Transport of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in late summer 2012

• Main Authors: Kondo, Yoshiko, Obata, Hajime., Hioki, Nanako, Ooki, Atsushi, Nishino, Shigeto, Kikuchi, Takashi, Kuma, Kenshi
• Format: Other/Unknown Material
• Language: English
• Published: Elsevier Ltd. 2016
• Subjects: Arctic Ocean; Canada Basin; Chukchi Sea; GRENE; Halocline; Trace metals; Bering Strait; canada basin; Chukchi; Sea ice
• Online Access: https://nagasaki-u.repo.nii.ac.jp/record/2085/files/DSR1_116_236.pdf

Distributions of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in September 2012 were investigated to elucidate the mechanisms behind the transport of these metals from the Chukchi Shelf to the Canada Basin. Filtered (<0.22 μm) and unfiltered seawater samples were analyzed to determine dissolved (D) and total dissolvable (TD) trace metal concentrations, respectively. We identified maxima in vertical profiles for the concentrations of D-Fe and TD-Fe, as well as for the other four analyzed trace metals, which occurred in the halocline and/or near-bottom waters. Concentration profiles of all trace metals except for Cd also tended to show peaks near the surface, which suggest that the inflow of low-salinity Pacific-origin water from the Bering Strait, as well as local fresh water inputs such as river water and melting sea-ice, influenced trace metal concentrations. The distribution patterns and concentration ranges were generally similar between the D and TD fractions for Ni, Zn and Cd, which indicate that Ni, Zn and Cd were present mainly in their dissolved forms, whereas the concentrations of TD-Fe and TD-Mn were generally higher than those of D-Fe and D-Mn, respectively. These results are consistent with the results of previous studies of this region. For both Fe and Mn, labile particulate (LP) concentrations (the difference between the TD and D fractions, which is acid-leachable fraction in the particles during storage at pH 1.5?1.6) were highest in the near-bottom waters of the Chukchi Shelf region. The relationships between the distance from the shelf break and the concentrations of trace metals revealed that Fe and Mn concentrations in halocline waters tended to decrease logarithmically with distance, whereas changes in the concentrations of Ni, Zn, Cd and phosphate with distance were small. These results suggest that the distributions of Fe and Mn were controlled mainly by input from shelf sediment and removal through scavenging processes. Based on the ...