南海生源物质通量与生物泵组成的初步解析

Biogeochemical Fluxes and Biological Pump Composition in the South China Sea

海洋"生物泵"是海洋去除大气CO2的一种机制。"生物泵"的强度可以用真光层以下水柱生源颗粒物质的输出通量来表示,常用的方法有放射性同位素示踪法和沉积物捕获器法。前者获得的是海洋某一时段、某一站位的颗粒物质通量;而后者除了获取短时间尺度(十几天)至年际尺度的物质通量以外,还可以利用收集到的样品开展地球化学、微体古生物学等分析,从而进一步推知生物泵的组成。迄今为止,利用沉积物捕获器开展南海生物地球化学通量研究已有20余年,已经有诸多成果发表。本文在总结已发表成果和笔者部分未发表数据基础上,对于南海北部海域生物地球化学通量变化、组成特征及其季节变化进行了回顾和总结,并与利用放射性同位素234Th/238U不平衡法获得的结果进行了比较。在此基础上,对南海生物泵结构和调控因子作了初步的分析探讨,发现,南海"碳酸盐泵"和"硅酸盐泵"具有同等重要的作用。指出,若要全面了解南海生物泵的时空变化及其调控机制,需要开展点(锚系潜标与浮标)、线(船基断面调查和过程研究)、面(时间序列的遥感资料)结合的综合观测和研究。

Biological pump is one of the mechanisms of carbon uptake by ocean. There are mainly two methods to measure the biological pump in the water column,one is the radio isotope234 Th /238 U based estimation,which provides particulate organic carbon export flux in a specific station in a moment,the other is time-series sediment trap based observation,which can not only measure particle flux in relative large spatial scale in a period from days to a month,but also collect samples for further geochemical and microfossil analyses. The study of biogeochemical fluxes in the South China Sea using time series sediment traps has been carried out for more than 20 years. In this paper,the biogeochemical fluxes,composition,and their seasonal variations in the northern South China Sea were reviewed based on our previous publications.These results were compared with the data obtained by234 Th /238 U disequilibrium method. In order to understand the controlling factors of biological pump in the South China Sea,a comprehensive study of buoy and mooring observation,shipbased survey and process studies as well as time-series remote sensing data is necessary.