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The acute and subchronic toxicity of major geochemical ions to fathead minnow - ion interactions and interspecies comparisons
Citation:
Erickson, R., D. Mount, B. Forsman, J. Hockett, C. Jenson, AND T. Norberg-King. The acute and subchronic toxicity of major geochemical ions to fathead minnow - ion interactions and interspecies comparisons. SETAC North America, Toronto, ON, CANADA, November 03 - 07, 2019.
Impact/Purpose:
This work significantly improves understanding of the acute and chronic toxicity of major geochemical ion mixtures to aquatic organisms and will support the development of aquatic life criteria for these ions by Office of Water.
Description:
Adverse effects from increased concentrations of major geochemical ions (Na+, K+, Ca2+, Mg2+, Cl, SO42, HCO3/CO32) to aquatic communities are evident in various locations. Experimental work has shown that the toxicity of ion mixtures to aquatic organisms is dependent on the specific mixture of ions present and on the receptor organism. Based on extensive testing of the acute toxicity of single salts and binary salt mixtures in various dilution waters to fathead minnow fry, the relationships of this toxicity to ion composition will be presented and contrasted with relationships for Ceriodaphnia dubia. For both species, key elements of these relationships include the importance of considering chemical speciation and activity, the existence of multiple mechanisms entailing both additive and independent interactions among ions, and effects of non-toxic levels of Ca on the toxicity of other ions. Differences between the species include a sulfate-dependent toxicity for minnows not evident for C. dubia, a better correlation of the toxicity of Na-dominated mixtures to Na activity for fathead minnows versus to total ions for C. dubia, and different interactions between Na and K. Ion toxicity to fathead minnow in early-life-stage and embryo-larval tests will be discussed and contrasted with the acute toxicity to fry. Consideration also will be given to the applicability of single salt toxicity tests to the more complex mixtures typical of major ion enrichment in surface waters.