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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of aquation and formation reactions of carbonato complexes. 10. Acid-catalyzed decarboxylation of carbonatotetrakis(pyridine)cobalt(III) ion (1976)
    s.l. : American Chemical Society
    Inorganic chemistry 15 (1976), S. 2631-2635 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic50165a011
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of nutrient (N, P, C) enrichment upon periphyton standing crop, species composition and primary production in an oligotrophic softwater lake (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 19 (1988), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The effects of nutrient addition upon algal periphyton standing crop and benthic community metabolism were investigated in Lake Lacawac, Pennsylvania. Nutrient-diffusing flower pot substrates were filled with combinations of P (0.015 mol Na2HPO4), N (0.15molNaNO3) and carbon as glucose (0.015mol (LG) or 0.15mol (HG)) or 0.58 mol NaHCO3 (C). Fifty-two pots representing ten treatments were placed in the lake on 5 May 1985 and sampled after 32-38 days.2. Maximum chlorophyll-a values of 23.82μgcm−2 and 29.72μgcm−2 were obtained on NPC and NPHG pots respectively, compared to 0.82μgcm−2 on control pots. Algal growth was not enhanced unless N and either organic or inorganic carbon were supplied. Ash Free Dry Mass was especially high on NPHG pots.3. Gross production, net production and community respiration were assessed with light-dark chambers affixed to the pots using microwinkler measurements of dissolved oxygen. Highest production rates were obtained on NC and NPC pots. Pots with NPLG and NPHG also showed significant increases in gross production compared to control levels (P 〈 0.01). Specific production (=gross production/chlorophyll-a) was significantly related to standing crop as chlorophylls (P 〈 0.001), alkalinity in the chambers (P 〈 0.00l) and light (P 〈 0. 05), but not to N or P supplied by the pots.4. The periphyton community was dominated by Chlorophyta, which averaged 86.1% of total algal biovolume. Enrichment with NC and NPC significantly enhanced the growth of three Chlorophyceae (Stigeoclonium, Scenedesmus and an unidentified coccoid) and two Cryptophyceae (Cryptomonas. Rhodomonas) (all P 〈 0.05). In contrast, the filamentous green alga Mougeotia dominated other treatments, but declined significantly with NPC enrichment (P 〈 0.05). Addition of NPHG stimulated an 8-fold increase in total biovolume and significant increases in growth of Cryptomonas, Rhodomonas and Euglena (all P 〈 0.05).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1988.tb00327.x
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  • 3
    Electronic Resource
    Electronic Resource
    Beetle assemblages in ponds: effects of habitat and site age (2000)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 44 (2000), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈list style="custom"〉1Water beetle assemblages were sampled in each of 18 freshwater ponds, including 11 recently constructed sites designed to provide mitigation for wetlands destruction elsewhere, and seven older reference sites. There were three objectives: (a) to relate taxon richness and biomass of the beetles to the same properties of the wider aquatic invertebrate community, (b) to evaluate changes in beetle assemblage structure over time, and (c) to determine habitat effects on taxonomic composition, mean body size and trophic guild structure of the beetle assemblage.2Forty-seven beetle genera were identified, representing 77 species. The beetles represented an average of 21.5% of total generic richness, but only 3.7% of total wet biomass of the wider invertebrate community.3Of all variables evaluated using canonical correspondence analysis (CCA), site age had the greatest influence on the beetle assemblage. Predatory dytiscids were early colonists at younger sites, while herbivorous curculionids and chrysomelids associated with particular types of vegetation typically occurred in older ponds. Mitigation ponds and reference ponds supported similar numbers of species. Reference sites, however, harboured substantially more unique species found at only a single site within the study area.4The presence of fish was also strongly related to beetle assemblage structure. Ponds with few or no fish contained about 3-fold higher biomass and 3-fold greater mean wet weight per individual compared to ponds with substantial fish assemblages.5Beetle assemblage composition varied among sites and sampling years, but beetle biomass, richness and species composition may be useful tools in evaluating the success of wetland mitigation efforts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00601.x
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  • 4
    Electronic Resource
    Electronic Resource
    Population responses of plant-associated invertebrates to foraging by largemouth bass fry (Micropterus salmoides) (1982)
    Springer
    Hydrobiologia 96 (1982), S. 169-176 
    Details
    ISSN: 1573-5117
