ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (4,342)
  • Quantum information
  • sediment
  • Physics  (4,028)
  • Biology  (250)
  • Energy, Environment Protection, Nuclear Power Engineering  (67)
Collection
  • Articles  (4,342)
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Estuarine and Coastal Marine Science 10 (1980), S. 699-702 
    ISSN: 0302-3524
    Keywords: England coast ; anaerobes ; hydrogen ; nitrogen fixation ; saltmarsh ; sediment ; sulphate ; sulphur bacteria
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 34 (1992), S. 347-363 
    ISSN: 0272-7714
    Keywords: Morlaix River estuary ; estuary ; fatty acids ; particulate organic matter ; sediment ; sewage influence ; sterols
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 34 (1992), S. 593-601 
    ISSN: 0272-7714
    Keywords: Gamma emitters ; Rhone estuary ; biodeposition ; mussel ; sediment ; tritium
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 38 (1994), S. 1-17 
    ISSN: 0272-7714
    Keywords: Dee Estuary ; fluxes ; particle mixing ; resuspension ; sediment ; trace metals
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 35 (1992), S. 105-111 
    ISSN: 0272-7714
    Keywords: comparison ; dry-sieving ; laser analysis ; particle size ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0272-7714
    Keywords: Hiroshima Bay ; bacteria ; biomass ; community structure ; phospholipid ester-linked fatty acids ; polyunsaturated fatty acids ; sediment ; sulphate-reducing bacteria
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical Systematics and Ecology 19 (1991), S. 395-400 
    ISSN: 0305-1978
    Keywords: Chitin ; chitin deacetylase ; chitinase ; chitosan ; estuary ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 11 (1997), S. 193-210 
    ISSN: 1436-3259
    Keywords: Turbulence ; sediment ; fluvial ; river ; bursting process ; statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Entrainment of sediment particles from channel beds into the channel flow is influenced by the characteristics of the flow turbulence which produces stochastic shear stress fluctuations at the bed. Recent studies of the structure of turbulent flow has recognized the importance of bursting processes as important mechanisms for the transfer of momentum into the laminar boundary layer. Of these processes, the sweep event has been recognized as the most important bursting event for entrainment of sediment particles as it imposes forces in the direction of the flow resulting in movement of particles by rolling, sliding and occasionally saltating. Similarly, the ejection event has been recognized as important for sediment transport since these events maintain the sediment particles in suspension. In this study, the characteristics of bursting processes and, in particular, the sweep event were investigated in a flume with a rough bed. The instantaneous velocity fluctuations of the flow were measured in two-dimensions using a small electromagnetic velocity meter and the turbulent shear stresses were determined from these velocity fluctuations. It was found that the shear stress applied to the sediment particles on the bed resulting from sweep events depends on the magnitude of the turbulent shear stress and its probability distribution. A statistical analysis of the experimental data was undertaken and it was found necessary to apply a Box-Cox transformation to transform the data into a normally distributed sample. This enabled determination of the mean shear stress, angle of action and standard error of estimate for sweep and ejection events. These instantaneous shear stresses were found to be greater than the mean flow shear stress and for the sweep event to be approximately 40 percent greater near the channel bed. Results from this analysis suggest that the critical shear stress determined from Shield's diagram is not sufficient to predict the initiation of motion due to its use of the temporal mean shear stress. It is suggested that initiation of particle motion, but not continuous motion, can occur earlier than suggested by Shield's diagram due to the higher shear stresses imposed on the particles by the stochastic shear stresses resulting from turbulence within the flow.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1572-8358
    Keywords: bioturbation ; modelling ; macrobenthic ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new model of bioturbation has been developed to describe short term sediment reworking induced by macrobenthic communities. The design of the model had to consider the mixing processes, firstly, at the organism level, and secondly, at community level. This paper describes the mixing mode of the four types of bioturbators defined by the authors: the biodiffusors, the upward-conveyors, the downward-conveyors and the regenerators. The mathematical formulation of these sub-models consists of ordinary differential equations. They take into account the size of the bioturbated zone, the output fluxes to the water column, tracer decay, physical mixing due to local currents and the type and intensity of the bioturbation processes. These sub-models make it possible to describe correctly the mixing events that have occurred in cores with each type of bioturbator. They also provide the basis for general bioturbation model, that will take into account the respective degrees of involvement of (i) the different bioturbation processes and their characteristics, (ii) the interference between the different processes, and (iii) make possible to predict the particle reworking in order to include it in studies of organic matter in early diagenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1420-9055
    Keywords: Iron ; manganese ; phosphate ; sediment ; diffusion ; eutrophic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water column data and porewater profiles are used to study the chemical evolution with time and with depth of a eutrophic lake. By using different approaches, diffusion fluxes for dissolved iron, manganese and phosphate are calculated and used to describe the processes occurring at the sediment-water interface as well as in the hypolimnion of the lake. These data are used in the elaboration of a qualitative model to describe the chemical behaviour of the sedimentary interface of an anoxic lake with emphasis on the Fe/P/S system. Acorona model is proposed to explain the evolution with time of the diffusion process by estimating the relative contribution of bottom and lateral sediment surfaces to the total fluxes of dissolved elements diffusing from the sediment to the overlying water. As the hypolimnion becomes more anoxic, it has been observed that lateral sediment surfaces (16 to 10 meters in depth) represents a larger supplier of diffusing dissolved components than the bottom sediment portion (bottom to 18 meters).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 47 (1991), S. 517-523 
    ISSN: 1420-9071
    Keywords: Bacterial activity ; sediment ; pore water ; deep sea ; electron acceptors ; microcosms ; nitrification ; denitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In spite of high pressures and low temperatures in abyssal sediments of the North Atlantic Ocean, bacterial activity is evident and highest in the top 10 cm. At these locations the input of degradable organic material to the deep-sea bottom is low. Oxygen, therefore, remains the dominant oxidant in surface sediments. Although alternative electron acceptors like nitrate, oxidized manganese and sulfate are present in large amounts, they are not utilized in this natural habitat. In sediment cores which were collected from the site for laboratory perturbation studies, it was possible to stimulate microbially mediated processes which are dormant in situ. When the oxygen supply was cut off, nitrate and manganese reduction occurred. Denitrification was the major process observed in the upper anoxic layers, while nitrate-ammonification and manganese reduction occurred in deeper sediment strata (4–8 cm). This is evidence for the presence of a variety of different bacteria and of an anaerobic heterotrophic potential. Most of the activity is located in the top 10 cm of these sediments. The shift to anaerobiosis initiates microbial activities through which metals are converted into their mobile species at the lowered redox potential. Evaluation of the suitability of the deep sea as a repository for waste materials will have to account for the large dormant potential of microbial activities and the consequences of their release by changing the environmental conditions at the sea floor.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1572-977X
    Keywords: erosion ; pioneer vegetation ; salt marsh ; seedlings ; sediment ; shear strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the last two decades a decrease of salt marsh area of at least 6% was found along the mainland coast of the Dutch Wadden Sea. However, it was not clear what determined the seaward boundary of the pioneer vegetation in this area. In the period 1993–1995, abiotic and biological variables were monitored along a transect from the mudflat to the low salt marsh in two sites, the Negenboerenpolder and the Noordpolder. At the Negenboerenpolder site the pioneer zone extended further from the dike and had a dense cover with vegetation when compared to the Noordpolder site. The observed difference in extension of the pioneer zone could not be attributed to differences in tidal frequency, sedimentation rate or nutrient availability. During the winter a dramatic loss in seed numbers was found at both sites. This loss decreased from mudflat to low marsh. The mud/sand ratio, on the other hand, increased from mudflat to low marsh and was higher in the Negenboerenpolder. The shear strength of the top soil layer measured with an in‐situ erosion flume was correlated to the mud/sand ratio and increased with an increasing mud content of the soil. The strength of the soil seems to be the key factor for the settlement and survival of Salicornia dolichostachya in the pioneer zone.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 19 (1998), S. 255-264 
    ISSN: 1573-0417
    Keywords: Lake Winnipeg ; magnetic resonance ; MRI ; SPRITE ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract As part of the Geologic Survey of Canada (GSC) Lake Winnipeg Study, we have successfully imaged the Lake Agassiz to Lake Winnipeg transition in Section 4 of Core Namao 94-900-122a (i.e., from 313 cm to 465 cm), using a newly-developed magnetic resonance imaging (MRI) technique called SPRITE (Single-Point, Ramped Imaging with T1 Enhancement). Whole core, gamma-ray attenuation measurements have been used to calculate the bulk porosity of the sediment at 1 cm intervals for comparison with the SPRITE images. Image contrast and image intensities observed in the SPRITE images of Section 4 are related to local porosity and magnetic susceptibility variations. In general, regions of the core with low signal intensity contain high porosity and low magnetic susceptibility. The best contrast between sediment layers is observed from regions of the core with high magnetic susceptibility. High signal intensity is observed from regions with low porosity and/or high magnetic susceptibility.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    ISSN: 1573-0417
    Keywords: sediment ; physical properties ; core-correlation ; stratigraphy ; acoustics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract High resolution sediment physical properties, measured on gravity and piston cores collected during cruises to Lake Winnipeg, include bulk density, acoustic velocity, magnetic susceptibility, shear strength and colour reflectance. The high resolution data are used here to construct complete stratigraphic (composite) sections of Lake Winnipeg sediments from a series of individual, discontinuous cores for the North and South Basins. These composite sections are used to evaluate basin-wide glacial and post-glacial depositional histories and to compare the northern and southern basin histories. In addition, these sections provide a baseline depth reference for interpretation of the biostratigraphy, paleomagnetic record and rock magnetic stratigraphy. Some of the data (density and shear strength) are also be used to estimate sediment stress history for the two major lithostratigraphic units and their variations across the basin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 9 (1993), S. 109-127 
    ISSN: 1573-0417
    Keywords: paleolimnology ; carotenoid ; chlorophyll ; pigment ; sediment ; fossil ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Limnological surveys show that fossil pigment concentration is an accurate predictor of algal production. However, experimental and mass flux studies indicate that 〉90% of pigment is degraded to colourless compounds before permanent burial. To reconcile these views, this paper reviews current literature on pigment degradation and proposes a hierarchical control model for pigment deposition and fossil abundance. Over the widest range of production, pigment deposition and fossil concentration are proportional to algal standing crop. However, within a narrower range, the actual concentration of pigment in sediments is regulated by photo- and chemical oxidation. Three phases of loss exist: rapid oxidation in the water column (T1/2=days); slower post-depositional loss in surface sediments (T1/2=years); and very slow loss of double bonds in deep sediments (T1/2=centuries). Despite losses during deposition, fossil and algal abundance remain correlated through time, so long as there is no change in basin morphometry, light penetration, stratification or deepwater oxygen content. At the finest scale, food-web processes can increase the preservation of pigments from edible algae by incorporating pigments into feces that sink rapidly and bypass water column losses. As a consequence of selective loss during deposition and initial burial, carotenoid relative abundance is an unreliable measure of phytoplankton community composition. Instead, absolute concentration — scaled to the historical maximum — should be used for fossil interpretations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 9 (1993), S. 179-188 
    ISSN: 1573-0417
    Keywords: distribution coefficient ; Kd ; 210Pb ; 210Po ; freshwater ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We have measured the distribution coefficient (Kd) of210Po and210Pb in laboratory systems and in natural freshwater systems. In the laboratory systems, an inverse relationship was observed between the particle concentration of sand or lake sediment, and the distribution coefficients of210Po and210Pb. The slope of the log-linearK d vs particle concentration relation is consistent with existingK d-particle concentration theories. These laboratory observations are consistent with similar measurements in two lakes. TheK d values of Po and Pb for the bottom sediment-pore water system with a high particle concentration were 10 to 100 times lower than those for dilute concentrations of particles suspended in the lake water. TheK d of210Pb in the sediments was 〉104 so that the diffusive transport of210Pb has only a small influence on the interpretation of210Pb concentration-depth profiles and the210Pb dating of these sediments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 1 (1988), S. 215-227 
    ISSN: 1573-0417
    Keywords: Carotenoids ; degradation ; myxoxanthophyll ; β-carotene ; sediment ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Reversed-phase thin layer chromatography was used to quantify carotenoid degradation resulting from the in vitro decomposition of Oscillatoria utermöhlii. Laboratory conditions simulated lacustrine sediments. The effects of light, oxygen, temperature and the presence of a sedimentary bacterial flora on the rate and extent of degradation were evaluated. Under anaerobic conditions, bacterially-mediated decomposition of O. utermöhlii did not result in statistically significant (P〉0.05) declines in the concentrations of most carotenoids at either 6 °C after 37 weeks or 21 °C after 26 weeks. Light, in the absence of oxygen, did not promote carotenoid degradation. Carotenoid concentrations declined linearly with time (25%–62% lost by 37 weeks) in a dark environment exposed to the atmosphere at 6 °C, but only if algae were exposed to lake sediments or water containing natural, lacustrine bacterial populations. No distinct difference between the rates of carotene and xanthophyll destruction was noted, although myxoxanthophyll was more labile than other cyanophyte carotenoids, especially at 21 °C (85% loss by 26 weeks). Based on these results and published descriptions of algal decomposition kinetics, I conclude that; 1) the high sedimentary carotenoid concentrations typical of productive lakes may reflect a preferential loss of nonpigmented organic matter and, 2) sedimentary bacterial activity alone may not affect the reliability of carotenoids as paleolimnological indicators of past algal abundances in lakes with completely anoxic sediments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 16 (1996), S. 133-149 
    ISSN: 1573-0417
    Keywords: climate ; hydrology ; paleoclimate ; sediment ; arctic ; Ellesmere Island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Streamflow, suspended sediment transport and meteorological variables at two elevations were measured through the 1990–1992 field seasons at Lake C2, Northern Ellesmere Island, as part of the Taconite Inlet Lakes Project. The objectives were to determine the extent to which suspended sediment flux responded to climatic variability, and to ascertain which meteorological variable was most strongly associated with daily discharge and sediment load. This study provided a partial test of our hypothesis that the annually-laminated sediments of Lake C2 contain a paleoclimate signal. Streamflow to the lake was almost exclusively the result of snowmelt, in response to inputs of atmospheric energy as measured by air temperature at the median watershed elevation (520 m). Sea-level air temperature, global solar and net all-wave irradiance were less clearly associated with discharge. Fluctuations of discharge and suspended sediment concentration were nearly synchronous, and non-linearly related. Daily sediment discharge was therefore linked by streamflow, with a time lag, to the energy available for snowmelt. Mean daily air temperature and cumulative degree-days above 0 °C, at 520 m elevation, were successfully used to predict the daily and seasonal discharge of runoff and sediment to the lake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 23 (2000), S. 213-221 
