39. Defining the Interplay Among Geochemistry, Biology, and Physics on the Cycling of Metals and Nutrients in an Aquatic Ecosystem Affected by Mining Activities and Urbanization
Ecosystems are communities of organisms that interact with each other and with the physical and chemical environment in which they live. Defining how an ecosystem functions or how it will respond to natural and anthropogenic changes requires a detailed understanding of complex geochemical, biological, and physical processes. This process-based understanding is important for successfully defining chemical or biological indicators that measure ecosystem health and for identifying those processes most detrimental to ecosystem health. This type of information is the foundation for assessing and managing the health of organisms and the quality of water and sediment in an ecosystem.
Quantitative models may serve as powerful tools for describing the cycling of energy and matter through ecosystems. State-of-the-art models incorporate process-based equations that capture current knowledge about the interdependence of geochemical, biological, and physical processes. The models provide spatial and temporal information about ecosystem variables (for example, chemical concentrations or assemblage structures) that can be compared with historical and real-time field measurements. With proper input data and validation, quantitative models for a given system can forecast how the ecosystem will likely respond to perturbations, such as climate warming, population growth, invasive species, or remediation activities.
Coeur d’Alene Lake in northern Idaho is an aquatic ecosystem that is affected by upstream historical mining activities and on-going urbanization within its watershed (Woods and Beckwith, 1997). Concentrations of dissolved zinc exceed water quality standards, phytoplankton growth and diversity are inhibited due to zinc toxicity and phosphate limitation, and bottom sediments are highly enriched in arsenic, cadmium, copper, lead, mercury, silver, and zinc. The southern portion of the lake lies within Coeur d’Alene Tribal lands, and the lake and surrounding area offer spectacular recreational opportunities. Therefore, understanding how metals, particularly zinc, and nutrients cycle in this ecosystem and how the ecosystem would be expected to respond to additional natural and anthropogenic perturbations (for example, remediation or climate change) is critical for successfully managing this resource over the long term.
The presence of metal contaminants and potential eutrophication in Coeur d’Alene Lake make it an interesting and unique ecosystem to examine the interplay among various biological organisms and their chemical and physical environment. To provide a tool for understanding how Coeur d’Alene Lake functions, researchers at the Centre for Water Research, University of Western Australia recently configured a state-of-the-art three-dimensional (3D) hydrodynamic-biogeochemical model (ELCOM-CAEDYM) for Coeur d’Alene Lake (Dallimore et al., 2007; Hipsey et al., 2007) under a cooperative agreement with the USGS and Idaho Department of Environmental Quality. The Estuary and Lake Computer Model (ELCOM) is the 3D hydrodynamic component and predicts water velocity, temperature, and salinity in aquatic systems. The Computational Aquatic Ecosystem Dynamics Model (CAEDYM) that is coupled to ELCOM includes detailed process-based descriptions of biological and geochemical processes. These include: cycling of C, N, P, O2, Si, and metals, aqueous chemical speciation, metal uptake by biota and associated toxicity effects, settling of organic and inorganic particles, fluxes of nutrients and metals across the sediment-water interface, growth or inhibition of pelagic species, respiration, and succession. The configured ELCOM-CAEDYM for the lake recently was transferred from the University of Western Australia to federal, state, and local agencies (that is, U.S. Geological Survey [USGS], Coeur d’Alene Tribe, and Idaho Department of Environmental Quality) involved in understanding and monitoring the Coeur d’Alene Lake ecosystem.
The research opportunity for the Mendenhall postdoctoral applicant is to explore and clarify the complex interrelationships among geochemistry, biology, and physics within the Coeur d’Alene Lake ecosystem by using and refining the state-of-the-art ELCOM-CAEDYM for the lake. This exploration could include, but is not limited to, how metal contaminant and nutrient cycling, water quality, biological communities, and lake stratification are affected by (1) changes in climatology (for example, high versus low runoff, wind stress, or global warming), (2) addition of other biological organisms (zooplankton or fish), (3) changes in the trophic status of the lake, (4) upstream remediation activities (decreased metal loading), or (5) urbanization (increased nutrient and particle loading). Modeling efforts could also determine the sensitivity of the ecosystem to multiple forcing factors and identify critical parameters or parameter interactions that serve as key indicators of the overall health of the ecosystem. In the near future, a detailed sediment diagenesis model will be incorporated into CAEDYM, thereby providing a dynamic link between water column and sediment processes and another avenue for research investigations. The applicant will need to integrate data from multiple scientific disciplines and potentially expand his/her scientific horizons to advance our understanding of physical and biogeochemical processes that control interactions among biota, nutrients, and metal contaminants in the water and sediment columns of aquatic ecosystems. The applicant also will have the opportunity to collaborate with other researchers at the Coeur d’Alene Tribe, Idaho Department of Environmental Quality, and other local, state, and federal agencies in developing model scenarios and research products that assist these agencies in monitoring and managing Coeur d’Alene Lake.
References
Dallimore, C.J., Hipsey, M.R., Alexander, R., and Morillo, S., 2007, Simulation model to evaluate Coeur d'Alene Lake's response to watershed remediation, v. 1, Hydrodynamic modeling using ELCOM. Centre for Water Research: The University of Western Australia Report WP 2133 CD.Proposed Duty Station: Seattle, WAHipsey, M.R., Alexander, R., and Dallimore, C.J., 2007, Simulation model to evaluate Coeur d'Alene Lake's response to watershed remediation, v. 2, Water quality modeling using ELCOM-CAEDYM. Centre for Water Research: The University of Western Australia Report WP 2132 MH.
Woods, P., F., and Beckwith, M.A., 1997, Nutrient and trace-element enrichment of Coeur d'Alene Lake, Idaho: U.S. Geological Survey Water-Supply Paper 2485, 93 p.
Areas of Ph.D.: Modeling of aquatic systems, limnology/oceanography, hydrology, aquatic geochemistry, aquatic biology, and ecology
Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Hydrologist, Research Chemist, Research Ecologist
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
Research Advisor(s): Laurie Balistrieri, (206) 543-8966, balistri@usgs.gov; James Kuwabara, (650) 329-4485, kuwabara@usgs.gov
Human Resources Office contact: Candace Azevedo, (916) 278-9393, caazevedo@usgs.gov
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Summary of Opportunities |