南海南部表层沉积物中生物硅的分布及其环境意义

对南海南部25个表层沉积样进行了生物硅的测定分析,试图揭示南海南部表层沉积生物硅的分布及其对现代海洋环境的指示意义,以便为古海洋学研究提供进一步的科学依据。研究发现,表层沉积物中生物硅含量与其所处水深呈显著正相关关系,相关系数达到0.782。陆架浅水区表层沉积物中生物硅含量非常低,不能反映表层水体中硅质生物生产力情况,这可能与沉积类型和陆源物质输入影响有关。深水区表层沉积物中生物硅的含量分布表明,其不仅能反映表层水体中硅质生物的古生产力水平,而且还能指示上升流的强弱,从而进一步证实了利用沉积物中生物硅含量来追踪上升流发育和变化的有效性与可信度。研究结果还显示,在研究区域中北部表层沉积生物硅中放射虫和海绵骨针较硅藻占有更大的比重,这可能是由于硅藻易被溶解并易被其他生物体摄食的缘故。在有上升流发育的海域,放射虫、硅藻和海绵骨针基本上表现出较高的丰度,这与高的生物硅含量相一致。

Distribution of biogenic silica in surface sediments from southern South China Sea and its environmental significance

Contents of biogenic silica were determined for 25 surface sediment samples obtained from the southern South China Sea(SCS) to study its distribution and its modern oceanic environmental significance,which may provide further scientific evidence for paleoceanographical explanation.This study shows that biogenic silica contents in the surface sediments have evidently positive correlation with water depth,and the correlation coefficient is up to 0.782.Biogenic silica content is very low in the continental shelf shallows and can not reflect the siliceous micropaleontological productivity of the surface water,which may be related to sedimentary type and dilution of terrigenous matter.The distribution of biogenic silica contents in the surface sediments from deep water areas can not only reflect the siliceous micropaleontological productivity of the surface water,but also indicate the strength of upwellings,further confirming that using the contents of biogenic silica in sediments to trace upwellings and their changes is effective and reliable.The results also show that radiolarian and poriferous specula have more contribution to biogenic opal in comparison with diatom in the surface sediments of the northern studied area,probably owing to the diatom easily dissolving away and being eaten by other organisms with little effort.In the upwelling areas,radiolarian,diatom and poriferous specula basically have high abundance,consistent with the high content of biogenic silica.