中文摘要：

于2011年10月在长江口邻近海域采集了31个站位的表层沉积物样品,利用原子荧光分光光度计测定了样品的As质量比,旨在通过分析毒性元素As在表层沉积物中的空间分布,探讨As的来源、赋存状态及其影响因素。结果表明,研究区表层沉积物中As质量比范围为0.92-23.25 mg/kg,平均值为6.98 mg/kg,呈近岸高远岸低的分布特征,且在泥质沉积区相对较高,高值区沿岸线呈明显的带状分布。As与沉积物粒度组成密切相关,即表层沉积物的粒径越小,As质量比越高,细粒沉积物是As的主要载体。表层沉积物中As与有机碳、总氮呈弱的正相关,表明生物虽可能对As分布有一定的影响,但相对于沉积物粒级组成而言不是主要控制因素。As质量比高值区与长江冲淡水和沿岸流的分布格局一致,尤其是在长江口门处的泥质区值最高。这一方面说明As主要来源于长江入海所携带的细颗粒悬浮物,另一方面说明长江入海冲淡水和研究区海洋流系控制着As的空间分布。As在研究区内总体上呈轻度富集,部分采样站位As的富集因子较高,说明长江口邻近海域存在一定程度As的人为污染（排污）和潜在的环境风险。

英文摘要：

The paper intends to present our analysis of As content of surface sediment samples collected from 31 stations in adjacent sea areas of Yangtze Estuary in October, 2011 with an atomic fluorescence spectrophotometer. On the basis of the analytical results, we have made a detailed discussion of the spatial distribution of the poisonous element As and its source in the above said area. The results of our analysis show that the content of As in the surface sediments of the area under discussion varies between 0.92 mg/kg and 23.25 mg/kg with average of 6.98 mg/kg. The content should be considered to be a great deal higher at the near-shore stations, especially in argillaceous sedimentary areas, though lower at the offshore sea waters. Generally speaking, the distribution of As exhibits in an obvious belt-shaped pattern. The excessive content of the toxic element is closely correlated with the grain-size distribution of sediments： the finer the sediment particles are, the higher the content of As in it, which indicates that the fine particles, the main carrier of As, exert a dominant influence on the distribution of As. In addition, the statisti- cal results prove that the content is weakly positively correlated with the contents of organic carbon and the total nitrogen, which suggests that the organisms may pose a certain influence, but not a controlling one on the distribution of As. With reference to the distribution anal- yses of the marine current system in the area under question, the dis- tribution of the higher As content in the area is consistent with the distribution of the diluted water of the Yangtze River and the littoral currents, which suggests that on the one hand, As mainly originates from the suspended fine particles flouting in the water and carried by the Yangtze influx into the East China Sea, on the other hand, its distribution is mainly influenced by the diffusion of the Yangtze influx and the littoral currents. In the final analysis, As has been slightly enriched in the area under study, with