1993～1996年南海中部海洋沉降颗粒通量的季节和年际变化

Seasonal and annual variations of marine sinking particulate flux during 1993～1996 in the central South China Sea

通过对南海中部1993～1996年获得的浅层和深层时间系列沉积物捕获器的样品分析，发现了稳定同位素值、颗粒总通量、碳酸盐、生物蛋白石、有机碳、表层初级生产力、浮游有孔虫总通量和属种的分布存在明显的季节性变化，其通量都是在东北季风和西南季风盛行期出现高值，在季风转向期出现低值．浮游有孔虫Globigerinoides sacculifer，G．ruber，Globigerinita glutinata，Neogloboquadrina dutertrei等种的通量和相对百分含量也是在东北季风和西南季风盛行期都出现高值，但Globigerina bulloides，Globorotalia menardii和Pulleniatina obliquiloculata等种则在东北季风盛行期出现高值，分析还发现Globigerinoides sacculifer和Globorotalia menardii等种的通量和百分含量以及有孔虫总通量和碳酸盐通量等从1993到1996年存在下降趋势，而Globigerina，bulloides和Globigerinita glutinata的通量和百分含量以及生物蛋白石通量等在该期间显示为上升趋势，浅层捕获器样品中的碳酸盐和有机碳的通量比深层的高．研究表明海洋沉降通量和浮游有孔虫属种的季节和年际变化主要受与东亚季风相关的表层初级生产力和海洋水文条件变化所控制，深层捕获器样品中的碳酸盐和有机碳的通量低应与碳酸盐溶解作用有关。

Total 67 samples from the shallow and deep time-series sediment traps are analyzed during 1993～1996 in the central South China Sea. The results indicate that the fluxes of stable isotope,total particulate matter, carbonate, biogenic opal, organic carbon, surface primary productivity, total planktonic foraminifera exhibit obvious seasonal and annual fluctuations. High values of the fluxes occur in the prevailing periods of the northeast and southwest monsoons respectively, and the low values occur during the periods between the monsoons. Fluxes of planktonic foraminiferal species and their percentages exhibit also obvious seasonal and annual fluctuations. These of Globigerinoides sacculifer, Globigerinoides ruber, Neogloboquadrina dutertrei and Globigerinita glutinata exhibit two prominent peaks which occur in the prevailing periods of the northeast and southwest monsoons respectively, while those of Globigerina bulloides, Pulleniatina obliquiloculata and Globorotalia menardii have only one peak in the prevailing periods of the northeast monsoon annually. In addition, fluxes and percentages of G. sacculifer and G. menardii as well as the fluxes of carbonate and total planktonic foraminifera decrease gradually from 1993 to 1996, while those of G. bulloides, G. glutinata and biogenic opal increase gradually from 1993 to 1996. The CaCO3 and fluxes in the shallow trap are higher than those in the deep one. The observations indicate that the seasonal and annual variations of the fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower CaCO3 and organic carbon fluxes in the deep trap are related to the dissolution.