Current and future development of mineral resources requires an evaluation of environmental risks. One challenge in assessing those risks is that drainage from mineralized environments contains multiple metals, each with a unique toxicity to a particular aquatic organism. However, current water quality criteria and risk assessment methods are based on the toxicity of individual metals rather than mixtures of several metals. Hence, new approaches and tools are needed to define the toxicity (or risk) of complex dissolved metal mixtures to aquatic organisms and to aid in the development of new generations of geoenvironmental models for mineral resources and water quality criteria for dissolved metal mixtures. Predicting health impacts of metal mixtures to aquatic biota is an area of current interest to national and international metal industries and regulating agencies. Nickel and cobalt, two elements found in drainage from platinum group element (PGE) deposits, are of particular interest because the mechanisms by which they cause toxicity are not well known. Previous work developed approaches for predicting the toxicity of metal mixtures to a variety of aquatic organisms (Balistrieri and Mebane, 2014; Balistrieri et al., 2015; Schmidt et al., 2010). In that work, water and biological data from the Central Colorado Assessment Project, biotic ligand models that predict accumulation of multiple metals on organisms, toxicity functions that relate multiple metal accumulation to biological response, and Monte Carlo simulations to predict the probability of health impacts to invertebrates from polymetallic vein and porphyry deposits with various types of hydrothermal alteration was used. This project extends that work by developing similar probability curves for multiple organisms exposed to potentially toxic dissolved metals (cobalt, copper, nickel, and zinc) derived from PGE deposits.
Development of probability curves of health impacts to aquatic life from dissolved metal mixtures derived from PGE deposits requires data on the toxicity of cobalt, copper, nickel, and zinc to aquatic organisms and comprehensive water data from areas draining PGE deposits. We use previously published metal toxicity information for a variety of organisms (trout, Hyalella azteca, Daphnia magna) and generate new toxicity data from mesocosm studies of natural communities of macro-invertebrates and cultured mayflies in the presence of single metal and binary metal mixtures. Our previous work involved mesocosm studies of cadmium, copper, and zinc effects on invertebrates; we plan to build on those studies by examining the toxicity of cobalt and nickel to invertebrates. Further, we plan to use the "biotic ligand model" sub-database of the USGS National Water Information System (NWIS), which contains concentration data on major and minor ions and dissolved organic carbon (DOC), to predict survival or community richness of aquatic life in streams within the mid-continent rift. This work complements existing research conducted in other Mineral Resources Program Midcontinent Rift projects by providing the toxicological perspective on links among ore deposit geology, aquatic geochemistry, metal toxicity, and the health of aquatic organisms.
Work involves synthesizing and modeling metal toxicity data and developing probability curves for the survival of aquatic life in the presence of drainage from PGE deposits. The modeling approach is presented in our recent publication (Balistrieri et al., 2015). To conduct our work, we combine multiple metal biotic ligand models, toxicity functions, and Monte Carlo simulations to predict the probability of health impacts to invertebrates in drainage from polymetallic vein and porphyry deposits. The results of this task will provide (1) information on the connections among ore deposit geology, aquatic geochemistry, metal toxicity, and aquatic toxicology and (2) tools that can be used to evaluate the risk of metal toxicity to aquatic organisms in watersheds containing mineralized rock or develop new water quality criteria.
A series of mesocosm experiments are being used to examine the toxicity of cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), and zinc (Zn) to natural communities of invertebrates and cultured, genetically pure mayflies (Neocloeon triangulifer). A mesocosm is an experimental tool that brings a small part of the natural environment under controlled conditions. Using Zn as a reference point, each experiment simultaneously considers impacts of individual metals and binary and/or ternary metal mixtures on the health of the aquatic organisms. Experiments are designed to use typical metal ratios found in the environment. Each mesocosm experiment builds on the previous experiment and provides fundamental data for developing models that describe and predict the toxicity of metal mixtures to aquatic life.
Our mesocosm experiments are conducted at the Aquatic eXperimental Laboratory (AXL) at the USGS Fort Collins Science Center. Mesocosm toxicity studies are labor intensive and require comprehensive chemical and biological analyses. Mesocosm studies involve: (1) deployment of well-washed rocks in a pristine stream for 40 days to allow colonization of macro invertebrates (upper left photo); (2) retrieval of those rocks that are then placed in 36 flow-thru "streams" at AXL (lower left photo); (3) manipulation of metal concentrations in the "streams"; (4) daily collection of emergent adults during the 30-day experiment (right photo); (5) multiple measurements of water quality (temperature, pH, dissolved major and minor ions, and dissolved organic carbon) during the experiment; and, at its conclusion, (6) identification and counting of larval invertebrates in each stream. The health metrics for these experiments are emergence, body size, and community diversity (or richness).
Balistrieri, LS, and Mebane, CA, 2014, Predicting the toxicity of metal mixtures: Science of the Total Environment, 466-467, p. 788-799, doi:10.1016/j.scitotenv.2013.07.034.
Balistrieri, L.S., Mebane, C.A., Schmidt, T.M., and Keller, W., 2015, Expanding a metal mixture toxicity model to natural stream and lake invertebrate communities: Environmental Toxicology and Chemistry, 34(4), p. 761-776, http://dx.doi.org/10.1002/etc.2824.
