Biogeochemical Cycling of Colloidal Trace Metals in the Arctic Cryosphere

Abstract

The 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 (∼0.003–0.200 μm) 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 (<0.003 μm), 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 ice‐free Arctic Ocean.

Toward a Better Understanding of the Global Ocean Copper Distribution and Speciation Through a Data‐Constrained Model

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Temporal Baseline of Essesntial and Non-essential Elements Recorded in Baleen of Western Arctic Bowhead Whale (Balaena mysticetus)

“…The Arctic environment has been warming at an unprecedented rate and the Arctic Ocean is especially sensitive to these changes. Higher atmospheric temperatures lead to ice and permafrost melting, riverine discharge, and coastal erosion (Overland et al 2002;Rydberg et al 2010;Jensen et al 2021). Snow, ice, and permafrost store and accumulate trace elements over time, then release large concentrations into the marine Arctic environment through melting events and runoff.…”

In Situ X-ray Fluorescence Evaluation of Metal Ion Adsorption on Ferric Oxyhydroxide in Frozen Solutions

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