    ISSN: 1573-0417
    Keywords: geochemistry ; heavy metals ; palaeolimnology ; sediment ; soil ; X-ray fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Energy dispersive isotope-source X-ray fluorescence (XRF) analysers are little used in academic environmental research, in spite of being ideally suited to a number of tasks. In this paper an XRF method is tested by measuring a wide range of environmental materials of known elemental composition. Precision, accuracy and detection limits are presented. Using isotope-source X-ray fluorescence analysis, the total concentrations of Si, Ti, Ca, K, Fe, Mn, Cl, S, Nb, Ni, Pb, Rb, Sr, Zn and Zr can be determined in soils and sediments at a rate of 〉70 samples per day. The combination of speed and accuracy makes the technique ideal for three classes of application within environmental research. First, in sediments and soils that are highly heterogeneous, reliable characterisation is more dependent upon the number of samples measured than on measurement precision or accuracy. Under these circumstances the method is sufficiently accurate to be used alone. This is also the case where there is high and wide ranging contamination of sediment or soil by Pb and Zn. Second, major elements (Si, Ti, Fe, Ca, K and S) can be measured with sufficient accuracy in sediments and soils to aid the interpretation of other sediment chemical analyses. Third, the technique is ideal for the rapid screening of sediment or soil, allowing effective targeting of samples for more time consuming or expensive analyses. The XRF method presented here offers rapid, non-destructive total elemental analysis of sediments and soils that is sufficiently accurate to be useful in environmental research.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 5 (1991), S. 263-266 
    ISSN: 1573-0417
    Keywords: scaled chrysophytes ; road salt ; Fonda Lake ; Michigan ; paleolimnology ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Chrysophyte scales were identified and enumerated from the recent sediments of Fonda Lake, Michigan. This lake has undergone marked salinification due to chloride intrusion from an adjacent salt-storage facility established in 1953. From 1950 to 1980, Mallomonas caudata dominated at all levels; this taxon appears to be chloride-indifferent. M. elongata and M. pseudocoronata appeared to be chloride-intolerant as they declined drastically in abundance when chloride levels attained a maximum (ca. 1968–1972). M. tonsurata, on the other hand, was more competitive during this period of maximum [Cl\s-]. This preliminary study suggests that chrysophyte scales may be useful paleoindicators of salinity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 7 (1992), S. 127-135 
    ISSN: 1573-0417
    Keywords: bacteria ; dormancy ; longevity ; sediment ; spores ; palaeoecology ; palaeolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Lake sediments contain viable allochthonous bacteria that can be cultured and used for palaeoecological studies. To be a good palaeoindicator, a bacterium must be able to survive in sediments for long periods of time, but also be unable to reproduce in the lake bottom. Bacteria can survive the unfavourable environmental conditions in lake sediments as resting cells. The endospore is the most specialized form and gives the bacterium an extreme longevity. The oldest viable endospores isolated from lake sediments that we are aware of are about 9000 years old. Several species, mainly in the genera Thermoactinomyces, Bacillus and Clostridium, form endospores. Clostridium perfringens has been used as palaeoindicator for sewage pollution, while Thermoactinomyces vulgaris is an indicator for past agricultural activity in the boreal forest zone and a potential climatic indicator in other vegetation zones. Although isolation and enumeration of bacterial endospores from lake sediments is rather easy and has considerable potential as a powerful tool in palaeoecology, the number of studies using palaeoecological approaches is limited.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 1573-0417
    Keywords: magnetic measurements ; Dianchi Lake ; sediment ; Palaeoenvironmental change ; particle-sizebased characterisation ; China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Mineral magnetic measurements have been made on a long sediment core from Dianchi Lake, Southwest China. They have been used for sediment stratigraphy, for bulk lithological classification and for detailed particle-size-based characterisation. These results are set alongside those derived from geochemical, granulometric and pollen analysis to reconstruct the environmental processes recorded in the radiocarbon dated sediment column. It is suggested that the variations of magnetic properties in this sediment core are mainly the result of changes in particle size constitution or organic content, implying shifts in the sedimentary environment. Three distinctive stratigraphic horizons, with several subdivisions, have been identified on the basis of the magnetic measurements. They are coincident with the pollen assemblage zones, indicating the different climatic periods in the Kunming Basin since late Pleistocene times. This paper proposes that a major shift in sedimentation, from lake to reedswamp, occurred in approximately 10 000–12 000 BP, in response to climatic change.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1573-0417
    Keywords: diatoms ; pollen ; sediment ; reservoir limnology ; land-use change ; Texas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract White Rock Lake reservoir in Dallas, Texas contains a 150-cm sediment record of silty clay that documents land-use changes since its construction in 1912. Pollen analysis corroborates historical evidence that between 1912 and 1950 the watershed was primarily agricultural. Land disturbance by plowing coupled with strong and variable spring precipitation caused large amounts of sediment to enter the lake during this period. Diatoms were not preserved at this time probably because of low productivity compared to diatom dissolution by warm, alkaline water prior to burial in the sediments. After 1956, the watershed became progressively urbanized. Erosion decreased, land stabilized, and pollen of riparian trees increased as the lake water became somewhat less turbid. By 1986 the sediment record indicates that diatom productivity had increased beyond rates of diatom destruction. Neither increased nutrients nor reduced pesticides can account for increased diatom productivity, but grain size studies imply that before 1986 diatoms were light limited by high levels of turbidity. This study documents how reservoirs may relate to land-use practices and how watershed management could extend reservoir life and improve water quality.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 7 (1992), S. 145-156 
    ISSN: 1573-0417
    Keywords: Experimental Lake Area (ELA) ; paleolimnology ; inferred pH ; diatoms ; acidification ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Relationships between sedimentary diatom assemblages and lakewater pH values from 36 lakes and experimentally acidified Lake 223, in the Experimental Lakes Area, were analyzed. The relationships were used to assign diatoms in the 36 lakes into pH preference groupings. Based on their regional distribution Cyclotella stelligera and Tabellaria flocculosa strain IIIp were categorized as pH indifferent, in comparison to other areas were they have been categorized as acidophilic. Two models were then applied to calculate transfer coefficients which were used to calculate diatom-inferred pH values for Lake 223. Index B and a multiple linear regression of the pH groupings yielded similar correlations (r2 0.82 and 0.84 respectively, p=0.0001). The multiple linear regression inferred a pH of 5.36 for acidified Lake 223 compared to a measured pH of 5.46.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 1573-0417
    Keywords: palaeolimnology ; environmental change ; sediment ; eutrophication ; chironomids ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The sedimentary chironomid stratigraphy in short-core samples covering approx. the past 150 years was studied in the northernmost basin of Lake Päijänne, southern Finland (62° 11′ N, 25° 48′ E). The basin has received effluent loading from the wood-processing industry and municipal waste water. Four developmental stages were distinguished based on the changes in chironomid assemblages: 1. Pre-industrial stage (dated by the210Pb method as covering approximately the period 1838–1936), 2. Stage of increasing pollution (approx. 1944–1973), 3. The ‘black decade’, or the period of worst pollution (approx. 1973–1983), and 4. Water protection stage (approx. 1983 onwards). During the first stage the basin suffered very little human interference and was oligotrophic, with values of 4.00–4.28 for Wiederholm's Benthic Quality Index (BQI). During the second stage it altered between weak mesotrophy and moderate mesotrophy, and the former profundal assemblages characterized byHeterotrissocladius subpilosus andMicropsectra were replaced bySergentia coracina andChironomus anthracinus gr. The BQI ranged from 2.75 to 3.50. This process led to the extirpation ofH. subpilosus. Eutrophication of the basin reached its climax during the ‘black decade’, representing moderate eutrophy with a BQI of 2.15. The profundal assemblages were composed mainly ofChironomus anthracinus gr. andC. plumosus gr. The adoption of more effective waste water purification processes in both the wood-processing industry and the municipal treatment plant markedly reduced effluent loading, especially BOD loading during the fourth stage, and this led to a recovery in the basin. At present it is mesotrophic, with a BQI of 2.90–3.00, and its biological conditions resemble those of the second stage in the 1950's and 1960's.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 1573-0417
    Keywords: jpalaeolimnology ; boreal lake ; diffuse loading ; eutrophication ; sediment ; trophic state ; diatoms ; chironomids ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The recent environmental history of Lake Lappajärvi in western Finland (63°00′ N, 23°30′ E, area 149 km2), a humic, brown water lake with an average phosphorus content of ca. 20 μg l–1, was studied from short core sediment samples taken from the two main basins of the lake. Based on the stratigraphy of diatoms and chironomids and the sediment quality it was possible to distinguish four developmental stages during the past century: (1) a pre-industrial stage covering the time up to about 1935; (2) a stage of increasing nutrient loading (ca. 1936–1960); (3) a stage of pronounced erosion from lake level regulation and extensive ditching of the catchment area (ca. 1960–1970); and (4) a meso-eutrophic stage from ca. 1970 onwards. Acidophilous Aulacoseira distans coll. and other species typical of dystrophic, nutrient-poor lakes characterized the diatom assemblages during the first stage, and the profundal zoobenthic assemblages, characterized by Heterotrissocladius subpilosus and Micropsectra, indicated good hypolimnetic oxygen conditions and a low sedimentation of organic matter (approx. less than 50 g m–2 a–1). The increased loading rapidly led to changes both in diatoms and chironomids (e.g., to an early extinction of H. subpilosus in the 1950s). The process finally led to eutrophication with a successive proliferation of diatom species such as Asterionella formosa followed by Aulacoseira ambigua, Fragilaria crotonensis, and finally Melosira varians. The relative proportion of alkaliphilous species reached a maximum in the final stage and the original profundal chironomid fauna was replaced by Chironomus anthracinus gr. and C. plumosus which are typical of profundal areas suffering from temporal oxygen deficit. It is notable that the considerable decrease in waste water loading from the point sources (80–86% ) during the past two decades has not led to a recovery in the lake. This highlights the importance of diffuse loading from agriculture, forestry and other human activities even to this comparatively large lake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Landscape ecology 11 (1996), S. 27-38 
    ISSN: 1572-9761
    Keywords: abandoned channels ; floodplain ; nitrogen ; organic matter ; phosphorous ; potassium ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of sediments in abandoned channels is an important component of their development as floodplain wetlands. The texture, organic matter, phosphorous, potassium, and nitrogen content of sediments were determined for abandoned channels along the Iowa and Cedar Rivers near their confluence in Iowa. Differences in the levels of these constituents were examined among categories of three landscape gradients: present connectivity to the river, time since abandonment, and proximity to agricultural land use. Local scale processes of ecological development are seen in the importance of time for increased organic matter and nitrogen. Basin scale processes of sediment transport and deposition are revealed by the importance of connectivity for decreases in these two elements, and by the counter-intuitive findings for nitrogen and especially phosphorous and potassium in relation to agricultural proximity. Location on a floodplain is important for differentiating development, but it cannot be reduced to univariate gradients.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Mangroves and salt marshes 2 (1998), S. 199-204 
    ISSN: 1572-977X
    Keywords: mangrove ; organic carbon ; Rhizophora ; root biomass ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Above‐ground and below‐ground root biomasses (Babove and Broot) were measured for young, isolated Rhizophorastylosa on Iriomote Island, Japan. The relationship between these two parameters was significant and given as the equation, Broot (g dry weight) = 0.394 × Babove (g dry weight) − 485  (r = 0.986). Multiple regression analyses also revealed good correlation between diameter and biomass of prop roots (Dprop and Bprop) and between prop root and root biomasses. Consequently, root biomass could be estimated from the measurements of diameter and biomass of prop roots using the multiple regression equation, Broot (g dry weight) = 80.0 ×Dprop (cm) + 0.86 ×Bprop  (g dry weight) − 251. The relationship between DBH (diameter at breast height) and prop root biomass was also adequately described using an allometric equation. In Hinchinbrook Channel, Australia, redox potential (measured as Eh) and organic carbon stocks in the top 5 cm of mangrove sediments were measured along a 600 m transect from the frequently inundated, Rhizophora dominated zone on the creek edge, towards higher grounds, where Ceriops spp. became increasingly dominant. Eh values were about −60 mV near the creek edge and increased to 260 mV on higher grounds. Organic carbon stocks showed an opposite trend to Eh, with the values decreasing from about 360 t C ha−1 to 160 t C ha−1. At 18 sites, representing six different habitats, organic carbon stocks were also measured along with the DBH of mangrove trees. DBH was converted into above‐ground biomass and then into root biomass using the equations obtained in the study on Iriomote Island. The average organic carbon stocks in the top 50 cm of sediments, above‐ground biomass and root biomass were 296 t C ha−1, 123 t C ha−1 and 52 t C ha−1, respectively, and accounted for 64%, 25% and 11% of the total organic carbon stock.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Mangroves and salt marshes 2 (1998), S. 205-221 
    ISSN: 1572-977X
    Keywords: carbon flux ; flocculation ; Hinchinbrook ; mangroves ; sediment ; turbidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A field and model study was undertaken in 1996/1997 of the dynamics of water, fine sediment and particulate carbon in the northern region of the mangrove‐fringed Hinchinbrook Channel, Australia. The currents were primarily tidal and modulated by the wind. Biological detritus acted as a coagulant for the fine cohesive sediment in suspension in the mangrove‐fringed, muddy coastal waters. Plankton and bacteria were the major aggregating agents at neap tides, and mangrove detritus at spring tides. The micro‐aggregates were typically several hundreds of micrometer in diameter and enhanced the settling rate. The fate of fine sediment and particulate carbon was controlled by the dynamics of the coastal boundary layer, a turbid shallow coastal water zone along the mangrove‐fringed coast. A tidally‐modulated, turbidity maximum zone was found in this layer. Wind stirring increased the turbidity by a factor of five. The channel behaves as a sink trapping fine sediment and particulate carbon. However, the sink was ‘leaky’ because the dynamics of the coastal boundary layer generated a net outflow of fine sediment out of the channel along the western coast. The biologically enhanced settling of cohesive sediment limited the offshore extent of the muddy suspension to within a few hundreds of meters from the coast. At spring flood tides, some of this particulate carbon was advected into the mangrove forest where it would remain trapped. On a yearly basis about six times as much particulate carbon was exported out of Hinchinbrook Channel through the coastal boundary layer than was trapped in the fringing mangroves.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Mangroves and salt marshes 3 (1999), S. 227-241 
    ISSN: 1572-977X
