Distribution,Source Identification And Ecological Risk Assessment Of Polycyclic Aromatic Hydrocarbons In Sediments Of Daihai

Polycyclic aromatic hydrocarbons(PAHs)are typical toxic organic pollutants.PAHs are difficult to degrade in the environment and it can get into the water through the ways of the surface runoff,atmospheric precipitation,farmland water back and so on.Due to the strong hydrophobic,PAHs can be accumulated in sediments.PAHs can be biological accumulated through the food chain,and the exposure of humans to PAHs may enhance the risk of cancer and other adverse health effects.This paper focus on the distribution of PAHs in the Daihai,analyzing the content distribution,composition characteristics,sources and ecological risk of the PAHs in the study area.We can draw the following conclusions:(1)The content of the sixteen PAHs of the surface sediments in the Daihai were among 204.59?344.49ng/g,and the average contents was 289.60ng/g.Wherein the percentage of low molecular weight PAHs(2 rings and 3 rings)was 57.18%,and the percentage of high molecular weight PAHs(4?6 rings)was 42.82%.The distribution of PAHs in the lake was decreasing from northwest to southeast.The content of 16 PAHs was positively correlated with the content of TOC.The low molecular weight PAHs was positively correlated with the content of TOC,but the high molecular weight PAHs were not correlated with TOC.The results of LMW/HMW ratio show that the source of PAHs in lake is the source of oil.The analytical results of Ant/(Ant+Phe)and Fla/(Fla+Pyr)indicate that the main sources for PAHs in Daihai are the burning of oil and coal,wood,grass and other burning.(2)The content of core sediments in the Daihai were among 254.54?343.69ng/g,the average contents was 300.30 ng/g.The PAHs are mainly composed of 2?3 rings PAHs,and 4 rings are more.5?6 rings are less.The total PAHs,2?3 rings PAHs,4 rings PAHs and 5?6 rings PAHs were significantly decreased with the increase of depth.The concentration of TOC in the site increased linearly with the increase of depth.TOC content was positively correlated with the total amount of PAHs,2?3 rings PAHs,4 rings PAHs and 5?6 rings PAHs.The vertical distribution of PAHs in Daihai sediments was affected by TOC.The results of LMW/HMW show that the source of PAHs in lake is the source of combustion.These Ant/(Ant+Phe)and Fla/(Fla+Pyr)two indicators indicate that the main source of PAHs at point 8 is the combustion of oil and the burning of coal,wood,grass and so on.(3)The SQC method showed that there were some potential ecological risks in Daihai,and the ecological risks were mainly derived from acenaphthene and fluorine.Moreover,benzo[b]fluoranthene,benzo[k]fluoranthene,benzo[g,h,i]perylene and indeno[1,2,3-cd]pyrene formation risk risks also need special attention.The quotient method showed that the ecological risk of naphthalene,fluorene,anthracene,fluoranthene,pyrene and benzo[a]pyrene in Daihai sediments was negligible.