C (90–140g·m-2·yr-1) and N (7–11g·m-2·yr-1) but not for P (0–1g·m-2·yr-1). The density of benthicinvertebrates (〉250 μm) and subsurface-depositfeeding oligochaetes also increased over time oncreated salt marshes. Invertebrate and oligochaetedensity were strongly related to MOM content(r2= 0.83–0.87) and soil organic C(r2= 0.52–0.82) and N (r2= 0.62–0.84). Thesefindings suggest that, in created salt marshes,development of the benthic invertebrate community istied to marsh soil formation, especially accumulationof organic matter as MOM and soil. Field studies thatmanipulate the quantity and quality of soil organicmatter are needed to elucidate the relationshipbetween salt marsh pedogenesis and benthicinvertebrate community development.
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  • 41
    ISSN: 1615-6102
    Keywords: Glutathione ; Root ; Chromosomal aberration ; Ultrastructure ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Young spruce seedlings (Picea abies [L.] Karst.) grown in hydroponic culture were exposed to three different concentrations (50,100, and 500 μM) of reduced glutathione for 24 h. These physiologically relevant concentrations of glutathione had a multiple effect on the investigated tissue. Feeding of glutathione to roots increased the concentrations of thiols (glutathione, cysteine, and γ-glutamyl-cysteine) in roots, decreased the rate of cell divisions, induced mitotic abnormalities, and affected the cell ultrastructure. Electron micrographs showed effects such as advanced vacuolation, dilated rough-endoplasmic-reticulum cisternae, and separations of the plasma membrane from the cell wall.
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  • 42
    ISSN: 1573-5036
    Keywords: ammonia exchange ; apoplast ; atmosphere ; glutamine synthetase ; nitrogen ; photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plants have a compensation point for NH3 which ranges from 0.1 to 20 nmol mol-1, and may be several-fold higher or lower than naturally occurring atmospheric NH3 concentrations. This implies that NH3 fluxes over vegetated surfaces are bi-directional and that ammonia exchange with the atmosphere in many cases contributes significantly to the nitrogen economy of vegetation. Physiological regulation of plant–atmosphere NH3 fluxes is mediated via processes involved in nitrogen uptake, transport and metabolism. A rapid turnover of NH3 + in plant leaves leads to the establishment of a finite NH3 + concentration in the leaf apoplastic solution. This concentration determines, together with that of H+, the size of the NH3 compensation point. Barley and oilseed rape plants with access to NH3 + in the root medium have higher apoplastic NH3 + concentrations than plants absorbing NO3 -. Furthermore, the apoplastic NH3 + concentration increases with the external NH3 + concentration. Inhibition of GS leads to a rapid and substantial increase in apoplastic NH3 + and barley mutants with reduced GS activity have higher apoplastic NH3 + than wild-type plants. Increasing rates of photorespiration do not affect the steady-state NH3 + or H+ concentration in tissue or apoplast of oilseed rape, indicating that the NH3 + produced is assimilated efficiently. Nevertheless, NH3 emission increases due to a temperature-mediated displacement of the chemical equilibrium between gaseous and aqueous NH3 in the apoplast. Sugarbeet plants grown with NO3 - seem to be temporarily C-limited in the light due to a repression of respiration. As a consequence, the activity of chloroplastic GS declines during the day causing a major part of NH3 + liberated in photorespiration to be assimilated during darkness when 2-oxoglutarate is supplied in high rates by respiration.
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  • 43
    ISSN: 1573-5036
    Keywords: cereal ; cereal quality ; cereal yields ; natural regeneration ; nitrogen ; nitrogen uptake ; rye-grass ; set-aside ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract During the period 1993–1997, at six contrasting sites located throughout England, two successive cereal test crops were grown both with and without nitrogen fertiliser after three or five years of set-aside or after continuous arable cropping. Vegetation during set-aside included natural regeneration and perennial rye-grass (Lolium perenne) with or without white clover (Trifolium repens), managed by mowing on one or more occasions per year. Establishment of the successive cereal test crops after destruction of the set-aside was generally not a problem. Fertile tiller numbers were increased by inclusion of clover in the set-aside cover or application of inorganic nitrogen. The presence of couch grass (Elytrigia repens) or volunteer cereals in the set-aside covers provided alternative hosts for take-all (Gaeumanomyces graminis) and eyespot (Pseudocercosporella herpotrichoides) and take-all caused some yield reductions in following cereal crops. Management during the set-aside period significantly affected grain yields of the subsequent cereal crops in the majority of the site-year combinations. However, these effects were not as large as would be expected after traditional break crops and were frequently masked by the application of nitrogen fertiliser. Mean yields increased by 80% due to the application nitrogen at the optimum rate compared to nil nitrogen. Most of the effects of set-aside treatment on grain yield were shown to be attributable to soil mineral nitrogen content, but at some sites, infections by take-all or eyespot also accounted for some of the variation. There were no effects of pests that could be related to treatment. The presence of sown clover during the set-aside period had the most consistent effect across sites, affecting tiller populations, grain yield and grain quality of cereal crops. At some sites, establishing a sown cover during the set-aside period, or cutting the cover more than once a year, improved grain yield and quality, and reduced the incidence of some specific weeds and disease.
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  • 44
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    Plant and soil 226 (2000), S. 57-69 
    ISSN: 1573-5036
    Keywords: ABA ; K/Na selectivity ; nitrate reduction ; nitrogen ; phloem ; phosphate ; root-shoot interactions ; salinity ; xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this paper four classes of co-operative root-shoot interations are addressed. (I) Nitrogen concentrations in the xylem sap originating from the root and in the phloem sap as exported from source leaves are much lower than those required for growth by apices and developing organs. Enrichment of xylem sap N is achieved by xylem to xylem (X-X) transfer, by which reduced N, but not nitrate, is abstracted from the xylem of leaf traces and loaded into xylem vessels serving the shoot apex. Nitrogen enrichment of phloem sap from source leaves is enacted by transfer of reduced N from xylem to phloem (X-P transfer). Quantitative data for the extent of the contribution of X-X and X-P transfer to the nutrition of young organs of Ricinus communis L. and for their change with time are presented. (II) Shoot and root cooperate in nitrate reduction and assimilation. The partitioning of this process between shoot and root is shifted towards the root under conditions of nitrate- and K-deficiency and under salt stress, while P deficiency shifts nitrate reduction almost totally to the shoot. All four changes in partitioning can be attributed to the need for cation-anion balance during xylem transport and the change in electrical charge occurring with nitrate reduction. (III) Even maintenance of the specificity of ion uptake by the root may – in addition to its need for energy – require a shoot-root interaction. This is shown to be needed in the case of the maintenance of K/Na selectivity under the highly adverse condition of salt stress and absence of K supply from the soil. (IV) Hormonal root to shoot interactions are required in the whole plant for sensing mineral imbalances in the soil. This is shown and addressed for conditions of salt stress and of P deficiency, both of which lead to a strong ABA signalling from root to shoot but result in different patterns of response in the shoot.
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  • 45
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    Plant and soil 219 (2000), S. 177-185 
    ISSN: 1573-5036
    Keywords: alfalfa ; growth ; Medicago sativa L. ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of biomass and N accumulation following defoliation of alfalfa and the application of N fertilization has rarely been studied under field conditions, particularly in the seeding year. Our objectives were to determine the effect of N fertilization on the dynamics of biomass and N accumulation during the first regrowth of alfalfa in the seeding year, and to determine if a model describing critical N concentration developed for established stands could be used in the seeding year. In two separate experiments conducted in 1992 and 1993, the biomass and N accumulation of alfalfa grown with three N rates (0, 40 and 80 kg N ha-1) were determined weekly. Maximum shoot growth was reached with 40 kg N ha-1 in 1992, and maximum shoot growth was not reached with the highest N fertilization rate in 1993. Nitrogen fixation, root N reserves and soil inorganic N uptake when no N was applied were, therefore, not sufficient to ensure non-limiting N conditions, particularly when growth rates were the highest between 14 to 21 d after defoliation. Nitrogen fertilization increased shoot biomass accumulation in the first 21 d of regrowth, biomass partitioning to the shoots and shoot and taproot N concentrations. The model parameters of critical N concentration developed by Lemaire et al. (1985) for established stands of alfalfa were not adequate in the seeding year. The N requirements per unit of shoot biomass produced are greater in the seeding year than on established stands, and this was attributed to a greater proportion of leaves in the seeding year.
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  • 46
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    Plant and soil 219 (2000), S. 273-278 
    ISSN: 1573-5036
    Keywords: cellulose ; lignin ; litter ; nitrogen ; Pinus radiata ; tannins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The quality of substrates in plantation forest litter, and their chemistry, can influence decomposition and N cycling. We studied the decomposition of Pinus radiata D. Don needles suspended on branches in windrows, for 3 yr after clear-cutting, using improved solid-state 13C NMR and chemical analysis. The NMR spectra suggested that the concentration of condensed tannins was 12–22%, and showed they were chemically altered during the period 4–12 months after clear-cutting. The spectra showed no evidence for further chemical modification of the tannins during the second or third years. Data for P. radiata needle decomposition in New Zealand indicated rapid loss of mass in the first 3 months, and condensed tannins did not appear to prevent mineralization of C or N. The tannin and lignin concentrations increased with decomposition of the needles, which was consistent with the early mineralization of readily available C compounds.
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  • 47
    ISSN: 1573-5036
    Keywords: cations ; fire ; nitrogen ; nutrients ; phosphorus ; slash-and-burn ; soil ; tropical forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The most commonly observed change in soil following slash-and-burn clearing of tropical forest is a short-term increase in nutrient availability. Studies of shifting cultivation commonly cite the incorporation of nutrient-rich ash from consumed aboveground biomass into soil as the reason for this change. The effects of soil heating on nutrient availability have been examined only rarely in field studies of slash-and-burn, and soil heating as a mechanism of nutrient release is most often assumed to be of minor importance in the field. Few budgets for above and belowground nutrient flux have been developed in the tropics, and a survey of results from field and laboratory studies indicates that soils are sufficiently heated during most slash-and-burn events, particularly in dry and monsoonal climates, to cause significant, even substantial release of nutrients from non-plant-available into plant-available forms in soil. Conversely, large aboveground losses of nutrients during and after burning often result in low quantities of nutrients that are released to soil. Assessing the biophysical sustainability of an agricultural practice requires detailed information about nutrient flux and loss incurred during management. To this end, current conceptual models of shifting cultivation should be revised to more accurately describe these fluxes and losses.
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  • 48
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    Plant and soil 223 (2000), S. 47-61 
    ISSN: 1573-5036
    Keywords: correlograms ; nitrogen ; soil arthropods ; soil resource islands ; variograms ; vesicular-arbuscular mycorrhizae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study compared the sizes, spacings and properties (soil moisture, pH, nitrogen, soil arthropods and VAM) of soil resource islands and bare patches in sagebrush-grass communities invaded by western juniper versus those without juniper. We analyzed 1000 surface soil samples taken from nine 50-m radius circular plots sampled in December of 1991 and May of 1992 on ‘The Island’, one of the few undisturbed areas of sagebrush-grass shrubland in Oregon. Spatial structure was interpreted from correlograms (Moran's I) and standardized semivariograms. The presence of juniper was associated with increased bare area and smaller, more widely spaced grass and sagebrush plants. Soil arthropod numbers and biomass in plots with juniper were only roughly one-fifth of those in sagebrush-grass plots in December. The dominant soil pattern in both sagebrush-grass and juniper-sagebrush-grass plots was regularly-distributed patches spanning a range of sizes and spacings. Plots with juniper had greater patchiness at shorter lags (〈3 m), and patchiness was more developed for soil moisture, net nitrification, and net N mineralization, whereas sagebrush-grass plots had greater patchiness at longer lags (3 – 9 m) and patchiness was more developed for NO3–N, arthropod numbers and biomass. These differences in soil patterns with and without juniper indicate that juniper responds to, or causes, changes in the size of resource islands under sage and grass when it invades sage-grass communities.