    Keywords: flux ; habitat creation ; nutrient ; organic ; pollution ; sea level rise ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Salt marshes are no longer viewed as intertidal wastelands of little value to anyone. They are now widely recognised as playing a major role in coastal defence, in wildlife conservation on the coast and as a key source of organic material and nutrients vitally important for a wide range of marine communities. This appreciation of the importance of salt marshes has been brought even more sharply into focus because of the threats posed by predicted rise in sea level as a result of global climatic change. Three decades ago the possibilities of exchanges of organic matter between salt marshes and the sea were already being recognised in certain areas but it is only in the past five years or so that this process has been studied in a wide range of different areas. Detailed studies have been made into the way that salt marsh fluxes change with the development of increasingly mature and, therefore, increasingly complex salt marsh communities. As well as being sources and sinks of mineral nutrients and organic matter, salt marshes can also function as a sink for pollutants that would otherwise be damaging to the environment. Salt marshes also act as a sink for sediment within coastal ecosystems. Through their various functions they can be seen to be acting as dynamic living filters for various ecologically important materials. With increasing threats to the survival of salt marshes as a result of man's activities in the coastal zone being augmented by the threats from predicted sea level rise, a new approach to salt marsh conservation has come to the fore and that is the actual creation of new salt marshes. For this process to be fully effective we have to make full use of our increased understanding of salt marsh structure and function. Following a review of the current state of the art in the field of salt marsh research, an assessment is made of specific future research needs. Despite the greatly increased effort which has been directed to salt marsh research over the past few years we still have to recognise that resources are limited and, therefore, critical evaluations of the various options regarding the direction of our future efforts need to be made.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Landscape ecology 6 (1992), S. 121-132 
    ISSN: 1572-9761
    Keywords: floodplain ; geomorphology ; sediment ; nutrients ; organic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is now well accepted that riparian forests have an important role in regulating upstream/downstream flow of matter and energy in river ecosystems. Since geomorphic processes determine the structure of channels and floodplains, we have investigated whether different geomorphic features of riparian forests had any effects on the ability of their soils to retain nutrients and organic carbon. Willow riparian forests were chosen within the annual floodplain of the Garonne River, southwest France, to represent two different geomorphic types. Erosional types of riparian forests (E-type) were characterized by sand deposition on their soils because of high current velocity which hampered fine particle deposition. Depositional types of riparian forests (D-type) were characterized by slower overflow velocity; consequently silt and clay were dominant in their soils. Soil samples were taken at the end of the vegetation growth period, coinciding with low water levels prior to annual floods. Erosion and sedimentation processes affected the distribution of total C,N, and P contents in riparian forest soils, since they were significantly correlated with soil grain size. D-type riparian forest soils act as a sink for upstream/downstream nutrients and carbon flows during floods through accumulation of total C,N and P from year to year. In contrast, E-type riparian forests act as potential nutrient sources during high water periods, since they may release from their soils large amounts of easily available C, N and P into the river. These results demonstrate that nutrients and carbon retention ability of riparian forests soils should be analyzed through their geomorphic features rather than by their vegetation composition. Even if they belong to the same vegetation succession, riparian forests should not be considered as a homogeneous buffering system for upstream/downstream flows of nutrients and organic carbon.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 144 (1995), S. 525-536 
    ISSN: 1420-9136
    Keywords: Tsunami ; coastal sedimentation ; sorting processes ; particle size ; modal population ; geomorphology ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper presents the result of a detailed granulometric investigation of sediments deposited by a modern tsunami, the 1992 tsunami in Flores, Indonesia. Eyewitness accounts indicate that sediments were deposited upon coastal lowlands over wide areas as a result of the tsunami inundation. Distinctive vertical and lateral variations in particle size composition are characteristic features of the tsunami deposits and these are intimately related to sedimentary processes associated with flood inundation. The geomorphological and sedimentary evidence is used here to establish a preliminary model of tsunami sedimentation. This information is believed to be of great value in understanding sedimentary processes associated with tsunami flooding and in the interpretation of palaeo-tsunami deposits.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 43 (1987), S. 234-241 
    ISSN: 1420-9071
    Keywords: Rain forest ; sediment ; latosol ; podzol ; geochemical land morphogenesis ; dynamic ; equilibrium and disequilibrium ; aluminium ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The dynamics of the forest to the north of Manaus is tightly linked to that of the soil. The latosol that covers the plateau, which supports a dense forest, consists from top to bottom of: (a) a brown, clayey organic horizon (0.3 m), (b) a yellow horizon, very rich in clay but permeable (from 0.3 to 4 m), (c) a nodular horizon rich in Al and Fe oxides (from 4 to 9 m), and (d) a horizon which still preserves the sedimentary structures of the parent sandstone, where quartz is intensely dissolved and kaolinite crystallizes in pores. In perfectly flat areas, the clay of the organic horizon is destroyed by acidocomplexolysis, and the dissolved Al is transported vertically by the drainage water. A part of this Al is used to make the gibbsite nodules of horizon (c), and the rest is used to make kaolinite in horizon (d). Because aluminum is thus conserved within any vertical prism, the rate of destruction of horizon (a) is equivalent to the rate of advance of the kaolinization zone into the sediment: the latosol is said to be in equilibrium, the surface remains perfectly flat as it slowly sinks, the quantity of kaolinite increases with time, and the silica released by quartz dissolution in the whole profile is exported by drainage water to the water table. In contrast, near drainage axes, however small initially, the drainage becomes inclined toward the axis. Part of the Al released by acidocomplexolysis of horizon (a) is now exported to rivers, and Al is no longer conserved within any given prism. The rate of advance of the kaolinization zone (d) into the sediment now becomes less than the rate of destruction of horizon (a) and the surface sinks faster than that of the surrounding plateau. After this differential ‘podzolization’ has gone on long enough, it creates a network of ‘geochemical valleys’ characterized by convex slopes and bounded by sandy soils (campinas). The vegetation becomes sparser and sparser. At the end, only some bushes and lichens survive on the white sand.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Keywords: Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 51 (1989), S. 306-316 
    ISSN: 1420-9055
    Keywords: Inorganic phosphorus ; sediment ; grain size ; reservoir
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inorganic P was fractionated into three categories (NaOH-, BD- and HCI-extractable) for 30 surface sediment samples in La Minilla Reservoir (Sevilla, Spain). The amount of reactive P extracted with NaOH (NaOH-RP) and with HCI (HCI-RP) correlated in a multivariate regression with the clay and sand content of the sediment. This multivariate function should aid in predicting the amount of phosphorus available to the sediment organisms, and it can also contribute to the knowledge of the phosphorus budget of the reservoir.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1420-9055
    Keywords: Coprostanol ; cholestanol ; cholesterol ; fecal indicator ; sediment ; microbial reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coprostanol has been proven to be a good specific allochthonous fecal indicator in sedimentary surface samples of the lake of Neuchâtel (Switzerland). Its concentration is slightly affected in surface sediment by the microbial reduction of cholesterol to cholestanol and coprostanol.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 54 (1992), S. 238-254 
    ISSN: 1420-9055
    Keywords: Chernobyl ; Cs-137 ; sediment ; pore water ; redox processes ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A rapid removal of Chernobyl137Cs from a number of large lakes has been previously reported. Our measurements of137Cs in water, sediments and pore water in the mono- and meromictic basins of Lake Lugano (Lago di Lugano) reveal generally slower half-removal times of 1.2 and 6.7 yrs, respectively. In the seasonally anoxic southern basin, this is most probably related to an intensive recycling of137Cs between water and sediments. In the permanently stratified northern basin the removal rate is much slower due to an important inventory build up in the deep anoxic part of the basin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 128 (1988), S. 683-724 
    ISSN: 1420-9136
    Keywords: Continental crust ; crustal evolution ; isotopes ; mantle ; recycling ; sediment ; subduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In order to understand the evolution of the crust-mantle system, it is important to recognize the role played by the recycling of continental crust. Crustal recycling can be considered as two fundamentally distinct processes: 1) intracrustal recycling and 2) crust-mantle recycling. Intracrustal recycling is the turnover of crustal material by processes taking place wholly within the crust and includes most sedimentary recycling, isotopic resetting (metamorphism), intracrustal melting and assimilation. Crust-mantle recycling is the transfer of crustal material to the mantle with possible subsequent return to the crust. Intracrustal recycling is important in interpreting secular changes in sediment composition through time. It also explains differences found in crustal area-age patterns measured by different isotopic systems and may also play a role in modeling crustal growth curves based on Nd-model ages. Crustal-mantle recycling, for the most part, is a subduction process and may be considered on three levels. The first is recycling with only short periods of time in the mantle (〈10 m.y.). This may be important in explaining the origin of island-arc and related igneous rocks; there is growing agreement that 1–3% recycled sediment is involved in their origin. Components of recycled crustal material, with long-term storage (up to 2.5 b.y.) in the mantle as distinct entities, has been suggested for the origin of ocean island and ultrapotassic volcanics but there is considerably less agreement on this interpretation. A third proposal calls for the return of crustal material to the mantle with efficient remixing in order to swamp the geochemical and isotopic signature of the recycled component by the mantle. This type of recycling is required for steady-state models of crustal evolution where the mass of the continents remains constant over geological time. It is unlikely if crust-mantle recycling has exceeded 0.75 km3/yr over the past 1–2 Ga. Good evidence exists that selective recycling is an important process. Sedimentary rocks preserved in different tectonic settings are apparently recycled at different rates, resulting in a bias in the sediment types preserved in the geologic record. Selective recycling has important implications for the interpretation of Nd model ages of old sedimentary rocks and in the analysis of accreted terranes. Although there is evidence that continental crust was formed prior to 3.8 Ga, the oldest preserved rocks do not exceed this age. It is likely that the intense meteorite bombardment, which affected the earth during the period 4.56–3.8 Ga, coupled with rapid mantle convection, which resulted from greater heat production, caused the destruction and probable recycling into the mantle of any early formed crust. Although crust-mantle recycling is seen as a viable process, it is concluded that crustal growth has exceeded crust-mantle recycling since at least 3.8 Ga. Intracrustal recycling has not been given adequate consideration in models of crustal growth based on isotopic data (particularly Nd model ages). It is concluded that crustal growth curves based on Nd model ages, while vastly superior to those based on K/Ar or Rb/Sr, tend to underestimate the volume of old crust, due to crust-mantle and/or intracrustal recycling.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 99 (1997), S. 81-88 
    ISSN: 1573-2932
    Keywords: channel ; bend ; sediment ; size ; gradation ; sorting ; bed ; topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Variations of sediment size and its gradation of the bed surface layer in a channel bend with nonuniform sediment are investigated experimentally. Four groups of sediment with the same initial median diameter (D0) but different initial size gradation (σ0) have been used for experiments which were run until the equilibrium bed topography was achieved. Analyses of experimental data have yielded the following results: (1) The time of equilibrium for bed evolution decreases as σ0 increases; (2) the median size of sediment (D) for a given section in the bend increases with increasing distance from the inner bank towards the outer bank, and it also increases with increasing σ0; (3) the value of D/D0 along the inner bank decreases with increasing σ0, and it also shows a gradual decrease in the upper half of the bend and a slight recovery in the lower half; and (5) the transverse variation of σ value exhibits a general trend increasing from the inner bank towards the outer bank.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 1573-2932
    Keywords: phosphorus ; P flux ; microbial activity ; redox ; simulation ; Lake Kinneret ; sediment ; accumulative P release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment-water interface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation of the bacteria at the SWI.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 99 (1997), S. 457-464 
    ISSN: 1573-2932
    Keywords: sediment ; phosphorus ; fractionation ; release ; humic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Lake Flosek (north-eastern part of Poland) is a small shallow and without outflow lake which has been limed in 1970. The concentration of Ca was increased from 3-4 mg L-1 to 17 mg L-1 in the water and from 0.2-0.3% dry weight to 0.9-1.7% dry weight in sediments (5 cm upper layer) due to CaCO3 addition to the lake. In the spring-summer seasons of 1992 and 1993, an experimental study was conducted in Lake Flosek to assess the capacity of bottom sediments to uptake and release mineral phosphorus. The rate of phosphorus exchange between sediments and near-bottom water was experimentally measured under conditions of high (100%), and of reduced (10%) oxygen saturation in near-bottom water. To determine the component of sediments responsible for the uptake of most phosphorus, the proportions of phosphorus forms in sediments were analysed. Sediments of Lake Flosek showed a slight tendency to release phosphates. The rate of this process was similar under high (100%) and low (10%) oxygen saturations ranging from - 0.161 to + 0.200 mg P m-2 d-1. This is much lower (by 1-2 orders of magnitude) than reported from other harmonic, non-humic lakes. In the total phosphorus pool, the highest content of phosphorus was found in the organic and residual phosphorus fractions (over 70% of the total phosphorus in sediments). The largest part of the readily extractable phosphorus was found in the fraction bound to Al and humic substances (41%). Both these fractions determine a weak exchange of phosphorus between sediments and water. No difference in P-release related to P-fraction compound was found in the cores taken from three sites in the lake.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 99 (1997), S. 477-486 
    ISSN: 1573-2932
    Keywords: sediment ; nitrogen ; phosphorus ; organic matter ; cluster analysis ; Gulf of Finland ; estuaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1573-2932
    Keywords: reservoir of heated water ; contamination ; cadmium ; copper ; nickel ; sediment ; water ; enrichment factor ; geoaccumulation index ; contamination factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, the contamination degree of the Rybnik Reservoir with cadmium, copper and nickel was analyzed. Quality of the water from the reservoir was determined by drawing comparisons between the metal content in the water and both the officially permitted levels (contamination factor) and levels of metals occurring in the water of non-contaminated areas (enrichment factor). Contamination of bottom sediment with chosen metals was analyzed with reference to the metal content in mudstone (geoaccumulation index, enrichment factor, contamination factor). Trends towards changing the metal content in the bottom sediment was analyzed by determining the enrichment factor of the surface layer of the bottom sediments in relation to a deeper layer. Enrichment of the bottom sediments with metals coming from the water was also determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    ISSN: 1573-2932
    Keywords: Aquaculture ; aggregation ; flocculation ; grain size ; sediment ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 1573-2932
