Wan-Li Ma

Seasonal variations of sources of polycyclic aromatic hydrocarbons (PAHs) to a northeastern urban city, China

Understanding the seasonal variations of sources of polycyclic aromatic hydrocarbons (PAHs) in air in urban region is important to the effective control of air pollution in the region. Based on a year round dataset (from August 2008 to July 2009), the sources of atmospheric PAHs in Harbin, a typical Chinese northeastern urban city, were analyzed by principal component analysis (PCA) and positive matrix factorization (PMF). The average total (gas plus particulate) PAH concentration varied from 6.3 ng m(-3) to 340 ng m(-3) with a mean of 100+/-94 ng m(-3), with higher concentrations in heating season than those in non-heating season. PCA and PMF identified similar source factors to atmospheric PAHs with obvious seasonal variation. The results obtained by PMF method indicated that the main sources were coal-fired boiler (39%), diesel engine (34%) and coal average (22%) in heating season and traffic emissions (59%), ground evaporation (18%) and coal average (17%) in non-heating season. Excellent correlation coefficients between predicted and measured concentrations of PAHs indicated that PMF was a useful model for source apportionment of PAHs in atmosphere.

An Asia-Specific Source of Dechlorane Plus: Concentration, Isomer Profiles, and Other Related Compounds

The distribution of dechloranes, a group of chlorinated flame retardants, were investigated in air, soil, and sediment around a newly discovered Dechlorane Plus (DP) production facility in China (Anpon). To date, the only known DP manufacturing plant is located in Niagara Falls, NY (OxyChem). Dechloranes including DP, Dechlorane (Mirex), and the recently discovered Dechlorane 602 (Dec 602) were detected in air, soil, and sediment, while Dechlorane 603 and Dechlorane 604 were below detection limit in all matrices. DP air concentrations near the facility ranged from 7737 to 26 734 pg m(-3), the greatest reported thus far. Soil concentrations in the same area for DP, Dechlorane, and Dec 602 were 1490+/-3580 ng g(-1), 81.6+/-96.5 ng g(-1), and 7.24+/-13.2 ng g(-1) dry weight, respectively. Interestingly, lower concentrations of DP (4.93+/-4.34 ng g(-1)), Dechlorane (30.2+/-19.9 ng g(-1)), and Dec 602 (2.14+/-2.23 ng g(-1)) were found in sediment from a nearby canal. Spatial trends of Dechlorane and Dec 602 in soil were similar to DP, implying that the DP manufacturing plant may also be a source of these other flame retardants. DP soil concentrations surrounding the facility decreased by an order of magnitude within 7.5 km. The syn-DP fractional abundance (fsyn) value (0.40) for the commercial DP product manufactured at Anpon was slightly higher than that (0.20-0.36) produced by OxyChem. The fsyn value in most air samples was largely similar to the Chinese commercial DP mixture, while most soil and sediment abundances were lower, suggesting a stereoselective depletion of syn-DP.

Atmospheric concentrations, sources and gas-particle partitioning of PAHs in Beijing after the 29th Olympic Games.

A comprehensive sampling campaign was carried out to study atmospheric concentration of polycyclic aromatic hydrocarbons (PAHs) in Beijing and to evaluate the effectiveness of source control strategies in reducing PAHs pollution after the 29th Olympic Games. The sub-cooled liquid vapor pressure (logP(L)(o))-based model and octanol-air partition coefficient (K(oa))-based model were applied based on each seasonal dateset. Regression analysis among log K(P), logP(L)(o) and log K(oa) exhibited high significant correlations for four seasons. Source factors were identified by principle component analysis and contributions were further estimated by multiple linear regression. Pyrogenic sources and coke oven emission were identified as major sources for both the non-heating and heating seasons. As compared with literatures, the mean PAH concentrations before and after the 29th Olympic Games were reduced by more than 60%, indicating that the source control measures were effective for reducing PAHs pollution in Beijing.

Polybrominated Diphenyl Ethers in Air across China: Levels, Compositions, and Gas-Particle Partitioning

