Biogeochemical dynamics of contaminated groundwater systems

点击翻译按钮获取中文摘要

My research addresses the practical need to protect groundwater resources and manage groundwater contamination. The societal costs for groundwater remediation are staggering an estimated $209 B in the USA over the next 30 years. In BC, the future cost of cleanup for abandoned mine sites is $1.27 billion according to the Chief Inspector of Mines (Vancouver Sun, Jan. 27, 2017) and greater than $500 M at the Faro Mine in the Yukon alone. If contamination can be prevented, or more cost-effectively remediated, then the savings can flow to other important societal needs such as education, healthcare and economic development. This research program focuses on the development framework to predict the quality of drainage from waste rock at mine sites and the investigation of bioelectric systems to remediate groundwater contamination. ******The two principal solid wastes at mine sites are waste rock and tailings, which together comprise the largest volume of materials handled in the world - at large mines, tens to hundreds of millions of tons of waste rock can be produced each year. Typically 4 or 5 volumes of this so-called waste rock is blasted, hauled and placed in piles for every volume of ore mined. The waste rock often contains minerals that when placed in large waste-rock piles and are thereby exposed to oxygen and water can oxidize (burn) releasing acid and metals into drainage. Mine owners, regulators and local communities would like to know the quality of the drainage before the mine is permitted and the waste piles, often several hundred meters tall, are built. Typically, analysts rely on short duration (50 100 wks) and small-scale tests (~500 g 100 kg) and try to extrapolate results to decades or centuries in the future for billions of kg of waste rock. One component of my program is directed at improving these predictions.******Oxidation processes are electric in nature. Living organisms, including humans, respire (burn) substances such as organic carbon by transferring electrons. In aerobic oxidation, electrons are transferred from organic matter to oxygen. In the last decade, it has been discovered that bacterial in the subsurface, which mediate most oxidation/reduction reactions in the environment, can transfer electrons to electrodes. Conceptually, electrodes can act as snorkels for bacteria, allowing them to oxidize contaminants in environments with no oxygen, as if they were, in effect, breathing oxygen. For bacteria, this allows them to oxidize substances more rapidly and vigorously than in absence of the electrode. My work looks to use this phenomenon to oxidize organic contaminants in groundwater that contains no oxygen, where organics can persist for long periods. These environments are surprisingly common. There are several sites along the Fraser River near Vancouver with this type of contamination. Bioelectric approaches hold great promise to remediate groundwater in BC and Canada.**