Tracing element migration in the geosphere and biosphere

点击翻译按钮获取中文摘要

The long-term goal of my research is to understand the migration of elements throughout the near-surface environment (i.e. geosphere) and across the interface between the geosphere and plants and animals (i.e. biosphere). This research involves both environmental sciences and mineral exploration, is comprised of both pure and applied research components, and will involve 3 BSc, 2 MSc, 5 PhD, 5 PDF and 2 Research Associates. The science behind this research is that sources of elements can be definitively identified in environments near the surface through their isotopes (same number of protons but different number of neutrons for an element) and concentrations, thereby identifying prospective areas for buried metal deposits and inputs of pollution in pristine areas. My research program during the next five years will focus along two diverse yet related themes: (1) mineral resources, which will involve tracing element migration from ore deposits at depth via their isotopes and trapping of them in the near-surface, and (2) geosphere-biosphere interactions, which will distinguish elements that have migrated from undercover ore deposits from those that have come from global pollution, using these elements in soils and tree-rings to help find more buried ore deposits, and to better track the migratory habits of animals because they have interacted with specific rock units. (1) Mineral resources have become more difficult to find since most of those exposed at the surface have been discovered. We will study areas of known deposits that include uranium in Saskatchewan and copper and nickel in Manitoba. Samples of drill core from the deposit, the overlying geology, and soils and trees at the surface will be collected. Drill core and overlying samples will collected, their mineral compositions characterized, and their chemistry and isotopes of elements measured. Techniques we have developed will be used to measure both element contents and their location in the samples, as well as their isotopes. For the soils, the clay minerals will be extracted because they are able to trap migrating elements. Their chemical and isotopic compositions will be measured to identify elements mobilized from the deposits. Hydrocarbons from clays and soils and their isotopic compositions also will be extracted to understand the role of microbes in mobilizing elements and fixing them in the near-surface environment. In the process, several HQP will be trained in multi-dimensional research and analytical geochemistry. (2) Geosphere-biosphere interactions will involve the use of tree-rings and complementary data from other surface media to distinguish deposit and pollution sources of metals. Also, as part of a collaborative effort over the next five years, I will be engaged in research using isotopes to trace element migration from oceanic, lake and wind-blown sources to produce carbonates in soils. This research will involve deciphering the character of carbonates in arid lake environments and in soils using “bio-active” trace elements and selected isotopes to reveal the effects of microbial processes on carbonate production. In a complementary study, migratory habits of birds will be traced with isotopes of hydrogen, carbon and nitrogen (all bio-active) and trace elements in feathers, blood and toenails to reflect the geology in which the birds grow these organs. This project will be the first to integrate isotope, trace elements, tissue morphology and biologic data to trace factors affecting the declining populations of migrating birds. Despite the seeming disparity, all of this research involves using isotopes and element contents to effectively trace the movement of elements in the near-surface environment for both pure and applied research goals.