Air samples were concurrently collected using high volume air samplers for 24 h every week from September 2008 to August 2009 at 15 sites (11 urban, 1 suburban, and 3 background/rural) across China. Twelve polybrominated diphenyl ether (PBDE) congeners (BDE-17, -28, -47, -66, -85, -99, -100, -138, -153, -154, -183, and -209) were measured. Total PBDE concentrations (∑12PBDEs) in air (gas + particle phases) were in the range of 11.0-838 pg m(-3) with a mean of 232 ± 72 (mean ± SE) pg m(-3). The site with the highest concentration was Guangzhou (838 ± 126 pg m(-3)), followed by Beijing (781 ± 107 pg m(-3)). Significant positive correlations were found between PBDEs levels and urban population (R = 0.69, P < 0.05) and gross industrial output values (R = 0.87, P < 0.001) as well. BDE-209 was the dominating congener with the contribution of 64 ± 23% to ∑12PBDEs, followed by BDE-47(8 ± 8%) and -99(6 ± 5%) at all urban and suburban sites. At background/rural sites, however, BDE-47 was the dominating congener, followed by BDE-99, together accounting for 52 ± 21% of ∑12PBDEs, while BDE-209 was only 11 ± 2%. It was found that PBDEs at the 15 sites showed a primary distribution and fractionation pattern. This study produced more than 700 pairs of air samples in gaseous and particulate phases with a wide temperature range of ∼60 °C, providing a good opportunity to investigate gas-particle partitioning for individual PBDE congeners. The results of gas-particle partitioning analysis for PBDEs using both subcooled-liquid-vapor pressure (PL)-based and octanol-air partition coefficient (KOA)-based models indicated that PBDEs in air at all sampling sites had not reached equilibrium because the slope values (mO) in the KOA-based equation and the opposite slope values (mP) in the PL-based equation at all 15 sampling sites were less than 1. It also found that both mO and -mP were significantly and positively correlated with the annual average temperatures of sampling sites and also significantly and negatively correlated with the mole masses of PBDE congeners, indicating a general trend that the higher the temperature at the sampling site and the lower the mole mass of the PBDE congeners are, the closer to the equilibrium the congeners approach and vice versa. To our knowledge, this is the first study to report the correlations of the slope values for both the KOA-based and PL-based equations with temperatures at sampling sites and mole masses for individual PBDE congeners.

Dechlorane plus in multimedia in northeastern Chinese urban region

Dechlorane plus (DP) was quantified by gas chromatography/mass spectrometry (GC/MS) in soil and ambient air (collected from Harbin City, a typical northeastern Chinese urban region), water and sediment samples (collected in the segment within Harbin of Songhua River, located in northeast of China). The average concentrations of DP in sediment and soil samples were 123.6 pg g⁻¹ dry weight (dw), and 11.3 pg g⁻¹ dw, respectively. However, the concentration of DP in water was below the method detection limit (MDL). The inter-media comparison between water and sediment suggested that the sediment may be a receptor for DP. For air samples, two methods were used for collecting air in order to compare, active air sampling (AAS) and passive air sampling (PAS). The average concentrations of DP were 0.4 pg m⁻³ and 6.9 pg m⁻³ for AAS and PAS samples, respectively. Discrepancies of deployment period and different calculated method for DP concentration may help to explain the remarkable difference between PAS and AAS. Overall, DP in all matrices in Harbin City showed lower concentrations than that in the Great Lakes region. The anti-DP isomer was consistently greater than that of the syn-DP isomer in all matrices. The average fractional abundance of the syn-DP isomer (f(syn)) was smaller than the technical DP composition (f(syn)=0.35) according to other studies in the Great Lakes region. As we know, this study is the first attempt to comprehensively study DP concentrations in four different matrices (water, ambient air, sediment and soil) in China.

Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Topsoils of Harbin, China

Levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in 17 topsoil samples collected in and around the city of Harbin, an industrial center in Northeast China for decades, are presented. Total concentrations (ng/g dry weight [dw]) ranged from 17 to 3,260 (mean: 508) for PAHs and 0.30 to 6.17 (mean: 1.63) for PCBs. As expected, large differences of the concentration levels of PAHs and PCBs in topsoil were found among the samples from urban, suburban, and background/rural sites. Total PCB and PAH concentrations were higher in industrialized areas than those at the other sites, with a ratio of up to one order of magnitude, possibly indicating the urban source of these chemicals. The PAH profiles were similar among samples, with high percentages of high molecular weight (HMW) PAHs and domination of four-ring PAHs. Compositions of PCB homologues showed that tri-CBs and tetra-CBs were abundant in all soil samples. There was also a higher abundance of low molecular weight (LMW) PCBs and lower abundance of HMW PCBs at background sites than other areas, indicating the urban fractionation phenomenon. Pyrogenic origins were the dominant PAH sources in surface soil at most urban sites, whereas petrogenic origins were the major PAH sources in surface soil at all the rural and background sites. The TEQ concentrations (pg/g dw) of all four dioxin-like PCBs (CBs 77, 81, 105, and 118) were 0.009 for humans and mammals, 0.005 for fish, and 1.42 for birds. Strong correlations were found between PAH and PCB concentrations and soil organic matter and, also, between PAH and PCB concentrations.