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  • 49
    ISSN: 1573-5036
    Keywords: crop residues ; nitrogen ; organic residues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted to test a new approach to the 15N isotope dilution technique for estimating crop N uptake from organic inputs. Soils were pre-labelled with 15N fertiliser and a carbon source. These were then incubated until there was stabilisation of the 15N abundance of the inorganic N pool and resumption of inorganic N concentrations. Residues were then applied to the soils and planted with ryegrass (Lolium perenneL.) to determine the nitrogen derived from the residue (Ndfr) using the isotope dilution equations. This method was compared with the direct method, i.e. where 15N-labelled residues were added to the soil and Ndfr in the ryegrass calculated directly. Estimates of percentage nitrogen derived from the residue (%Ndfr) alfalfa (Medicago sativaL.) in the ryegrass, were similar, 22 and 23% for the direct and soil pre-labelling methods, respectively, in the Wechsel sandy loam. Also, estimates of the %Ndfr from soybean (Glycine max (L.) Merr) residues in the Krumbach sandy loam were similar 34% (direct) and 36% (soil pre-labelling approach). However, in the Seibersdorf clay loam, the %Ndfr from soybean was 49% using the direct method and 61% using the soil pre-labelling method; yet Ndfr from common bean residue was 46% using the direct approach and 40% using the pre-labelling, not significantly different (P 〉 0.05). The soil pre-labelling approach appears to give realistic values for Ndfr. It was not possible to obtain an estimate of Ndfr using the soil pre-labelling method from the maize residues (Zea mays L.) in two of the soils, as there was no increase in the total N of the ryegrass over the growing period. This was probably due to microbial immobilisation of inorganic N, as a result of the wide C:N ratio of the residue added. The results suggest that the new soil pre-labelling method is feasible and that it is a potentially useful technique for measuring N release from a wide range or organic residues, but it requires further field-testing.
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  • 50
    ISSN: 1573-5036
    Keywords: carbon ; functional types ; leaf tensile strength ; litter quality ; mass loss ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Litter decomposition, a major determinant of ecosystem functioning, is strongly influenced by the litter quality of different species. We aimed at (1) relating interspecific variation in leaf litter decomposition rate to the functional types different species belong to; and (2) understanding the chemical and/or physical basis for such variation and its robustness to environmental factors. We selected 52 Angiosperms from a climatic gradient in central-western Argentina, representing the widest range of functional types and habitats published so far. Ten litter samples of each species were simultaneously buried for 9 weeks during the 1996 summer in an experimental decomposition bed. Decomposition rate was defined as the percentage of dry mass loss after incubation. Chemical litter quality was measured as carbon (C) content, nitrogen (N) content, and C-to-N ratio. Since tensile strength of litter and living leaves were strongly correlated, the latter was chosen as an indicator of physical litter quality. A subset of 15 species representing different functional types was also incubated in England for 15 weeks, following a similar experimental procedure. Litter C-to-N and leaf tensile strength of the leaves showed the strongest negative associations with decomposition rate, both at the species and at the functional-type level. Decomposition rates of the same species in Argentina and in England were strongly correlated. This reinforces previous evidence that species rankings in terms of litter decomposition rates are robust to methodological and environmental factors. This paper has shown new evidence of plant control over the turnover of organic matter through litter quality, and confirms, over a broad spectrum of functional types, general models of resource allocation. The strong correlations between leaf tensile strength – a trait that is easy and quick to measure in a large number of species – decomposition rate, and C-to-N ratio indicate that leaf tensile strength can be useful in linking plant quality to decomposition patterns at the ecosystem level.
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  • 51
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    Plant and soil 219 (2000), S. 57-69 
    ISSN: 1573-5036
    Keywords: decomposition ; litter quality ; mycorrhiza ; nitrogen ; phosphorus ; saprotrophic microorganisms ; tannins ; forest soils ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied variation in forest floor thickness in four plantations of red pine (Pinus resinosa Ait.) which were similar in age, soil type and associated vegetation. The plantations were located (west to east) in the Clear Creek, Moshannon, Sproul and Tiadaghton State Forests of Pennsylvania, USA. A gradient in forest floor thickness exists across these plantations; the forest floor is thickest in the west and it becomes progressively thinner toward the east. Decomposition of imported litter increased from west to east, suggesting that the variation in forest floor thickness is related to variation in the rate of decomposition. Decomposition rates were related to saprotroph abundance. Variation in forest floor N and phenolic concentrations, in overall mycorrhiza density and in the relative proportions of three common mycorrhiza morphotypes could not explain the variation in decomposition rate. The P concentrations and pH of the forest floor were significantly lower at Clear Creek and Moshannon, where decomposition rates were lowest, compared to Sproul and Tiadaghton, where decomposition rates were most rapid. This suggests that P concentration and pH may have exerted some control on decomposition.
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  • 52
    ISSN: 1573-5036
    Keywords: climate change ; immobilisation ; mineralisation ; N-turnover ; nitrogen ; soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The following arguments are outlined and then illustrated by the response of the Hurley Pasture Model to [CO2] doubling in the climate of southern Britain. 1. The growth of N-limited vegetation is determined by the concentration of N in the soil mineral N pools and high turnover rates of these pools (i.e., large input and output fluxes) contribute positively to growth. 2. The size and turnover rates of the soil mineral N pools are determined overwhelmingly by N cycling into all forms of organic matter (plants, animals, soil biomass and soil organic matter — `immobilisation' in a broad sense) and back again by mineralisation. Annual system N gains (by N2 fixation and atmospheric deposition) and losses (by leaching, volatilisation, nitrification and denitrification) are small by comparison. 3. Elevated [CO2] enriches the organic matter in plants and soils with C, which leads directly to increased removal of N from the soil mineral N pools into plant biomass, soil biomass and soil organic matter (SOM). ‘Immobilisation’ in the broad sense then exceeds mineralisation. This is a transient state and as long as it exists the soil mineral N pools are depleted, N gaseous and leaching losses are reduced and the ecosystem gains N. Thus, net immobilisation gradually increases the N status of the ecosystem. 4. At the same time, elevated [CO2] increases symbiotic and non-symbiotic N2 fixation. Thus, more N is gained each year as well as less lost. Effectively, the extra C fixed in elevated [CO2] is used to capture and retain more N and so the N cycle tracks the C cycle. 5. However, the amount of extra N fixed and retained by the ecosystem each year will always be small (ca. 5–10 kg N ha-1 yr-1) compared with amount of N in the immobilisation-mineralisation cycle (ca. 1000 kg N ha-1 yr-1). Consequently, the ecosystem can take decades to centuries to gear up to a new equilibrium higher-N state. 6. The extent and timescale of the depletion of the mineral N pools in elevated [CO2] depends on the N status of the system and the magnitude of the overall system N gains and losses. Small changes in the large immobilisation—mineralisation cycle have large effects on the small mineral N pools. Consequently, it is possible to obtain a variety of growth responses within 1–10 year experiments. Ironically, ecosystem models — artificial constructs — may be the best or only way of determining what is happening in the real world.
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  • 53
    ISSN: 1573-5036
    Keywords: deciduous tree ; foliar pigmentation ; fungus ; litter mass loss ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We tested the hypothesis that there is a causal connection between autumn colour, nutrient concentration and decomposibility of fresh leaf litter. Samples from patches of different autumn colours within the leaves of the deciduous tree sycamore (Acer pseudoplatanus) were sealed into litter bags and incubated for one winter in an outdoor leaf mould bed. Green leaf patches were decomposed faster than yellow or brown patches and this corresponded with the higher N and P concentrations in the former. Black patches, indicating colonisation by the tar spot fungus Rhytisma acerinum, were particularly high in P, but were decomposed very slowly, owing probably to resource immobilisation by the fungus. The results supported the hypothesis and were consistent with a previous study reporting an interspecific link between autumn coloration and decomposition rate. Autumn leaf colour of deciduous woody plants may serve as a useful predictor of litter decomposibility in ecosystem or biome scale studies where extensive direct measurements of litter chemistry and decomposition are not feasible.
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  • 54
    ISSN: 1573-5117
    Keywords: Stable isotope tracers ; carbon ; nitrogen ; mangroves ; litterfall ; suspended matter ; zooplankton ; macrobenthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable carbon isotopic composition and C/N ratio were used to trace the input of carbon associated with mangrove litter into the estuary of the Godavari–Gautami delta system and Kakinada bay (Andhra Pradesh, India). Suspended organic matter in the mangrove channels was more depleted in 13C (average δ13C = −24.5‰) than in Kakinada bay which showed δ13C values for suspended matter (average δ13C = −22.7‰) closer to those expected for marine phytoplankton. Suspended organic matter from mangrove channels was enriched in nitrogen (average C/N atom ratio ≤ 12.7) and 13C (average δ13C = −24.5‰) relative to mangrove leaf litter, which had a C/N ratio of 75 and a δ13C value of −28‰. Lowest C/N ratios for suspended matter were observed during southwest monsoon when rainfall was highest. Although in general, mangrove litter fall was also lower during this period, no clear correlation was observed between litter fall and C/N ratio of suspended matter. In general, the composition of suspended matter pointed towards phytoplankton as a major component. Isotopic composition of zooplankton suggested selective feeding on 13C-enriched, marine phytoplankton in open Kakinada bay and on 13C-depleted organic matter, such as estuarine phytoplankton and mangrove litter, in the mangrove channels. From the δ13C signature, it appeared that mangrove carbon was present to some extent in zooplankton and macrofauna from the mangrove mudflats and channels, but the signal rapidly decreased in Kakinada bay. Nitrogen isotopic composition of zooplankton and macrofauna indicated a progressive enrichment of 15N away from the mangrove forest towards the northern part of Kakinada bay, in approach of Kakinada city. This is thought to reflect input of anthropogenic nitrogen enriched in 15N and subsequent uptake of this enriched nitrogen into the aquatic food chain.
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  • 55
    ISSN: 1573-515X
    Keywords: Bouteloua eriopoda ; Chihuahuan Desert ; desertification ; hydrology ; Larrea tridentata ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Losses of dissolved nutrients (N, P, K, Ca, Mg, Na,Cl, and SO4) in runoff were measured on grasslandand shrubland plots in the Chihuahuan desert ofsouthern New Mexico. Runoff began at a lowerthreshold of rainfall in shrublands than ingrasslands, and the runoff coefficient averaged 18.6%in shrubland plots over a 7-year period. In contrast,grassland plots lost 5.0 to 6.3% of incidentprecipitation in runoff during a 5.5-year period. Nutrient losses from shrubland plots were greater thanfrom grassland plots, with nitrogen losses averaging0.33 kg ha−1 yr−1 vs0.15 kg ha−1 yr−1, respectively, during a 3-year period. Thegreater nutrient losses in shrublands were due tohigher runoff, rather than higher nutrientconcentrations in runoff. In spite of these nutrientlosses in runoff, all plots showed net accumulationsof most elements due to inputs from atmosphericdeposition. Therefore, loss of soil nutrients byhillslope runoff cannot, by itself, account for thedepletion of soil fertility associated withdesertification in the Chihuahuan desert.
