Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $14,550 Total Non-Federal Funds: $29,100
Principal Investigators: Jeff Langman, James Moberly
Abstract: Release of metals and sulfur into the natural environment because of the mining and subsequent weathering of sulfide minerals is a significant risk to water quality and ecosystem services; yet, our understanding of the influence of seasonal conditions on metal and sulfur mobility in mining-impacted environments is limited. With extraction of sulfide minerals, metals and sulfur may be released into the environment through physical transport as sediments or released through chemical weathering and transport as free ions, multi-metal nanoparticles, sulfur colloids, or organometallic complexes. Deposition of sulfide minerals in benthic zones presents unique challenges to land managers tasked with remediation of mining-impacted environments. A reservoir of sulfide minerals in benthic sediments that is weathering under variable seasonal conditions may allow for the mobilization/immobilization of metals and sulfur that can alter lake water chemistry and influence biota such as plankton and larger algae. Metal and sulfur release is highly difficult to estimate in these organic-rich environments where variation in ligands and oxidizing/reducing conditions may occur with changes in burial depth and by season. A primary control in the metal-ligand environment is the chemical state of sulfur because of sulfur’s ability to form various intermediary compounds such as disulfides, polythionates, and colloids that will influence metal mobility. The potential presence/absence and stability/nonstability of intermediary sulfur forms present remediation challenges. This study will examine the seasonal relation of metals and sulfur in the mining-impacted benthic sediments of a lateral lake in the lower Coeur d’Alene River Basin and the influence of this relation on porewater and lake water chemistry. The study will involve the extraction of porewater from mining-impacted benthic sediments for chemical analysis and the determination of the sediment’s sulfur forms through synchrotron X-ray analysis. This study will be used as a pilot project for a future investigation to examine the formation, size, behavior, and fate of metal and sulfur forms because of a seasonal changes in mining-impacted benthic sediments to better understand their influence on lake water chemistry and biota.