2018年春季西太平洋Kocebu海山区海水中颗粒态有机碳的地球化学特征

Geochemical Characteristics of Particulate Organic Carbon in the Kocebu Seamount Waters of the Western Pacific Ocean in Spring 2018

海山区颗粒有机碳的地球化学特征研究对深入认知大洋海山生态系统的物质循环过程具有重要意义。基于2018年3月对西太平洋Kocebu海山的综合调查,探讨了Kocebu海山区海水中颗粒有机碳的分布、来源及组成等地球化学特征。结果表明,随着水深的增加,颗粒有机碳浓度逐渐降低,并在接近海山底部的水层中略有回升。在各水团中,颗粒有机碳平均浓度的大小依次为北太平洋热带水大于北太平洋中层水大于底层水,其中在底层水中,山顶附近站位的颗粒有机碳浓度低于远离海山的站位。海山山顶上方750~1 500 m水层中存在上升流,进而在该区域内形成颗粒有机碳浓度12.50μg/L等值线隆起,但未形成"海山效应"。Kocebu海山区的颗粒有机碳主要为海源输入,颗粒有机碳/颗粒态有机氮平均值为3.75。在0~300 m的水层中,仅叶绿素最大值层中的颗粒有机碳/叶绿素a小于200,表明该水层中颗粒有机碳主要为生命态形式;而300 m水层中,颗粒有机碳/叶绿素a急剧升高,非生命态颗粒有机碳在总颗粒有机碳中贡献最大。

The study of the geochemical characteristics of the POC in the seamount area will be of great significance for further understanding the material cycle process in the seamount ecosystem. Based on a comprehensive survey of the Kocebu seamount in the Western Pacific Ocean in March,2018,the distribution,source and composition of Particulate Organic Carbon(POC)in the seawater of the Kocebu seamount area were discussed. The results showed that the concentration of POC in the Kocebu seamount area gradually decreased with the increasing water depth,and slightly rose in the water layers near the bottom of the seamount. The average concentration of POC in each water mass was sorted from high to low in the order of North Pacific Tropic Water,North Pacific Intermediate Water and Deep Water(DW),and the concentration of POC at stations near the seamount summit was lower than that far from the seamount in the DW. There was upwelling at the water layers of 750~1 500 m above the seamount summit,causing the uplift of the 12.50 μg/L POC isoline in this region,however,no "seamount effect" was formed. The POC was mainly imported from the sea with an average POC/PON of 3.75. At the water layers of 0~300 m,only the POC/chlorophyll a(Chl a) at deep chlorophyll maximum layer was less than 200,indicating that the POC in this region was mainly in a form of life,while at the water layer of 300 m,the POC/Chl a increased sharply,indicating that the non-living POC contributed the most to the total POC.