Pollution Characteristic And Gas-particle Partition Of PCDD/Fs And PBDEs At Urban Point Source

This thesis is focusing on PCDD/Fs and PBDEs level and it’s impacts on environment of two typical urban point sources of MSWIs and EAF plant. The optimized gas-particle partition models were optimized and by using optimized model, the gas-particle behavior of the pollutants were compared between point source and non-point source.The air samples, soil samples, fly ash samples and flue gas samples were purified with the Optimized Soxhlet cleaning methods of PCDD/Fs and PBDEs by the following steps: silica-acid silica gel column, and carbon column, then the PCDD/Fs and PBDEs were determinated by HRGC/HRMS and GC/MS respectively. ELISA method were also used for PCDD/Fs analysis in solid samples. Source analysis were using PCA, HCA and K-mean, the air- soil exchange analysis were using Fugacity model. We optimized the gas-particle partition models, using the optimized models we compared the different between point sources and non non-point source.The characteristics of PCDD/Fs at the two urban poin sources are as follows. At the MSWIs, the PCDD/Fs level in soil samples are 17.2~157 pg/g(0.59~8.81 pg WHO-TEQ/g), OCDD is the dominant congener, the dominant contributor to TEQ are 2,3,4,7,8-Pe CDF and 1,2,3,7,8-Pe CDD. The PCDD/Fs level in air samples are 873~1120 fg/m3(51.2~61.6 fg WHO-TEQ/m3), 2,3,4,7,8-Pe CDF is the dominant contributor. The TEQ level of fly ash is 613~597pg WHO-TEQ/g, and the TEQ level of flue gas is 49 pg WHO-TEQ/m3 which is under the newest dioxin emissions limitation of China’s national standard. At the steel plant area, the PCDD/Fs level in soil samples are 26.1~101 pg/g(0.72~4.44 pg WHO-TEQ/g), OCDD is the dominant congener, the dominant contributor to TEQ is 2,3,4,7,8-Pe CDF. The PCDD/Fs TEQ level of fly ash is 67.5~71.8pg WHO-TEQ/g. The PCDD/Fs TEQ level of flue gas is 0.394 ng/m3(0.0358 ng WHO-TEQ/m3). Source apportionment indicated, the MSWIs and Refinery plant are the prime source of PCDD/Fs in environmental samples, and traffic source is another source. The impact of PCDD/Fs pollution of steel plant was less than MSWIs, and and traffic source is another source for this area. The soil-air exchange of fugacity ratio(ff) of PCDD/Fs is 0.01~0.13, which indicated the trend of transmission from air to soil, the low-chlorided compounds were closed to equilibrium states, and the temperature have no effect on this tendency.The characteristics of PBDEs at the two urban poin sources are as follows. At the MSWIs, the level of BDE-209 in soil samples are 5180~169000 ng/kg,with contribution higher than 94.0% to ∑12PBDEs. BDE-209 is the dominant congener with 82.6%~92.5% of ∑12PBDEs in air samples. The levels of ∑12PBDEs in fly ash are 8580 ng/kg and 7720 ng/kg, and 6.84 ng/m3 in flue gas. At the steel plant area, The level of BDE-209 are 893~10600 ng/kg in soil samples, with contribution higher than 93.0% to ∑12PBDEs. The PBDEs level in air samples is 13.9~102 pg/m3,BDE-209 is the dominant congener with 68.0%~95.9% of ∑12PBDEs. The PBDEs level of fly ash are 5590 ng/kg and 5730ng/kg, and 5.7 ng/m3 in flue gas. Source apportionment indicated, PBDEs in the environment samples were derived from the combustion and using of commercial Deca-BDEs and Penta-BEDs, Deca-BDEs is the dominant pollutants. The impact of PBDEs pollution of steel plant was less than MSWIs. The soil-air exchange of fugacity ratio(ff) of PBDEs are 10-1~ 10-4, which indicated the trend of transmission from air to soil, and the ff value of point source is lower than non-point source.Based on the equivalence and convertibility of PL and KOA, the Junge-Pankow model and Hamer-Bidleman model were the same for describing the Φ value. Thus we establish a formula for calculating θ in equilibrium state. We also defined the predicted model for Φ values with steady state, and establish a formula for calculating the θ.Gas-particle partition results indicated, PBDEs were mainly in particle phase, the fraction of particle-bound PBDEs increases as the brominated level increases. The estimated levels of particle phase are higher than measured levels for steady state equilibrium by using PL and KOA models, and good agreements were obtain between measured and theoretical estimates of steady states absorption model. The Gas-particle partition of poin source presents equilibrium state influenced by pollutant emission. The fraction of particle-bound PCDD/Fs increases as the chlorination level increases, and the fraction level of particle-bound PCDD were higher than PCDF. Generally, good agreements were obtained between measured and theoretical estimates of both the Junge-Pankow model and Harner-Bidleman model with close to equilibrium states for PCDD/Fs, but the steady states model were limited for PCDD/Fs gas-particle partition modeling. The θ value calculated by the formula is better than the value recommended by the references applied in equilibrium state and steady state.