Search

The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m, with an average of 30.26 ng m in 2010, and 65.30 to 91.00 ng m, with an average of 78.15 ng m in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase. In 2010, 82.57-97.16% of the total SCCPs were found in the gas phase, except that in winter, where 63.11% of the total SCCPs were in the particulate phase; the air concentrations of SCCPs in gas phase were summer > autumn > spring > winter, which was positively correlated with the change of the average ambient temperature, while it was the contrary in particulate phase. In autumn, the gas phase and the total air concentration of SCCPs in 2016 were 2.57 times more than that in 2010, while the congener group patterns of SCCPs were similar. Spearman's rank correlation analysis between the concentrations of SCCPs with meteorological parameters was conducted. The gas-particle distribution was examined through the relationship of the logarithm of the gas-particle partition coefficient with that of the subcooled vapor pressure and the octanol-air partitioning coefficient of SCCPs. Results indicated that the absorption mechanisms contributed more to the partitioning process. The exposure risk of SCCPs was evaluated, which illustrated that the estimated exposure of SCCPs via the outdoor environment in Dalian did not exceed the health concern threshold of the European risk assessment. [ABSTRACT FROM AUTHOR]

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the urban air of Dalian, China was monitored from November 2009 to October 2010 with an active high-volume sampler and a semipermeable membrane device (SPMD) passive sampler. The samples were analyzed for the sixteen US EPA priority monitoring PAHs using GC/MS. The concentrations of ∑PAHs in particle and gas phases ranged from 3.2–90.6 ng m−3and 40.8–155 ng m−3, respectively. The PAHs of 3–4 rings covered 89.2% of the total concentrations (gas phase + particle phase). Furthermore, the gas-particle partitioning phenomena and the results measured from the field versus those predicted by the Junge-Pankow adsorption model, octanol-air partitioning coefficient (KOA) based absorption model, the absorption into the organic matter plus the adsorption to the soot carbon model using the soot-air partitioning coefficients (KSA) were discussed in this article. The dominant contributors of PAHs in the gas phase of active samples and SPMD passive samples were similar. The SPMD mainly sequestrated gas phase PAHs. The linear correlation coefficients betweenCSPMDandCair-gaswere 0.7316 and 0.7403;CSPMDandCair-totalwere 0.7397 and 0.7409 at Dalian Jiaotong University sampling site and Dalian Meteorological Observatory sampling site, respectively. The quantitative structure-property relationship (QSPR) of the sampling rate of SPMD for PAHs was studied, which can be predicted by the core–core repulsion energy and the energy of the highest occupied molecular orbital of PAH molecules. [ABSTRACT FROM AUTHOR]

PCDD/Fs in the urban air of Dalian, China were monitored with high-volume active sampler from November 2009 to October 2010. The concentration of ClDD/Fs ranged from 3065 to 49538 fg m, with an average of 10249 fg m. The international toxic equivalents (I-TEQ) value of that was 61.8-1182 fg m, with an average of 235 fg m, which was comparable to those in the other urban locations around the world. It was found that the ClDD/Fs appeared to be present mainly in the particle phase during winter, spring and autumn, while during summer which were dominantly in gas phase. The ratio of ClDD/Fs present in particle phase increased with the increasing level of chlorination. The concentrations of PCDFs and PCDDs decreased with the increase of chlorinated level, while the concentrations of 2,3,7,8-PCDDs congeners increased with the increase of chlorination level. The homolog profiles of the concentrations of PCDFs presented were higher than those of the PCDDs, which indicated the PCDD/Fs pollution source of the air in Dalian was characteristic for thermal source pollution. The correlation analysis of meteorological parameters with the concentrations of ClCDD/Fs was conducted using SPSS packages, and it was found that the ambient temperature and atmospheric pressure were important factors influence the concentration of PCDD/Fs in the air. The respiratory risk and intake dioxins of the residents around the sampling sites were studied in the paper. It was found that Junge-Pankow model was much more accurate in predicting the gas-particle partitioning behavior of PCDD/Fs homologues during winter, while the Harner-Bidleman model shows better agreement with the measured data during winter and summer. [ABSTRACT FROM AUTHOR]