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Seasonal Variation and Gas/Particle Partitioning of PCBs in Air from Central Urban Area of an Industrial Base and Coastal City-Tianjin, China
並列摘要
The 26 air samples were collected from Tianjin urban areas from July 2010 to May 2011 for the analysis of 86 PCB congeners to investigate the gas/particle partitioning of PCBs. The total PCBs concentration (in pg/m^3) ranged from 31.28 to 650.33 (mean: 273.77) and showed a significantly seasonal variation as summer ＞ autumn ＞ spring ＞ winter. Gas PCBs accounted for 80.79% of total PCBs. The fraction of each gas PCB homolog increased with the decreasing chlorine atoms. The contribution of gas PCBs to total PCBs showed a strong seasonal variation with summer (94.07%) ＞ autumn (78.91%) ＞ spring (78.19%) ＞ winter (56.02%). Tri-, tetra- and penta-PCBs were the predominantly homologs in Tianjin atmosphere. The natural logarithm of partial pressure of PCBs were well correlated with the inverse absolute environmental temperature (R=0.79). The steep slope of -4933.64 obtained from Clausius-Clapeyron (C.C) plot indicated the influence of local PCBs sources. In generally, the C.C slopes and the surface-air exchange enthalpy (ΔH_(SA)) for different PCB homologs increased with the increasing chlorine atoms. The fraction of particle bound PCBs were underestimated for PCBs with PL 0 ＞ 10 ^(-3.85) Pa and overestimated for PCB congeners with PL 0 ＜ 10 ^(-3.85) Pa by Junge-Pankow model. The logarithm of particle/gas partitioning coefficients (log K_P) of PCBs were well correlated with the logarithm of respective sub-cooled vapor pressures (log P_L^0) (R=0.72) and the octanol-air partition coefficient (log K_(OA)) (R=0.77). The slopes for log KP against log P_L^0 and log K_(OA) plots were -0.44 and 0.48, deviated The 26 air samples were collected from Tianjin urban areas from July 2010 to May 2011 for the analysis of 86 PCB congeners to investigate the gas/particle partitioning of PCBs. The total PCBs concentration (in pg/m^3) ranged from 31.28 to 650.33 (mean: 273.77) and showed a significantly seasonal variation as summer ＞ autumn ＞ spring ＞ winter. Gas PCBs accounted for 80.79% of total PCBs. The fraction of each gas PCB homolog increased with the decreasing chlorine atoms. The contribution of gas PCBs to total PCBs showed a strong seasonal variation with summer (94.07%) ＞ autumn (78.91%) ＞ spring (78.19%) ＞ winter (56.02%). Tri-, tetra- and penta-PCBs were the predominantly homologs in Tianjin atmosphere. The natural logarithm of partial pressure of PCBs were well correlated with the inverse absolute environmental temperature (R=0.79). The steep slope of -4933.64 obtained from Clausius-Clapeyron (C.C) plot indicated the influence of local PCBs sources. In generally, the C.C slopes and the surface-air exchange enthalpy (ΔH_(SA)) for different PCB homologs increased with the increasing chlorine atoms. The fraction of particle bound PCBs were underestimated for PCBs with PL 0 ＞ 10 ^(-3.85) Pa and overestimated for PCB congeners with PL 0 ＜ 10 ^(-3.85) Pa by Junge-Pankow model. The logarithm of particle/gas partitioning coefficients (log K_P) of PCBs were well correlated with the logarithm of respective sub-cooled vapor pressures (log P_L^0) (R=0.72) and the octanol-air partition coefficient (log K_(OA)) (R=0.77). The slopes for log KP against log P_L^0 and log K_(OA) plots were -0.44 and 0.48, deviated significantly from the expected -1 and +1 for the equilibrium state of gas/particle partitioning, possibly explained by the emission of PCBs and particles from the local industries and other sources. The TEQ concentrations (fg/m^3) for 12 dioxin-like PCB congeners ranged from 35.628 to 612.796 with the mean value as 144.878. significantly from the expected -1 and +1 for the equilibrium state of gas/particle partitioning, possibly explained by the emission of PCBs and particles from the local industries and other sources. The TEQ concentrations (fg/m^3) for 12 dioxin-like PCB congeners ranged from 35.628 to 612.796 with the mean value as 144.878.