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  • 56
    ISSN: 1573-5117
    Keywords: nutrient flux ; nitrogen ; phosphate ; tidal flats ; temperature ; geographical comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During an annual cycle, flux rates of oxygen, nitrate, nitrite, ammonium, phosphate and silicate were measured in light and dark bell jars at three sites in Ria Formosa (Algarve, Portugal) enclosing either a natural macrophytic community (macroalgae on sand or mud, a seagrass bed of Zostera noltii) or bare sediments. The results are compared with a preceeding study in which the same bell jar technique has been applied in the Sylt-Rømø Bay of the northern Wadden Sea. Nitrate flux was mainly directed from the water column to the benthic communities in Ria Formosa, as well as in the Sylt-Rømø Bay. However, nitrate uptake was higher in the northern, more eutrophic study area. In Ria Formosa, nutrient concentrations were lower than in the Sylt-Rømø Bay possibly due to strong water exchange with Atlantic waters. High temperatures and strong insolation had a greater impact on nitrate fluxes in Ria Formosa than in the Sylt-Rømø Bay. Bioturbating macrofauna increased ammonium efflux in the Sylt- Rømø Bay while this effect was not as pronounced in the Ria Formosa study sites. Benthic phosphate uptake dominated in the Ria Formosa and was correlated to initial phosphate concentrations in incoming waters. At both study sites, oxygen and nutrient fluxes were correlated with temperature. Additionally, flux rates were strongly influenced by biotic components and levels of eutrophication. A literature survey showed that mainly in temperate regions, material fluxes increase with temperature, whereas in warmer areas, ammonium and phosphate fluxes between sediment and water were generally lower.
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  • 57
    ISSN: 1573-1561
    Keywords: Nicotiana sylvestris ; nitrogen ; nicotine ; allocation ; growth ; reproduction ; induced defenses ; costs of defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We present the first evidence for a fitness cost of an inducible response that is detectable in a nitrogen (N) currency. Nicotine is an induced defense in Nicotiana sylvestris that can utilize 5–8% of the plant's total N, an investment that apparently cannot be recouped by metabolism. Induced nicotine production is endogenously regulated by jasmonic acid (JA), and we treated leaves with the methyl ester of this wound hormone (MeJA) in quantities (0, 25, 250 μg) known to elicit changes in endogenous JA and subsequent nicotine responses comparable to those elicited by mechanical wounding and herbivory in this species. We grew plants in competition chambers (CCs) in which three same-sized plants could compete for a communal but fixed pool of 15NO3 to quantify the outcome of competition for this fitness-limiting resource that is used both in defense and seed production. Competition profoundly increased all measures of growth and reproductive performance measured per milligram of N acquired. While plants acquired all the N supplied to them in the hydroponic solution, plants grown in CCs (as compared those grown in individual chambers—ICs) retained more of this N and produced more biomass, had larger nicotine contents, allocated less of their N to nicotine, produced larger floral stalks with more flowers, aborted fewer flowers, matured more capsules, and produced a greater mass of seed. Plants grown in ICs produced heavier seed, but this difference did not translate into a difference in seed viability. MeJA treatment increased nicotine concentrations in proportion to the amount applied and significantly reduced growth (13–23%) and reproductive (31–44%) performance for plants grown with uninduced competitors, reflecting a large opportunity cost of induction. The effects of MeJA treatment on growth and reproduction were significantly less pronounced for plants grown in ICs. MeJA treatment significantly reduced the ability of plants to compete for [15N]KNO3 (reducing uptake by 9.5% and 23.7% for 25- and 250-μg MeJA-treated plants, respectively); no reductions in N acquisition were found in IC grown plants treated with MeJA. This impairment of competitive ability could account for 41–47% of the jasmonate-induced reductions in biomass by the day 15 harvest and 12–20% of the reductions in seed set and, in addition, created by "opportunity benefit" for neighboring uninduced plants, which grew larger, aborted fewer flowers, and matured more seed (a 28% increase) than did uninduced plants competing with similarly uninduced plants. Competition dramatically increased plant growth and reproductive performance, and MeJA treatment of these high-performing plants significantly reduced their competitive ability, which translated into opportunity costs for induced plants and opportunity benefits for neighboring uninduced plants. Induced plants minimized these fitness costs by reducing their use of recently acquired N for nicotine biosynthesis when growing with competitors. MeJA treatments also altered stalk length, flower production, flower abortion, and allocation to seed mass. In spite of all this plasticity, induced responses incur large fitness costs, costs that could be in part attributed to reductions in competitive ability for N. We conclude that inducibility functions to minimize these costs.
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  • 58
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    Nutrient cycling in agroecosystems 56 (2000), S. 79-85 
    ISSN: 1573-0867
    Keywords: exchangeable cations ; nitrogen ; soil carbon ; soil quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The long term impact of excreta return on some chemical and biological properties of a pasture soil fertilised with sulphur and phosphate was studied in a system that had been with or without excreta for 23 years. Excreta free areas that had developed under electric fencelines, and parallel transects in the paddocks, were sampled to provide this comparison. Sampling was to 300 mm depth in 0–75, 75–150 and 150–300 mm sections. Total carbon and nitrogen were 20% higher in the 0–150 mm soil layer of areas receiving excreta but did not differ in the 150–300 mm layer. Carbon:nitrogen ratios were similar in both systems as was mineralisable nitrogen, both absolutely and as a percentage of total in the 0–75 mm layer. Significantly more N was mineralised in the 75–150 mm layers of the areas receiving excreta but this was reversed in the 150–300 mm layer. Nitrification rate was higher in all layers of the excreta areas. Inorganic and organic P fractions did not differ significantly. Total P was significantly higher in the 0–75 mm layer and significantly lower in the 150–300 mm layer of the excreta areas. Exchangeable potassium was much higher throughout the excreta areas while this was offset by calcium. The sum of the cations was similar in both areas. Excreta affected most of the diagnostic soil tests used for fertiliser recommendations. The soil properties measured did not reflect clearly the differences in productivity that were obvious in the two areas. It is concluded that excreta return has a impact resulting in increased organic matter storage. Short-term effects of urine have a greater impact on productivity. The major effect is on the disposition of cations and available P.
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  • 59
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    Nutrient cycling in agroecosystems 57 (2000), S. 75-82 
    ISSN: 1573-0867
    Keywords: nitrogen ; leaching ; paddy soil ; wheat ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen in percolation water was observed in paddy field soil under rice/wheat rotation. Different N-application rates were designed. Porous pipes were installed in triplicate at depths of 30, 60 and 90 cm to collect the water in the period of wheat growth. Suction cups were installed in triplicate at the same depths to collect the water during the period of rice growth. NH4 +, NO3 - and total N in the water were analysed with a continuous-flow nitrogen analyzer. Results showed that nitrate was the predominant form of nitrogen in percolation water during the period of wheat growth. Nitrate leaching was high in early spring after the `tillering fertilisation'. More than 50 mg l-1 of nitrate concentration in percolation water was observed for 30 and 60 cm in depth and more than 15 mg l-1 were observed for 90 cm. The concentration decreased quickly and was very low, less than 2 mg l-1 usually, in the earring stage of wheat. Nitrate in water was low, less than 1.5 mg l-1 usually, when the field was flooded during the period of rice growth. Some soluble organic N existed in the water. Nitrate in percolation water increased when the field was drained. The leaching loss of nitrogen during winter wheat growth period was estimated to be about 3.4% of the N-fertiliser applied at the normal application rate of farmers; for the rice growth period it was around 1.8%. Although a reduced N-application decreased N leaching, it caused a marked decrease in crop yield.
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  • 60
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    Nutrient cycling in agroecosystems 56 (2000), S. 231-240 
    ISSN: 1573-0867
    Keywords: nitrogen ; N ; nitrate ; ammonia ; dairy farming ; systems research ; environment ; sandy soils ; groundwater ; leaching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the sandy regions of The Netherlands, high losses of N from intensified dairy farms are threatening the environment. Therefore, government defined decreasing maximum levy-free N surplusses for the period 1998–2008. On most dairy farms, the current N surplus has to be reduced by half at least. Farmers fear that realizing these surplusses will be expensive, because it limits application of animal manure, which then has to be exported or additional land has to be bought. Moreover, farmers are worried about the impact on soil fertility. To explore the possibilities for reducing surplusses of average intensive farms by improved nutrient management, farming systems research is carried out at prototype farm ‘De Marke’. Results are compared with results of a commercial farm in the mid-1980s, the moment that systems research started and introduction of the milk quota system put a halt to further intensification. Results indicate that average intensive farms can realise a reduction in N surplus to a level below the defined final maximum, without the need to buy land or to export slurry. Inputs of N in purchased feeds and fertilisers decreased by 56 and 78%, respectively. Important factors are reduced feed intake per unit milk, as a result of a higher milk yield per cow, less young stock and judicious feeding, an improved utilization of ‘home-made’ manure and a considered balance between the grassland and maize area. Changed soil fertility status did not constrain crop production. Nitrate concentration in the upper groundwater decreased from 200 to 50 mg l-1, within a few years.
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  • 61
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    Nutrient cycling in agroecosystems 57 (2000), S. 13-22 
    ISSN: 1573-0867
    Keywords: biogeochemistry ; estuary ; nitrogen ; river ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long-term results of the monthly measurement of dissolved inorganic nitrogen (DIN) concentrations in three major rivers in China are presented. These data are combined with river discharge data to calculate the DIN loads discharged into the ocean. About 774.90 × 103, 55.38 × 103and 144.55 × 103tons of DIN were transported to their respective estuaries each year by the Changjiang, the Huanghe and the Zhujiang in 1980–1989, mainly in the form of nitrate (〉 80 percent). The annual transport of DIN and mean concentration of nitrate in the Changjiang had increased drastically (four-fold) in the last 29 years, especially during the 1980s. Although nitrate concentrations of the Zhujiang and the Huanghe had also increased in the 1980s, their total annual loads of DIN varied mainly with annual runoff volumes, showing no obvious uptrends. Our results also demonstrate that the majority of the DIN load of each river was transported in the high-flow period (70–80 percent). A positive relationship is observed between the annual DIN transport of the Changjiang and the annual application of chemical fertilizers in its catchment. The annual DIN loads of the Huanghe and the Zhujiang were influenced mainly by runoff volume, and also by application of chemical fertilizers.
