Accumulation mechanisms of trace metals into Arctic sea ice

• Main Author: Evans, La Kenya Elizabeth
• Other Authors: 西岡, 純, 鈴木, 光次, 力石, 嘉人, 豊田, 威信, 近藤, 能子
• Format: Other/Unknown Material
• Language: English
• Published: Hokkaido University
• Subjects: 450; Arctic; Arctic Ocean; Chukchi Sea; Chukchi; Sea ice
• Online Access: http://hdl.handle.net/2115/84539; https://doi.org/10.14943/doctoral.k13542

In the last 20 years the Arctic Ocean has experienced over 32% loss of summer sea ice. This loss can influence the cycling of biogeochemical materials, affecting seawater’s biology and chemistry. Sea ice is important for the supply of biogeochemical materials (trace metals, nutrients, dissolved organic matter, suspended particulate matter, etc.) to the surface waters of the polar oceans, but its role is not clear. In this study we focus on trace metals. Understanding the accumulation and release mechanisms into Arctic sea ice will clarify the geochemical behaviour of trace metals. Both dissolved (D, <0.2 μm), and labile particulate (LP, Total Dissolvable - Dissolved) Fe, Mn, and Cd were examined in sea ice and seawater collected from the Chukchi Sea, Arctic Ocean. Samples were pre-concentrated utilizing the solid-phase extraction NOBIAS Chelate PA-1 resin (Hitachi High-Technologies Corporation) and analyzed on a Graphite Furnace Atomic Absorption Spectrometer. Chukchi seawater showed high percentages for DMn (71.5%) and DCd (66.3%) with a high percentage of LPFe (94.1%). In seawater, DCd was the only metal to correlate with phosphate (R2 = 0.78) indicating a biogeochemical cycling source. Chukchi seawater concentrations of Fe and Mn may have been controlled through external sources. Sediments (shelf or river) supplied LPFe and LPMn. DFe and DMn were supplied by the Alaskan Coastal Current. Trace metal concentrations in Chukchi drifting ice were heterogeneous. Drifting ice showed high percentages for the LP fraction (99.2% Fe, 63.6% Mn and 71.2% Cd). This data indicated that, regardless of the trace metal behavior in Chukchi seawater, Chukchi drifting ice was observed to have a preference to accumulate or retain the LP trace metal fraction. To examine possible trace metal accumulation processes utilized by Arctic sea ice, the association between trace metal concentrations and ice structure were observed in floe ice. The structure of sea ice reflects the process of ice formation, which may aid in the ...