楚科奇海表层海水颗粒物组成与来源

THE COMPOSITION AND SOURCES OF SUSPENDED PARTICLES OF IN THE CHUKCHI SEA AND THE CENTRAL ARCTIC OCEAN

对研究区内第五次北极科学考察所取的表层海水颗粒物的浓度、显微组成、有机碳、氮含量及其同位素组成进行了分析。结果表明,楚科奇海域表层海水颗粒物浓度介于0.56—4.01 mg·L-1,具有冰区边缘高于开阔水域的特点。陆架区颗粒有机质相对含量高(TOC:9.78%—20.24%;TN:0.91%—2.31%),有机碳、氮同位素值相对重(δ13C:-23.29‰—-26.33‰PDB;δ15N:6.14‰—7.78‰),有机质主要来源于海洋生物,含有部分陆源有机质;陆坡及北冰洋核心区的颗粒有机质含量,除SR15站外,相对低(TOC:8.06%—8.96%;TN:0.46%—0.72%),有机碳、氮同位素值轻(δ13C:-26.93‰—-27.78‰PDB;δ15N:4.13‰—4.84‰),颗粒物有机质以陆源为主。陆坡区SR15站表层海水颗粒物中异常高的陆源有机质(TOC:27.94%,TN:1.16%;δ13C:-27.43;δ15N:3.81)可能来自源于东西伯利亚的穿极洋流。海冰携带的颗粒物(包括冰藻)是冰区边缘表层海水颗粒物的重要来源,在陆架区海冰融化,向水体中释放了大量生物体;而陆坡区和北冰洋核心区,海冰对颗粒物的贡献以碎屑矿物和黏土矿物为主。

Suspended particle samples were collected at 11 stations in the shelf and slope regions of the Chukchi Sea and the central Arctic Ocean during the Fifth Chinese Arctic Research Expedition in the summer 2012. The particle concentrations, TOC, TN and the carbon and nitrogen isotopic compositions of the samples were analyzed. The concentration of suspended particles is between 0.56 mg. L-1 and 4.01 mg . L-1 , with the samples collected from the edge area of the sea ice having higher concentrations. The content of organic matter is higher in the shelf area （ TOC ： 9.78 % --20.24% ; TN ： 0.91% --2.31 % ）, and with heavier isotopic compositions （ δ13C ： - 23.29‰-- 26.33‰; δ15N： 6.14‰--7.78‰）, indicating that the organic matter is mostly marine with some terrigenous input in this area. In the slope and the central Arctic Ocean, the organic matter content is lower （ TOC ： 8.06% -- 8.96%; TN： 0.46%---0.72%）, except for sample SR15, and with lighter isotopic compositions （δ13C： -26.93‰---27.78‰; δ15N： 4.13‰---4.84‰）, indicating that the organic matter is mostly terrigenously derived in these regions. The extremely high amount of terrigenous organic matter （TOC： 27.94%, TN： 1.16% ; δ13C： -27.43‰; δ15N： 3.81‰） implies that it has been carried by transpolar currents from the East Siberian Sea. The materials, including sea-ice algae, carried by sea ice are the primary source for particles in the edge area of the sea ice. The melting of sea ice released a substantial amount of biomass on the shelf, but a large amount of detrital and clay minerals on the slope and in the central Arctic Ocean.