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  • 62
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    Nutrient cycling in agroecosystems 57 (2000), S. 1-12 
    ISSN: 1573-0867
    Keywords: Asia ; fertilizer ; ammonia ; food ; greenhouse effect ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The addition of anthropogenic N by food and energy production to the global environment contributes to the greenhouse effect, acid deposition, photochemical smog, stratospheric ozone depletion and eutrophication of fresh and marine waters. On a global basis, anthropogenic N mobilization is greater then natural sources of bio-reactive N. Currently, Asia is a hotspot of N mobilization and distribution to downwind and downstream environments, primarily due to food production. Asia's contribution will continue to increase, not only due to population growth, but also to increases in the per capita consumption of food and energy. This paper provides an overview of the global N cycle, presents an analysis of N dynamics within agroecosystems, examines N mobilization in Asia and discusses possible rates of N mobilization in the future.
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  • 63
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    Agroforestry systems 50 (2000), S. 59-75 
    ISSN: 1572-9680
    Keywords: below-ground competition ; carbohydrates ; nitrogen ; nutrient leaching ; resin cores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree pruning is a common management practice in agroforestry for mulching and reducing competition between the annual and perennial crop. The below-ground effects of pruning, however, are poorly understood. Therefore, nutrient dynamics and root distribution were assessed in hedgerow plantings of Acacia saligna (Labill.) H.L. Wendl. after tree pruning. Pruning to a height of 1.5 m was carried out in March and September 1996. In July and October 1996, the fine root distribution (〈 2 mm) and their carbohydrate contents were determined at three distances to the tree row by soil coring. At the same time, foliar nutrient contents were assessed, whereas nutrient leaching was measured continuously. The highest root length density (RLD) was always found in the topsoil (0–0.15 m) directly under the hedgerow (0–0.25 m distance to trees). Pruning diminished the RLD in the acacia plots at all depths and positions. The relative vertical distribution of total roots did not differ between trees with or without pruning, but live root abundance in the subsoil was comparatively lower when trees were pruned than without pruning. In the dry season, the proportion of dead roots of pruned acacias was higher than of unpruned ones, while the fine roots of unpruned trees contained more glucose than those of pruned trees. Pruning effectively reduced root development and may decrease potential below-ground competition with intercropped plants, but the reduction in subsoil roots also increased the danger of nutrient losses by leaching. Leaching losses of such mobile nutrients as NO3− were likely to occur especially in the alley between pruned hedgerows and tended to be higher after pruning. The reduced size of the root system of pruned acacias negatively affected their P and Mn nutrition. Pruning also reduced the function of the trees as a safety net against the leaching of nutrients for both NO3− and Mn, though not for other studied elements. If nutrient capture is an important aim of an agroforestry system, the concept of alley cropping with pruning should be revised for a more efficient nutrient recycling in the system described here.
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  • 64
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    International journal of thermophysics 21 (2000), S. 1033-1044 
    ISSN: 1572-9567
    Keywords: intermolecular potential ; nitrogen ; speed of sound ; virial coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Speeds of sound in nitrogen were measured at temperatures between 170 and 400 K at amount-of-substance densities between 40 and 400 mol·m−3. From these measurements, second and third acoustic virial coefficients were obtained. The parameters of two- and three-body isotropic intermolecular potential-energy models were optimized in a simultaneous fit to the second and third acoustic virial coefficients and the ordinary second and third virial coefficients of nitrogen reported by Nowak et al. The results, which shows that the acoustic and ordinary virial coefficients are mutually consistent, may be used to predict second and third virial coefficients, and their acoustic counterparts, over a wide range of temperatures. The parameters of an anisotropic site-site potential-energy model were also obtained from a fit to the acoustic and ordinary second virial coefficients alone.
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  • 65
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    International journal of thermophysics 21 (2000), S. 983-997 
    ISSN: 1572-9567
    Keywords: acoustic resonator ; argon ; Greenspan viscometer ; helium ; helium-xenon mixture ; methane ; nitrogen ; speed of sound ; viscosity of gases ; xenon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An improved Greenspan acoustic viscometer (double Helmholtz resonator) was used to measure the viscosity of gases at temperatures from 250 to 400 K and at pressures up to 3.4 MPa. The improvements include a vibration damping suspension and the relocation of the fill duct. The fill duct, which is needed to supply gas to the resonator, was connected to the center of the resonator to eliminate acoustic coupling between the resonator and the manifold. In anticipation of handling corrosive gases, all surfaces of the apparatus that are exposed to the test gas are made of metal. The viscometer was tested with argon, helium, xenon, nitrogen, and methane. Isothermal measurements were carried out at 298.15 and 348.15 K and at pressures up to 3.2 MPa. Without calibration, the results differed from published viscosity data by −0.8% to +0.3% (0.47% r.m.s.). These results are significantly better than previous results from Greenspan viscometers. The measurements also yielded the speed of sound, which differed from literature data by +0.16% to +0.20% (0.18% r.m.s.). Adding empirical effective-area and effective-volume corrections to the data analysis decreased the r.m.s. deviations to 0.12% for the viscosity and to 0.006% for the speed of sound. No unusual phenomena were encountered when the viscometer was tested with a helium-xenon mixture between 250 and 375 K.
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  • 66
    ISSN: 1572-9680
    Keywords: biomass transfer ; integrated nutrient management ; nitrogen ; nutrient cycling ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tithonia diversifolia, a shrub in the family Asteraceae, is widely distributed along farm boundaries in the humid and subhumid tropics of Africa. Green biomass of tithonia has been recognized as an effective source of nutrients for lowland rice (Oryza sativa) in Asia and more recently for maize (Zea mays) and vegetables in eastern and southern Africa. This paper reviews the potential of tithonia green biomass for soil fertility improvement based on recent research in western Kenya. Green leaf biomass of tithonia is high in nutrients, averaging about 3.5% N, 0.37% P and 4.1% K on a dry matter basis. Boundary hedges of sole tithonia can produce about 1 kg biomass (tender stems + leaves) m−1 yr−1 on a dry weight basis. Tithonia biomass decomposes rapidly after application to soil, and incorporated biomass can be an effective source of N, P and K for crops. In some cases, maize yields were even higher with incorporation of tithonia biomass than with commercial mineral fertilizer at equivalent rates of N, P and K. In addition to providing nutrients, tithonia incorporated at 5 t dry matter ha−1 can reduce P sorption and increase soil microbial biomass. Because of high labor requirements for cutting and carrying the biomass to fields, the use of tithonia biomass as a nutrient source is more profitable with high-value crops such as vegetables than with relatively low-valued maize. The transfer of tithonia biomass to fields constitutes the redistribution of nutrients within the landscape rather than a net input of nutrients. External inputs of nutrients would eventually be required to sustain production of tithonia when biomass is continually cut and transferred to agricultural land.
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  • 67
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    Antonie van Leeuwenhoek 77 (2000), S. 117-133 
    ISSN: 1572-9699
    Keywords: Archaea ; Bacteria ; hydrothermal vents ; in situ hybridization ; molecular ecology ; probes ; 16S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The study of the structure and diversity of hydrothermal vent microbial communities has long been restricted to the morphological description of microorganisms and the use of enrichment culture-based techniques. Until recently the identification of the culturable fraction required the isolation of pure cultures followed by testing for multiple physiological and biochemical traits. However, peculiar inhabitants of the hydrothermal ecosystem such as the invertebrate endosymbionts and the dense microbial mat filaments have eluded laboratory cultivation. Substantial progress has been achieved in recent years in techniques for the identification of microorganisms in natural environments. Application of molecular approaches has revealed the existence of unique and previously unrecognized microorganisms. These have provided fresh insight into the ecology, diversity and evolution of mesophilic and thermophilic microbial communities from the deep-sea hydrothermal ecosystem. This review reports the main discoveries made through the introduction of these powerful techniques in the study of deep-sea hydrothermal vent microbiology.
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  • 68
    ISSN: 1573-5036
    Keywords: Carbohydrates ; CO2 ; lignin ; nitrogen ; proanthocyanidins ; soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Increased atmospheric carbon dioxide (CO2) concentration will likely cause changes in plant productivity and composition that might affect soil decomposition processes. The objective of this study was to test to what extent elevated CO2 and N fertility-induced changes in residue quality controlled decomposition rates. Cotton (Gossypium hirsutum L.) was grown in 8-l pots and exposed to two concentrations of CO2 (390 or 722 μmol mol-1) and two levels of N fertilization (1.0 or 0.25 g l-1 soil) within greenhouse chambers for 8 wks. Plants were then chemically defoliated and air-dried. Leaf, stem and root residues were assayed for total non-structural carbohydrates (TNC), lignin (LTGA), proanthocyanidins (PA), C and N. Respiration rates of an unsterilized sandy soil (Lakeland Sand) mixed with residues from the various treatments were determined using a soda lime trap to measure CO2 release. At harvest, TNC and PA concentrations were 17 to 45% higher in residues previously treated with elevated CO2 compared with controls. Leaf and stem residue LTGA concentrations were not significantly affected by either the elevated CO2 or N fertilization treatments, although root residue LTGA concentration was 30% greater in plants treated with elevated CO2. The concentration of TNC in leaf residues from the low N fertilization treatment was 2.3 times greater than that in the high N fertilization treatment, although TNC concentration in root and stem residues was suppressed 13 to 23% by the low soil N treatment. PA and LTGA concentrations in leaf, root and stem residues were affected by less than 10% by the low N fertilization treatment. N concentration was 14 to 44% lower in residues obtained from the elevated CO2 and low N fertilization treatments. In the soil microbial respiration assay, cumulative CO2 release was 10 to 14% lower in soils amended with residues from the elevated CO2 and low N fertility treatments, although treatment differences diminished as the experiment progressed. Treatment effects on residue N concentration and C:N ratios appeared to be the most important factors affecting soil microbial respiration. The results of our study strongly suggest that, although elevated CO2 and N fertility may have significant impact on post-harvest plant residue quality of cotton, neither factor is likely to substantially affect decomposition. Thus, C cycling might not be affected in this way, but via simple increases in plant biomass production.
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  • 69
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    Plant and soil 220 (2000), S. 35-47 
    ISSN: 1573-5036
    Keywords: drainage ; fertilisation ; nature management ; nitrogen ; nutrient contents ; nutrients ; peat ; phosphate ; potassium ; restoration ; rewetting ; shoot biomass ; species richness ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Restoration of wet grassland communities on peat soils involves management of nutrient supply and hydrology. The concept of nutrient limitation was discussed as well as its interaction with drainage and rewetting of severely drained peat soils. Different methods of assessing nutrient limitation were compared and the type and extent of nutrient limitation were determined for several wet grassland communities. It was concluded that a full-factorial field fertilisation experiment is the most preferable method. Plant tissue analyses and soil chemical analyses were considered less suitable, although they may provide helpful additional information. Fertilisation experiments in the laboratory using sods or using test plants appear to be the proper means to study mechanisms or processes, but have a restricted predictive value for field situations. Generalising the results, it seems that many relativily undisturbed grassland plant communities on peaty soils are characterised by N limitation. Phosphate limitation for vegetation on peat soils is mainly observed in specific circumstances such as extreme calcium richness, high concentrations of Fe or as a result of drainage or long-term hay cropping. The latter two may also cause K limitation. Rewetting is regarded as a prerequisite in restoring wet grassland communities. Further restoration measures to influence nutrient availability depend on aims of the management and the individual site conditions.
