北极楚科奇海海底表层沉积物有机碳的生物地球化学特征

1999年7月和2003年7月在北极科学考察中获取的楚科奇海海底表层沉积物有机碳质量分数的分析结果表明,楚科奇海海底表层沉积物有机碳平均质量分数约为1.41%,远高于我国东海和世界部分大陆架沉积物;有机碳/氮比值为8.69,反映了有机物以海洋自生为主的混合性来源;有机碳与有机氮之间显著相关(R=0.93);有机碳质量分数与粒度明显相关(R=0.71),细粒粘土质沉积物中的有机碳质量分数高于砂质沉积物的;在水深200m以内,有机碳质量分数随水深加大有一定的增加;有机碳质量分数与生源硅质量分数明显相关;有机碳质量分数随纬度变化较小。结合2次北极考察的实测结果,对楚科奇海海底表层沉积物中的有机碳来源进行了初步讨论,认为沉积有机碳埋葬可能主要取决于生物泵。

Biogeochemical Characteristics of Organic Carbon in Surface Sediments From the Chukchi Sea

The organic carbon(OC) contents in surface sediments from the Chukchi Sea collected by Chinese Arctic Research Expedition during July 1999 and July 2003 were analyzed.It is shown from the analysis results that the mean OC contents in surface sediments from the Chukchi Sea are about 1.41%,and are much higher than those from the East China Sea and some shelf areas in the world;the ratio of ogranic carbon to nitrogen(C/N ratio) is 8.69,which reflects the mixed source of organic matter with the marine autogenic material being the main source;the OC content is strongly correlated with the ogranic nitrogen content(R=0.93);the OC content is significantly correlated with the grain size of sediment(R=(0.71)),and the OC content in fine-grained clayey sediment is higher than that in sandy sediment;the OC content in water depths to 200 m increases with increasing depth;the OC content is significantly correlated with the biogenic silicon content;and the OC content varies slightly with the latitude.A preliminary discussion on the OC source in surface sediments from the Chukchi Sea is made together with the observed data during 2 arctic expeditions,and it is concluded that the burial of sedimentary OC may depend mainly on the biological pump.