    Keywords: mercury ; methylmercury ; sediment ; polychaete ; Nereis diversicolor ; methylation ; bioaccumulation ; Scheldt estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Total mercury (Hg) and methylmercury (MeHg) concentrations were determined in sediments and in the polychaete worm Nereis diversicolor at 13 stations of a brackish water intertidal mudflat of the Scheldt estuary. Hg and MeHg concentrations in sediments ranged from 144 to 1192 ng g−1 dw and from 0.8 to 6 ng g−1 dw, respectively. Both Hg and MeHg concentrations increased with an increase of organic matter (OM) content and fine grain fraction. In contrast, Hg accumulation by N. diversicolor was significantly (p 〈 0.05) higher at stations with sandy sediments (mean value: 125 ng g−1 dw) than at stations with muddy sediments (mean value, 80 ng g−1), probably because Hg availability for bioaccumulation at muddy stations was reduced by high OM content of the muddy sediments. MeHg accounted for an average of 0.7% of the total Hg in sediments and 18% of the total Hg in N. diversicolor. Seasonal variations significantly affected Hg concentrations in sediments and MeHg in N. diversicolor. Total Hg concentrations in sediments were significantly (p 〈 0.05) higher in autumn and winter than in spring and summer whereas MeHg concentrations were lowest in winter compared to the other seasons. On the other hand, total Hg concentrations in the worms were lowest in spring whereas MeHg concentrations were significantly (p 〈 0.01) higher in spring and summer than in autumn and winter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 99 (1997), S. 245-254 
    ISSN: 1573-2932
    Keywords: PCB ; organochlorine pesticide ; sediment ; organic carbon content ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCB congeners and organochlorine pesticides (DDT, lindane and HCB) distribution were studied in Lake Orta sediments. The results indicated a contaminated area in the nor-them part of the sub-basin. The observed high levels of organochlorine compounds (OCs) may he explained by the focusing phenomenon, ie. the preferential transport of lighter and smaller particles from the emission sources to this area. The PCBs and DDT values were correlated with the organic carbon content and the heavy metal contamination. The toxicity of the sediment samples was related also to PCB content. PCBs and OCs pollution of Lake Orta was of the same order of magnitude as in Lake Como, which is the most contamined lake in Northern Italy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1573-2932
    Keywords: fish farms ; fecal waste ; sediment ; geochemistry ; metabolism ; macrofauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Benthic observations were carried out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference or control locations) were at distances 〉 50 m from net-pens. Total S− and redox potential (Eh) in surface sediment and Benthic O2 uptake and CO2 release were sensitive indicators of benthic organic enrichment. High variability between replicate measurements of sediment gas exchange could reflect spatial patchiness in sedimentation of fecal waste and food pellets under fish pens. Biomass of deposit feeders was significantly increased at cage sites but total macrofauna biomass was similar at cage and reference locations. Surface sediment water content, modal grain size, pore water salinity and sulfate, and total biomass of macrofauna were the least sensitive indicators of enrichment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 1573-3017
    Keywords: lead ; waterfawl ; sediment ; toxicity ; mining ; risk assessment ; swans ; ALAD ; protoporphyrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract For many years, waterfowl have been poisoned by lead after ingesting contaminated sediment in the Coeur d'Alene River Basin, in Idaho. Results of studies on waterfowl experimentally fed this sediment were combined with results from field studies conducted in the Basin to relate sediment lead concentration to injury to waterfowl. The first step in the model estimated exposure as the relation of sediment lead concentration to blood lead concentration in mute swans (Cygnus olor), ingesting 22% sediment in a rice diet. That rate corresponded to the 90th percentile of sediment ingestion estimated from analyses of feces of tundra swans (Olor columbianus) in the Basin. Then, with additional laboratory studies on Canada geese (Branta canadensis) and mallards (Anas platyrhynchos) fed the sediment, we developed the general relation of blood lead to injury in waterfowl. Injury was quantified by blood lead concentrations, ALAD (δ-aminolevulinic acid dehydratase) activity, protoporphyrin concentrations, hemoglobin concentrations, hepatic lead concentrations, and the prevalence of renal nuclear inclusion bodies. Putting the exposure and injury relations together provided a powerful tool for assessing hazards to wildlife in the Basin. The no effect concentration of sediment lead was estimated as 24 mg/kg and the lowest effect level as 530 mg/kg. By combining our exposure equation with data on blood lead concentrations measured in moribund tundra swans in the Basin, we estimated that some mortality would occur at a sediment lead concentration as low as 1800 mg/kg.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    ISSN: 1573-5125
    Keywords: seston ; epipelon ; sediment ; wind effects ; resuspension ; horizontal transportation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Horizontal variation of seston concentration in the shallow, eutrophic Loosdrecht Lakes (A=9.8 km2; $$\overline z $$ =1.9 m) was studied in relation to windspeed and effective fetch. Simple wave theory was applied in order to predict resuspension using wind data from a nearby meteorological station. Most results were consistent with the theory, but a clear limit for the occurrence of resuspension could not be established. Generally, changes in epipelon—the particles at the sediment-water interface — were not directly related to computed frequency of resuspension at the sampling station. The frequency was estimated for 37 grid points over the entire lake. Resuspension was computed to affect high percentages of the lake area in winter. In summer the frequency was much lower, but in June and July 1984 there were days with nearly 50% of the lake area subject to resuspension. The resulting input of particulate organic carbon into the water column during these days was estimated to equal 12–25 times the daytime phytoplankton carbon fixation. Most of the resuspended matter appeared to be redeposited rapidly. The computed frequency of resuspension for the 37 locations of the lake varied between 7 and 48 days in 1984.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 27 (1993), S. 51-58 
    ISSN: 1573-5125
    Keywords: river ; sediment ; chloroform ; mineralization ; anaerobic ; reductive dechlorination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of14CO2 from 3 μg l−1 labelled chloroform was studied in anaerobic Dutch river sediments. All incubations were performed under anaerobic conditions. The observed first order mineralization kinetics showed half-lives of 2–37 days at 20°C in 12 muddy sediments. In contrast most of the sandy sediment samples did not show a mineralization of chloroform. Most probable number analysis revealed about 3.104 chloroform mineralizing bacteria per g of dry sediment in a muddy sediment and 1–2.103 chloroform mineralizing bacteria per g of dry sediment in a sandy sediment. Therefore the persistence of chloroform in sandy sediments is not caused by the absence of chloroform mineralizing bacteria but by the inactivity of these bacteria. This inactivity of the sandy sediments might allow chloroform from infiltrating river water to reach the groundwater. Mud samples from a relatively unpolluted site showed a similar chloroform mineralization rate compared with the polluted sediments from the rivers Rhine and Meuse. The data indicate that the reductive dechlorination of aliphatic compounds is not influenced at the polluted sites.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    ISSN: 1573-5125
    Keywords: macro-invertebrates ; sediment ; river ; multivariate analysis ; species composition ; density ; biomass ; contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Composition, densities and biomass of sublittoral macrozoobenthos were investigated at 14 sites in the enclosed Rhine-Meuse Delta. The aim was to identify the main macrozoobenthic assemblages and to establish their relationship with environmental conditions, including sediment pollution. Most sites were dominated by the tubificidsLimnodrilus hoffmeisteri andL. claparedeanus. Four zoobenthic assemblages could be identified. They are related to different geomorphological phases of a basin filling up with fluvial sediment causing a longitudinal sediment gradient. The ’Rhine river’ assemblage was found in the Nieuwe Merwede, filled up in the 1970's, the ’soft mud’ assemblage in the Hollands Diep at sites with high sedimentation rates; the ’basin silt’ assemblage in the Amer, Hollands Diep and Haringvliet, at sites with lower sedimentation rates, and the ’basin shoal’ assemblage at former flats with low sedimentation rates. CANOCO was used to relate the TWINSPAN indicator species to a selection of environmental parameters. Sediment pH, water content, sand fraction, total polycyclic aromatic hydrocarbons (PAH) and current velocity explained 44% of the variance of the average abundance of the indicator taxa per site. Sediment firmness, indicated by sediment water content, and high ammonium concentrations probably were together responsible for the very low densities in the ’soft mud’ assemblage. Densities and biomasses in the other assemblages were low as well, except for theDreissena polymorpha habitat, where very high total zoobenthic biomass values (max. 55.8 g m−2) were observed. It is argued that sediment contamination has a considerable impact on macrozoobenthic densities and species composition in all assemblages, the ’basin shoal’ assemblage excepted.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 20 (1986), S. 213-224 
    ISSN: 1573-5125
    Keywords: phosphorus ; sediment ; accumulation ; internal loading ; model ; mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two simple conceptual approaches for the description of phosphorus accumulation and release from sediments are presented. The first model is a mass-balance over the well-mixed top-layer, and demonstrates the enhanced initial effect of sediment dilution on the long-term accumulation, which is magnified in the resulting internal loading, as a consequence of diffusive and advective transport, chemical equilibria, and mineralization. Two assumptions for the spatial distribution of mineralization are evaluated in two sets of analytical solutions for a number of boundary conditions. Results of model calculations are compared with some field data of Loosdrecht Lakes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    ISSN: 1573-5125
    Keywords: accumulation ; bats ; Chironomidae ; Chiroptera ; food chain transfer ; heavy metals ; Myotis dasycneme ; PAHs ; PCBs ; pesticides ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transfer ratios of metals, PCBs, pesticides and PAHs from the sediment to chironomid larvae and adults collected in a highly contaminated area, the Biesbosch, were studied. Metal concentrations in larvae were 0.28 (Cd), 0.02 (Cr), 0.52 (Cu), 0.06 (Hg), 0.03 (Pb), 0.32 (Zn) times those found in standard sediment, on a dry weight basis. Hg and Zn were well transported to the adult stage. Dry weight ratios of contaminant residues in adults and in larvae were 0.38 (Cd), 0.23 (Cr), 0.62 (Cu), 1.03 (Hg), 0.08 (Pb), 0.94 (Zn). For PCBs and pesticides, the concentration ratios of chironomid larvae fat to sediment (dry organic matter) varied around 3.3, which is consistent with laboratory studies. Organochlorine residues in adult fat were comparable to those in larvae lipids. However, the concentrations of non-ortho PCBs were 1.7 times higher in adults. For polycyclic aromatic hydrocarbons (PAH), larval fat:sediment (organic matter) concentration ratios ranged from 0.004 to 0.1. Adult: larvae ratios for PAHs varied between 0.2 and 0.6. For naphthalene a much higher transport ratio of 2 was found. Chironomid adults are the most important potential food source of the Pond bat, which lives in low densities in the Biesbosch. The contaminant concentrations measured in the chironomids do not exceed diet levels that are thought to be safe for mammals. However, Pond bats collected in less contaminated areas contained PCB-concentrations of 9, 33 and 76 mg kg−1 lipid weight, which are above concentrations that cause reproduction effects on Mink.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 21 (1987), S. 127-132 
    ISSN: 1573-5125
    Keywords: coastal seas ; organic matter ; sediment ; watercolumn ; respiration rate ; sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Conclusion In ecosystems like the Dutch Wadden Sea a carbon budget can be made roughly However, there are in space as well as in time a lot of gaps in the observations. Especially from subtidal sediments of inlets and gullies are no observations available. Also the quantification of the different functional groups of the anaerobically respiring organisms (manganese reducers, denitrifiers, iron reducers, methane formers) in the decomposition is absent. And what is the role and quantitative importance of fermenting organisms? Finally, the quantification of the use of the reduced end products of anaerobic respiring organisms is unknown.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 24 (1990), S. 13-21 
    ISSN: 1573-5125
    Keywords: Biodegradation ; chloroform ; benzene ; sediment ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In anaerobic methanogenic sediment microcosms14C labelled chloroform was degraded mainly to carbon dioxide. At a concentration of 4 μg.l−1 the mineralization followed first order kinetics with a half life of 12 days at 10°C and 2.6 days at 20°C. At a concentration of 400 μg.l−1 the mineralization rate increased with time and followed logarithmic kinetics with a μmax of 0.02.d−1 at 10°C. The logarithmic kinetics can be explained by growth of the bacteria on the higher concentration of chloroform with a generation time of 35 days. Shaking and oxygenation did not inhibit the mineralization of chloroform, probably because of bacterial consumption of the dissolved oxygen. 14C labelled benzene was mineralized only for a small percentage to14C labelled carbon dioxide while other, not acid extractable, degradation products were formed. Under anaerobic conditions after one day when 5% of the benzene was degraded to carbon dioxide, the mineralization ceased, while the disappearance of benzene proceeded. With air in the headspace of the incubation bottles 25% of the benzene was mineralized to carbon dioxide. The anaerobic degradation of benzene at a concentration of 100 μ.l−1 showed similar kinetics as the degradation at 1 μg.l−1. Hence no adaptation of the microflora in the sediment occurred during the 63 days of the experiment at 100 μg.l−1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    ISSN: 1573-5125
    Keywords: Chroöcoccal Cyanobacteria ; Lake Maarsseveen I ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four species of chroöcoccal Cyanobacteria were dominant in Lake Maarsseveen I in 1987:Gomphosphaeria lacustris, Chroöcoccus sp.,Aphanocapsa sp. andMicrocystis aeruginosa. The first two were dominant in the water column, the latter two in the sediment. In the water columnAphanocapsa, Microcystis andGomphosphaeria appeared and showed highest abundance at the same time, whileChroöcoccus filled the gaps between the peaks of the others. The distribution in the sediment was related to its texture.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 1573-5125
    Keywords: trace metals ; benthos ; invertebrates ; sediment ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cadmium, zinc, lead and copper concentrations in benthic invertebrates and sediment were determined during two consecutive winters in the Maarsseveen Lakes system. A sequential extraction procedure was applied to estimate the bioavailability of the trace metals in the sediment. Based on the trace metal analyses of organisms and sediment, it is concluded that the Maarsseveen Lakes system has background levels of cadmium, zinc, lead and copper. As the majority of metals was present in geochemically more stable sediment phases, the sequential extractions provided limited additional information on trace metal bioavailability.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 25 (1991), S. 173-176 
    ISSN: 1573-5125
    Keywords: mercury ; fish ; sediment ; human hair ; pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Total mercury was measured in different compartments of Lake Xolotlán's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 μg Hg.g−1±0.46 at the surface, with extreme values of 0.16 and 1.8 μg.g−1. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 μg.Hg−1 in January and 506 μg.g−1 in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 μg.g−1±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 μg.g−1±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 μg.g−1±1.29 inC. managuense and 0.62 μg.g−1±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 μg.g−1±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 μg.g−1±6.34 (n=58), and in women 3.39 μg.g−1±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 μg.g−1±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 33 (1999), S. 225-233 
    ISSN: 1573-5125
    Keywords: erosion ; fetch ; numerical model ; sediment ; waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sand beaches and spits of the southern embankment of the inner Tagus estuary indicate the influence of locally generated wind waves. The aim of this study is to evaluate the ability of these waves to resuspend bottom sediments, and sustain the longshore transport. For this purpose, local wave climates were obtained by running a wave forecasting numerical model for three selected target areas. Results suggest that local wave climate is largely responsible for sand movement and accumulation in the marginal zones of the inner estuary facing the longest effective fetch. Two main areas of longshore transport were identified in the inner Tagus estuary with similar annual gross transport rates, of about 12 000 m3 yr−1. Results obtained for the annual net drift amount and direction are in agreement with geomorphology and accretion direction of the beaches. Wave-induced longshore transport rates agree with field observations and erosional evolution of the Alfeite sand beach during the last century.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic ecology 27 (1993), S. 301-308 