    Keywords: Micropterus ; Sida ; chironomids ; chydorids ; fry ; littoral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of foraging by largemouth bass fry (Micropterus salmoides) upon invertebrates associated with aquatic macrophytes was determined using six 4 m2 exclosures in Cochran Lake, Michigan during June 1978. The cladoceranSida crystallina rapidly declined in exclosures with fry, but increased in control exclosures without fry. Chironomids and chydorids showed little change in the exclosures. Invertebrate populations and foraging by fry were also monitored in the lake during 1976 and 1979.Sida declined rapidly in June of both years. In 1979, a decline from 2.2 × 103 to 0.3 × 103 individuals per m2 and a sharp drop in the proportion of adults between 19 and 22 June coincided with the entry of a large school of fry into the study site on 19 June. Chironomids also declined during June of both years, while chydorids became increasingly abundant in mid-summer and showed no evidence of depletion by the fish. These results suggest that populations of certain prey, which are found locally in high densities in the littoral zone, may be highly susceptible to brief episodes of intense predation by fish fry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185432
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  • 5
    Electronic Resource
    Electronic Resource
    The effects of endosulfan and fertilizer source on soil fertility (1983)
    Springer
    Plant and soil 74 (1983), S. 189-202 
    Details
    ISSN: 1573-5036
    Keywords: Cabbage ; Compost ; Endosulfan ; Fertilizer ; Potato ; Strawberry ; Tissue composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A field study conducted for three years on three different, soil types showed that the insecticide, endosulfan, had little effect on crop yield and plant tissue composition of cabbage, potato and strawberries. These crops were sprayed 0,2 or 8 times per season with a commercial endosulfan preparation. The mature tissue was analysed for N, P, K, Ca, Mg, Mg, Zn, Cu and B. The crops were fertilized with one rate of inorganic fertilizer or Organigro, a composted manure. The fertilizer source had some influence on crop yield and tissue composition, but the response was not always consistent from soil to soil, crop to crop or year to year. Generally, N, Zn, and Mn tissue levels were higher in crops where inorganic fertilizer was used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02143609
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of liming on nutrient limitation of epilithic algae in an acid lake (1990)
    Springer
    Water, air & soil pollution 52 (1990), S. 133-147 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The processes of lake acidification and lake restoration frequently involve major changes in DIC and DIN, both of which may potentially limit algal growth. We evaluate nutrient limitation of benthic algal biomass and species abundances during summers 1987 and 1989, before and after the liming of Lake Earnest (NE Pennsylvania) in November 1988. Limestone addition caused immediate increases in pH from 4.7 to 7.2. Alkalinity was −34 μeq L−1 in summer 1987, but rose to 620 μeq L−1 in summer 1989, whereas DIN declined from 10.7 μmol L−1 to 1.1 μmol L−1 The algae were sampled after 45 to 46 d from clay flower pot substrates diffusing combinations of N, P and C. Algal biomass was strongly C-limited in 1987, but NP-limited in 1989. Mougeotia sp., which comprised 〉99% of total algal biovolume prior to liming, declined to 〈 1% of the community on control substrates, while Oedogonium sp. increased to 43% of total biovolume in 1989. The stimulation of chlorophyll-a accrual with C-enrichment during 1987 was consistent with the later increase in chlorophyll-a on control substrates following liming. Species enhanced by the diffused nutrients, however, generally differed from those which dominated the natural community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283119
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  • 7
    Electronic Resource
    Electronic Resource
    Artificial substrates which release nutrients: Effects on periphyton and invertebrate succession (1984)
    Springer
    Hydrobiologia 114 (1984), S. 29-37 
    Details
    ISSN: 1573-5117
    Keywords: periphyton ; artificial substrate ; phosphate ; nitrate ; chlorophyll ; succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nutrient-diffusing substrates for periphyton were made from clay flower pots (O.D. = 8.8 cm), sealed with plastic petri dishes, and filled with 2% agar and specified nutrients. When placed in water, the nutrients slowly diffuse through the agar and clay walls of the pots, becoming available to organisms colonizing the outer surface. Forty-eight pots, 16 containing 0.1 M KH2PO4, 16 with 0.1 M NaNO3, and 16 with no added nutrients, were placed at 0.5 m depth in Douglas Lake, Michigan. Four pots of each nutrient treatment were sampled for algal periphyton and invertebrates after 7, 14, 25, and 36 days. A total of 72 algal species were enumerated. Of these, Epithemia adnata (Kütz.) Bréb., Rhopalodia gibba (Ehr.) O. Müll, and Anabaena sp. experienced strong growth stimulation in response to phosphate addition. No significant effects of nitrate addition were noted. Measures of algal community structure also reflected the impact of phosphate addition. Final algal biomass was enhanced 10-fold, successional change was prolonged, and species diversity declined relative to nitrate and control pots. Chironomids, chydorid Cladocera, and gastropods dominated the invertebrate fauna found on the pots. Densities of the small, algivorous chironomid Corynoneura nr. lobata Edwards were highest on phosphate pots at the end of the study, in apparent response to the increase in periphyton biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016599
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of nutrient (N, P, C) enrichment, grazing and depth upon littoral periphyton of a softwater lake (1989)
    Springer
    Hydrobiologia 173 (1989), S. 69-83 
    Details
    ISSN: 1573-5117
