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Assessing and predicting the ecological effects of elevated ions/conductivity associated with mining and other land uses


This task takes a multi-faceted approach to fully understanding the causes of the adverse effects associated with different mixtures of elevated dissolved ions (i.e., Na+, K+, Ca2+, Mg2+, Cl-, SO42- , HCO3-) often measured as increases in conductivity or total dissolved solids in streams and other freshwater ecosystems.  Increased conductivity can result from many land use practices, but has been strongly associated with mineral and energy extraction practices, such as those of mountaintop mining and the construction of valley fills during coal mining.  In this task, existing acute toxicity models for commonly used benchmark organisms will be enhanced to more rigorously cover water chemistries associated with mountaintop mining, and expanded to include sublethal toxicity in addition to lethality.  Where warranted, additional toxicity studies will be conducted with other freshwater organisms, such as aquatic insects, that may be more sensitive to elevated dissolved ions than more commonly used organisms. 

Rationale and Research Approach:

Elevated ion concentrations, whether measured individually or by combined measures, such as conductivity or total dissolved solids, have been identified as a cause of stream impairments associated with recent mineral and energy extraction practices. However, the roles of individual ions or combinations of ions in these effects are not well understood, and a more complete understanding would help focus approaches for mitigating these effects. As described in the task description, the products will take several different approaches to more fully understanding the causes of the adverse effects associated with different mixtures of ions and these results will be synthesized into a unified assessment. Individual products will result from new laboratory bioassay experiments either with standard organisms or with species determined to be more sensitive to elevated dissolved ions. Other products will complement these laboratory bioassay approaches with studies in artificial streams colonized by more complete stream biotic assemblages or analyses of field data for standard stream assemblages, such as fish or macroinvertebrates. The physiological literature will be reviewed to better understand the roles of the different ions in osmoregulation and ionic regulation.

MED Scientists:

Russ Erickson
Correne Jenson
Terry Highland
Jim Hockett
Dale Hoff
Dave Mount
Teresa Norberg-King



Expected Products:




Sep 30, 2014

2.4.C.3.B A predictive acute toxicity model predicting the toxicity of any ion combination to commonly used benchmark organisms (Ceriodaphnia dubia, Daphnia magna, and fathead minnow).

David Mount
Sep 30, 2013 2.4.C.2 Development of XC95s for conductivity associated with mountaintop mining and valley fills for fish species in the Appalachian, a species sensitivity distribution (SSD) for fish species only, and a genera level SSD that adds the fish to the original macroinvertebrate SSD. Appendices for this report will conduct causal and confounding variable analyses for fish to support the development of the SSDs for conductivity. David Mount
Sep 30, 2016 2.4.C.8 Single-species bioassays with different test species and artificial stream studies, to make predictions about the effects of different ionic mixtures on fish and macroinvertebrate assemblages. with predictions compared to field observational data to test laboratory results extrapolation to the field. David Mount
Sep 30, 2016 2.4.C.5 An assessment of major ion sensitivity of alternative test organisms found to be sensitive in field settings. David Mount
Sep 30, 2015 2.4.C.4 An extension of the acute ion toxicity model to address chronic toxicity. David Mount

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