    ISSN: 1573-5125
    Keywords: PCB ; PAH ; γ-HCH ; dissolved ; particulate ; sediment ; input ; Scheldt estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The behaviour of some organic micropollutants in the abiotic compartments water, particulate matter and bottom sediments of the Scheldt estuary, S.W. Netherlands, was studied between 1986 and 1989. Special attention was given to two individual PolyChlorinated Biphenyl congeners (PCB 52 and PCB 153), two Polycyclic Aromatic Hydrocarbons (PAHs) fluoranthene and benzo(a)pyrene and γ-HCH. Dissolved PCBs and γ-HCH behave conservatively during estuarine mixing. The concentration of γ-HCH in the fresh-water is extremely high in spring compared to the other seasons. Dissolved fluoranthene does not behave conservatively. The concentration of dissolved fluoranthene in the freshwater endmember shows a seasonal dependence with highest concentrations in winter and lowest in summer. Benzo(a)pyrene could hardly be detected in the dissolved phase with the methods used. PCBs and PAHs in particulate matter and sediments behave essentially conservatively as a result of the mixing of riverine particulates with high, and marine particulates with low organic micropollutant contents. Particulate fluoranthene is removed at low salinities under (nearly) anoxic conditions probably by microbial degradation. The rivers Scheldt and Rupel appear to be the major sources for the compounds studied. However, in particular the organic micropollutant contents of the sediments indicate that important emissions along the estuary were or are still present. Measurements of individual PCBs and PAHs in the 〈63 μm fraction of a dated sediment core from a salt marsh in the eastern part of the Scheldt estuary show that the recent input of PCBs and PAHs into the estuaryis probably 2–3 times lower than the maximum input in the mid-1960s. The PCB profile shows postdepositional congener-selective mobilization caused by advective transport. The PAH assemblage is remarkably uniform in the sediment core. The PAH ratios indicate that combustion of coal is the main source of PAHs in the Scheldt estuary.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 311 (1995), S. 21-30 
    ISSN: 1573-5117
    Keywords: microphytobenthos ; chlorophyll-a ; primary production ; annual cycle ; depth distribution ; hydrodynamic energy ; sediment ; elevation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The temporal dynamics and spatial distribution of microphytobenthic chlorophyll-a in the layer 0–1 cm were determined in the Western Scheldt estuary over the period 1991–1992. Connections between the annually averaged benthic chlorophyll-a and station elevation and sediment composition (as a measure of the hydrodynamic energy caused by currents and waves) were also examined. Microphytobenthic chlorophyll-a showed one main peak in early summer and a smaller peak in autumn. The mean chlorophyll-a concentration of 113 mg Chl-a m−2 in the upper centimeter is of the same order of magnitude as in other estuarine areas. The average annual primary production of the microphytobenthos has been estimated at 136 g C m−2 y−1 The primary production of sediment inhabiting microalgae is at least 17% of the total primary production in the estuary. Considerable differences in annually averaged chlorophyll-a emerges between the stations. These differences are related mainly to the interaction between station elevation and clay content of the sediment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 312 (1995), S. 191-208 
    ISSN: 1573-5117
    Keywords: index of biotic integrity ; stream ; fish ; erosion ; sediment ; physical habitat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Indices of biotic integrity (1131) were computed for two annual fish collections from 27 locations along the bluffline bordering the Mississippi River alluvial plain in northwestern Mississippi. Study sites exhibited varying degrees of physical habitat degradation due to accelerated channel erosion. Objectives of index application were to quantify existing environmental quality and to test the IBI as a tool for relating fish population characteristics to physical degradation. Physical habitat data were collected concurrently with fish at all sites, and physical habitat descriptors were compared with the IBI scores and component metrics. Three to 23 fish species were captured from each site, and species richness explained 64–70% of the variance in IBI scores. Fish collections were dominated by insectivores tolerant of habitat and water quality degradation. Suckers and piscivores were relatively uncommon. The IBI scores were generally not reflective of physical habitat conditions. Variation in IBI scores was indicative of only the grossest differences in physical habitat quality. Weak relationships between physical habitat quality and IBI scores may have been due to large temporal variations in biotic integrity typical of degraded habitats. Alternatively, water quality degradation, which we did not measure, may have confounded relationships between physical habitat and fish metrics. Regional application of the IBI as a habitat assessment tool in landscapes with widespread physical degradation must overcome lack of suitable reference sites, large temporal variation in IBI scores, and small numbers of fish per collection, leading to lower confidence levels for IBI scores. The scarcity of lightly impacted sites may hinder detection of biotic integrity response along gradients of physical habitat quality.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 1573-5117
    Keywords: Ammonium ; denitrification ; lake ; sediment ; bioturbation ; Chironomus plumosus ; isotope pairing ; acetylene blockage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxygen uptake, ammonium flux and denitrification were determined insediment from a eutrophic lake in southern Sweden. Part of the sediment wasbioturbated by incubation in a laboratory mesocosm by incubation containing2000 tube-dwelling larvae of Chironomus plumosus L. m−2.Oxygen consumption was increased 2-fold in the bioturbated compared with thenonbioturbated sediment, some 20% of the increase could be explainedby chironomid respiration. There was a net release of ammonium from thebioturbated sediment to the overlying water. Only 11–45% ofthis could be explained on the basis of larval excretion. With increasingnitrate concentration, denitrification of the nitrate coming from the water(dw) increased to a greater extent in the bioturbated than in thenon-bioturbated sediment, whereas denitrification of the nitrate from thecoupled nitrification-denitrification (dn) was unaffected. The acetyleneblockage technique underestimated denitrification by 63–88%compared with the nitrogen isotope pairing technique. The results indicatethat bioturbation by tube-dwelling chironomid larvae can have a major impacton the nitrogen turnover in lake sediment, mobilising the ammonium to thewater and stimulating denitrification by reducing the diffusive barrierblocking nitrate from reaching anoxic zones in the sediment. Under theaerobic conditions under which the experiments were conducted, thebioturbated eutrophic sediment acted as a more pronounced sink for inorganicnitrogen compared with the non-bioturbated sediment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 1573-5117
    Keywords: nematoda ; ecology ; stratification ; bathymetry ; sediment ; Königssee
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vertical distribution of nematodes up to 20 cm sediment depth was studied over a one-year period in the alpine, oligotrophic lake Königssee. Ten water depths were examined, four of which correspond to the littoral (1 m, 2 m, 5 m, 10 m), three to the littoriprofundal (15 m, 20 m, 30 m) and three to the profundal (60 m, 120 m, 190 m). The sediment was devided into four layers (0–2 cm, 2–5 cm, 5–10 cm and 10–20 cm). (1) The highest proportion of nematodes was found in the top layer. Out of 45 263 nematodes, 89% were found in the first 5 cm of the sediment and only 1 % deeper than 10 cm. (2) The proportion of nematodes in the top layer increased along with water depth. Water depth was a better predictor of percentage of nematodes in the top layer than particle size or content of organic carbon in the sediment. (3) There were considerable differences among species in their vertical distribution in the sediment. (4) There was a significant trend for juveniles to occupy more superficial layers than adults across various species. (5) There are time related vertical preferences among adults and juveniles of several nematode species across the year, suggesting vertical migration in the sediment (e.g. Aphanolaimus aquaticus Daday, Eumonhystera longicaudatula Gerlach & Riemann, Tobrilus gracilis Bastian, Monhystera paludicola de Man, Ethmolaimus pratensis de Man and Ironus tenuicaudatus de Man). The factors determining the vertical variation in nematode abundance in freshwater systems across space and time are still unknown.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    ISSN: 1573-5117
    Keywords: Macroinvertebrates ; colonization ; artificial substrates ; natural substrate ; sediment ; lotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A field study was designed to concurrently evaluate differences in colonization by benthic macroinvertebrates on a range of artificial substratum types (single particles of natural rock or clay brick and baskets of natural substratum) after three colonization periods (1, 8 and 29 days). Fauna on the artificial substrata were compared to natural substratum and the effect of natural epilithic cover on colonization by zoobenthos was determined. Densities of total number of organisms and the seven most abundant taxa, total number of taxa and quantity of organic material were greater on the natural substratum than on the artificial substratum types. Relative abundances of taxa on pairs of the artificial substratum types, unlike pairs of each artificial substratum type and the natural substratum, were statistically correlated. Among the artificial substratum types densities of total number of organisms and about one-half of the most abundant taxa, total number of taxa and quantity of organic material were greatest in the substratum baskets. Natural epilithic cover on the single rock particles and substratum baskets affected the densities of total number of organisms and two of the seven most abundant taxa. These taxonomic groups were at approximately two to six-fold greater densities on the substrata with fine sediment. consistent patterns in densities of the zoobenthos on the substrata were found after each colonization period. In our study all measures of the macroinvertebrate assemblages (densities of each taxon, total number of organisms, total number of taxa and relative abundances of taxa), with few exceptions, were different between each artificial substratum type and natural substratum. This result showed the abundance and composition of the macroinvertebrate fauna on artificial substratum types were different from the natural substratum. Therefore, the choice of using artificial substrata instead of direct sampling of the natural substratum should be carefully made. Among the artificial substratum types relative abundances of taxa were similar on the single substratum particles and substratum baskets indicating single particles instead of baskets might be used to sample the zoobenthos. Investigators should consider the potential effect of the natural epilithic cover of substratum particles on colonization by zoobenthos when choosing the type of artificial substratum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    ISSN: 1573-5117
    Keywords: bivalves ; oxygen ; condition ; copper ; bioavailability ; translocation ; sediment ; silt fraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of differences in the level of oxygenation of sediment or water on the condition and copper content of two bivalves, the Baltic clam Macoma balthica and the cockle Cerastoderma edule, were assessed. Specimens from four intertidal flats in the Netherlands and France were compared, translocated and exposed to different levels of oxygen in the laboratory. Cockles showed no significant differences in condition and copper content between animals from light (= more oxygenated) and dark (= less oxygenated) sediments. Baltic clams also showed no differences in condition, but the clams had a higher copper content (concentration as well as body burden) in dark than in light sediments. During the translocation experiments no significant changes occurred. In the laboratory experiments the level of oxygen had no effect on the condition or copper content of the Baltic clam. The only factor affecting the copper content of Baltic clams was the addition of copper to the water or sediment. The copper, organic carbon and silt fraction (〈 16 µm) was higher in dark sediments than in light sediments. The copper content in the sediment was positively related to the silt and organic carbon content. We argue that the relation between coloration (= degree of oxygenation) of sediments and the copper content of Baltic clams could be indirect: due to a higher silt fraction and/or organic content at some places on a tidal flat, these places are more hypoxic and therefore darker, whereas simultaneously these places have a higher copper concentration because of more copper-complexing sites (and surface), whereby the higher copper concentration in the sediment relates to a higher copper concentration in the clams.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    ISSN: 1573-5117
    Keywords: blue-green algae ; recruitment ; sediment ; phosphorus ; alum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sediment-to-water recruitment of blue-green algae was investigated in a shallow lake following treatment with aluminum sulfate and sodium aluminate to control sediment phosphorus (P) release. A comparison of results from two summers each before and after treatment indicates that the treatment did not universally impact the recruitment of either sporulating or non-sporulating forms of blue-green algae. Blooms of Anabaena, Aphanizomenon, and Coelosphaerium resulted predominantly from growth in the water column following strong recruitment episodes lasting up to two weeks, while Microcystis populations were relatively insensitive to periodically high inputs from recruitment. The development of planktonic populations of Gloeotrichia echinulata, by contrast, were largely dependent on sustained recruitment in response to adequate light and temperature regimes at the sediment surface. The cellular P content of recruited G. echinulata colonies was unaffected by the accumulation of aluminum floc to the lake sediments. Both G. echinulata and C. naegelianum showed elevated levels of cellular P in newly recruited colonies as compared to planktonic colonies, indicating P transport from the sediments to the water column. Total P translocation by blue-green algae was negligible in the absence of a substantial recruitment of G. echinulata. The recruitment of G. echinulata, and hence the magnitude of P translocation, was therefore more responsive to environmental conditions prevalent at the sediments than to direct effects of the treatment itself.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 297 (1995), S. 29-41 
    ISSN: 1573-5117
    Keywords: organic phosphate ; inorganic phosphate ; phosphate fractionation ; sediment ; coastal lagoons ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A major problem of the Mediterranean coastal lagoons is an excessive input of nutrients (i.e. N and P), causing eutrophic conditions in summer. The sediments of these lagoons can serve as a reservoir by fixing phosphate, or as a source when this phosphate is released under certain conditions. Knowledge of nutrient sources and fluxes is needed if coastal lagoons are to be protected against eutrophication. Therefore, we have evaluated the total pool of phosphate in the lagoon sediments, and the quantity of phosphate which may be released. Sediment profiles have been analysed at two stations of the ‘Lagune de Thau’ both in and outside the oyster-bank zone. A sequential fractionation, using chelating agents was performed to extract the inorganic (iron and calcium bound phosphate) and the organic phosphate fractions. A statistical analysis of the data set has revealed several significant factors which explain the fluctuations of the concentrations of each phosphate fraction. These factors are: the time of year (seasons), the depth (5 cm layers of sediment), and the site (station). A spatial and a temporal variation of the concentration of Tot-P was found. The largest variation between the two different zones appeared only in the first five cm of sediment. There is only a slight seasonal variation in the amount of phosphate at other depths at the two different zones. Season and station are the factors which control the variations in distribution of phosphate fractions. The spatial and temporal variations of the iron and calcium bound phosphate are explained by the redox potential and pH in the top layer of the sediment.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    ISSN: 1573-5117
