Ecological Risk Assessment Of Substituted Aromatic Hydrocarbons In Yangtze River Estuary

The Yangtse estuary, which is the biggest estuary in China occupies an important position in the international estuary and the coast field. In recent years, organic pollution in the Yangtze estuary area has become more and more serious question which has been influenced by the natural factors and human activities. In this article the Yangtze estuary area (31°00'-32°00'N,121°00'-122°00'E) were selected as the study region and the substituted aromatic hydrocarbons in water and surface sediment from the Yangtze estuary in May,2007 were analyzed. According to the related standards and the assessment models, the pollution status and risk assessment of this area were stated. The results showed that:1. Six substituted aromatic hydrocarbons including 1,3-Dichlorobenzene,1,4-Dichlorobenzene,1,2-dichlorobenzene, hexachlorobenzene,2,4-dinitrotoluene,1,2,4-Trichlorobenzene were detected in water of the Yangtze River Estuary. And it demonstrated obvious spatial distribution. The concentration of pollutants were lower than the standard of Surface Water Environment Quality Standard (GB3838-2002) except 2,4-dinitrotoluene.Technical Guidance Document (TGD) on the risk assessment of chemicals by European Union and Probabilistic Risk Assessment were adopted in this paper to assess the ecological risks of substituted aromatic hydrocarbons in water of the Yangtze River estuary. The results consistently indicated that the six substituted aromatic hydrocarbons except 1,2,4-Trichlorobenzene did not cause potential damage to the Yangtze River Estuary ecosystem.2. Six substituted aromatic hydrocarbons including 1,3-dichlorobenzene,1,4-dichlorobenzene,1,2-dichlorobenzene, hexachlorobenzene,2,4-dinitrotoluene,2,6-dinitrotoluene were detected in sediment of the Yangtze River Estuary. And it demonstrated obvious spatial distribution as in the water.The preliminary risk assessment of 1,3-dichlorobenzene, 1,4-dichlorobenzene,1,2-dichlorobenzene, hexachlorobenzene was carried out using the standard for freshwater sediment pollutants by Washington Department of Ecology. The results showed that hexachlorobenzene had potential ecological risk in part of Yangtze River estuary and other pollutants were not.