Enrichment of Trace Metals (V, Cu, Co, Ni, and Mo) in Arctic Sediments—From Siberian Arctic Shelves to the Basin. Issue 4 (23rd March 2021)

• Record Type: Journal Article
• Authors: Li, Li; Wang, Xiaojing; Ren, Yijun; Su, Huaqiang; Hu, Limin; Yang, Gang; Li, Zhongqiao; Bosin, Aleksandr A.; Astakhov, Anatolii S.; Chen, Jianfang; Liu, Yanguang; Shi, Xuefa
• Is Part Of: Journal of geophysical research. Volume 126:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-23
• Subjects: Arctic sediments -- Chukchi Sea -- East Siberian shelf -- metal speciation -- trace metals -- vanadium; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2020JC016960
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: With 50% of the Arctic Ocean is consisted of continental shelves, extensive shelf‐basin exchange processes exist here and plays a key role in regulating the biogeochemical recycling process of trace metals in the Arctic region. In this study, short sediment cores were collected along three transects from Siberian‐Chukchi shelves to adjacent slope/basin areas. An increasing trend was found for the bulk concentrations of several metals (V, Cu, Co, Ni, and Mo) from shelf to slope/basin cores with increasing water depth. Sequential extraction experiments indicated that the Fe/Mn oxide fractions increased significantly from shelf (9%–21%) to basin cores (24%–76%) for Cu, Co, Ni, and V, while the organic/sulfide phase remained significant (∼40%) for Mo. In addition, the observed dissolved metal concentrations in porewater indicated the remobilization of Fe, Mn, and Mo from shelf sediment, while V was always removed from water to the sediment, both on the shelf or in the slope/basin. Overall, in combination with the statistical analysis, we proposed that metals are transported from shelves to the central Arctic and are scavenged mainly by Mn oxides from the water column, which results in the enrichment of metals in slope/basin sediment. With the climate change, such transport and accumulation mechanism may be intensified over time, slowly leading the Arctic sediment to be a more and more important sink for those metals. Plain Language Summary: Siberian shelves in the Arctic Ocean are the widest and shallowest shelves in the World Ocean. Recently published studies on dissolved trace metals in Arctic waters and sediments indicated that intensive shelf‐basin interactions play a key role in regulating the geochemical recycling process of trace metals in this region. However, the transport and accumulation mechanism of metals in the adjacent slope/basin sediments are not well known, especially lacking evidence from the sediment aspect. In this study, short sediment cores were collected along three transects from Siberian‐Chukchi shelves to adjacent slope/basin areas with increasing water depth. An increasing trend of the bulk concentrations for several trace metals (V, Mo, Cu, Co, and Ni) was found from shelf cores to slope/basin cores, and the Fe/Mn oxide fraction of those metals increased significantly in slope/basin cores compared to shelf cores. In addition, dissolved metal profiles in porewater indicated remobilization (Fe, Mn, Mo) and scavenging (V) processes of different metals in shelf sediments. In combination with the statistical analysis results, it is proposed that the dissolved metals are mainly scavenged by Mn oxides from the water column and buried in slope/basin sediments, resulting in the enrichment. Key Points: Increased bulk concentrations of V, Mo, Cu, Co, and Ni were found from Siberian‐Chukchi shelf cores to adjacent slope/basin cores Fe/Mn oxides bound fractions increased significantly in slope/basin cores compared to shelf cores for V, Cu, Co, and Ni Dissolved metals are transported to the central Arctic by the Transpolar Drift and scavenged by Mn oxides, resulting in metal enrichment