| Polycyclic aromatic hydrocarbons are the compounds which can keep persistant in the environment and cause harmful effects to human being by environmental transformation and enrichment of food chain. In the recent years, the significant use of coal and the release of motor vehicle exaust in the Poyang Lake Eco-economic Zone make the increasing contamination of PAHs in the environment which cause that PAHs was detected in the urban cycle atmosphere and soil phase. Most of recent studies are mainly for a single medium, and pay less attention to the polluted characteristics and the environmental process of PAHs in multimedium environment like atmosphere, soil and sediment and water phase. This dissertation analyzes PAHs' contamination condition, composition and distribution characteristics by collection of samples from the medium of soil, sediment, water and atmosphere of Poyang Lake.The average content of total PAHs from the medium of soil, sediment, water and atmosphere of Poyang Lake are 242.64ng/g, 394.74ng/g, 0.246ug/L and 26.07ng/m3 relatively which are all lower than average content of PAHs from all these mediums in the country. The medium of soil and sediment act as the source and sink of the PAHs from Poyang Lake Eco-economic Zone. PAHs from soil, sediment, and PM2.5 in the atmosphere are mainly exist as large molecules including 4 or more rings while the one from water are mainly exist as small molecules including 3 or less rings. It is verified that PAHs from Poyang Lake Eco-economic Zone are mainly produced by combustion of fossil fuels and partially from direct discharge of oil and biomass burning.There are differences in the time distribution of PAHs from PM2.5 in the atmosphere of Poyang Lake Eco-economic Zone which lead to seasonal variation. The PAHs concentration performed in different seasons as: winter> summer. The special distribution performed as: Nanchang> Jiujiang. Seasonal variation may due to the increasing of energy consumption in winter. Spacial distribution may be attributed to the different energy structure. It is acknowledged by the annual variation of PM2.5 in the atmosphere of Nanchang that the PM2.5 in Nanchang's atmosphere increases year by year. It is mainly because the increasing trend of the energy consumption and the climate variation of Nanchang. What's more, researchers have found that PAHs concentration has a negative correlation with temperature, relative humidity and rainfall capacity.The risk assessment of PAHs in the sediment of Poyang Lake was conducted by ERL and ERM method and PAHs quality evaluation of the fresh water sediment in Canada Quebec. It can be shown that the PAHs in the sediment of Poyang Lake is smaller than ERL which achieves small adverse effect and low ecological risk. Risk assessment of PAHs in the soil of Poyang Lake was conducted by quality evaluation of Canada Quebec and Netherland. The results show that the PAHs in the soil is close to Rare Effect Level(REL) which accords with standard of low risk.The risk assessment of PAHs in the water and atmosphere of Poyang Lake was conducted by TEQ, which is the equivatent carcinogemic concentration of BaP. And lifetime cancer risk is used to conduct health assessment. It was calculated that the risk for lifelong carcinogenic disease is 2.7×10-7,which is acceptable. The excess risks for lifelong carcinogenic disease(R)of adult and children in the atmosphere are 1.35×10-6 and 5.85×10-7, which is smaller than the maximum acceptable risk of 10-6-10-5 and within the acceptable level. |
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