Key Laboratory of Submarine Geosciences & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China.
Key Laboratory of Submarine Geosciences & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China.
Mar Environ Res. 2023 Oct;191:106127. doi: 10.1016/j.marenvres.2023.106127. Epub 2023 Aug 9.
During the 6th (2014) and 7th (2016) Chinese Arctic Expedition (CHINARE), samples of suspended particulate matter (SPM) were collected from both surface (depth: <1.0 m) and subsurface (depth: approximately between 10 and 150 m) waters over the northern shelf of the Bering Sea and in the western Arctic Ocean. To investigate the distribution and sources of organic matter in both the surface water and the vertical profile, the concentration and stable carbon isotopic composition of SPM, particulate organic carbon (POC), and particulate nitrogen (only in surface water samples) were determined, and some particle samples were selected for examination using scanning electron microscopy. Results showed apparent geographical partitioning and temporal variation in both the concentration and the composition of SPM. Higher SPM concentrations were observed in nearshore, shelf break, and sea ice edge areas; the distribution of POC concentration displayed a similar pattern, with higher values found from the northern part of the Bering Shelf to southern parts of the Chukchi Shelf. In surface water, SPM mainly comprised clay and detrital minerals with higher POC contents, lighter δC values, and higher POC/PN ratios, indicating organic matter predominantly derived from terrestrial sources in areas south of St. Lawrence Island and north of 73°N. The downward trend of heavier δC values, together with reduction in clay and detrital minerals, suggests that vertical transport of SPM is hindered by stratification, resulting in transport of terrestrial materials toward northern basin areas. In the Chukchi Slope and Canada Basin areas, extremely light δC values (as low as -33.41‰ PDB) were mainly observed at depths of 20-60 m, where the Polar Mixed Layer (PML) intersects with the Upper Halocline Layer (UHL). Under the condition of low sea ice extent in 2016, the POC-δC values were heavier in the PML than in the UHL in the Chukchi Slope and Canada Basin areas. These findings provide insights into the sources, transport, and fate of organic matter in the Pacific Arctic region, which have important implications for understanding the biogeochemical cycles and ecosystem dynamics in this remote and rapidly changing environment.
在第六次（2014 年）和第七次（2016 年）中国北极考察中，从白令海北部陆架和北极西部海域的表层（深度<1.0 m）和次表层（深度约为 10 至 150 m）水中采集了悬浮颗粒物（SPM）样品。为了研究表层水和垂直剖面中有机物的分布和来源，测定了 SPM、颗粒有机碳（POC）和颗粒氮（仅在表层水样中）的浓度和稳定碳同位素组成，并选择了一些颗粒样品进行扫描电子显微镜检查。结果表明，SPM 的浓度和组成在地理上存在明显的分区和时间变化。在近岸、陆架坡折带和海冰边缘地区，SPM 浓度较高；POC 浓度的分布也呈现出类似的模式，白令陆架北部到楚科奇陆架南部地区的浓度较高。在表层水中，SPM 主要由粘土和碎屑矿物组成，具有较高的 POC 含量、较轻的 δC 值和较高的 POC/PN 比值，表明有机物质主要来源于圣劳伦斯岛以南和 73°N 以北地区的陆源。向下趋势较重的 δC 值，以及粘土和碎屑矿物的减少，表明 SPM 的垂直传输受到分层的阻碍，导致陆地物质向北部盆地地区的传输。在楚科奇斜坡和加拿大盆地地区，在 20-60 m 深处主要观察到非常轻的 δC 值（低至-33.41‰ PDB），在那里极锋混合层（PML）与上强盐跃层（UHL）相交。在 2016 年海冰范围较低的情况下，楚科奇斜坡和加拿大盆地地区 PML 中的 POC-δC 值比 UHL 中的重。这些发现为了解太平洋北极地区有机物的来源、传输和归宿提供了线索，对理解这个偏远和快速变化环境中的生物地球化学循环和生态系统动态具有重要意义。
