Water Resources Research Act Program

Details for Project ID 2016ID208B

Seasonal Flux of Environmental Conditions and Metal Solutes in the Shallow Groundwater Environment of the Mining-Impacted Upper Coeur d

Institute: Idaho
Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $13,914 Total Non-Federal Funds: $27,928

Principal Investigators: Jeff Langman

Abstract: The release of transition metals and metalloids into the environment from the oxidative dissolution of metal sulfide minerals in waste rock has been a significant environmental issue since the advent of mining. The non-destructive nature of metals allows for the long-term persistence of metal contamination, which is compounded by the seasonal flux of environmental conditions that can enhance or limit mineral weathering and metal mobility. Certain water resources in Idaho continue to suffer significant impairment because of the release of metals from the weathering of sulfidic ore and waste rock, particularly in the Bunker Hill Mining and Metallurgical Superfund Site in the Coeur d'Alene River Basin. The impact of mining on Idaho's water resources should not be viewed as a legacy issue, because mining continues in the Coeur d'Alene River Basin and other parts of the State and the proposed Cu-Mo mine in Boise County has the potential to become the world's largest Mo open pit mine. Mining is part of the State's legacy and is part of the State's future, which underscores our need to further understand the potential environmental impacts from legacy and new mining practices. The seasonal flux of transition metals such as Cd, Fe, Pb, and Zn released from metal sulfide minerals during oxidative dissolution can be overlooked because of the assumption of macroenvironment and steady state conditions that may limit metal mobility in hydrologic systems. The current understanding of the form and size of natural metal particles released into the environment and the influence of the particle size on fate and transport lacks resolution. The heterogeneity and seasonal flux of environmental conditions in waste rock and sediments may allow for periodic releases of metals, which can include nanoscale metal colloids and co-associated minerals formed in interstitial microenvironments. The importance of this proposed investigation is the current difficulty in predicting the persistence of metal nanoparticles in hydrologic systems because of a lack of clarity in their formation and behavior. The purpose of this proposed study is to examine the seasonal flux of environmental conditions and metal particle size and form in the shallow groundwater along Canyon Creek in the mining-impacted Burke Canyon in the Coeur d'Alene River Basin. This study will be used to preliminary evaluate the form and composition of metal nano- and micro-particles to understand the influence of the seasonal flux of environmental conditions on the metal particle formation and transport. The study will involve the deployment of multiparameter probes and the collection of groundwater samples. Analyses will include the determination of seasonal metal concentrations, particle size distributions, amorphous or mineral preferences, and likelihood of organometallic complexation. This study will be used as a pilot project for a future investigation to examine the formation, size, behavior, fate, and transport of metal nanoparticles as inorganic and organic colloids and co-associated minerals in interstitial waters and in larger macroenvironments of mining-impact basins.