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  • 70
    ISSN: 1573-5036
    Keywords: carbon ; defoliation ; nitrogen ; phosphorus ; sheep urine ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have determined the temporal changes in the concentration of dissolved organic carbon (DOC) and P and N components in soil solution following application of synthetic sheep urine (500 kg N ha-1) to a brown forest soil in boxes sown with Agrostis capillaris. Three contrasting defoliation treatments (no cutting, single cut before urine application and regular cutting twice per week) plus a fallow soil were studied. The synthetic urine contained 15N labelled urea and was P-free. Intact soil cores were taken after 2, 7, 14, 21 and 56 d and centrifuged to obtain soil solution. The urea in the synthetic urine was rapidly hydrolysed in the soil, increasing soil solution pH, DOC and total dissolved phosphorus (TDP) concentrations. For the regularly defoliated sward, DOC and P reached maximum concentrations (4000 mg DOC L-1 and 59 mg TDP L-1) on day 7. From their peak values, pH and DOC and P concentrations generally decreased with time and at day 56 were near those of the control. Concentrations of NH4 + and NO3 - in the no-urine treatments fluctuated and the greatest treatment differences were between the fallow soil and the soil sown with grass. Adding synthetic urine increased NH4 + concentrations during the first week, but NO3 - concentrations decreased. This was consistent with the 15N labelling of the NO3 - pool which required 3 weeks to reach that of 15NH4 +. Dissolved organic nitrogen (DON) reached a maximum value at day 7 with a concentration of 409 mg N L-1. The DON in soil solution contained no detectable amounts of 15N label indicating that it was derived from sources in the soil. Differences in soil solution composition related to the effect of the other cutting treatments and the fallow treatment were small compared to the effect of synthetic urine addition.
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  • 71
    ISSN: 1573-5036
    Keywords: carbon ; geostatistics ; nitrification potential ; nitrogen ; pH ; root biomass ; soil respiration ; spatial Heterogeneity ; variability scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Geostatistical techniques were used to quantify the scale and degree of soil heterogeneity in 2 m2 plots around 9-year-old poplar trees and within a wheat field. Samples were taken during two years, on an unaligned grid, for analysis of soil respiration, C and N content, available P, gravimetric moisture, pH, nitrification potential, and root biomass. Kriged maps of soil respiration, moisture, and C content showed strong spatial structure associated with poplar trees but not with wheat rows. All soil properties showed higher autocorrelation in June than in April. Isopleth patchiness for all variates was less in June. This was associated with lower respiration rates due to lower litter decomposition. From the degree and scale of heterogeneity seen in this study, we conclude that the main causes of soil heterogeneity at this scale (2 m2) are likely to be found at micro scales controlled in part by plant root and plant residue patterns. These must be understood in the evaluation of ecosystem processes.
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  • 72
    ISSN: 1573-5036
    Keywords: carbon ; CO2 enrichment ; nitrogen ; particulate organic matter ; roots ; tallgrass prairie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We determined the effects of elevated [CO2] on the quantity and quality of below-ground biomass and several soil organic matter pools at the conclusion of an eight-year CO2 enrichment experiment on native tallgrass prairie. Plots in open-top chambers were exposed continuously to ambient and twice-ambient [CO2] from early April through late October of each year. Soil was sampled to a depth of 30 cm beneath and next to the crowns of C4 grasses in these plots and in unchambered plots. Elevated [CO2] increased the standing crops of rhizomes (87%), coarse roots (46%), and fibrous roots (40%) but had no effect on root litter (mostly fine root fragments and sloughed cortex material 〉500 μm). Soil C and N stocks also increased under elevated [CO2], with accumulations in the silt/clay fraction over twice that of particulate organic matter (POM; 〉53 μm). The mostly root-like, light POM (density ≤1.8 Mg m-3) appeared to turn over more rapidly, while the more amorphous and rendered heavy POM (density 〉1.8 Mg m-3) accumulated under elevated [CO2]. Overall, rhizome and root C:N ratios were not greatly affected by CO2 enrichment. However, elevated [CO2] increased the C:N ratios of root litter and POM in the surface 5 cm and induced a small but significant increase in the C:N ratio of the silt/clay fraction to a depth of 15 cm. Our data suggest that 8 years of CO2 enrichment may have affected elements of the N cycle (including mineralization, immobilization, and asymbiotic fixation) but that any changes in N dynamics were insufficient to prevent significant plant growth responses.
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    Plant and soil 225 (2000), S. 153-165 
    ISSN: 1573-5036
    Keywords: carbon ; decomposer food web ; indirect effects ; microbes ; nitrogen ; plant growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the sensitivity of soil microbial communities and ecosystem processes to variation in the vertical and horizontal structure of decomposer food web under nitrogen poor and N-enriched conditions. Microcosms with humus and litter layer of boreal forest floor, birch seedlings infected with mycorrhizal fungi, and decomposer food webs with differing trophic group and species composition of soil fauna were constructed. During the second growing period for the birch, we irrigated half of the microcosms with urea solution, and the other half with de-ionised water to create two levels of N concentration in the substrate. During the experiment night time respirations of the microcosms were measured, and the water leached through the microcosms was analysed for concentration of mineral N, and nematode numbers. The microcosms were destructively sampled after 37 weeks for plant biomass and N uptake, structure of soil animal and microbial community (indicated by PLFA profiles), and physical and chemical properties of the humus and litter materials. Predatory mites and nematodes had a negative influence on the biomass of their microbivorous and microbi-detritivorous prey, and microbi-detritivores affected the biomass and community structure of microbes (indicated by PLFA-analysis). Moreover, predatory mites and nematodes increased microbial biomass and changed the microbial community structure. The decomposer food web structure affected also N uptake and growth of plants. Microbi-detritivorous fauna had a positive effect, whereas predators of microbial and detritus feeding fauna exerted a negative influence on plant N uptake and biomass production. The impact of a trophic group on the microbes and plant was also strongly dependent on species composition within the group. Nitrogen addition magnified the influence of food web structure on microbial biomass and plant N uptake. We suggest that addition of urea-N to the soil modified the animal-microbe interaction by increasing microbial growth and altering community structure of microbes. The presence of microbi-detritivores and predators reduced loss of carbon from the microcosms, and the food web structure influenced also water holding capacity of the materials. The changes in plant growth, nutrient cycling, size of N and C pools, and in the physical properties of the soil emphasize the importance and diversity of indirect consequences of decomposer food web structure.
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  • 74
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    Plant cell, tissue and organ culture 61 (2000), S. 59-67 
    ISSN: 1573-5044
    Keywords: alar ; in vitro plantlet ; mannitol ; nitrogen ; rooting ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of leaf area of in vitro propagated potato (Solanum tuberosum L.) plantlets for further growth during acclimatisation and the after-effects of in vitro treatments on growth were examined. The in vitro treatments included different levels of alar, nitrogen or mannitol or different temperatures during the last in vitro phase, the rooting phase. Leaf area or ground cover was recorded one day after planting to soil and at the end of the first phase of ex vitro growth, the acclimatisation phase. Regression analysis showed that leaf area of a transplant at the end of acclimatisation phase was positively influenced by leaf area of the same plantlet at the beginning of the phase. The relative increase in leaf area during acclimatisation (increase/early leaf area) was linearly related to the inverse of the early leaf area, indicating almost comparable relative increases for plantlets having larger early leaf areas, but more variable responses for plantlets having smaller early leaf areas. In vitro treatments mainly affected leaf area of transplants through their effects on early leaf area. Adding alar, reducing nitrogen and reducing temperature increased leaf area. Reducing mannitol increased ground cover. A lower nitrogen concentration and higher temperature in some cultivars had slight negative effects on the relative increase in leaf area after acclimatisation. For nitrogen these negative effects were less significant than the positive effects through early leaf area. Results stress the importance of manipulation of leaf area in vitro to enhance plant performance in later stages of growth.
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  • 75
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    Hydrobiologia 426 (2000), S. 185-192 
    ISSN: 1573-5117
    Keywords: nutrient competition ; periphyton ; nitrogen ; silicate ; eutrophication ; benthic microalgae ; hard substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to understand the effect of changing nutrient conditions on benthic microalgae on hard substrates, in-situ experiments with artificial substrates were conducted in Kiel Fjord, Western Baltic Sea. As an extension of previous investigations, we used artificial substrates without silicate and thus were able to supply nutrient media with different Si:N ratios to porous substrates, from where they trickled out continuously. The biofilm developing on these substrates showed a significant increase in biovolume due to N + P enrichment, while Si alone had only minor effects. The stoichiometric composition of the biomass indicated nitrogen limitation during most of the year. The C:N ratios were lowered by the N + P addition. The algae were dominated by diatoms in most cases, but rhodophytes and chlorophytes also became important. The nutrient treatment affected the taxonomic composition mostly at the species level. The significance of the results with regard to coastal eutrophication is discussed.
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  • 76
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    Journal of aquatic ecosystem stress and recovery 8 (2000), S. 53-66 
    ISSN: 1573-5141
    Keywords: Canada ; nitrogen ; periphyton ; phosphorus ; pulp mill effluent ; rivers ; sewage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate the effects of pulp mill and municipal sewageeffluents on the nitrogen (N) and phosphorus (P) status of northernCanadian rivers, the Northern River Basins Study required an integratedresearch and assessment program consisting of field observation andexperimentation. Analysis of monitoring data collected over 3–13 yshowed that on an annual basis, pulp mills contributed 22% of theP and 20% of the N load discharged from the Wapiti to the Smokyriver, and 6 to 16% of the P load and 4 to 10% of the Nload in the Athabasca River. Despite these low contributions, N and Pconcentrations were elevated below pulp mill discharges on all threerivers during the low discharge period of September to April. Insitu experiments conducted with nutrient diffusing substrata showedthat periphyton biomass was maintained at low levels by insufficient Pin the upper reaches of the Athabasca River and insufficient N+P inthe Wapiti River upstream of point-source discharges. In contrast,effluent loading from pulp mill and sewage inputs alleviated nutrientlimitation downstream of major discharges on both rivers. Experimentsconducted in artificial streams located beside the Athabasca Riverupstream of the first pulp mill showed that P addition increasedperiphyton biomass (expressed as chlorophyll a content) suchthat biomass increased sharply at low P concentrations (2–5µg/L soluble reactive P) and approached saturation at 35µg/L soluble reactive P. As a result of recommendations fromthis integrated program of river monitoring and experimentation,nutrient loading has been reduced to the most affected river(Wapiti-Smoky) and federal and provincial departments of environment arereviewing loading limits for other river reaches.
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  • 77
    ISSN: 1573-5117
    Keywords: Ascophyllum ; Fucus ; CNBM ; light ; nitrogen ; phlorotannins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phlorotannins, C-based defence compounds in brown seaweeds, show a high degree of spatial and temporal variation within seaweed species. One important model explaining this variation is the Carbon Nutrient Balance Model (CNBM), which states that the relative supply of carbon and limiting nutrients will determine the level of defence compounds in plants. Nitrogen is often considered to be the limiting nutrient for marine macroalgal growth and the CNBM thus predicts that when the carbon:nitrogen ratio is high, photosynthetically fixed carbon will be allocated to production of phlorotannins. In the present study, we evaluated the effects of light (i.e. carbon) and nitrogen on the phlorotannin content of two intertidal brown seaweeds, Ascophyllum nodosum and Fucus vesiculosus. This was done in an observational field study, as well as in a manipulative experiment where plants from habitats with different light regimes were subjected to different nitrogen and light treatments, and their phlorotannin content was measured after 14 days. The results showed that there was a negative relationship between tissue nitrogen and phlorotannin content in natural populations of F. vesiculosus, but not in A. nodosum. In the short term, the phlorotannin content in both algal species was not affected by changes in nitrogen availability. Exposure to sunlight had a positive effect on the phlorotannin content in natural populations of both algal species but, in the manipulative experiment, only F. vesiculosus showed a rapid response to changes in light intensities. Plants subjected to sunlight contained higher phlorotannin content than shaded plants. In conclusion, the results imply that nitrogen availability explains some of the natural variation in the phlorotannin content of F. vesiculosus, but the light environment has greater importance than nitrogen availability in predicting the phlorotannin content of each species.