    Keywords: Nanakita River Estuary ; isotope ratio ; carbon ; nitrogen ; deposit-feeding polychaetes ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two types of deposit-feeding polychaetes, Neanthes japonica and Notomastus sp., and their surrounding sediments were collected from the Nanakita River Estuary and a small brackish lagoon (Gamõ Lagoon) in northeastern Japan. The samples were examined using stable isotope analysis to assess the site specific feeding mode of the animals and their trophic status. N. japonica is a surface deposit-feeder and Notomastus sp. is a subsurface deposit-feeder. In the estuary, the sedimentary δ 5N tended to become isotopically heavier from the upper estuary (2.0 ∼ 3.9‰) to the river mouth (4.3 ∼ 6.2‰), while sedimentary organic δ 13C constant value (−26.8 ∼ −24.4, average −25.6‰) throughout the river estuary. The δ 13C values of N. japonica were similar to those of the surrounding sediment in the upper estuary, whereas in the lower estuary, N. japonica had a heavier δ 13C value than the surrounding sediment. The δ 13C and dg 15N values indicated that the carbon, but not the nitrogen, of N. japonica was derived from upland plants in the upper estuary. In the lower estuary, a significant fraction of carbon of N. japonica was derived from phytoplankton. Notomastus sp. exhibited heavier δ 13C values than the surrounding surface sediment throughout the estuary and had heavier δ 13C values than N. japonica in the same location. These results suggest selective utilization of sedimentary carbon by those animals following bacterial processing and subsequent fractionation. The difference in δ 15N between sedimentary organics and corresponding polychaetes was 5 ± 1‰ and rather higher than 3.4 ± 1.1‰ expected for normal trophic effects in other animals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 303 (1995), S. 211-219 
    ISSN: 1573-5117
    Keywords: sediment ; guilds ; fish community metrics ; riparian zones ; ecological health
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Riparian buffer zones serve several important roles in linking a stream to its watershed. A main function is controlling the dynamics of sedimentation. This paper documents how siltation impacts fish communities and how proper riparian management can mitigate the negative effects of sedimentation. Two studies examined the relation between stream siltation and fish community characteristics. Community responses to siltation were poorly described by common structural indices. Community level responses to varying siltation were most consistently described by changes in functional characteristics of the resident fish species using a guild-based analysis. Herbivores, benthic insectivores and simple lithophilous spawners were most sensitive to siltation while other guilds were not. These results were repeatable in both intraregional comparisons among sites of similar size and character, and in interregional comparisons of streams which varied in characteristics besides siltation. This suggests the index may be useful in separating the effects of siltation from other environmental variables. A discussion of bufferstrip characteristics important in mitigating against, or preventing, excess siltation is presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 322 (1996), S. 129-136 
    ISSN: 1573-5117
    Keywords: Lake Ladoga ; phosphorus ; sediment ; pore water ; phosphorus release ; internal phosphorus loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sedimentary phosphorus fractions and phosphorus release from the sediments were studied in Lake Ladoga at altogether 46 sampling sites, representing the full range of sediment types encountered in the lake. Determination of P fractions and physico-chemical analyses were made of surface sediment cores (10–20 cm long, each sampled at 3–4 levels) and in the overlying water. The range of total phosphorus per dry weight of sediment was 0.2–3.3 mg g−1, and that of inorganic P 0.1–2.5 mg g−1. The levels of interstitial soluble phosphorus, range 2–613 µg 1−1 for total P and 1–315 µg 1−1 for inorganic P, were higher than those of dissolved P concentrations in the overlying water. Diffusive fluxes of phosphate from sediment to the overlying water were estimated using three independent methods. The estimated range was 4–914 µg P m−2 d−1; the mean value for the whole bottom area, 0.1 mg P m−2 d−1, is lower than previously published estimates. The estimated annual contribution of sedimentary inorganic P flux to Lake Ladoga water is equal to 620 tons of P per year, which amounts to more than 10% of the estimated external P load into the lake. 68% of the total diffusive flux emanates from deep water sediments, which are not exposed to seasonal variation of conditions. In deep lakes, such as Lake Ladoga, phosphorus release from the sediments is controlled primarily by diffusive mechanisms. Wave action and currents as well as bioturbation are probably of importance mainly in shallow near-shore areas. Phosphorus release by gas ebullition and macrophytes is considered negligible.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 323 (1996), S. 107-118 
    ISSN: 1573-5117
    Keywords: organic matter ; respiration ; hyporheic zone ; sediment ; stream ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Community respiration in hyporheic sediments (HCR) was studied in a characteristic riffle-pool-sequence of a mountain stream. HCR activity at the riffle site strongly exceeded that at the corresponding pool site with a mean ratio of 5.3. The vertical distribution of HCR activity was homogeneous in the pool, while there was a distinct maximum in the uppermost layer in the riffle. Similarly, the spatial distribution of certain fractions of particulate organic matter (POM), and their turnover, was largely determined by stream morphology. Mean annual HCR per unit area of stream bed was estimated as 1.71 g O2 m−2 d−1. Hence, HCR contributes significantly to total heterotrophic activity in streams, thus enhancing the relative importance of heterotrophic processes in running waters containing hyporheic zones.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    ISSN: 1573-5117
    Keywords: submersed macrophytes ; nutrients ; biomass ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We identified factors influencing biomass and nutrient content in E. densa in an enriched pampean stream of Argentina. Physical (current velocity, temperature), chemical (pH, conductivity, dissolved oxygen, nutrient content in water and sediments), and biological variables (biomass and nutrient content of E. densa, biomass of periphyton and other macrophytes) were estimated at each sampling occasion, and mean monthly values estimated. Biomass and nutrient content in E. densa were correlated with these physical-chemical and biological variables. Biomass was positively correlated with ammonium in stream water (P〈0.05) and sediment total nitrogen (P〈0.01). Nitrogen showed a positive relationship with ammonium (P〈0.01), and a negative one with nitrate and periphyton biomass (P〈0.05). Phosphorus was positively correlated with soluble reactive phosphorus (P〈0.01). The growth of other macrophyte species in the stream seemed to influence E. densa biomass, probably through competition for light. Current velocity was low and not significantly related with E. densa biomass, however, a flood at the beginning of the study washed the macrophyte stand downstream.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 352 (1997), S. 49-59 
    ISSN: 1573-5117
    Keywords: mangrove ; treatment ; sewage ; plant ; sediment ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field work has been conducted in a 300-hectare natural mangrove intertidal wetlands in Shenzhen, a newly developed city in southern China, to study the feasibility of using mangrove wetlands as a sewage treatment facility. The present paper reports the results obtained in the recent year, between December1994 and December 1995. Two parallel elongated sites(Sites A & B, each 180 m × 10 m) extending from land to sea were chosen for study. Since September 1991,Site A has received settled municipal sewage three times a week during the low ebb tide period when sediments at landward regions were dry. The hydraulic loading was 20 m3 per discharge and wastewater was soaked into the sediments within 50 m of the discharge points before the next incoming tide. Site B served as a control. Over the past months in 1994and 1995, surface sediments and plant leaves were collected at identified locations in two sites at every six month intervals. The impact of sewage on mangrove plant growth was assessed by monitoring plant height, diameter and number of trees using the fixed plot technique. The plant density, stem diameter and tree height of two dominant mangrove species, Kandelia candel and Aegiceras corniculatum, found in Site A were comparable with those of Site B. No significant difference was detected between two sites in terms of plant growth and death rates. These results indicate that sewage discharge over a period of about two years did not exhibit any apparent effect on plant growth. The nutrient and organic matter concentrations of surface sediments in Site A were also not significantly different from those found in Site B, except at the very landward regions (2 to 40 m away from landwards). The nutrient concentrations of sediments collected in sampling locations near the discharge points of Site A were however significantly higher than that of the control. In both sites, the organic C, total N and P, NH4 +-N and NO3 −-N concentrations in the surface sediments exhibited a descending trend from landwards to seaward regions, with notably higher values found in the landward locations. Seasonal variation in NH4 +-N content was obvious, and more ammonium nitrogen was recorded in July than in December. Leaf samples of the two dominant plant species collected from Site A had similar total N and organic C concentrations as those from Site B. These findings suggest that mangrove intertidal wetlands are of great potential for natural wastewater treatment,and are unlikely to produce any harmful effect on the higher plant communities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    ISSN: 1573-5117
    Keywords: carbon dioxide ; fluxes ; phosphate ; sediment ; sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluxes of CO2 and o-P across the sediment-water interfacewere measured adding different amounts of sulfatein order to quantify the influence in these processes againsta control, and using chloramphenicol as an inhibitor ofbacterial activity. These experiments were performed underoxic and anoxic conditions. Results show that the additionof sulfate stimulated the fluxes of CO2 and o-P, whilethe use of chloramphenicol decreased these fluxes. Theratio of o-P release to Org-C release ranged from 1 to 5 underoxic conditions and from 18 to 42 under anoxicconditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 332 (1996), S. 119-129 
    ISSN: 1573-5117
    Keywords: sediment ; diatoms ; cyanobacteria ; flagellates ; amino acids ; microautoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grain density microautoradiography (MAR) was used to study uptake of dissolved amino acids (DFAA) in microalgal communities from a sandy bay on the west coast of Sweden. A mixture of fifteen 3H-labeled amino acids (final concentration 20–80 nmol l−1) was added to sediment samples collected from two depths (0.5 and 4 m), on five occasions representing different seasons. On all sampling occasions, the microflora was dominated by diatoms (〉 85% of the total biomass). Cyanobacteria occurred in the summer and autumn, but never dominated the biomass. Between 5 and 48% of all counted algal cells showed uptake (1–44% of algal biomass). Uptake was recorded for all majors microalgal groups (diatoms, cyanobacteria and autotrophic flagellates). Uptake was more frequent on the shallow site and the highest proportion of cells showing uptake occurred in May. Although uptake was common among both motile and attached growth forms, on several occasions uptake frequencies were higher for attached cells. As the attached fraction is frequently burried out of the photic zone, and not able to rapidly migrate towards light, this implies that heterotrophic capacity should be valuable. Also at species level, some taxa showed higher uptake frequencies than others, for example populations of motile diatom species that displayed a seasonal behaviour (‘blooming species’), such as Nitzschia cf. dissipata and Cylindrotheca closterium. Other species showing frequent uptake were the coccoid colony-forming cyanobacterium Microcrocis sp., and the filamentous cyanobacterium Phormidium sp.. The results suggest that there is a high potential for DFAA uptake in the microphytobenthic community and that for some growth forms and species this could imply a competitive advantage.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 1573-5117
    Keywords: salt marshes ; primary production ; decomposition ; sediment ; carbon isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper deals with the organic matter dynamics of a dwarf shrub species, Atriplex portulacoides, which characterizes the majority of ungrazed European salt marshes. These dynamics were investigated by the simultaneous estimation of primary production, litter production, decomposition processes and accumulation of organic matter in sediment. We used harvested biomass techniques and the litter-bag method, as well as more recent techniques such as determination of natural isotopic compositions. The results of this study have been compared with those of other studies of salt marshes of the Eastern Coast of America dominated by Spartina alterniflora. Studies of the fate of halophytic organic matter in salt marshes have shown that processes such as consumption, decomposition, or flooding rapidly could distribute organic material to different compartments of the marsh system. Aboveground productivity of A. portulacoides was 1700 g m-2 yr-1. Approximately 80% of this production was transformed rapidly in necromass. A large part of this dead material (86%) fell as litter directly onto the sediment at the sampling site. The remainder was washed away by tides, either out of the marsh, or into the upper marsh where it accumulated in drift lines. Decomposition of A. portulacoides on the sediment was followed using litter-bags. Decay constants, based on the first order decay function, ranged between 0.0404 d-1 and 0.0113 d-1 and appeared high when compare with data obtained in other American and European salt marshes. Nitrogen immobilisation was not detectable in this decomposition experiment. During decay, nitrogen concentrations increased, whereas absolute amount of nitrogen decreased. After microbial decomposition, plant detritus was rapidly incorporated into sediment. The carbon isotopic composition of organic matter in sediment showed that organic matter in the middle marsh came from both aboveground production of A. portulacoides and microalgae. The patterns for these two kinds of organic matter in different granulometric fractions depended on tidal submersion frequency. During the summer, when the salt marsh was not disturbed by tides, the clay fraction got richer in plant organic matter, whereas, during the other periods, this fraction was characterized by microalgal organic matter. This study provides new data about the dynamic of organic matter. It remains still difficult to establish comparisons between North American and European salt marsh functioning according to the variability of primary production, microbial decomposition and tidal range in these ecosystems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    International journal of salt lake research 5 (1996), S. 35-44 
    ISSN: 1573-8590
    Keywords: enzymatic indicator ; sediment ; therapeutic mud
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Sediments of 56 salt lakes from Romania were studied enzymologically. The following 7 enzymatic and nonenzymatic catalytic activities have been measured: phosphatase, H2O2-splitting in nonautoclaved (catalase) and autoclaved samples, TTC reduction in nonautoclaved (dehydrogenase) and autoclaved samples, without or with glucose addition. A formula is proposed for the evaluation of the enzymatic potential of salt lake sediments or other habitats. A hierarchy of the studied lakes has been established on the basis of the enzymatic potential of their sediments expressed as enzymatic indicator.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    ISSN: 1572-9834
    Keywords: peat ; sulfur ; iron ; gypsum ; calcification ; biogeochemical cycles ; sediment ; redox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Major biogeochemical processes in the newly created, shallow Lake Agmon (Hula Valley, northern Israel) were investigated from 1994 to 1996. Sediment cores, lake water and porewater were analyzed for chemical composition and spatial distribution. Sediment analyses revealed that Lake Agmon has two different sediment types: peat sediments in the northern and central parts, and marls in the southern part. The basic composition of the lake's water was controlled mainly by the mixing of two distinct water types (Jordan River and water drainage), and by evaporation. About 3/4 of the lake water originated from the Jordan Inlet, a quarter through the Z Canal Inlet (peat drainage) and a minor amount from groundwater seepage. Lake Agmon is unique among freshwater wetlands owing to its high SO 4 2− content, which is ca. 1/3 that of sea water. This characteristic is ascribed to the dissolution of secondary gypsum, formed in the peat soils since the drainage of the historic Hula Marsh. Leaching gypsum from the shallow sediments during the first few months after flooding was followed by a later stage of constant diffusion and advection of SO 4 2− from gypsum dissolution in deeper sediments. Gypsum dissolution in lake sediments contributed ca. half of the SO4 2− and Ca2+ inputs to the lake. The concomitant increase of Ca2+ combined with alkalinity release due to organic matter decomposition in the sediments led to the precipitation of CaCO3. This precipitation was enhanced by photosynthesis, particularly during summers, and consumed about a tenth of the Ca2+ and third of the alkalinity outputs from the lake. Iron-hydroxide was the main agent for microbial oxidation of organic matter, surpassing by far the role of sulfate, nitrate and manganese as electron acceptors. The produced Fe2+ was transported upward by diffusion and advection and oxidized to ferric iron at the sediment-water interface. There is evidence, however, that some sulfate was reduced, but most of the produced sulfide reacted with ferrous iron and accumulated in the sediments as FeS minerals. Therefore, despite high sulfate concentrations, the high iron availability restricted release of toxic sulfides into the water and thereby served to maintain reasonable water quality.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    ISSN: 1572-9834
