Comparison of the contributions of polychlorinated dibenzo-p-dioxins and dibenzofurans and other unintentionally produced persistent organic pollutants to the total toxic equivalents in air of steel plant areas.

The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and the "dioxin-like" (dl) compounds polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polybrominated dibenzo-p-dioxins (PBDDs), and dibenzofurans (PBDFs), were determined in the air samples collected from six steel plants. The toxic equivalent (TEQ) concentrations of the PCDDs, PCDFs, dl-PCBs, dl-PCNs, PBDDs, and PBDFs in the air were 0.01-0.19 pg WHO-TEQ Nm(-3), 0.01-0.69 pg WHO-TEQN m(-3), 0.001-0.089 pg WHO-TEQ Nm(-3), 0.002-0.011 pg TEQ Nm(-3), 0.004-0.02 pg TEQ Nm(-3), and 0.02-0.12 pg TEQ Nm(-3), respectively. The PCNs were the most abundant compounds (by mass concentration), contributing about 87% of the total mass concentrations of the analytes that were found in the air of the steel plant areas. The PCDFs contributed about 47% of the total TEQs, following by the PBDFs (28%) and the PCDDs (18%). The dioxin-like compounds together contributed up to 40% of the total TEQs, so their contributions to the toxic effects that could be caused by exposure to the air of the steel plant areas were significant. The congener profiles in the air were similar to the congener profiles that were found in stack gas emissions, indicating that the steelmaking plants were possible sources of the PCDDs, PCDFs, and dioxin-like compounds that were found in the air of the steel plant areas.

Li S ，Liu G ，Zheng M ，Liu W ，Wang M ，Xiao K ，Li C ，Wang Y ... -  《-》

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice straw smoke and their origins in Japan.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.

Minomo K ，Ohtsuka N ，Nojiri K ，Hosono S ，Kawamura K ... -  《-》

Atmospheric distribution of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls around a steel plant area, northeast China.

Air monitoring of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) was carried out in June 2008 and January 2009 to investigate the concentrations, profiles and estimating potential inhalation risks to the local residents around a steel plant area in northeast China. The air concentrations and WHO-TEQs of PCDD/Fs ranged 94-4944fgm(-3) (average 1352fgm(-3)) and 3-247fgm(-3) (average 81fgm(-3)), respectively. The WHO-TEQ concentrations of dioxin-like PCBs ranged 1-18fgm(-3) (average 5fgm(-3)), contributing to 3.6-26% of the total TEQ. Higher PCDD/F concentrations were observed in the winter, whereas higher dioxin-like PCB concentrations were found in the summer. The seasonal trend can be related to the significant correlation between the concentrations of dioxins and the reciprocal of temperature (positive for PCDD/Fs, P<0.01; negative for dioxin-like PCBs, P=0.05). A significant positive correlation (P<0.0001) was found between the concentration of total suspended particulate (TSP) and PCDD/F concentrations, but not for PCB congeners. Although the steel plant sites showed higher dioxin levels than the residential and background areas, the PCDD/F levels in the atmosphere of the steel plant area was at a relatively low level. The results from this study provides further aid in evaluating the impact of steel plants as PCDD/Fs emission sources to the ambient air in China.

Li Y ，Wang P ，Ding L ，Li X ，Wang T ，Zhang Q ，Yang H ，Jiang G ，Wei F ... -  《-》

Estimation and characterization of unintentionally produced persistent organic pollutant emission from converter steelmaking processes.

Li S ，Zheng M ，Liu W ，Liu G ，Xiao K ，Li C ... -  《-》

Concentrations, profiles, and emission factors of unintentionally produced persistent organic pollutants in fly ash from coking processes.

The coking process has been found to be an important source of unintentionally produced persistent organic pollutants (UP-POPs). However, the concentrations, profiles, and emission factors of UP-POPs in fly ash from coke plants have not been studied. In this study, six UP-POPs (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz), and pentachlorobenzene (PeCBz)) were identified and quantified in fly ash from eight coke plants. The average concentrations of the PCDDs, PCDFs, and "dioxin-like" PCBs were 1.5, 2.26, and 0.26 pg TEQ g(-1), respectively, and the average concentrations of the PCNs, HxCBz, and PeCBz were 256, 290, and 146 pg g(-1), respectively. The proportion each homolog contributed to the total concentration of the PCDFs, PCBs, and PCNs decreased with increasing chlorination level. The PCDFs contributed the biggest proportion of the total UP-POPs toxic equivalents (TEQs), and the average emission factors in fly ash were 10.5, 17.3, and 1.82 ng TEQt(-1) for the PCDDs, PCDFs, and "dioxin-like" PCBs, respectively, and 1,792, 2,028, and 1,025 ngt(-1) for the PCNs, HxCBz, and PeCBz, respectively. These data are essential for establishing an integrated UP-POP release inventory.

Liu G ，Liu W ，Cai Z ，Zheng M ... -  《-》