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  • 78
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    Hydrobiologia 432 (2000), S. 101-111 
    ISSN: 1573-5117
    Keywords: Hawaii ; light ; nitrogen ; nutrients ; periphyton ; phosphorus ; spate ; stream
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To date, most studies of light- and nutrient-limited primary productivity in forested streams have been carried out in deciduous forests of temperate, continental regions. Conceptual models of light and nutrient limitation have been developed from these studies, but their restricted geographic range reduces the generality of such models. Unlike temperate continental streams, streams on tropical high islands are characterized by flashy, unpredictable discharge and riparian canopies that do not vary seasonally. These contrasting conditions suggest that patterns of light and nutrient limitation in tropical streams may differ from those in temperate streams. The effects of light, and nitrogen and phosphorus availability on periphyton accrual (measured as chlorophyll a per unit area) were investigated using field experiments in 4 low-order streams on the island of Oahu, Hawaii. Levels of chlorophyll a in partially-shaded stream pools were significantly greater than in heavily-shaded pools, and nutrient-enrichment increased the level of chlorophyll a in partially-shaded pools but not in heavily-shaded pools. In each stream, phosphate enrichment resulted in an increase in the level of chlorophyll a, but nitrate enrichment had no effect. Spates following rainstorms occur frequently in these streams, and may increase periphyton productivity by increasing the flux of nutrients to algal cells. However, differences in inorganic nitrogen and phosphorus concentrations measured during spates and baseflow were small, and during some spates, concentrations of these two nutrients declined relative to baseflow concentrations. These observations suggest that phosphorus limitation was not alleviated by spates.
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  • 79
    ISSN: 1573-515X
    Keywords: C:N ratio ; dissolved organic carbon ; dissolved organic nitrogen ; nitrogen ; stream chemistry ; watershed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Relatively high deposition ofnitrogen (N) in the northeastern United States hascaused concern because sites could become N saturated.In the past, mass-balance studies have been used tomonitor the N status of sites and to investigate theimpact of increased N deposition. Typically, theseefforts have focused on dissolved inorganic forms ofN (DIN = NH4-N + NO3-N) and have largelyignored dissolved organic nitrogen (DON) due todifficulties in its analysis. Recent advances in themeasurement of total dissolved nitrogen (TDN) havefacilitated measurement of DON as the residual of TDN− DIN. We calculated DON and DIN budgets using data onprecipitation and streamwater chemistry collected from9 forested watersheds at 4 sites in New England. TDNin precipitation was composed primarily of DIN. Netretention of TDN ranged from 62 to 89% (4.7 to 10 kghaminus 1 yrminus 1) of annual inputs. DON made up themajority of TDN in stream exports, suggesting thatinclusion of DON is critical to assessing N dynamicseven in areas with large anthropogenic inputs of DIN.Despite the dominance of DON in streamwater,precipitation inputs of DON were approximately equalto outputs. DON concentrations in streamwater did notappear significantly influenced by seasonal biologicalcontrols, but did increase with discharge on somewatersheds. Streamwater NO3-N was the onlyfraction of N that exhibited a seasonal pattern, withconcentrations increasing during the winter months andpeaking during snowmelt runoff. Concentrations ofNO3-N varied considerably among watersheds andare related to DOC:DON ratios in streamwater. AnnualDIN exports were negatively correlated withstreamwater DOC:DON ratios, indicating that theseratios might be a useful index of N status of uplandforests.
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  • 80
    ISSN: 1573-515X
    Keywords: acid deposition ; atmospheric deposition ; nitrate ; nitrification ; nitrogen ; soil carbon ; soil chemistry ; stream water acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Cumulative effects of atmospheric N deposition mayincrease N export from watersheds and contribute tothe acidification of surface waters, but naturalfactors (such as forest productivity and soildrainage) that affect forest N cycling can alsocontrol watershed N export. To identify factors thatare related to stream-water export of N, elevationalgradients in atmospheric deposition and naturalprocesses were evaluated in a steep, first-orderwatershed in the Catskill Mountains of New York, from1991 to 1994. Atmospheric deposition of SO 4 2− , andprobably N, increased with increasing elevation withinthis watershed. Stream-water concentrations ofSO 4 2− increased with increasing elevationthroughout the year, whereas stream-waterconcentrations of NO 3 − decreased withincreasing elevation during the winter and springsnowmelt period, and showed no relation with elevationduring the growing season or the fall. Annual exportof N in stream water for the overall watershed equaled12% to 17% of the total atmospheric input on thebasis of two methods of estimation. This percentagedecreased with increasing elevation, from about 25%in the lowest subwatershed to 7% in the highestsubwatershed; a probable result of an upslope increasein the thickness of the surface organic horizon,attributable to an elevational gradient in temperaturethat slows decomposition rates at upper elevations. Balsam fir stands, more prevalent at upper elevationsthan lower elevations, may also affect the gradient ofsubwatershed N export by altering nitrification ratesin the soil. Variations in climate and vegetationmust be considered to determine how future trends inatmospheric deposition will effect watershed export ofnitrogen.
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  • 81
    ISSN: 1573-515X
    Keywords: carbon ; landscape geochemical flows ; model ; nitrogen ; phosphorus ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The importance of landscape geochemical flows wasinvestigated using a dynamic model simulating carbon,nitrogen and phosphorus cycling in riverine wetlands,which has been described in a previous paper. Thehydro-geomorphic unit (HGMU) concept was incorporatedin the model by defining a separate, completeunit-model for each unit (HGMU) within the wetland.These unit-models were connected by defining the flowsof nitrogen and phosphorus between them. These flows,also called landscape geochemical flows, usuallyconsist of flows of water containing N and P. The model was applied to a site at Kismeldon Meadows,in south-western England. This site consists of twounits, a slope and a floodplain, separated by a ditch,which catches most of the run off and shallowgroundwater flows from the slope. Only an estimated1% of the N and P that leaves the slope unit in thewater outflow reaches the floodplain unit; the rest iscaught in the system of ditches, which prevent thegeochemical flows taking their natural course. Toexamine the influence of this system of ditches, themodel was run for the same site, but without theditches. This is comparable to a situation of arestored site, where run off and shallow groundwaterflows containing nutrients, can freely get from theslope to the floodplain. The computer simulation experiment reconnecting theslope and floodplain showed that this (1) increasedthe nutrient input into the floodplain, causing ahigher biomass production, and (2) increased thewetness of the floodplain, causing slowerdecomposition, which together (3) led to a faster soilorganic matter accumulation in the floodplain.Nutrient inflows became relatively more importantcompared to atmospheric deposition, especially forphosphorus. By connecting the slope and the floodplainmore nitrogen and less phosphorus flowed into theriver.
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  • 82
    ISSN: 1573-515X
    Keywords: chloride ; internal eutrophication ; nitrogen ; peat soil ; phosphorus ; phytometer ; sulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Inputs of surface waters high in chloride and sulphateincreased the availability of nutrients in fenpeatlands. This `internal eutrophication' wasdemonstrated with test plants (`phytometers') andthrough water and soil analysis. Three experiments arepresented in which the level of chloride and/orsulphate was increased to 3 mmolc l−1. Inexperiment 1 chloride levels were increased from 0.5to 3 mmolc l−1 as CaCl2 or NaCl. Inexperiment 2 and 3 similar increased levels forchloride and sulphate (3 mmolc l−1; as NaCland Na2SO4) were used. The following resultswere found: (i) No differences in soil total-N and total-P werefound before and after the treatments in any of thethree experiments. (ii) Experiment 1 showed a significant increase inBio-Available P (BAP) in pots planted with Anthoxanthum odoratum as well as in bare pots for theNaCl and CaCl2 treatments. The plants in thesetreatments had taken up much more P. (iii) Experiment 2 showed an increase in soil BAPafter treatment with chloride and sulphate in potsplanted with Anthoxanthum odoratum. The chloridetreatment had no effect on plant biomass, whereas thesulphate treatment resulted in a reduction in rootbiomass and root N and P content. The shoots showedan increase in P content in the sulphate and chloridetreatments, while N content remained the same. (iv) In experiment 3, treatments with chloride andsulphate led to significantly increased biomass and Puptake of Anthoxanthum odoratum. Again, noeffects on N uptake were found. These experiments provide evidence for distinctlyincreased availability of phosphate in peat soils whenthese come into contact with water with evenmoderately increased sulphate or chloride levels.Surface water originating from the Rhine river, whichis enriched in chloride and sulphate, is oftensupplied to fen reserves in The Netherlands, tocompensate for water losses due to agriculturaldrainage in the region. The results of this study showthat phosphate availability to the vegetation may risedrastically, with detrimental effects on the speciesdensity and the occurrence of rare species in thevegetation. Hence, supply of this water should beavoided.
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  • 83
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    Environmental monitoring and assessment 63 (2000), S. 431-446 
    ISSN: 1573-2959
    Keywords: aquatic bacteria ; benthic macroinvertebrates ; bioindicator ; eutrophication ; nitrogen ; phosphorus ; stream pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A combination field and laboratorystudy was conducted to evaluate the ability of arecently developed bioindicator to detect detrimentalnutrient conditions in streams. The method utilizesbacterial growth on aquatic insects to determinenutrient impacts. Field investigations indicated thatelevated concentrations of nitrate and phosphate wereassociated with growth of filamentous bacteria oninsect body surfaces, and that there was a significantreduction in the density of major insect taxa in thenutrient-enriched stream reaches. Laboratoryinvestigations confirmed a strong linkage betweenbacterial growth and reduced survival of insects. Survival was examined for insects with bacterialinfestation ranging from 0% to greater than 50%coverage of the body surface. A threshold forcatastrophic mortality occurred at about 25% bodycoverage; there were few survivors above that amount. Based on these findings, the diagnostic endpoint forthe bioindicator is 25% body coverage by bacterialgrowth, a level that signifies major impacts and isalso easy to detect visually. This study providesadditional evidence that the insect-bacteriabioindicator is a reliable tool for assessing nutrientimpacts on stream macroinvertebrate communities. Thebioindicator should prove useful for identifyingnutrient-impacted sites as well as monitoring thesuccess of management actions to improve water quality.
