1112 / 2024-09-20 13:18:22

Preservation and Reactivity of Organic Matter in Surface Sediments of the Largest Marginal Sea of the Arctic Ocean

East Siberian Arctic Shelf (ESAS), surface sediment, amino acids, biospheric organic carbon

In the rapidly evolving Arctic environment, there has been a significant rise in the influx of terrestrial and marine organic carbon and nitrogen into the ocean, emphasizing its crucial role in the global carbon cycle. However, a substantial amount of this biogenic organic carbon (BOC) is sequestered in sediments on the continental shelf, underscoring the necessity of exploring its destiny within these sediments. The East Siberian Sea (ESS), the largest and shallowest marginal sea in the Arctic, presents itself as an optimal setting for such investigations. This study concentrated on surface sediment samples collected during the 2016 Sino-Russian Arctic joint expedition. Amino acids were employed as a baseline and integrated with relevant physicochemical parameters, including lignin and IP25, to scrutinize the origins, transportation, and degradation of organic matter within the ESS. The findings revealed that the concentration of total hydrolyzable amino acids (THAA) varied between 2.61 and 32.46 μmol/g. The BOC present in the sediments is primarily a blend of terrestrial and marine sources, with a significant contribution from microbial activity. Moreover, the BOC in surface sediments has undergone considerable degradation, with higher degradation rates observed offshore compared to nearshore areas, and elevated levels on the western side of the sea relative to the eastern side. During the lateral transport of BOC, beyond hydrodynamic forces, microbes played a pivotal role in degradation, acting as key regulatory agents in the transfer and transformation of BOC within the sediment.