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Availability And Toxicity Of Nickel To Lotic Periphyton And Macroinvertebrates, Stephanie Marie Bessom
Availability And Toxicity Of Nickel To Lotic Periphyton And Macroinvertebrates, Stephanie Marie Bessom
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There is a lack of information regarding the bioaccumulation and toxicity of nickel (Ni) to lotic ecosystems. The objective of this study was to investigate the source, uptake, and toxicity of Ni by periphyton and macroinvertebrates (Hyalella azteca and Daphnia magna) in simulated stream ecosystems that included sediment and water. Periphyton were exposed to two types of sediment, a low-organic sandy mixture and a high organic silt, treated with varying levels of Ni. After 96 h, Ni levels in overlying water and periphyton were related to those in sediments, although differences existed between sediment types. Tests with 64Ni added to …
Investigating Nickel Flux And Toxicity In Clay Sediments With Batch And Stream Recirculating Flume Experiments, Christina Elizabeth Cloran
Investigating Nickel Flux And Toxicity In Clay Sediments With Batch And Stream Recirculating Flume Experiments, Christina Elizabeth Cloran
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Using batch and stream recirculating flume experiments to compare and contrast one clayey sediment (Warden Ditch) and two analytical grade clay minerals (montmorillonite and kaolinite), the dynamic interactions between two aquatic stressors (suspended solids and nickel) were explored. Aldrich humic acid was incorporated to demonstrate the mitigating effects of dissolved organic carbon (DOC) on Ni toxicity. The flux of Ni between compartments (dissolved and sorbed) was quantified as a partition/distribution coefficient. The USEPA test organism Daphnia magna (neonates, < 24 h) was utilized to evaluate toxicity in dynamic non-renewal, short-term bioassays. Generally, toxicity showed a linear relationship with turbidity level. Conversely, sorption coefficients were experiment specific, making them difficult to predict and assess. Clay functioned as an adsorbent, scavenging Ni. Results support the hypotheses that solids and metals act as stressors in streams, DOC attenuates the toxicity of Ni, and Ni fluxes quickly between system compartments.