    Keywords: periphyton ; nutrient limitation ; littoral ; softwater ; grazing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three field experiments were performed in Lake Lacawac, PA to determine the importance of potentially limiting nutrients relative to other factors (grazing, depth) in structuring shallow water algal periphyton communities. All three experiments measured periphyton growth (as chlorophyll-a, AFDM or biovolumes of the algal taxa) on artificial clay flower pot substrates which released specified nutrients to their outer surfaces. Control of standing crop by nutrient supply rate vs. grazing was examined in Expt. I. Substrates releasing excess N and P, together with one of 4 levels of C (as bicarbonate) were placed either inside or outside exclosures designed to reduce grazer densities. Chlorophyll-a rose from 1.1–25.6 µg.cm−2, and some dominant taxa (e.g., Oedogonium, Nostoc, Anacystis) were replaced by others (e.g., Scenedesmus, Cryptomonas) as bicarbonate supply increased. Reductions in invertebrate density did not significantly affect chlorophyll-a at any of the nutrient levels. Reasons for the species shift were further evaluated in Expt. II, using a minielectrode to measure the elevation of pH within the periphyton mat through photosynthetic utilization of bicarbonate. The pH adjacent to pots diffusing N, P and large quantities of bicarbonate, and supporting high chlorophyll-a densities of 32 µg cm−2, averaged 10.0 compared to 6.3 in the water column. Pots diffusing only N and P supported 0.7 µg chlorophyll-a cm−2 and elevated pH to 8.2. We suspect that bicarbonate addition favored efficient bicarbonate users (e.g., Scenedesmus), while inhibiting other taxa (e.g., Oedogonium) because of the attendant high pH. Expt. III was designed to test effects of depth (0.1 m vs. 0.5 m) and N (NH4 + vs. NO3 −) upon the growth response to bicarbonate observed in Expts. I and II. Similar standing crop and species composition were noted on pots at 0.1 m vs. 0.5 m. Enrichment with NH4 + vs. NO3 − also appeared to have little effect upon the periphyton community. Shallow water periphyton communities in Lake Lacawac, when supplied with sufficient N and P, appear to show a distinctive response to increasing bicarbonate concentration and pH which is robust to moderate variation in grazer densities, distance from the water surface, and the form of N enrichment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008600
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  • 9
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    Field scale fertilizer recommendations: The spatial scaling problem (1996)
    Canadian Science Publishing
    Details
    Publication Date: 1996-02-01
    Description: Soil fertility may vary considerably within a field. The effects of variable soil fertility on the relationships among average crop yield response, average soil test, and fertilizer applied evenly to a field have not been examined. This paper develops stochastic equations to describe the average yield gain on a field basis from the application of a single constant rate of fertilizer, in fields with variable soil fertility. The equations are solved numerically for the specific case of nitrogen fertilizer on corn (Zea mays L.) in Ontario, Canada. The results suggest that since the relationships among yield response, soil test, and applied fertilizer are non-linear, a single soil test calibration cannot exist for fields with different spatial variability. Soil test calibrations obtained from sites with low variability (for example small plots) will not hold for sites with higher variability (for example farm fields). Calibrations obtained from sites with low variability will under-predict the optimum economic fertilizer rate for sites with low variability will under-predict the optimum economic fertilizer rate for sites with high variability. The results do not invalidate soil test calibration relationships per se. The challenge is to combine these calibrations with additional knowledge about the spatial distribution and field-scale variability of soil test values in order to maximize economic benefit. Key words: Spatial variability, soil test, fertilizer recommendation, yield, corn, field scale
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 10
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    Nitrous oxide production by manure samples collected from six manure-handling systems (2001)
    Canadian Science Publishing
    Details
    Publication Date: 2001-02-01
    Description: Stored manures are often considered to be source of nitrous oxide (N2O). A study was done to identify manure characteristics and handling stages related to N2O production. In two laboratory experiments we investigated the production of N2O from several animal manures collected at different stages of manure handling or locations in stored-manure systems. Denitrifying enzyme activity, denitrification and CO2 production rates and chemical and fibre characteristics of manure samples were also determined. Most samples had low rates of N2O production. Exceptions were open piles of fresh beef manure and the moist surface layer near the base of an open pile of poultry manure. Production of N2O was most highly correlated with nitrite plus nitrate (NO2− + NO3−) content of manure regardless of whether results were expressed on a wet or a dry weight basis. Denitrification was the most probable source of N2O because N2O production with acetylene and denitrifying enzyme activities was higher than N2O production without acetylene. Stored manure is potentially an important source of N2O emissions, particularly when storage conditions are conducive to formation of (NO2− + NO3−). Key words: Nitrous oxide production, denitrification, denitrifying enzyme activity, manure
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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