The effects of various water chemistry parameters on the toxicity of copper to larval fathead minnows were investigated. Increased pH, hardness, sodium, dissolved organic matter, and suspended solids each caused toxicity to decrease on the basis of total copper concentrations. In contrast, added potassium resulted in increased toxicity. Alkalinity had no observed effect on total copper LC50s, but its effects might have been masked by those of the cations added with it. In most cases, the effects of water chemistry were found to be similar for different endpoints (growth, survival at different durations), but there were differences in the relative magnitude of some effects across these endpoints. Over all experimental treatments, 96-h total copper LC50s varied 60-fold. Every water chemistry parameter also caused toxicity to vary significantly when expressed on the basis of cupric ion selective electrode measurements, sometimes more so than on the basis of total copper. Therefore, this study does not support attributing to cupric ion a singular importance in regulating toxicity to this test organism. A variety of copper species might be contributing to toxicity and it is evident that toxicity is also affected by water chemistry in ways not related to copper speciation.

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In this paper we describe test methods utilizing the aquatic oligochaete Lumbriculus variegatus to assess the acute and chronic toxicity and the presence of bioaccumulatable compounds in contaminated sediments. Lurnbriculus variegatus was chosen as a test species because (a) it represents an ecologically relevant component of freshwater ecosystems (i.e., oligochaetes); (b) it is suitable for long-term testing and evaluation of chronic toxicity end points (e.g., growth, reproduction); (c) it is exposed via all important routes of concern, including ingestion of contaminated particles; and (d) it has sufficient biomass to assess bioaccumulation of contaminants. Also, Lumbriculus variegatus is easily cultured and handled. Described herein are culturing procedures and test protocols (e.g., test length, sample size, feeding, etc.) for Lumbriculus variegatus, as well as two examples of the types of experimental data generated when using the oligochaete in tests with contaminated sediments.

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