Professor Diane McKnight Distinguished Seminar October 31 2018
CWEST Distinguished Seminar
Wednesday, October 31st, 2018
SEEC Sievers Room S228
Dr. Diane McKnight
Professor of Environmental Engineering & Environmental Studies, INSTAAR Fellow, Founding CWEST Director
Title: Trouble ahead, trouble behind: acid rock drainage and climate change in the Rocky Mountains
Abstract:
In the Rocky Mountain watersheds, weathering of disseminated pyrite in the country rock and in mining workings generates acidic, metal-enriched water that drains into streams and rivers. This process is referred to as acid rock drainage (ARD) and is a long-term and pervasive environmental problem in the Rocky Mountains. Contamination has not abated since the mining boom ended about 70 years ago, largely because these contaminants are continuously generated from the exposure to oxygen of pyrite in the mine workings and tailings. Typically these streams have high dissolved concentrations of toxic metals, such as Zn, Cu, Cd and Pb, and their streambeds are covered with metal oxides, especially below the mine inflows. These streams and rivers support species-poor aquatic ecosystems, and fish are typically absent. Furthermore, metal concentrations and acidity in the summer and fall have been steadily increasing over the past several decades in an ARD watershed. Another trend is that the resorts in mountain regions have been pursuing a 鈥渇our seasons resort鈥 approach as an adaptation to changing climate. ARD thwart these plans by constraining the use of stream water for snowmaking and impacting summer recreation such as fishing and rafting. In addition to general environmental concerns, this situation has focused attention on potential remediation of abandoned mines. One challenging question for state and federal agencies and watershed stakeholders鈥 groups is determining which of the many abandoned mines in a catchment are the main ARD sources. This challenge can be addressed through field sampling, stream-scale experiments, and modelling. The ARD problem in mountain catchments illustrates how improved understanding of specific processes in a will be inadequate to address current water resource problems unless we can understand the role of climate variability in controlling the hydrology in the future.