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Open access publications by faculty, postdocs, and graduate students in the School of Marine Science & Policy
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Browsing Open Access Publications by Subject "Arctic Ocean"
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Item The changing CO2 sink in the western Arctic Ocean from 1994 to 2019(Global Biogeochemical Cycles, 2021-12-28) Ouyang, Zhangxian; Li, Yun; Zhong, Wenli; Murata, Akihiko; Nishino, Shigeto; Wu, Yingxu; Jin, Meibing; Kirchman, David; Chen, Liqi; Cai, Wei-JunThe Arctic Ocean has turned from a perennial ice-covered ocean into a seasonally ice-free ocean in recent decades. Such a shift in the air-ice-sea interface has resulted in substantial changes in the Arctic carbon cycle and related biogeochemical processes. To quantitatively evaluate how the oceanic CO2 sink responds to rapid sea ice loss and to provide a mechanistic explanation, here we examined the air-sea CO2 flux and the regional CO2 sink in the western Arctic Ocean from 1994 to 2019 by two complementary approaches: observation-based estimation and a data-driven box model evaluation. The pCO2 observations and model results showed that summer CO2 uptake significantly increased by about 1.4 ± 0.6 Tg C decade−1 in the Chukchi Sea, primarily due to a longer ice-free period, a larger open area, and an increased primary production. However, no statistically significant increase in CO2 sink was found in the Canada Basin and the Beaufort Sea based on both observations and modeled results. The reduced sea ice coverage in summer in the Canada Basin and the enhanced wind speed in the Beaufort Sea potentially promoted CO2 uptake, which was, however, counteracted by a rapidly decreased air-sea pCO2 gradient therein. Therefore, the current and future Arctic Ocean CO2 uptake trends cannot be sufficiently reflected by the air-sea pCO2 gradient alone because of the sea ice variations and other environmental factors.Item The Role of Coastal Yedoma Deposits and Continental Shelf Sediments in the Arctic Ocean Silicon Cycle(Global Biogeochemical Cycles, 2024-01-09) Ray, Nicholas E.; Martens, Jannik; Ajmar, Marco; Tesi, Tommaso; Yakushev, Evgeniy; Gangnus, Ivan; Strauss, Jens; Schirrmeister, Lutz; Semiletov, Igor; Wild, BirgitThe availability of silicon (Si) in the ocean plays an important role in regulating biogeochemical and ecological processes. The Si budget of the Arctic Ocean appears balanced, with inputs equivalent to outputs, though it is unclear how a changing climate might aggravate this balance. In this study, we focus on Si cycling in Arctic coastal areas and continental shelf sediments to better constrain the Arctic Ocean Si budget. We provide the first estimate of amorphous Si (ASi) loading from erosion of coastal Yedoma deposits (30–90 Gmol yr−1), demonstrating comparable rates to particulate Si loading from rivers (10–90 Gmol yr−1). We found a positive relationship between surface sediment ASi and organic matter content on continental shelves. Combining these values with published Arctic shelf sediment properties and burial rates we estimate 70 Gmol Si yr−1 is buried on Arctic continental shelves, equivalent to 4.5% of all Si inputs to the Arctic Ocean. Sediment dissolved Si fluxes increased with distance from river mouths along cruise transects of shelf regions influenced by major rivers in the Laptev and East Siberian seas. On an annual basis, we estimate that Arctic shelf sediments recycle approximately up to twice as much DSi (680 Gmol Si) as is loaded from rivers (340–500 Gmol Si). Key Points - Coastal erosion loads 30–90 Gmol Si yr−1 to the Arctic Ocean in the form of amorphous silicon - Continental shelf sediments in the Arctic Ocean recycle more silicon than is loaded from rivers - Approximately 4.5% of silicon loaded on the Arctic Ocean is buried in continental shelf sediments