Source And Multimedia Environmental Behavior Of PAHs In Dalian Urban Area

PAHs are ubiquitous organic pollutants in the environment. PAHs are formed from the incompleted combutions of fossil fuels and organic materials. Most of PHAs are of carcinogenic, teratogenic and mutagenic effect. Dalain is in the northeast of China, and the fuel consumption is mainly from coal, from which PAHs pollution can't be ignored. Until now, the source, state, and multimedia environmental behavior of PAHs hadn't been elucidated. It is obvious that the study on source and multimedia environmental behavior of PAHs is of very important significance to PAHs pollution control and elimination.Based on the surveyed fossil fuel consumptions in 4 urban area of Dalian and corresponding compiled emission factors, 17 PAHs emissions were estimated about 34 t/a, in which from vehicles, coal-fired boilers, and heavy and diesel oil -fueled in industrial processes is 14%, 80% and 6% respectively. Contributors from different sources to individual PAHs emission are different. 3 rings to 5 rings PAHs emissions are mainly from vehicles, but 2 rings and 6rings PAHs emissions are mainly from coal consumption.The environmental geological, meteorologic, hydrological, vegetable and urban constructive data in 4 urban areas of Dalian were surveyed. Based on these data, the multimedia environmental model was built in 4 urban area of Dalian, in which the fugacity theory was used and estimated PAHs emission was input. The main environmental media, such as air, coastal water, soil, sediment and film were included in the model. In order to validate the model, pine needles were also included. The model validation shows that the differences between predicted and measured concentrations of most PAHs in aerosol, sediment are 0.5 log-unit and that of BaA and BaP in pine needle are also 0.5 log-unit, which is in accordance with the model precision.From the calculation, the concentration, accumulated mass, mass distribution, advective inflow and outflow flux, degradation loss flux, intermedia transport flux and residence time of 10 PAHs in air, coastal water, sediment, pine needle and film in 4 urban area of Dalian are shown.The main input of PAHs is advective inflow (except Naph), and the main output of PAHs is advective ouflow. PAHs consistently achieve their highest concentrations in film with sediement, soil, pine needle, water and air. Low molecular weight (LMW) PAHs are mainlyaccumulated in air and high molecular weight (HMW) PAHs are mainly in soil and sediment. There is no simple line relationship between acculumated mass and direct emission. Degradation loss ratios of LMW PAHs are little than that of HMW PAHs. The largest degradation flux of LMW PAHs is in air, but that of HMW PAHs is in soil and sediment. The residence time of PAHs (except Naph) in soil and sediemt is the highest, and that in air is less than 1 h. For the intermedia transports, the atmospheric deposition to flux film and film wash off flux to water is the largest, which shows that the film increases the mobility of PAHs in urban environment. For the atmosphric transport processes to other media, the main processes are air-phase diffusions for LMW PAHs and aerosol dry or wet depositions for HMW PAHs.