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  • 84
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    Water, air & soil pollution 119 (2000), S. 121-137 
    ISSN: 1573-2932
    Keywords: nitrogen ; wet deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We measured concentrations and fluxesof major ions in wet deposition, throughfall andstream water in a forested watershed on the AlleghenyPlateau of western Maryland to investigatecanopy-atmosphere interactions and to calculate input–output budgets. Wet deposition was dominated byH+, SO 4 2− , NO 3 − andNH 4 + ions. Hydrogen and SO 4 2− accounted for 70 and 58% of the total cation andanion equivalents, respectively. Annual wet depositionrates of SO 4 2− (0.56 keq ha−1 yr−1), NO 3 − (0.31 keq ha−1 yr −1)and NH 4 + (0.17 keq ha−1 yr −1)were at the high end of the range in wet depositionrates reported for other sites in the eastern UnitedStates. On an annual basis, the forest canopy consumed20% of the free acidity in incident precipitation,had no net effect on Na+ and NH 4 + deposition, and was a net source of K+,Ca2+, Mg2+, SO 4 2− andNO 3 − ; 1.5 to 22 times greater than the wetdeposition rates. On an annual basis, the watershed ofthe unnamed tributary to Herrington Creek (HCWS)retained essentially all of the throughfall H+ andNH 4 + inputs, 35% of the throughfall K+input and 62% of the throughfall NO 3 − input. In contrast, HCWS was a net source ofSO 4 2− , Cl−, Ca2+, Mg2+ andNa+; export rates were 2 to 5 times greater thanthroughfall inputs. Sulfate was the dominant anionassociated with cation leaching, accounting for 78%of the total anion export of 1.8 keq ha−1 yr −1 in 1996–1997.
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  • 85
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    Journal of comparative physiology 170 (2000), S. 531-535 
    ISSN: 1432-136X
    Keywords: Key words Large intestine ; Furrow of proximal colon ; Digesta ; Bacteria ; Soft and hard feces ; Nutrias ; Myocastor coypus ; AbbreviationsN nitrogen ; TAA total amino acids ; DAP diaminopimelic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The bacterial level of soft feces is higher than that of hard feces in nutrias. This suggests the heterogeneity of bacterial density in the large intestine. To show the heterogeneity of bacteria in the contents of the large intestine in nutrias, we divided the contents of the large intestine into 12 regions, then measured the nitrogen (N), total amino acids (TAA) and diaminopimelic acid (DAP), a bacterial marker, of these regions. Levels of N, TAA and DAP varied along the cross section of the proximal colon. The greater curvature of the main lumen and furrow had higher N, TAA and DAP concentrations than the lesser curvature. We also examined the involvement of the furrow in producing two types of feces differing in bacterial nitrogen content by surgically preventing the flow of the furrow contents. We compared the concentrations of N, TAA and DAP between soft and hard feces among operated, sham-operated and intact animals. Surgical closure of the furrow abolished the difference in levels of N, TAA and DAP between soft and hard feces, suggesting that the furrow of the proximal colon is responsible for making the bacterial density higher in soft feces than in hard feces.
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  • 86
    ISSN: 1573-9058
    Keywords: carbon ; C/N ; direct and indirect effects ; nitrogen ; soluble sugars ; starch ; specific leaf area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dark respiration rate in the night (R D) was measured in five-year-old Scots pine (Pinus sylvestris L.) trees grown for two years under ambient (AC) and elevated (AC + 400 µmol mol−1 = EC) CO2 concentrations in open top chambers. Two needle age classes (i.e., current-year and one-year-old) were measured at AC and EC in both AC- and EC-grown pines. Additionally different chemical characteristics were determined on the needles, such as nitrogen (N), carbon (C), starch, and soluble sugar concentrations as well as specific leaf area. The direct, short-term and indirect, long-term effects of EC on R D for the two needle age classes were examined. R D was expressed on a per needle area, needle mass, N, C, and C/N bases. Direct effects were only pronounced in the AC treatment where inhibition of R D was found at EC in both current- and one-year-old needles. Indirect effects were only significant in one-year-old needles where a decrease was found in the EC grown trees as compared with AC ones when R D was expressed per unit needle mass, C, or C/N. R D per unit needle area and needle N were not sensitive to long-term EC, in any needle age class. Long-term EC treatment also influenced the response of the two needle age classes. One-year-old needles from the EC treatment had significantly lower R D than current-year needles, but no such response was observed in the AC treatment. Our experiment re-emphasised the importance of expressing R D on different bases for a correct interpretation of the responses to EC. Moreover, we showed that different needle age classes can respond differently to a CO2 enrichment.
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  • 87
    ISSN: 1573-2932
    Keywords: eutrophication ; nitrogen ; phosphorus ; river ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Nitrogen (N) and phosphorus (P) concentrations were determined in sediment samples along the bed of Catatumbo river in both Colombian and Venezuelan territories until the river outlet in Maracaibo lake. Total phosphorus was determined by digestion with HCl followed by analysis using the ascorbic acid method and total nitrogen was done using the standard microkjeldahl method plus nitrate-nitrite. Ammonium, orthophosphate and nitrate were determined using standard methods after extraction steps. The mean concentrations along the river bed were found in an interval of 0.035 and 1.492 mg g-1 dry sed. for nitrogen and 0.027 and 1.039 mg g-1 dry sed. for phosphorus at 95% confidence level. The mean molar ratio N/P in the river bed was 4.42 and 3.46 for river outlet zones in the lake, which indicates that nitrogen is the limiting nutrient. For comparison with previous results of lake sediments from sites near the river outlet it was concluded that Catatumbo river is a significant source of nutrients to the Maracaibo Lake system because sediment nutrients concentrations from Catatumbo river were higher than the ones in Maracaibo Lake. Statistic studies showed significant differences between countries, zones and similar behaviour in the river bed as related to the affluent rivers.
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  • 88
    ISSN: 1573-2932
    Keywords: nitrification ; nitrogen ; nitrogen mineralization ; soil water ; stream chemistry ; wilderness area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Nitrogen (N) deposition and its impact on terrestrial and aquatic ecosystems is a concern facing federal land managers at the Lye Brook Wilderness in Vermont and other protected aras throughout the northeastern United States. In this study, we compared N production in soils with N concentrations and outputs in leachates to determine how forest cover types differ in regulating N losses. Also, precipitation inputs and modeled estimates of streamwater outputs were used to calculate a watershed N budget. Most ammonium and nitrate were produced in organic soils with deciduous cover. Softwood stands had low net nitrification rates and minimal N leaching. A comparison of watershed inputs and outputs showed a net gain in total dissolved N (5.5 kg ha-1 yr-1) due to an accumulation of dissolved inorganic N. The Lye Brook Wilderness ecosystem has N budgets similar to other forested ecosystems in the region, and appears to be assimilating the accumulating N. However seasonal losses of nitrate observed in mineral soils and streamwater may be early warnings of the initial stages of N saturation.
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  • 89
    ISSN: 1573-2932
    Keywords: on-site treatment ; fecal coliform bacteria ; nitrate leaching ; nitrogen ; on-site treatment ; septic effluent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Groundwater effluent sample collectors(zero-tension lysimeters) were installed directlybelow the drainfields of three residential onsitetreatment systems in the Clover/Chambers Creek aquiferregion of Pierce County near Tacoma, WA. The use of asplit effluent delivery system from the septic tank,where half the effluent was delivered under pressureto a normal native soil-only filter system and halfwas delivered to a sand filter system, allowed thedirect comparison of the two commonly-utilized septicsystems for treatment levels. Septic tank effluent(from the septic tank) and percolating water (between0.3 and 0.9 m beneath the effluent distributionlines) was collected between May 1991 and April 1994on 30 occasions. Samples were analyzed for fecalcoliform bacteria, nitrate, nitrite, ammonium andtotal reduced (Kjeldahl) nitrogen. Results of thisstudy indicate that the use of sand filters greatlyincreased removal of fecal coliform bacteria and totalnitrogen. Soil-only filter systems had an average of91% removal of fecal coliforms and 47%of total N; whereas sand filter systems had an averageof 99.8% removal of fecal coliforms and 80% of total N.
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  • 90
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    Environmental and resource economics 16 (2000), S. 347-362 
    ISSN: 1573-1502
    Keywords: cost-effectiveness ; nitrogen ; nonpoint ; policy ; value ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract Wetlands, in Sweden and elsewhere, have been suggestedas effective and low-cost sinks for agriculturalpollution. This paper estimates the value of usingwetlands for abatement of agricultural nitrogen loadon the Baltic Sea. A replacement value of wetlands isestimated for Sweden. The replacement value is definedand estimated as the difference between twocost-effective reductions of agricultural nitrogenpollution: one that uses wetlands for nitrogenabatement, and one that does not. It is shown that theuse of wetlands as nitrogen sinks can reduce the totalabatement costs of nitrogen emissions by 30% forSwedish agricultural sources of nitrogen pollution.
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  • 91
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    World journal of microbiology and biotechnology 16 (2000), S. 495-497 
    ISSN: 1573-0972
    Keywords: Bacteria ; biodegradation ; 2,4-D ; soil microcosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Bacterial isolates (NJ 10 and NJ 15) capable of degrading the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were isolated from agricultural soil by enrichment culture technique. The isolates exhibited substantial growth in mineral salt medium supplemented with 0.1–0.5% of 2,4-D as a sole source of carbon and energy. Based on their morphological, cultural and biochemical characteristics, the isolates NJ 10 and NJ 15 have been identified as Pseudomonas species and Pseudomonas aeruginosa, respectively. Biodegradation studies in a soil microcosm enriched with pure cultures of the isolates demonstrated a time-dependent disappearance of 2,4-D from the 100 mg/kg herbicide-amended soil. The HPLC data analysis revealed 96.6 and 99.8% degradation in the soil inoculated with the pure cultures of isolates NJ 10 and NJ 15, respectively with in 20 days of incubation at 30 °C. Both the isolates showed significant solubilization of inorganic phosphate [Ca3(PO4)2] on the specific Pikovskaya's medium.
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  • 92
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    World journal of microbiology and biotechnology 16 (2000), S. 115-134 
    ISSN: 1573-0972
    Keywords: Bacteria ; biocontrol ; biological control ; compost ; disease ; fungi ; microbiology ; pathogen ; suppression ; turf ; turfgrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The relationships among the chemical, physical and biological aspects of compost and their role in suppression of turfgrass pathogens are reviewed. The composting process, mediated by microbial activity, is affected by physical and chemical characteristics which include temperature, aeration, moisture content, C:N ratio and pH. In the absence of parameter restrictions, the microbial community follows a predictable successional pattern resulting in the re-colonization of compost with metabolically active mesophilic populations that can be suppressive towards plant pathogens. Although mechanisms of suppression are not fully understood, those postulated include physiochemical and biological characteristics. The physiochemical characteristics of composts can alter suppressive properties through direct effects on pathogens and antagonistic microorganisms, or indirect effects on host systems through the supply of nutrients, improvement of soil structure, porosity and water retention capabilities, along with other factors. Biological characteristics centre on microbial community involvement in suppressive mechanisms, which can include one or a combination of competition for nutrients, antibiosis, lytic and other extracellular enzyme production, parasitism, predation and host-mediated induction of resistance. As a result of the potential benefits of compost, there is considerable interest in determining the capacity for composts to suppress turfgrass pathogens. Although the exact mechanisms of suppression are largely unknown, there appear to be several factors that play an integrated role. The use of composts that successfully suppress turfgrass diseases will permit a reduction in the use of chemical controls, and slow the development of fungicide resistance.
