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Importance of seasonal sea ice in the western Arctic ocean to the Arctic and global microplastic budgets

Wed, 15 Sep 2021 00:00:00 GMT

Title: Importance of seasonal sea ice in the western Arctic ocean to the Arctic and global microplastic budgets Authors: Kim, Seung-Kyu; Lee, Hee-Jee; Kim, Ji-Su; Kang, Sung-Ho; Yang, Eun Jin; Cho, Kyoung-Ho; Tian, Zhexi; Andrady, Anthony Abstract: Arctic sea ice entraps microplastics (MP) from seawater and atmosphere and is recognized as sink and transport vector of MPs. However, ice-trapped fraction in the global MP budget, contribution of atmospheric input, and linkage among Arctic basins remain unclear. To assess them, we investigated the number- and mass-based data separated by size and shape geometry for MPs in sea ice, snow, and melt pond water from the western Arctic Ocean (WAO). A significant dependency of MP data on measured cutoff size and geometry was found. For the same size range and geometry, sea ice MPs in WAO ((11.4 ± 9.12) × 103 N m-3 for ≥ 100 μm) were within comparable levels with those in other Arctic basins, but showed closer similarity in polymer and shape com- positions between WAO and Arctic Central Basin, indicating the strong linkage of the two basins by the Transpolar Drift. Our budgeting shows that a significant amount of plastic particles ((3.4 ± 2.6) × 1016 N; 280 ± 701 kilotons), which are missed from the global inventory, is trapped in WAO seasonal sea ice, with < 1% snowfall contribution. Our findings highlight that WAO ice zone may play a role as a sink of global MPs as well as a source of Arctic MPs.

Korea-Arctic Ocean Observing System (K-AOOS) final report

Thu, 29 Jul 2021 00:00:00 GMT

Title: Korea-Arctic Ocean Observing System (K-AOOS) final report Authors: Kang, Sung-Ho

N2O dynamics in the western Arctic Ocean during the summer of 2017

Tue, 15 Jun 2021 00:00:00 GMT

Title: N2O dynamics in the western Arctic Ocean during the summer of 2017 Authors: Heo, Jang-Mu; Kim, Seong-Su; Kang, Sung-Ho; Yang, Eun Jin; Park, Ki-Tae; Jung, Jinyoung; Cho, Kyoung-Ho; Kim, Ju-Hyoung; Macdonald, Alison M.; Yoon, Joo-Eun; Kim, Hyo-Ryeon; Eom, Sang-Min; Lim, Jae-Hyun; Kim, Il-Nam Abstract: The western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0-50 m) and deep layers (200-2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0-50 m) of the southern Chukchi Sea and the intermediate (50-200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean:+2.3 +/- 2.7 mu mol N2O m(-2) day(-1)), whereas the northern region acted as a sink (mean - 1.3 +/- 1.5 mu mol N2O m(-2) day(-1)). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O "hot spot", and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes.

Tracing riverine dissolved organic carbon and its transport to the halocline layer in the Chukchi Sea (western Arctic Ocean) using humic-like fluorescence fingerprinting

Tue, 01 Jun 2021 00:00:00 GMT

Title: Tracing riverine dissolved organic carbon and its transport to the halocline layer in the Chukchi Sea (western Arctic Ocean) using humic-like fluorescence fingerprinting Authors: Jung, Jinyoung; Son, Jin Eui; Lee, Yun Kyung; Cho, Kyoung-Ho; Lee, Youngju; Yang, Eun Jin; Kang, Sung-Ho; Hur, Jin Abstract: Dissolved organic carbon (DOC) and the fluorescence properties of dissolved organic matter (FDOM) were inves- tigated using parallel factor analysis (PARAFAC) for seawater samples collected in the Chukchi Sea (65°N？78°N, 170°E？160°W) during summer 2017. River water (friver) and sea-ice meltwater (fsea ice melt) fractions were also derived using oxygen isotopes ratios (δ18O) to examine the influence of sea ice on riverine DOM. The spatial dis- tributions of friver, riverine DOC, and the humic-like fluorescent component (C1) showed an overall south-north gradient, with higher values in the northern Chukchi Sea in summer. Pronounced accumulation of river water and riverine DOM was also observed in the anticyclonic Beaufort Gyre at the eastern stations of the northern Chukchi Sea in association with a long water residence time. Estimated riverine DOC in the surface layer accounted for 27 ± 9% (range: 17？47%) of the total DOC in the southern Chukchi Sea, and 39 ± 6% (range: 32？49%) and 31 ± 4% (range: 25？37%) for the eastern and western stations of the northern Chukchi Sea, respec- tively. Humic-like C1 showed negative and positive relationships with sea-ice meltwater-corrected salinity (Ssim_corrected) and friver, respectively. However, Arctic river waters with distinct humic-like C1 characteristics were likely mixed in the northern Chukchi Sea. The vertical distributions of riverine DOC, humic-like C1 fluores- cence, and friver generally decreased with water depth, reflecting the strong influence of riverine DOM in the sur- face layer. Although riverine DOM and friver were dominant in the upper 50 m of the water column, they were also pronounced in the upper halocline (50？200 m), in which fsea ice melt dropped below zero. Our results indicated the existence of brine rejected from growing sea ice, and that sea-ice formation was a key factor for the transport of riverine DOM to the upper halocline layer in the northern Chukchi Sea.