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Waterborne and sediment selenium (Se) data, in conjunction with selected physicochemical parameters, were collected from streams of the middle Arkansas River basin, Colorado, USA, to examine the factors affecting sediment Se accumulation in a lotic environment. An empirical model of dissolved-to-sediment Se transfer in western streams, as an interactive function of sediment organic carbon content (R2 = 0.78, p < 0.001, n = 34), was developed and validated. Sediment Se and associated biological effects data were compiled from the literature, to provide an estimate of sediment Se concentration thresholds that have biological effects. Based on this preliminary analysis, sediment Se concentrations of 2.5 ?g/g would...
A number of streams in Colorado were found to contain waterborne selenium concentrations that consistently exceeded the current U.S. EPA chronic criterion of 5 Î&frac14;g/L and often exceeded the acute criterion of 20 Î&frac14;g/L. Despite these elevated concentrations, no biological impact was observed. These findings led to a review of selenium exposure pathways in freshwater. The literature strongly indicates that chronic selenium toxicity can result from accumulation of selenium in the sediment, movement into the food chain, and resulting dietary uptake. Chronic toxicity does not appear to be strictly a result of waterborne selenium concentrations. In fact, dissolved selenium concentrations are a poor predictor...
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Data regarding the evaluation of the toxicity of zinc in 1-, 3-, 8-, 24-, and 48-hour exposures with a cladoceran (Ceriodaphnia dubia), and in 1-, 3-, 8-, 24-, and 96-hour exposures with rainbow trout (Oncorhynchus mykiss) on survival and mobility of test organisms.
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Description of Work Determine the relative sensitivity of two species of amphibians (i.e. Wood Frogs Rana sylvatica, Cricket Frogs Acris crepitans blanchardi, American Toad Bufo americana) to exposure to acute and chronic levels of nitrate, nitrite and ammonia. This data will be used to evaluate the current ammonia criteria and for possible inclusion in the development of criteria for nitrite and nitrate.
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Description of Work The work completed for this template will provide the following information: 1) Generate acute and chronic toxicity data for freshwater mussels and snails to enhance the protection of listed/endangered species in the GL basin; 2) Refine methods and conduct acute and chronic toxicity tests on amphibians; 3) Develop and test methods for conducting chronic toxicity tests for mayflies.


map background search result map search result map Determination of the Sensitivity of Two Species of Amphibians to Toxicity From Nitrate, Nitrite and Ammonia Toxicity Testing for Stream Dwelling Amphibians, Mussels, and Mayflies Acute and latent effects of zinc on two commonly tested species (Ceriodaphnia dubia and Oncorhynchus mykiss) Acute and latent effects of zinc on two commonly tested species (Ceriodaphnia dubia and Oncorhynchus mykiss) Toxicity Testing for Stream Dwelling Amphibians, Mussels, and Mayflies Determination of the Sensitivity of Two Species of Amphibians to Toxicity From Nitrate, Nitrite and Ammonia