    Keywords: Florida ; lake ; 210Pb dating ; macrophytes ; nutrients ; paleolimnology ; river ; sediment ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used paleolimnological methods to investigate spatial and temporal patterns of bulk sediment and nutrient (C, N, P) accumulation in Lakes Hell ‘n’ Blazes (A = 154 ha, zmax = 240 cm), Sawgrass (A = 195 ha, zmax = 157 cm) and Washington (A = 1766 ha, zmax = 322 cm), in the Upper St. Johns River Basin, Florida. The study was designed to evaluate long-term changes in sedimentation and nutrient storage in the basin, and was one component of a larger project addressing flood control, wetland restoration, and water quality improvement. These three study lakes are wide, shallow waterbodies in the upper reaches of the St. Johns River channel. Sediment mapping indicates soft, organic deposits are distributed uniformly throughout Lakes Hell ‘n’ Blazes and Sawgrass. In contrast, much of Lake Washington is characterized by sandy bottom, and organic sediment is largely restricted to the north end of the lake. Lakes Hell ‘n’ Blazes and Sawgrass are effective sediment traps because dense submersed macrophytes and their associated epiphytes reduce flow velocity, intercept suspended particles, and utilize dissolved nutrients. Abundant Hydrilla, combined with short fetch, prevents resuspension and downstream transport of sediments. Larger Lake Washington is probably wind-mixed and resuspended organic sediments are redeposited to downstream sites. 210Pb-dated sediment cores show that organic sediment accumulation began in all three lakes before 1900, but that bulk sediment and nutrient accumulation rates have generally increased since then. The increases are probably attributable, in part, to anthropogenic activities including 1) hydrologic modifications that reduced flow rates in the channel, 2) discharge of nutrient-rich waters from urban, agricultural and ranching areas, and, 3) introduction and periodic herbicide treatment of the exotic macrophytes Eichhornia and Hydrilla.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 176-177 (1989), S. 253-262 
    ISSN: 1573-5117
    Keywords: Geochemistry ; river ; water ; sediment ; heavy metal ; speciation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concentration of the heavy metals Cu, Cd, Pb and Zn in surface water and sediment samples taken from the length of the Xiangjiang River in China, revealed significant pollution in the vicinity of two industrial centres (Shuikoushan & Zhuzhou). Additional insight into the potential adverse effects of these elevated concentrations was obtained from studies of the physiochemical forms (speciation) of these metals in the water column and in sediments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 159 (1988), S. 237-245 
    ISSN: 1573-5117
    Keywords: mesocosm ; sediment ; trace element ; radionuclide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radiotracers injected as soluble salts into ≈1.2 m3 limnocorrals in a shallow dystrophic lake were transported rapidly (2 to 12% d−1) from the water to the bottom sediments. Removal rates of most contaminants declined after ≈14 days. Tracers were removed from the water much more rapidly than stable element analogs present naturally. After 3 weeks Am, Co, Ra, Hg, Sn and Fe activities on the enclosure walls were greater than 15% of the activity in the water. However, activity on the walls was a small fraction (〈 6%) of the total amount of tracer injected. Particle fluxes inside the corrals were lower and much less variable than those measured outside. This difference appears to result from greater resuspension of bottom sediments in the lake than in the enclosures. Both particle-bound and soluble tracers were measured in cores of bottom sediments. Tracer sorption onto particles, diffusion into the bottom sediments, and uptake on the plastic enclosure walls were rapid and reversible. Tracer kinetics were very reproducible in replicate enclosures, providing a simple, experimental system in which limnological conditions can be manipulated. Loss rates and distributions of stable isotopes and radioisotopes can be used to develop and test a general model of element transport applicable to both short and long term analyses.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    ISSN: 1573-5117
    Keywords: algae ; chlorophyll a ; nutrient cycling ; periphyton ; phosphorus release ; phytoplankton ; sediment ; blackwater swamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a 20-month study, phytoplankton and periphyton chl a, and dry mass of macroscopic algal aggregates in four marshes and a lake within the Okefenokee Swamp (Georgia, USA) were comparable to other wetlands and lake littoral areas. Chlorophyll levels in two marshes were inversely related to water level and phytoplankton at three marshes developed unimodal maxima following macrophyte dieback. Standing stocks in a vernally inundated marsh were greater than a nearby marsh which was permanently inundated; chlorophyll levels displayed longer blooms in the inundated marsh during periods of low rainfall or after drought. Field dynamics, sediment sorption characteristics and algal bioassays suggest that evaporative drawdown stimulates algae by release of nutrients from exposed peat, while high water levels reduce nutrient release from sediments and disperse phytoplankton through flushing. Equilibrium phosphate concentrations of sediments and algal levels were higher at an abandoned rookery than a nearby non-rookery area, indicating nutrient enrichment from residual guano deposits.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 192 (1990), S. 191-203 
    ISSN: 1573-5117
    Keywords: sediment ; pH ; redox ; phosphorous ; liming ; bioturbation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The addition of powdered limestone to intact sediment cores from oligotrophic, acid Lake Hovvatn caused pH to increase, redox potential (E7) to drop, and permitted net precipitation of phosphorous (P) from the water column. Significant pH increase was found to a sediment depth of 6 cm and a maximum increase in pH from 4.9 to 6.5 was found at a depth of 0.5 cm when dosed with 36 g m−2 of lime. Such pH increase creates important changes in sediment equilibrium chemistry and enhances habitat suitability. In the case of Hovvatn, however, sediments would consume only 5 kg of the 91 tons of applied limestone. Superficial sediments remained oxidized, but below 0.5 cm, E7 in limed sediment declined significantly more than in unlimed sediments, with a maximum difference of 102 mV versus −66 mV at a depth of 6 cm in unlimed and limed cores, respectively. Abiotic reactions account for 82 ± 54% of this reduction and the remainder is due to the oxidation of organic matter by bacteria. Precipitation of CaSO4, reduction of the sediments by organic compounds at elevated pH and inhibition of the downward diffusion of O2 by the limestone powder are potential abiotic mechanisms which could drive E7 down. Enhanced P release was not found at lowered E7, and supernatent TP concentrations dropped from 11.7 to 4.4 µg P l−1. More P was swept from solution in cores which recieved larger lime doses. The presence of chironomids caused sediment pH to increase by as much as 1.2 pH units, presumably due to NH4 release, reduced sediment E7 by as much as 171 mV and facilitated TP release during the first 17 d of core incubation. Field measurements of vertical distributions of sediment pH and E7 before and after the liming of Hovvtn corroborated laboratory findings.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 235-236 (1992), S. 71-83 
    ISSN: 1573-5117
    Keywords: sediment ; resuspension ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Material transported by the Öre River in northern Sweden is all deposited within the estuary which means that resuspension is necessary for the transport of particles out of the estuary. Wave-induced sediment resuspension in the estuary was studied by monitoring the distribution of suspended particles during a resuspension-redeposition cycle. The particle concentration in the water mass was measured with a light scattering probe, calibrated by comparison with the amount of particles collected on a filter. After a long period with calm weather and a low river input less than 100 tonne of suspended particulate matter was present in the estuary. However, during a period with stormy conditions significant resuspension of sediment particles occurred within the estuary. Two days after the storm approximately 1125 tonne of suspended particulate matter was found in the estuary. Most (61%) of the suspended matter was found in the deepest third of the water column, although up to 17% was present in the top third of the water column. The total load of particulate matter in the water column remained constant until day four after the storm, but a significant redistribution of the particulate matter occurred both in the vertical and horizontal directions. Nine days after the storm, a significant amount of particles (c. 350 tonnes) was still in suspension.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 1573-5117
    Keywords: LAS ; fate model ; lake estuary ; sediment ; diffusive exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Linear alkylbenzenesulfonate (LAS) was detected in a 0–30 cm deep sediment column collected in Lake Teganuma (one of the most polluted lakes in Japan). The range of the LAS concentration in sediments was between 0.1 and 500 µg g−1 (C11-C14 homologs per dry solid) and its vertical profile showed a seasonal variation. A mathematical model, which includes a diffusion term and a biodegradation term, was used to simulate the temporal variation of LAS in the sediment column and to calculate the diffusive flux rate of LAS across the sediment/water interface. An averaged diffusion coefficient of 2.4 × 10−5 cm2 s−1 for the sediment interstitial water was obtained from sediment core samples located in Lake Teganuma. The biodegradation rate constant (0.002 d−1) of LAS in the sediment obtained from the model analysis was considerably less than that reported for LAS in anaerobic waters. These results confirm that a model describing diffusive transport and biodegradation of LAS in the sediments can simulate the temporal variation of LAS in near surface sediments. The diffusive flux rate from overlying water to bottom sediment was calculated to be between −0.20 and 0.52 (C11-C14 LAS) mg m−2 h−1 and the annual net flux rate was 0.7 g m−2 y−1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    ISSN: 1573-5117
    Keywords: organic micropollutants ; heavy metals ; water quality ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Linggi River drainage basin in Negeri Sembilan Malaysia is the major source of potable water for the townships of Seremban and Port Dickson. Water quality is threatened by industrial and commercial development taking place in the basin. This study investigated the concentrations and distribution of organic micro-pollutants and heavy metals within the catchment. Arsenic, copper, cadmium, lead, mercury and zinc were determined in water and sediment samples. All heavy metal concentrations were increased down the basin; arsenic and copper concentration in particular were elevated probably due respectively to flow in of arsenical herbicides in rubber and oil palm plantations and copper sulphate and an additive in pig food. Total phenol concentration also increased considerably within the catchment as a result of urbanisation. Five priority phenolic pollutants (2,4-dimethylphenol; 4-chloro-3-methylphenol; 2,4,6-trichlorophenol; 4-introphenol; pentachlorophenol) were found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 235-236 (1992), S. 723-730 
    ISSN: 1573-5117
    Keywords: sediment ; heavy metals ; environmental control ; industrial emissions ; sequential leaching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A number of investigations of river pollution in Austria are reported. Analysis of wastewater and river water was supplemented by investigations of sediments to characterize the influence of the different emission sources on the aquatic ecosystems. Examples of sediment investigations as tools for environmental monitoring are presented and the advantages of these methods are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 235-236 (1992), S. 611-622 
    ISSN: 1573-5117
    Keywords: cadmium ; cobalt ; sediment ; sulphide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sediment sample with high organic matter and trace metal content was suspended in synthetic river water for four weeks under an inert gas atmosphere. Subsequently, the anaerobic suspension was reoxidized by bubbling air through it. The concentrations of dissolved oxygen, sulfide, ferrous iron, manganese, cadmium, cobalt and the pH-value were measured at close time intervals during the anaerobic incubation. The anaerobic suspension was a post-oxic or sub-oxic environment with oxygen and total sulfide concentrations less than 1 µmole 1−1. Concentrations of dissolved ferrous iron and manganese were 50–150 µmole 1−1 and 5–30 µmole 1−1, respectively. The total sulfide concentration was measured using a sensitive voltammetric technique, with a detection limit of 1 nmole 1−1. A sequential extraction procedure was applied to two sediment samples taken at the end of the anaerobic incubation and after one week of reoxidation. The extractions indicated that cadmium was bound in sulfide minerals under post-oxic conditions. Thermodynamic equilibrium calculations revealed that the concentrations of dissolved cobalt in the post-oxic suspension were limited by the precipitation of cobalt sulfide minerals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 235-236 (1992), S. 623-628 
    ISSN: 1573-5117
    Keywords: arsenobetaine ; arsenic ; cycle ; degradation ; microorganisms ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two growth media containing arsenobetaine [(CH3)3 As+ CH2COO−] were mixed with coastal marine sediments, the latter providing a source of microorganisms. The mixtures were kept at 25 °C in the dark and shaken for several weeks under an atmosphere of air. The disappearance of arsenobetaine and the appearance of two metabolites were followed by HPLC. The HPLC-retention time of the first metabolite agreed with that of trimethylarsine oxide [(CH3)3AsO]. The second metabolite was identified as arsenate (As(V)) using hydride generation/cold trap/GC MS analysis and thin layer chromatography. This is the first scientific evidence showing that arsenobetaine is degraded by microorganisms to inorganic arsenic via trimethylarsine oxide. The degradation of arsenobetaine to inorganic arsenic completes the marine arsenic cycle that begins with the methylation of inorganic arsenic on the way to arsenobetaine.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    ISSN: 1573-5117
    Keywords: oligochaetes ; sediment ; As ; Cd ; Cu ; Pb ; Zn ; speciation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The sediments of the River Danube in the Reservoir at Altenwörth/Lower Austria, are moderately polluted with Zn, Pb, and Cd, whereas concentrations of As, Co, Cr, Cu and Ni are typical of background values. Deposit-feeding oligochaetes living in these sediments were analyzed for their trace element concentrations (As, Cd, Cu, Pb, Zn) to study pathways of recycling of sediment bound amounts to the food web. Compared with background values of benthic deposit feeders from the literature, Cu and As are low, whereas some samples were enhanced in Pb, Cd and Zn. Within the rather narrow concentration ranges, relations of tissue concentrations with chemical and mineralogical compositions of the sediment were hardly found. Increase of clay mineral contents went in parallel with increasing Cd, Zn, and Cu in the tissues, and As in the tissues with total As content. Pb in the tissues was closely related to Pb-concentrations in the pore water. By means of sequential leaching, some further relations between trace element contents in the tissues and solid phases were found. The organic detrital phase positively correlates with As-uptake, whereas hydroxylamine-reducible Mn/Fe-oxyhydroxides influence the Pb-level, and dithionite-reducible Fe/Mn influence the Cu-level. Exchangeable and weak-acid-mobile fractions of the respective metals, however, did not correlate with tissue-levels, nor did the oxalate-extractable Fe-hydroxide coatings, which carry a major part of the heavy metals at fine grain sizes in the Danube sediments investigated. Zn in the tissues was largely independent from all investigated parameters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    ISSN: 1573-5117
    Keywords: sediment ; phosphorus ; release ; anaerobiosis ; bacteria ; pH ; dystrophic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les bactéries peuvent jouer un rôle considérable dans le relargage anaérobiques du phosphore, soit en catalysant la réduction des hydroxydes de fer, soit comme source directe d'orthophosphates. On a étudié leur importance dans la libération de phosphore à partir des sédiments d'un lac du bouclier canadien, très riches en matière organique. Le relargage de phosphore et de fer a été mesuré en condition aérobique et anaérobique, avec ou sans stérilisation, et à différents pH. On a également mesuré l'évolution du nombre et de l'activité des bactéries dans les sédiments. Le relargage de P après stérilisation peut être expliqué par la lyse cellulaire. Comparativement à la stérilisation, les changements dans la concentration en oxygène ou l'acidification ont peu ou pas d'effet sur le relargage du P. Les mouvements du fer et du phosphore se produisent indépendament à partir de ces sédiments. La plus grande partie du fer total dissous semble lié aux acides humiques, ce qui n'est pas le cas du phosphore.
