Polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) and polychlorinated biphenyls(PCBs) were monitored in a seasonal passive sampling scheme during June 2008 and January 2009 to investigate the spatial concentration,congener profiles and evaluate the potential inhalation risk in different functional areas in Tianjin,China.The spatial air concentrations and I-TEQs ranged 1.08×102-8.19×10 3 fg m-3(average 2.63×103 fg m-3) and 4.08-325 fg I-TEQ m-3(average 91.4 fg I-TEQ m-3) respectively for PCDD/Fs.The concentration and I-TEQs of PCBs were 3.08×104-3.01×105 fg m-3(average 1.39×105 fg m-3) and 1.72-49.6 fg I-TEQ m-3(average 18.5 fg I-TEQ m-3).It is obvious that PCB concentrations were several hundred times higher than the PCDD/Fs.However,the ambient air PCDD/Fs contributed a major part to the total toxicity equivalents,varying from 72.7% to 89.0%(average 81.8%).The atmospheric PCDD/F levels were observed to be higher in winter for most of sampling sites in the downtown.Besides,inhalation risk assessment showed that local residents might suffer more risk near the point sources than those in living area,industrial zones and background area in Tianjin City.However,the total daily dioxin intake was approximately several to hundreds of times lower than the WHO criteria,showing relatively low exposure risks from the impact of industry point sources in Tianjin City.
The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were investigated within a seasonally active sampling scheme during Jun 2008 and Jan 2009 in Tianjin City, northern China. The PCDD/F concentrations ranged 14.2-172 fg I-TEQ/m3 （average 69.3 fg I-TEQ/m3） in summer and （89.8-1.01） x 103 fg I-TEQ/m3 （average 509 fg I-TEQ/m3） in winter, respectively, except for the E-waste dismantling site where much higher values were observed （1.04 x 103 fg I-TEQ]m3 in summer and 7.123 x 103 fg I-TEQ/m3 in winter）. The results indicated a significantly seasonal trend with higher TEQ values in winter as compared with summer, which could be related to increased emission sources and seasonal variations of the atmospheric boundary layer height. 2,3,4,7,8-PeCDF was the dominant contributor to the total PCDD/F toxic equivalents, and 2,3,7,8-TCDD was detected at almost all the sampling sites in winter. Most of the similarly substituted PCDD/F congener pairs exhibited high correlations, suggesting that they might have similar environmental fate or sources. But different seasonal and spatial distributions of PCDD/F concentrations indicated that the emission sources might be intermittent.
Lei DingYingming LiPu WangXiaomin LiZongshan ZhaoQinghua ZhangTing TuanGuibin Jiang
Antarctica is an important research region for assessing persistence and long-range atmospheric transport (LRAT) of persistent organic pollutants (POPs). In this study, XAD-resin passive air sampling was conducted near the Chinese Great Wall Station, Antarctica, during a one-year sampling period in 2009-2010. The air concentrations of polychlorinated biphenyls (PCBs) were at a very low level, with total PCBs in the range of 26.74-45.08 pg m 3. PCB profiles were dominated by tetra-PCBs, tri-PCBs and di-PCBs, indicating LRAT was responsible for the pollutants in the Antarctic atmosphere. The sampling site near the Chinese Great Wall Station did not show higher PCB levels than the other sites, suggesting that PCB sources associated with the Great Wall Station were negligible. PCB-11 is a non-Aroclor congener, which has specific sources compared to other Aroclor PCB congeners. PCB-11 was observed in all air samples, with an average concentration of 1.22 pg m 3. To our knowledge, this study is the first investigation of PCB levels and distribution in the atmosphere around the Chinese Great Wall Station, Antarctica.
LI YingMingGENG DaWeiHU YongBiaoWANG PuZHANG QingHuaJIANG GuiBin
The concentrations and geographical distribution of hexabromocyclododecane （HBCD） were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection （LOD） to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of t-IBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that y-HBCD dominated in most of the sediment samples, followed by ct- and [3-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.
