USGS Home
Contact USGS
Search USGS

Ecological and Toxicological Impacts of Metal Mixtures in Mineralized Rock Drainage

• Project Home
• Modeling Predictions
• Mesocosm Experiments
• Field Studies
• Key project staff

Water Quality and Aquatic Life Standards that are set by federal and state regulatory agencies are used to evaluate the quality of our nation’s water and the health of aquatic ecosystems.  These standards currently are based on hardness of the water and are determined for single metals, not for mixtures of metals that are typically found in natural systems.  Metal mixtures potentially can be more or less toxic or have the same toxicity as single metals to aquatic organisms.  However, models that predict the toxicity of metal mixtures to aquatic organisms are in their infancy. 

This project examines and models the effects of dissolved metal mixtures on the health of aquatic organisms.  The metals of interest are cadmium (Cd), copper (Cu), and zinc (Zn) at concentrations and ratios that are present in drainage from mineralized ore deposits.  The survival of trout and the diversity, richness, or abundance of insects (benthic invertebrates) and planktonic communities in aquatic systems affected by metal mixtures are evaluated.

What is the goal of the project?

To quantitatively link the geochemistry of mineralized rock drainage that contains mixtures of dissolved metals to the health of natural biological communities.  This goal will be accomplished by evaluating several different modeling approaches that predict the toxicity of metal mixtures to various aquatic organisms using:

• recently published data from field studies that examined the health of trout, benthic macroinvertebrates, and zooplankton in waters of variable chemical composition
• new data from a series of well-controlled laboratory experiments using natural invertebrate communities exposed to a range of dissolved metal (Cd, Cu, and Zn) concentrations in single metal or multiple metal combinations
• new data from field studies of water geochemistry and invertebrate communities in watersheds in Colorado and Idaho that contain mineralized ore deposits

Why is the work important?

This project

1. incorporates multiple levels of studies (modeling, laboratory experiments, and field studies) that are designed to advance the prediction of toxicological and ecological effects of waters from mineralized deposits
2. provides fundamental science that links past and future mineral resource development with environmental health
3. enhances the scientific foundation that is used to develop new water quality criteria, prepare for future regulatory demands, ensure adequate environmental protection for aquatic organisms, and manage our nation’s natural resources.