| Due to the rapid development of economy in recent decades,the intensity of human activities has increased,a large number of polycyclic aromatic hydrocarbons（PAHs）have been discharged into rivers and transported to the offshore,bringing negative impacts on the coastal ecological environment.The Xinyanggang River and the Sheyang River are the important coastal rivers flowing into the sea in Jiangsu Province.The paper studied the distribution,sources and influencing factors of PAHs in sediment of the Xinyanggang River and the Sheyang River,which was of great significance to the pollution control and environmental protection of coastal waters in Jiangsu Province.The main conclusions were as follows:（1）The silt content of sediment cores was the highest in basins,ranging from 52.52%to80.14%.The content of black carbon of sediment cores was 0.29-5.49 mg/g.The average content of?16PAHs（ng/g）of S-8,S-11,X-8,X-20 and X-23 sediment cores in basins was516.34,145.79,502.09,762.52 and 27.73,respectively.The main sources of PAHs in sediment cores were coal and biomass combustion and fossil fuel combustion,and their contribution rates to the Xinyanggang River and the Sheyang river were 45.23%and 54.77%,56.78%and 34.65%,respectively,among which the source of PAHs in sediment cores from the Sheyang River also existed oil leakage source（8.57%）.（2）The increasing trend of PAHs content in sediment core was basically consistent with the trend of economic development.The rising level of urbanization and industrialization will increase energy consumption and PAHs emissions.The establishment of watershed protection zones and government regulation of coastal industries will reduce fossil fuel consumption and PAHs pollution level.The content of PAHs in different sediment core was positively correlated with different socioeconomic development factors.The positive correlation coefficient between the content of PAHs in sediment core S-8 and S-11 and the consumption of diesel oil and kerosene was the highest,respectively（0.91 and 0.69,respectively）.The positive correlation coefficient between the PAHs content in sediment core X-8 and the industrial consumption of kerosene was the highest（0.57）.The positive correlation coefficient between the PAHs content in sediment core X-20 and most socio-economic indexes was more than 0.70.The content of PAHs in sediment core X-23 was positively correlated with the agricultural population（0.64）,and negatively correlated with other social and economic indicators.（3）The average contents of?16PAHs（ng/g）of surface sediments in the Sheyang River and the Xinyanggang River were 248.06 and 3209.46,respectively.The main sources of PAHs in surface sediments were fossil fuel combustion and coal and biomass combustion,and their contribution rates to the Xinyanggang River and the Sheyang river were 61.63%and 38.67%,43.28%and 56.72%,respectively.The PAHs pollution level of surface sediments in Xinyanggang River was higher than that of most rivers in China,and more than 40%of the stations have high PAHs pollution level,which had certain risks and toxicity to the ecological environment.The average silt content and the average black carbon content of surface sediments in the Sheyang River and the Xinyanggang River was 69.89%and 67.01%,1.57mg/g and 1.89 mg/g,respectively,there was no significant correlation between PAHs content and particle size and black carbon.The content of PAHs was positively correlated with the area of urban and agricultural land.（4）The results of the geographically weighted regression model showed that there was a strong positive correlation between PAHs and urban land use,while the high correlation between PAHs and agricultural land use only existed in the small watershed dominated by agricultural land use.In the area with high percentage of grassy forest land,PAHs of surface sediment was negatively correlated with grassy forest land,and this area had low PAHs pollution degree.The positive correlation coefficient between PAHs of surface sediment and population density was higher than that of all land use types,and it was more sensitive to population density in watershed with high grass forest area.These results indicated that the content of PAHs was affected by regional land use type and intensity of human activities.Increasing the area of grassland forest can reduce the serious impact of human activities and reduce the concentration of PAHs. |
