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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 16 (1982), S. 791-796 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 18 (1984), S. 383-385 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 20 (1986), S. 817-821 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 23 (1989), S. 768-774 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 25 (1991), S. 921-924 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-2932
    Keywords: selenium ; biogeochemical cycling ; bioaccumulation ; toxicity experiments ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We conducted a joint experimental research and modeling study to develop a methodology for assessing selenium (Se) toxicity in aquatic ecosystems. The first phase of the research focused on Se cycling and accumulation. In the laboratory, we measured the rates and mechanisms of accumulation, transformation, and food web transfer of the various chemical forms of Se that occur in freshwater ecosystems. Analytical developments helped define important Se forms. We investigated lower trophic levels (phytoplankton and bacteria) first before proceeding to experiments for each successive trophic component (invertebrates and fish). The lower trophic levels play critical roles in both the biogeochemical cycling and transfer of Se to upper trophic levels. The experimental research provided the scientific basis and rate parameters for a computer simulation model developed in conjunction with the experiments. The model includes components to predict the biogeochemical cycling of Se in the water column and sediments, as well as the accumulation and transformations that occur as Se moves through the food web. The modeled processes include biological uptake, transformation, excretion, and volatilization; oxidation and reduction reactions; adsorption; detrital cycling and decomposition processes; and various physical transport processes within the water body and between the water column and sediments. When applied to a Se-contaminated system (Hyco Reservoir), the model predicted Se dynamics and speciation consistent with existing measurements, and examined both the long-term fate of Se loadings and the major processes and fluxes driving its biogeochemical cycle.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 57-58 (1991), S. 23-30 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The uptake of three forms of Se, selenate, selenite and selenomethionine, was examined in three species of freshwater algae, Anabaena flos-aquae (Cyanophyceae), Chlamydomonas reinhardtii (Chlorophyceae), and Cyclotella meneghiania (Bacillariophyceae) in a defined medium using radiotracers at Se concentrations representative of contaminated systems. Based on the relative accumulation by live vs. heat-killed cells, and linear accumulation through time, selenate accumulation by all three species appears to be a physiological process. However, selenite accumulation at these concentrations appears to be due largely to sorption rather than active uptake, as shown by rapid initial accumulation and the fact that accumulation by heat-killed cells was nearly equal to that of dead cells. Both selenate and selenite uptake rates increased linearly with concentration over the range of 1 to 50 µg L−1. Selenomethionine uptake is a biological process with saturable uptake kinetics (Ks ranging from about 2 to 30 µg L−1 Se), with much greater uptake rates than the other two forms, and little inactive sorbtion to heat-killed cells.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 57-58 (1991), S. 3-11 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Toxic substances exert impacts on ecosystems at several levels: biogeochemical, toxicological, and populations/communities. Integrating exposure (biogeochemistry) and effects (toxicology) into an ecological context requires models as a necessary step to prediction and assessment of effects on populations and their interactions. To this end, research is being conducted to develop techniques for predicting the effects of Se on aquatic ecosystems. The objective is to develop mechanistic models to predict biogeochemical cycling, toxicological processes, and toxic effects on population and community dynamics. Earlier research demonstrated that different chemical forms of Se have different toxicological properties. Biogeochemical research culminated with a dynamic model of the Se cycle. In ongoing research, experiments are being conducted on microorganisms, phytoplankton, microzooplankton, zooplankton, benthic invertebrates, and fish to measure uptake, biotransformation, and depuration kinetics of different chemical forms of Se, transfer through the food web, and effects on growth, reproduction, community interactions, and survival. This information will provide the basis for the ecosystem effects model.
    Type of Medium: Electronic Resource
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