Tungsten is a valuable industrial metal with limited effective substitutes for its many industrial uses. Tungsten is classified as a critical mineral by many countries, including Canada and the United States. As such, tungsten mining is expected to increase in the future, generating waste with potential as point sources of metal leaching to the environment. Concerns about the toxicity of tungsten have recently emerged, but the element is not regulated in mine waste. The geochemical behavior of tungsten is understudied, hampering the ability to predict tungsten leaching from past, present, and future mining operations. The low-temperature aqueous mobility of tungsten is pH dependent, with adsorption as a primary factor limiting its dissolved concentrations in the environment. Tungsten, which forms strictly anionic species, adsorbs to mineral surfaces at low pH, and is most mobile in alkaline waters. The speciation of tungsten has been shown to affect its adsorption propensity, with WO42- more strongly adsorbed than polymeric and thiolated species. Aqueous tungsten concentrations generally decrease with decreasing pH in surface waters, groundwaters, geothermal waters, and mine tailings. Although progress has been made, the mechanisms of scheelite and wolframite dissolution are still poorly understood. Mine waste generated from processing tungsten-rich ores contains elevated tungsten concentrations; the weathering behavior of scheelite and wolframite need more research to mitigate the potential for tungsten leaching during the long-term storage of mine waste. Identifying mineralogical changes to scheelite and wolframite that may occur during ore processing and weathering of mine waste would be beneficial for understanding the leaching behavior of these minerals. Based on current knowledge, it is likely that tungsten is mobilized as both dissolved anions and adsorbed to colloidal particles. Improved understanding of the environmental geochemistry of tungsten will help ensure its sustainable supply in the future and permit more effective remediation at abandoned and existing mines.

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The first of many thank-you's goes to my supervisors, Heather Jamieson and Matt Leybourne, for their mentorship, guidance, and patience over the past few years. I am extremely privileged, honored, and proud to be part of the Jamieson Clan and the QFIR family, and couldn't have asked for a more wonderful group of people to develop my career as a geochemist with. The Winter Wonderlands, defense parties, and Grad Club beer discussions were some of the highlights of my time at Queen's. Heather, I fell in love with the north during our trip to Cantung, and our long, beautiful drives to and from the mine will be forever in my mind. Thank you so much for giving me this opportunity, and for the opportunities that have stemmed as a result from completing this thesis. Matt, your contributions to this thesis are innumerable. Having access to world class analytical facilities at QFIR, and same-day access to a worldclass geochemist for answers to my (often redundant) questions has been invaluable. Both of you held infinite patience during periods when I was low, and I honestly don't think my thesis would have been completed without your understanding. It has been a pleasure working with both of you. This thesis is dedicated to Kurt Kyser, who took me under his wing that one fateful summer in Kingston. After expressing my interest in geochemistry, Kurt offered me a summer student position at QFIR and exposed me to my first taste of analytical and field work, which lead to me completing an undergraduate thesis under his supervision. Kurt's enthusiasm for science, his lust for life, and his dedication to QFIR inspired me to pursue a career in geochemistry, and even more so to pursue a life of passion. I wish you could have reviewed this thesis, that we could've share the excitement of the results, or even just to have seen you shake your head and say, "nah". This thesis wouldn't be possible without Hendrik Falck, the Cantung connoisseur. Thank you for assisting with field work, and for sharing your big-brain knowledge of the Cantung deposit, of the history of the mine, and of the physiography of the Flat River valley. A brewpub visit in is order during my next visit to Yellowknife! A very special thank-you is in order for Dan Layton-Matthews, who first sparked v my interest in geochemistry via ternary diagrams in second year petrology, and another to Noel James for our discussions about big-picture global issues, science and creativity, and for just being a rad dude. Guy Narbonne, thank you for taking care of me when I got sick in Namibia, and for expressing not even the slightest discontent about missing part of the Etosha safari. Rob Harrap, I don't know how to express my thanks to you. We've had so many discussions throughout my undergraduate and master's degrees about anything and everything, but the ones where I came in distressed and left with some clarity are undoubtedly the most important.To all of the QFIR family, thank you for all of the analytical assistance, the laughs, and the wine over the years. April, your bubbli...