    Notes: Abstract Bacteria can play an important role in the process of anaerobic phosphorus release: they can act as a direct source of orthophosphates, or as a catalyst of iron hydroxyde reduction. We studied their influence on phosphorus release from highly organic sediments of a Canadian shield lake. Phosphorus and iron release were measured under aerobic and anaerobic conditions, with or without sterilization, and at different pH. We measured also the abundance and activity of bacteria in sediments. The increased P release after sterilization can be explained by cell lysis. Compared to sterilization, changing oxygen concentrations or acidification had little or no effect on P release. In these sediments, phosphorus and iron movements were independent. Most of the total dissolved iron seemed to be linked to humic acids, but not phosphorus.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 253 (1993), S. 311-317 
    ISSN: 1573-5117
    Keywords: phosphorus ; sediment ; iron ; aluminum ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus can occur in sediments in different forms and accordingly its availability varies. The distinction between the phosphorus fractions is made with two chemical extraction methods; an ammonium oxalate-oxalic acid extraction and an extraction according to Hieltjes & Lijklema (1980). The iron and aluminum liberated with the ammonium oxalate-oxalic acid extraction method is linearly correlated (r 2 = 0.73) with the phosphorus liberated in the first two steps of the Hieltjes and Lijklema extraction by: P = 0.035 (Fe + Al) + 0.001 (P, Fe and Al in mmol g−1). The iron and aluminum (hydr)oxides are very important fractions in the sediment adsorption capacity for phosphorus. The phosphorus sorption capacity (PSC) is 0.080 mol P (mol (Fe + Al))−1 and the adsorption constant (k) is 11.9 µmol P l−1. Here it is assumed that iron and aluminum (hydr)oxide have the same affinity for phosphorus.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    ISSN: 1573-5117
    Keywords: phosphorus ; retention ; sediment ; release ; fractionation ; iron:phosphorus ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During each of the first 8 years following an 80–90% reduction in external phosphorus loading of shallow, hypertrophic Lake Søbygaard, Denmark in 1982, phosphorus retention was found to be negative. Phosphorus release mainly occurred from April to October, net retention being close to zero during winter. Net internal phosphorus loading was 8 g P m−2 y−1 in 1983 and slowly decreased to 2 g P m−2 y−1 in 1990, mainly because of decreasing sediment phosphorus release during late summer and autumn. The high net release of phosphorus from Lake Søbygaard sediment is attributable to a very high phosphorus concentration and to a high transport rate in the sediment caused by bioturbation and gas ebullition. Sediment phosphorus concentration mainly decreased at a depth of 5 to 20 cm, involving sediment layers down to 23 cm. Maximum sediment phosphorus concentration, which was 11.3 mg P g−1 dw at a depth of 14–16 cm in 1985, decreased to 8.6 mg P g−1 dw at a depth of 16–18 cm in 1991. Phosphorus fractionation revealed that phosphorus release was accompanied by a decrease in NH4Cl-P + NaOH-P and organic phosphorus fractions. HCl-P increased at all sediment depths. The Fe:P ratio in the superficial layer stabilized at approximately 10. Net phosphorus release can be expected to continue for another decade at the present release rate, before an Fe:P ratio of 10 will be reached in the sediment layers from which phosphorus is now being released.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    ISSN: 1573-5117
    Keywords: heavy metals ; sediment ; zooplankton ; epibenthic invertebrates ; Banc d'Arguin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concentrations of copper, zinc, lead and cadmium in the surface sediment (upper 5 mm) were generally higher in the silt fraction than in the bulk sediment. No significant geographical trend in the metal concentrations of the surface sediments was found, nor a correlation between concentrations in bulk sediment as well as in the silt fraction and the % silt could be established. In general, the metal concentrations in both bulk sediment and silt are lower, when compared to marine environments in other climatological regions. In zooplankton, the metal concentrations were relatively high: expressed in µg g−1 on a dry weight (D.W.) basis, they ranged from 15–90 for copper, 70–580 for zinc, 12–55 for lead and 4–10 for cadmium. In epibenthic invertebrate species, both in crustaceans and bivalve molluscs, the concentrations of copper, zinc, and lead were in the same order of magnitude as compared to corresponding species from other geographical latitudes. Cadmium concentrations were relatively low, ranging from 0.13–0.42 µg g−1 D.W. in the bivalve molluscs Pitaria tumens and from 0.04–0.27 µg g−1 D.W. in the shrimp Processa elegantula. Also in the crab species Ilia spinosa, Inachus sp. and Pagurus sp., the cadmium concentrations were low, varying between 0.1 and 0.2 µg g−1 D.W. No significant relation between the metal concentration in whole-body samples and sediment (either bulk or silt) was present. Also no gradient was apparent in concentrations in organisms sampled at different depths (5 to 200 m) along two off-shore transects perpendicular to the Banc d'Arguin. Data indicated lower metal concentration in epibenthic organisms from sampling stations along a northern transect (southwest of Cap Blanc) than in organisms from the southern transect, off Cap Timiris. Evidence was obtained for a considerable atmospheric input of heavy metals, in particular zinc and lead, in a certain area along the continental slope of the Banc d'Arguin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 243-244 (1992), S. 157-166 
    ISSN: 1573-5117
    Keywords: ETS ; carbon balance ; microplankton ; zooplankton ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ETS-activity of microplankton (1–60 µm), net zooplankton (60–250 µm and 〉 250 µm) and sediment was measured in the hypertrophic Keszthely-basin and in the meso-eutrophic Siófok-basin of Lake Balaton in 1988–1989. Six times higher microplanktonic and 1.35–1.75 times higher zooplanktonic ETS-activities l−1 were found in the Keszthely-basin than in the Siófok-basin. The equivalent relationship for the microplanktonic ETS-activity m−2 was 3.83–3.93 to 1 in 1988 and 1989. This ratio in the case of the zooplankton was 1.07–1.09 to 1. The zooplanktonic ETS-activity represented 6.0–10.8% of the total measured sestonic ETS-activity in the Keszthely-basin and 19.0–30.5% of that in the Siófok-basin in 1988 and 1989. The results suggest a decreasing trend in the contribution of net zooplankton metabolic activity in the whole metabolism of the water column with increasing primary production. The sediment was biologically active to 30–35 cm depth in the Keszthely-basin and to 15–20 cm depth in the Siófok-basin. In the Keszthely-basin and in the Siófok-basin, relative decrease in the sediment ETS-activity cm−3 with depth were 10% cm−1 and 25% cm−1 respectively. The sediment ETS-activity m−2 was much higher than that in the plankton: 7.8 times in the Keszthely-basin and 9.3 times in the Siófok-basin. The Keszthely-Siófok basins ratio for the sediment ETS-activity m−2 was 3 to 1. According to the ETS-activity data, Lake Balaton plankton itself can oxidize all the organic matter produced in the water column. The sestonic and sediment respiratory potentials together are much higher than is necessary for complete oxidation of the plankton-assimilated carbon.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    ISSN: 1573-5117
    Keywords: sediment ; copper ; benthic invertebrates ; toxicity ; Keweenaw Waterway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Keweenaw Peninsula in northern Michigan was once a major copper mining area and these mining activities were responsible for depositing tons of tailings in and around the Keweenaw Waterway. In recent years there has been concern about possible toxic effects of the contaminated sediments on aquatic communities in the system. In the fall of 1990, sediments were collected from various locations along the Waterway. Ten-day tests were conducted with the samples using three species of benthic invertebrates that have been proposed as suitable for evaluating the toxicity of freshwater sediments: Hyalella azteca (amphipods), Chironomus tentans (chironomids) and Lumbriculus variegatus(oligochaetes). A number of sediments were toxic to one or more of the three species and, in general, there was good agreement among the tests with regard to identifying toxic samples. Unexpectedly, the relative sensitivity of the three species to the test sediments was not accurately predicted from water-only copper exposures. This indicates that factors modifying exposure, such as different lifestyles and/or varying sensitivity to physico-chemical characteristics of sediments can influence results of sediment toxicity tests.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    ISSN: 1573-5117
    Keywords: acid volatile sulfide ; metal ; bioavailability ; sediment ; freshwater ; temperature ; seasonal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acid volatile sulfide (AVS) is a natural agent in sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. Because of its influence on metal bioavailability, AVS has been proposed as a key normalization phase for the development of sediment quality criteria for metals. However, studies conducted primarily in marine and estuarine systems have shown that AVS concentrations can vary markedly both temporally and with (sediment) depth. In this study, AVS concentrations were measured monthly for 16 mo in several segments of sediment cores from three freshwater lakes: Caribou Lake, Fish Lake and Pike Lake in northeastern Minnesota, USA. The concentrations of AVS in cores from the three lakes varied inversely with sediment depth. AVS concentrations also varied seasonally by as much as two orders of magnitude and were directly correlated with changes in water temperature. The correlation between AVS and temperature likely was related both to changes in primary productivity and sediment microbial activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 120 (1985), S. 207-223 
    ISSN: 1573-5117
    Keywords: nitrate ; phosphorus ; denitrification ; fractionation ; sediment ; anaerobic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Addition of nitrate to an oxygen depleted sediment leads to a stimulation of the mineralization process if a major part of the nitrate is dissimilatorily reduced. This may cause an increased release of phosphate from some sediments. Nitrate, however, maintains a high redox potential at the sediment surface and thus prevents a release of iron-bound phosphorus. These two counteracting effects of nitrate addition to sediment-water systems were demonstrated in laboratory experiments. A high supply of nitrate to a phosphorus-saturated sediment caused an increased release of phosphate and ammonium once the nitrate had been used up. However, from other sediments there was no or very little release of phosphate but an increased release of ammonium caused by high nitrate dissimilation, probably due to the very high capacity of these sediments to bind liberated phosphate or due to storage of phosphorus in an increased bacterial biomass. Phosphorus fractionation, before and after the experiments with the sediments, provided information on transfers to, from and within the sediments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 134 (1986), S. 117-120 
    ISSN: 1573-5117
    Keywords: rotifer ; method ; indicator ; resting eggs ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes a possible method of compiling a rotifer species list for any site from a single visit. Sediment samples collected from Loch Leven on one occasion in winter were exposed to light and a range of temperature conditions in the laboratory. Resting eggs in the sediment were induced to hatch. The resultant species list was very similar to that obtained from regular plankton collections over the previous six year period.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...