Farley, Kevin J., Meyer, Joseph S., Balistrieri, Laurie S., De Schamphelaere, Karel C., Iwasaki, Yuichi, Janssen, Colin R., Kamo, Masashi, Lofts, Stephen, Mebane, Christopher A., Naito, Wataru, Ryan, Adam C., Santore, Robert C., and Tipping, Edward, 2015, Metal Mixtures Modeling Evaluation: 2. Comparison of Four Modeling Approaches: Environmental Toxicology and Chemistry, 34(4), p. 741-753, http://dx.doi.org/10.1002/etc.2820.
Mebane, C.A., Schmidt, T.S., and Balistrieri, L.S., 2017, Larval aquatic insect responses to cadmium and zinc in experimental streams: Environmental Toxicology and Chemistry, 36(3), p. 749-762, doi:10.1002/etc.3599.
Wanty, R.B., Balistrieri, L.S., Wesner, J.S., Walters, D.M., Schmidt, T.S., Podda,F., De Giudici, G., Stricker, C.A., Kraus, J., Lattanzi, P., Wolf, R.E., Cidu, R., 2015, Isotopic insights into biological regulation of zinc in contaminated systems: Procedia Earth and Planetary Science, 13, p. 60-63, doi:10.1016/j.proeps.2015.07.014.
Balistrieri, L.S., 2015, Potential toxicity of multiple metals associated with platinum group element (PGE) deposits [poster]: Mineral Resources Program Science and Information Forum, Reston, VA.
Balistrieri, L., and Wanty, R., 2015, Bioregulation of Zn isotopes & survival strategies in metal-rich waters [invited talk]: Chemical Oceanography Lunch Seminar Series, School of Oceanography, University of Washington.
Mebane, C.A., 2016, 164 Beakers, buckets, and brooks: utility of mesocosm-type studies in aquatic life criteria derivation and validation [abs.]: 2016 SETAC North America 37th Annual Meeting, 6-10 November 2016, Orlando, FL.
Mebane, C., Eakins, R.J., Fraser, B.G., and Adams, W.J., 2015, Species Sensitivity Distributions (SSDs) for aquatic insects and metals inferred from recovery trajectories versus traditional laboratory approaches [abs.]: 2015 SETAC North America 36th Annual Meeting, Salt Lake City, UT.
Mebane, C.A., Schmidt, T.S., and Balistrieri, L.S., 2014, The cadmium paradox: Lethal to aquatic insects at low concentrations, but moderated by zinc in ambient freshwater settings? [abs.]: 2014 SETAC North America 35th Annual Meeting, Vancouver, B.C. Canada.
Miller, J., Schmidt, T.S., Balistrieri, L.S., and Mebane, C., 2015, Full life-cycle sensitivity of the mayfly Neocloeon triangulifer (Ephemeroptera: Baetidae) to copper and zinc [abs.]: 2015 SETAC North America 36th Annual Meeting, Salt Lake City, UT.
Schmidt, T.S., Balistrieri, L.S., and Mebane, C.A., 2014, Stream mesocosm testing of metal mixtures: Presentation at Fall 2014 Metals Meeting, Colorado School of Mines.
Schmidt, T.S., Mebane, C.A., and Balistrieri, L.S., 2016, Mesocosms: Old techniques can provide new insight on aquatic life criterion development [abs.]: 2016 SETAC North America 37th Annual Meeting, 6-10 November 2016, Orlando, FL.
Schmidt, T.S., Mebane, C.A., and Balistrieri, L.S., 2015, Aquatic insect responses to metal mixtures [invited abs.]: Aquatic Toxicology Symposium, Port Townsend, WA.
Schmidt, T.S., Mebane, C.A., and Balistrieri, L.S., 2014, Single and binary mixtures of cadmium and zinc suggest dipteran emergence is more sensitive to metals than mayfly emergence? [abs.]: 2014 SETAC North America 35th Annual Meeting, Vancouver, B.C. Canada.
Schmidt, T.S., Mebane, C.A., and Balistrieri, L.S., 2014, Emergence dynamics altered by dissolved cadmium and zinc in a 30-day mesocosm experiment [abs.]: Joint Aquatic Sciences Meeting, Portland, OR.
Schmidt, T.S., Miller, J., Mebane, C.A., and Balistrieri, 2016, Metal-mixture toxicity (Copper + Nickel + Zinc) to aquatic insect communities in mesocosms [abs.]: 2016 SETAC North America 37th Annual Meeting, 6-10 November 2016, Orlando, FL.
Schmidt, T.S., Rogers, H., Mebane, C.A., and Balistrieri, L.S., 2015, Mesocosm experiments evaluate metal mixture toxicity on aquatic insects [abs.]: 2015 SETAC North America 36th Annual Meeting, Salt Lake City, UT.
Project staff participated in a Metal Mixture Modeling Evaluation (MMME) research project and workshop commissioned by four global metal and mining organizations. The MMME project was designed to compare existing bioavailability-based approaches for assessing metal mixture toxicity in freshwater systems (Balistrieri et al., 2015; Farley et al., 2015).