Biogeochemical Cycling of Colloidal Trace Metals in the Arctic Cryosphere
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AbstractThe surface waters of the Arctic Ocean include an important inventory of freshwater from rivers, sea ice melt, and glacial meltwaters. While some freshwaters are mixed directly into the surface ocean, cryospheric reservoirs, such as snow, sea ice, and melt ponds act as incubators for trace metals, as well as potential sources to the surface ocean upon melting. The availability and reactivity of these metals depends on their speciation, which may vary across each pool or undergo transformation upon mixing. We present here baseline measurements of colloidal (0.0030.200m) iron (Fe), zinc (Zn), nickel (Ni), copper (Cu), cadmium (Cd), and manganese (Mn) in snow, sea ice, melt ponds, and the underlying seawater. We consider both the total concentration of colloidal metals ([cMe]) in each cryospheric reservoir and the contribution of cMe to the overall dissolved metal phase (%cMe). Notably, snow contained higher (cMe) as well as higher %cMe relative to seawater for metals such as Fe and Zn across most stations. Stations close to the North Pole had relatively high aerosol deposition, imparting high (cFe) and (cZn), as well as high %cFe, %cZn, %cMn, and %cCd (>80%). In contrast, surface seawater concentrations of Cd, Cu, Mn, and Ni were dominated by the soluble phase (<0.003m), suggesting little impact of cMe from the melting cryosphere, or rapid aggregation/disaggregation dynamics within surface waters leading to the loss of cMe. This has important implications for how trace metal biogeochemistry speciation and thus fluxes may change in a future icefree Arctic Ocean.
Jensen, L. T., Lanning, N. T., Marsay, C. M., Buck, C. S., Aguilar-Islas, A. M., Rember, R., ... Fitzsimmons, J. N.
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Jensen, Laramie T||Lanning, Nathan T||Marsay, Chris M||Buck, Clifton S||Aguilar-Islas, Ana M||Rember, Robert||Landing, William M||Sherrell, Robert M||Fitzsimmons, Jessica N
