| 李科,金海燕,赵香爱,庄燕培,季仲强,张扬,陈建芳.白令海及西北冰洋有机质来源与新鲜程度的脂肪酸指示[J].海洋学报,2020,42(10):14-27 |
| 白令海及西北冰洋有机质来源与新鲜程度的脂肪酸指示 |
| Sources and degradation of organic matter in the Bering Sea and the western Arctic Ocean: Implication from fatty acids |
| 投稿时间：2019-10-24 修订日期：2019-12-02 |
| DOI：10.3969/j.issn.0253-4193.2020.10.002 |
| 中文关键词: 白令海 西北冰洋 有机质 脂肪酸 生物泵 北极快速变化 |
| 英文关键词:Bering Sea western Arctic Ocean Organic Matter fatty acid biological pump abrupt Arctic climate change |
| 基金项目:国家自然科学基金（41776205，41406217，41976226）；南北极环境综合考察与评估专项（Chinare 2017-03-04）。 |
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| 中文摘要: |
| 白令海、西北冰洋等高生产力海域在北冰洋“生物泵”中起到重要作用；海水升温、海冰消退等北极快速变化，将强烈影响该海域“生物泵”的结构与规模，并在沉积物中有机质的来源与新鲜程度上有所体现，可用脂肪酸加以指征。对第五次、第六次中国北极科学考察在以上海域采集的表层沉积物进行脂肪酸含量（以沉积物干重计）及组成分析，结果显示楚科奇海陆架总脂肪酸含量非常高((97.15±55.31) μg/g)，白令海盆最低((15.00±1.30) μg/g)，加拿大海盆、楚科奇海陆坡、白令海陆架居中(分别为(88.65 ±3.52) μg/g，(70.35±11.32) μg/g与(38.28±14.89) μg/g)。海源脂肪酸占总脂肪酸比例最高(86.82%±7.08%)，陆源次之(8.45%±6.62%)，细菌最低(4.63%±2.24%)；硅藻指数(16:1ω9/16:0)在楚科奇海陆架(> 0.82)、白令海陆架边缘(> 0.65)较高，其他区域均较低。脂肪酸结果表明：(1) 该海域沉积有机质主要来自海源，陆源贡献小；在北部、南部楚科奇海陆架、白令海陆架边缘，硅藻生物量占主要优势；细菌脂肪酸比例显著低于温暖海域，指示低温抑制细菌活动。(2) 楚科奇海陆架区硅藻生产力高、细菌活动弱，新鲜有机质沉降效率高，但对未来海水升温、浮游植物群落变化也较为敏感。(3) 加拿大海盆、楚科奇海陆坡的浮游植物群落由绿藻与金藻主导。以上结论说明脂肪酸可指示表层沉积物中有机质的来源与新鲜程度；未来，脂肪酸有望进一步揭示北冰洋“生物泵”对北极快速变化的响应。 |
| 英文摘要: |
| The Bering Sea and western Arctic Ocean, as high production areas, play a key role in the Arctic Ocean biological pump, and are vulnerable to abrupt climate change, especially sea water warming and sea ice melt. Alterations in biological pump can influence the sources and degradation of sedimentary organic matter, and thus can be indicated by fatty acid (FA) content and composition of sediment. FA analysis of surface sediments, collected during the 5th and 6th Chinese Arctic Research Expeditions, showed that the total FA of the Chukchi Shelf was exceptionally high ((97.15 ±55.31) μg/g), while the Bering Basin was the lowest ((15.00 ±1.3) μg/g), and the Canada Basin, the Chukchi Shelf and the Bering Shelf were intermediate ((88.65 ±3.52) μg/g，(70.35 ±11.32) μg/g and (38.28 ±14.89) μg/g, respectively). Marine FAs (short chain saturated FA + unsaturated FA) accounted for the most abundant (86.82% ±7.08%), terrestrial FAs (long chain saturated FA) as the second abundant (8.45% ±6.62%), while bacterial FAs (odd FA) as the least (4.63% ±2.24%); diatom index (16:1ω9/16:0) was high at the southern and northern Chukchi Shelf (> 0.82) and the Bering Shelf edge (> 0.65), while it was low at the rest areas. These results indicated that: (1) marine source was the major contributor of sedimentary organic matter of the Bering Sea and the western Arctic Ocean, while terrestrial one contributes minor; diatom predominates was the primary producers of the southern and northern Chukchi Shelf and the Bering Shelf edge; percentage of bacterial FAs was remarkably low, comparing with tropical and temperate seas, suggesting a suppressed bacterial activity under low temperature; (2) labile organic matter accumulation rate was extremely high at the Chukchi Shelf, and was extremely sensitive to sea water warming and sea ice melt; (3) chlorophyceae and prymnesiophyceae dominate phytoplankton community at the Canada Basin and the Chukchi Slope. In conclusion, FA of surface sediment can be used to indicate sources and degradation of organic matter in the Bering Sea and the western Arctic Ocean; further, combining with other samples and biomarkers, FA was viable to shed light on the response of biological pump under the abrupt Arctic climate change. |
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