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  • 93
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    Biologia plantarum 43 (2000), S. 611-613 
    ISSN: 1573-8264
    Keywords: carbon ; hydrogen ; nitrogen ; reducing sugars ; starch ; summer and winter temperature regime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two-year-old plants of Karwinskia humboldtiana Zucc. and Karwinskia parvifolia Rose grown from the seeds in greenhouse were transferred to the growth cabinet and cultivated for two months under different temperature regimes (35/20 °C - the summer temperature regime, SR, and 20/5 °C - the winter temperature regime, WR). These temperatures were similar to the temperature conditions in the natural areas of the species studied (Nuevo León, Mexico). The root respiration rate was higher in the plants cultivated under SR than in those under WR. Roots of K. parvifolia res faster in both temperature regimes than roots of K. humboldtiana. Starch content in roots was higher in the plan cultivated under SR, however, concentrations of the other investigated organic and inorganic compounds were higher in the plants cultivated under WR. In K. humboldtiana roots, higher concentration of reducing sugars, carbon and hydrogen were found than in K. parvifolia.
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  • 94
    ISSN: 1573-8264
    Keywords: alfalfa ; arbuscular mycorrhizal fungi ; nitrogen ; nitrogen-fixing bacteria ; phosphorus ; plant growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of this research was to carry out a critical study of the method of obtaining size equivalence between non-symbiotic alfalfa and alfalfa associated with Glomus and/or Rhizobium by applying fixed addition rates of nutrients to the non-symbiotic controls. The experimental design included three nutrient response curves in which the levels of added phosphorus and/or nitrogen were constant during the whole plant growth process: 1) a phosphorus response curve, in order to compare the growth of double symbiotic plants with that of only-Rhizobium inoculated ones; 2) a nitrogen response curve, that consisted of a comparison between the growth of double symbiotic alfalfa and four treatments associated only with Glomus; 3) a phosphorus and nitrogen response curve, to compare the growth of non-inoculated alfalfa with that of double symbiotic plants. Although similar size was achieved among some treatments at harvest, shoot growth over time and nutrient concentrations in tissues differed, indicating that growth equivalence did not mean functional equivalence. A second experimental design was performed taking into account the establishment of microsymbionts for determining the adequate moment to add supplemental phosphorus and/or nitrogen. It included four treatments: a) double symbiotic plants (MR); b) plants inoculated with Rhizobium only (R); c) plants inoculated with Glomus only (M), and d) non-inoculated plants (N). Great similarity in terms of plant growth and nutrient contents in tissues were obtained. Moreover, symbiotic plants were able to produce similar dry matter than non-symbiotic ones under P and N limitations.
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  • 95
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    Entomologia experimentalis et applicata 92 (1999), S. 205-216 
    ISSN: 1570-7458
    Keywords: Samea multiplicalis ; Spodoptera pectinicornis ; Pistia stratiotes ; waterlettuce ; nitrogen utilization efficiency ; compensatory feeding ; nitrogen ; biological control of weeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Compensatory responses of caterpillars fed low quality food include increased consumption and utilization of essential nutrients. Information about an insect's responses to nutritional challenges from their host plants could benefit weed biological control efforts in the selection and establishment of new agents. The target weed, Pistia stratiotes L. (Araceae) is a floating aquatic plant that has relatively low nitrogen levels which are further diluted with high water content. Efforts to establish the insect Spodoptera pectinicornis (Hampson) (Lepidoptera: Noctuidae) for biological control of P. stratiotes could benefit by examining the nutritional responses of a similar widely established lepidopteran species, Samea multiplicalis (Guenèe) (Lepidoptera: Pyralidae). Larvae of this species were fed leaves of P. stratiotes plants that had been fertilized (NPK) at high and low rates. The leaves of the fertilized plants had a 4.3-fold increase in nitrogen (dry weight) and a 1.6-fold increase in water content. The results suggest that no compensatory increases occurred in larvae fed leaves from the low fertilized plants as no changes were found in fresh mass consumption or nitrogen utilization efficiency. Consequently, development time from second-third instars to pupation was delayed about 3 days compared with larvae fed the high nitrogen leaves. Furthermore, consumption of nitrogen was only 30% and its accumulation into larval tissues was only 60% compared with the larvae fed the high fertilized leaves. The resulting larvae had both a final biomass and a growth rate that were reduced by 40%. Regardless of plant fertilizer level, the larvae fed at a rate 5–10 times greater than that of similar lepidopteran species consuming either low or high quality diets, suggesting that the S. multiplicalis larvae may be functioning at their biological limit for ingesting food.
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  • 96
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    Entomologia experimentalis et applicata 92 (1999), S. 165-177 
    ISSN: 1570-7458
    Keywords: Chrysomelidae ; herbivory ; Asteraceae ; life history ; nitrogen ; plant quality ; season
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytophagous insects which feed on the leaves of herbaceous host plants have to adapt their life histories to the fact that protein nitrogen is usually highest in growing tissues in spring. We monitored field populations of larvae and adults of three chrysomelid species (Galeruca tanaceti (L.) (main host Achillea millefolium (L.) Yarrow), Cassida rubiginosa (Mueller) (main host Cirsium arvense (L.) Scop.) and Oreina luctuosa (Suffrian) (host Centaurea scabiosa (L.)) together with the amount of protein nitrogen of their food resources and host plant biomass. As expected, the development of host quality, measured as concentration of protein nitrogen, and host plant biomass showed inverse trends during the season. The euryphagous G. tanaceti attacks Achillea early and profits from high nitrogen concentrations in the leaves. Occasional overexploitations of local populations of Achillea are compensated by the capacity to move to other host species. In C. rubiginosa, a species with a host range restricted to the Cardueae, the main larval feeding activity is postponed to a period when the nitrogen content of the host leaves had dropped to 50% of its initial value, but when host plant biomass had increased by 30%. In the monophagous O. luctuosa the larval development is synchronized with a still later phase of host phenology, at which the nitrogen content is below 50% but plant biomass has reached its maximum. There seem to be selection factors, which oppose the use of high quality food in spring and which force the latter two species to postpone their larval development to a later time in the year. This could be caused by numerous factors like, for example, mean daytime temperature. Later in the season the larvae have to cope with the low quality of their host plants. They have, however, the advantage of large quantities of food available. A laboratory study with adults and mature larvae of O. luctuosa shows that this species can overcome low levels of protein nitrogen either by selecting younger leaves with higher nitrogen concentrations or by increasing the daily food consumption rate (RCR) on leaves with a low level of nitrogen and by a prolongation of the feeding period. In this way the larvae compensate the effect of lower daily growth rates (RGR) and a lower food conversion index (ECI) on poor food quality: Regardless of the level of protein nitrogen there was no statistically significant difference in total gain of weight during the third-instar feeding period and in the weight at the end of the third larval stage. The three investigated chrysomelids show that there exists a broad spectrum of adaptations to overcome the dilemma of variable food quality.
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  • 97
    ISSN: 1572-879X
    Keywords: adsorption ; adsorption isotherms ; dinitrogen ; FTIR spectroscopy ; geminal species ; NaY ; nitrogen ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Adsorption of N2 on NaY zeolites at 85 K and equilibrium pressures higher than 1 kPa results in the formation of geminal dinitrogen complexes characterized by an IR band at 2333.5 cm−1 (2255.4 cm−1 after adsorption of 15N2). With decreasing equilibrium pressure the complexes tend to loose one N2 ligand, thus forming linear species characterized by an IR band at 2336.8 cm−1 (2258.7 cm−1 after adsorption of 15N2). All species disappear completely after evacuation. Co-adsorption of N2 and CO revealed that the dinitrogen complexes are formed on Na+ cations. The changes in the concentrations of the linear and geminal N2 species with the changes in the equilibrium pressure are excellently described by equations of adsorption isotherms proposed earlier for mono- and di-carbonyls.
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  • 98
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
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  • 99
    ISSN: 1432-0789
    Keywords: Key words Grasslands ; Management ; Microbial biomass ; Bacteria ; Fungi ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  There is much interest in the development of agricultural land management strategies aimed at enhancing reliance on ecosystem self-regulation rather than on artificial inputs such as fertilisers and pesticides. This study tested the usefulness of measures of soil microbial biomass and fungal:bacterial biomass ratios as indicators of effective conversion from an intensive grassland system, reliant mainly on fertilisers for crop nutrition, to a low-input system reliant mainly on self-regulation through soil biological pathways of nutrient turnover. Analysis of soils from a wide range of meadow grassland sites in northern England, along a gradient of long-term management intensity, showed that fungal:bacterial biomass ratios (measured by phospholipid fatty acid analysis; PLFA) were consistently and significantly higher in the unfertilised than the fertilised grasslands. There was also some evidence that microbial biomass, measured by chloroform fumigation and total PLFA, was higher in the unfertilised than in the fertilised grasslands. It was also found that levels of inorganic nitrogen (N), in particular nitrate-N, were significantly higher in the fertilised than in the unfertilised grasslands. However, microbial activity, measured as basal respiration, did not differ between the sites. A field manipulation trial was conducted to determine whether the reinstatement of traditional management on an improved mesotrophic grassland, for 6 years, resulted in similar changes in the soil microbial community. It was found that neither the cessation of fertiliser applications nor changes in cutting and grazing management significantly affected soil microbial biomass or the fungal:bacterial biomass ratio. It is suggested that the lack of effects on the soil microbial community may be related to high residual fertility caused by retention of fertiliser N in the soil. On the basis of these results it is recommended that following the reinstatement of low-input management, the measurement of a significant increase in the soil fungal:bacterial biomass ratio, and perhaps total microbial biomass, may be an indicator of successful conversion to a grassland system reliant of self-regulation.
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  • 100
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    Biology and fertility of soils 29 (1999), S. 170-177 
    ISSN: 1432-0789
    Keywords: Key words Chitin degradation ; Succession ; Fungi ; Bacteria ; Actinomycetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The dynamics of culturable chitin-degrading microorganisms were studied during a 16-week incubation of chitin-amended coastal dune soils that differed in acidity. Soil samples were incubated at normal (5% w/w) and high (15% w/w) moisture levels. More than half of the added chitin was decomposed within 4 weeks of incubation in most soils. This rapid degradation was most likely due to fast-growing chitinolytic fungi (mainly Mortierella spp. and Fusarium spp.) at both moisture levels, as dense hyphal networks of these fungi were observed during the first 4 weeks of incubation. Chitin N mineralization was inhibited by cycloheximide, and fast-growing fungal isolates were capable of rapid chitin decomposition in sterile sand, further suggesting that these fungi play an important role in initial chitin degradation. The strong increase in fast-growing fungi in chitin-amended dune soils was only detected by direct observation. Plate counts and microscopic quantification of stained hyphae failed to reveal such an increase. During the first part of the incubation, numbers of unicellular chitinolytic bacteria also increased, but their contribution to chitin degradation was indicated to be of minor importance. During prolonged incubation, colony forming units (CFU) of chitinolytic streptomycetes and/or slow-growing fungi increased strongly in several soils, especially at the 5% moisture level. Hence, the general trend observed was a succession from fast-growing fungi and unicellular bacteria to actinomycetes and slow-growing fungi. Yet, the composition of chitinolytic CFU over time differed strongly between chitin-amended dune soils, and also between the two moisture levels. These differences could not be attributed to pH, organic matter or initial microbial composition. The possible consequence of such unpredictable variation in microbial community composition for the use of chitin-amendments as a biocontrol measure is discussed.
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