2015年春季长江口表层沉积物生源要素分布和来源

Spatial distributions and sources of biogenic elements in the surface sediment from the Yangtze River Estuary in spring 2015

根据2015年5月对长江口及其邻近海域的生态环境调查资料,探讨长江口春季表层沉积物总有机碳(TOC)、总氮(TN)、总磷(TP)和生源硅(BSi)4类生源要素的空间分布和来源。结果表明:2015年春季长江口表层沉积物TOC、TN、TP和BSi平均含量分别为0.315%、0.041%、0.066%和0.450%,其中,沉积物中TOC、TN受到陆源输入和海洋自生输入双重影响,且海洋自生组分的贡献较大,二者空间分布均呈现南部分布最高并沿西北方向递减趋势;TP分布主要受陆源输入影响,并呈西北向东南递减趋势;BSi来源于生物沉积,总体呈现南部高、北部低的分布趋势。与2007年相比,长江口表层沉积物有机碳、氮含量降低,东南外海区域替代浑浊区域成为表层沉积物生源要素含量最高区域,且陆源输入对长江口表层沉积物生源要素的贡献趋于减弱。

This study aims to assess the surface sediment of the Yangtze River Estuary based on the ecological environment investigation of the Yangtze River Estuary and its adjacent areas in May 2015,the spatial distributions,and sources of biogenic elements(including total organic carbon,total nitrogen,total phosphorus,and biogenic silicon).The results revealed that the mean concentrations of TOC,TN,TP,and BSi were 0.315%,0.041%,0.066%,and 0.450%,respectively.Both TOC and TN were significantly affected by terrestrial inputs and marine autogenic materials,with the latter one exerting the major impact.While the highest contents of TOC and TN were found in the southern coastal zone,lower contents were distributed in the northwest offshore area.In addition,the distribution of TP was primarily affected by terrigenous inputs;it decreased gradually from the northwest to the southeast at first but,then,increased.Furthermore,the BSi content was derived from the biological deposition,with the higher content found in the southern area and the lower content in the northern zones.Compared to 2007,the TOC and TN contents in the surface sediments from the Yangtze River Estuary decreased in 2015,and the southeast offshore area,which was the maximum turbidity zone in 2007,had the highest content of biogenic elements in the surface sediments.Overall,the contribution of terrigenous inputs to the surface sediments in the Yangtze River estuary appeared to have weakened over the years.