Pathways of Essential Trace Elements in Land and Coastal Sedimentary Environments: Past, Present, Future

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The research concentrates on the refinement and analysis of the pathways and cycles of ten biologically essential trace elements: cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), vanadium (V), and zinc (Zn). These elements are to a variable extent essential to land and aquatic plant growth, and a deficiency or excess of the individual elements in soils and continental waters may affect not only the functioning of their own biogeochemical cycles, but the cycles of other elements coupled to them as well. In general, the deficiencies or excesses of the essential trace elements in different compartments of the surficial environment can be caused by such processes as anthropogenic releases, historical changes in the rates of denudation, climatic changes, changes in the types of vegetation cover, and possibly, releases from meteorite impacts in the geologic past. In the first step of our work on the ten essential elements we plan to establish and refine the mass balance and flux values in the continental, aquatic and near-shore oceanic environments. The second step is theoretical analysis of the main mechanisms that control the fluxes of the ten elements, and of the factors responsible for the coupling of their cycles to the global cycles of carbon (C) and phosphorus (P). Third step is development of conceptual and mathematical models, and their sensitivity analysis, for the individual and coupled cycles of these trace elements, within a general frame of reference of the carbon and phosphorus cycles, as has been worked out in our, and other investigators', earlier research. The goals of the proposed work are understanding of the baseline picture of the ten essential trace elements in the global biospheric change, their potential significance as environmental indicators for the geologic past, and obtainment of the upper bounds on their fluxes and storage rates under different sets of environmental conditions.