汕头湾表层沉积物重金属污染与潜在生态风险评价

Evaluation on the pollution and potential ecological risk of heavy metals for the surface sediment in Shantou estuary

汕头湾作为华南地区重要的出海门户，汕头市主要的旅游区和水产养殖基地，其环境污染问题已成为制约当地经济发展的重要因素，为此2002年在此开展了重大科技术兴海项目，以海洋沉积物质量标准、单因子污染指数和潜在生态风险评价体系对汕头湾表层沉积物重金属污染现状和潜在生态风险进行了评价。结果表明：汕头湾表层沉积物中Cd，Cu，Pb，Zn的平均含量超过海沉积物质量标准（I类）；以单因子污染指数评价，Cd达到很强污染等级，Zn为强污染，Cu，Ni，Pb为中等污染；以单元素生态系数（E：）评价，只有Cd的潜在生态风险达到很强等级，其它元素则只属于轻微潜在风险范畴；以多元素潜在生态风险指数（肼）评价，汕头湾的潜在生态风险水平处于中等强度；重金属含量分布特征与重金属污染及潜在生态风险的空间差异性一致，表现为由上游至下游呈波状递减趋势，其中以牛田洋和汕头港上游最为严重；这一污染特征主要是由集水区域内的产业结构特点、河流入海口及排污口的分布以及汕头湾的地理和水文特性所决定的。

Shantou estuary is not only one of most important area for navigation in southem China, but also play a significant role in aquiculture and tourism in Shantou city. A science and technology project for marine development was started in 2002, because the pollution situation of Shantou estuary was so serious and hamper the local economic development. As a part of this research, the pollution degrees and the potential ecological risks associated with heavy metals content and distribution pattern in surface sediment of Shantou estuary were assessed with the method of single factor pollution index, marine sediment quality and Hakanson＇s potential ecological index. The results showed that： the average contents of Cd, Cu, Zn, Pb in surface sediment of Shantou estuary were higher than marine sediment quality standards （ I ）. Based on the single factor pollution index of target heavy metals, the surface sediment of Shantou estuary have to be considered as most strongly polluted with Cd, strongly polluted with Zn and moderately polluted with Cu, Ni, Pb. Based on ecological risk factor （Er）, the potential ecological risk to the Shantou estuary contamination was very strong with Cd, and only slight with other elements. Based on the multi-elements potential ecological risk indices （R/）, the Shantou estuary was moderately polluted by heavy metals. The spatial difference of heavy metal pollution and their potential ecological risk have a consistent pattern with that of heavy metals content, which showed a decrease trend as waves from upstream to downstream of Shantou Estuary with a distinct peak in Niutanyang and upper region of Shantou harbor. This phenomenon maybe caused by the river inlet, sewer outlet distribution pattern in the study region, together with geographical and hydrological characteristics of Shantou estuary.