Polybrominated diphenyl ethers (PBDEs) in the indoor dust in China: Levels, spatial distribution and human exposure

Indoor environment is an important source of human exposure to several toxicants, such as brominated flame retardants. Indoor dust samples were collected in winter season in 2010, which covered 23 provinces across China, for the analysis of polybrominated diphenyl ethers (PBDEs). Concentrations of PBDEs (Σ14PBDEs) ranged from 8.92 to 37,500 ng/g, with the mean of 3520 ng/g. BDE-209 was the most dominate congener, followed by BDE-183, BDE-47 and BDE-99. PBDE concentrations and the longitude were significantly correlated (p<0.05), which was consistent with the status of social-economic development and human activities. The results of exposure to PBDEs through dust ingestion and dermal absorption indicated that the toddlers had the highest exposure dose, with the median value of 6.0 ng/kg-bw/day. According to the hazard quotients, health risk of PBDEs via dust ingestion in China is currently acceptable. Monte Carlo simulation was implemented to quantify the uncertainty and sensitivity of exposure models for determining the most influential variables. The results suggested that more specific and accurate parameters should be used for dust ingestion and dermal absorption exposure models in future.

Concentrations and sources of polycyclic aromatic hydrocarbons in indoor dust in China.

Indoor dust samples were collected across China in the winter of 2010 from 45 private domiciles and 36 public buildings. 16 polycyclic aromatic hydrocarbons (PAHs) were determined by GC-MS. Total concentrations of PAHs ranged from 1.00 μg/g to 470 μg/g with a mean value of 30.9 μg/g. High-molecular weight (HMW) PAHs (4 to 6 rings) are the predominant PAHs found in indoor dust, accounting for 68% of the total PAH concentration in private domiciles, and 84.6% in public buildings. Traffic conditions and cooking methods were the two key factors controlling PAH levels, especially for coal combustion and vehicular traffic emission sources. A significant positive correlation was observed between PAH concentrations in indoor dust and based on location (latitude and longitude). The latitudinal distribution indicated a higher usage of coal for heating in Northern China than in Southern China. The longitudinal distribution indicated that the usage of oil and mineral fuels as well as economic development and population density increased from West China to East China. In addition, diagnostic ratios and principal component analysis (PCA) were used to explore source apportion, as indicated in both the pyrogenic and petrogenic sources of PAHs in indoor dust in China. Furthermore, the BaP equivalent was applied to assess the carcinogenic risk of PAHs, which also indicated that traffic emissions and coal combustion were the two major contributions to carcinogenic risk of PAHs in indoor dust in China.

Brominated flame retardants in the urban atmosphere of Northeast China: Concentrations, temperature dependence and gas–particle partitioning

57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m(3) and 180 pg/m(3), respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas-particle partitioning coefficients (logKp) for most low molecular weight BFRs were highly temperature dependent as well. Gas-particle partitioning coefficients (logKp) also correlated with the sub-cooled liquid vapor pressure (logPL(o)). Our results indicated that absorption into organic matter is the main control mechanism for the gas-particle partitioning of atmospheric PBDEs.

Temporal trends of polybrominated diphenyl ethers (PBDEs) in the blood of newborns from New York State during 1997 through 2011: analysis of dried blood spots from the newborn screening program.

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants, and on a global basis, North American populations are exposed to the highest doses of PBDEs. In response to the exponential increase in human exposure to PBDEs during the late 1990s, some PBDE formulations were phased out from production in the early 2000s. The effectiveness of the phase-out of commercial penta-BDE and octa-BDE mixtures in 2004 in the U.S. on human exposure levels is not known. Dried blood spots (DBSs), collected for the newborn screening program (NSP) in the U.S., are a valuable resource for the elucidation of trends in exposure to environmental pollutants in newborns. In this study, seven PBDE congeners were determined by gas chromatography-high resolution mass spectrometry (GC-HRMS) in archived DBS samples (in total, 51 blood spot composites from 1224 newborns) collected from newborns in New York State (NYS) from 1997 to 2011. The most frequently detected PBDE congener was BDE-47, with a detection rate (DR) of 86%, followed by BDE-99 (DR: 45%) and BDE-100 (DR: 43%). The mean concentrations determined during 1997 through 2011 in the whole blood of newborns were 0.128, 0.040, and 0.012 ng/mL for BDE-47, -99, and -100, respectively. A significant correlation was found among the concentrations of three major congeners (p < 0.001). PBDE concentrations were similar during 1997 through 2002 and, thereafter, decreased significantly, which was similar to the trends observed for perfluorinated compounds (PFCs) in DBS samples. Occurrence of PBDEs in the whole blood of newborns confirms that these compounds do cross the placental barrier.