Xiao-Bai Xu

Headspace liquid-phase microextraction of trihalomethanes in drinking water and their gas chromatographic determination

In the present work, a novel method for the determination of trihalomethanes (THMs) such as chloroform, dichlorobromomethane, chlorodibromomethane and bromoform in drinking water has been described. It is based on coupling headspace liquid-phase microextraction (HS-LPME) with gas chromatography-electron capture detector (GC-ECD). A microdrop of organic solvent at the tip of a commercial microsyringe was used to extract analytes from aqueous samples. Three organic solvents-xylene, ethylene glycol and 1-octanol-were compared and 1-octanol was the most sensitive solvent for the analytes. Extraction conditions such as headspace volume, extraction time, stirring rate, content of NaCl and extraction temperature were found to have significant influence on extraction efficiency. The optimized conditions were 15ml headspace volume in a 40ml vial, 10min extraction time and 800rpm stirring rate at 20 degrees C with 0.3gml(-1) NaCl. The linear range was 1-100mugl(-1) for THMs. The limits of detection (LODs) ranged from 0.15mugl(-1) (for dichlorobromomethane and chlorodibromomethane) to 0.4mugl(-1) (for chloroform); and relative standard deviations (RSD) for most of THMs at the 10mugl(-1) level were below 10%. Real samples collected from tap water and well water were successfully analyzed using the proposed method. The recovery of spiked water samples was from 101 to 112%.

A wintertime study of polycyclic aromatic hydrocarbons in PM2.5 and PM2.5–10 in Beijing: Assessment of energy structure conversion

Sixteen priority polycyclic aromatic (PAHs) in PM(2.5) and PM(2.5-10) samples collected from 20 sites in Beijing, China in December 2005 and January 2006 were analyzed to determine the composition, spatial distribution and sources. Total PAHs of PM(2.5) and PM(2.5-10) ranged from 5.2 to 1062.2 ng m(-3) and 7.6 to 759.7 ng m(-3), respectively, categorized as heavier pollution. Among five kind of functional zones involved, industrial center, commercial area and village were heavily polluted. The mean concentration of PAHs in PM(2.5) of 407 ng m(-3) was 1.67-fold of that in PM(2.5-10), which was relatively high compared to the previous studies (winter in 2001 and 2002). The most evident change was the increase of Flu, BbkF and InP, which are believed to be less harmful and related to the increasing use of clean energy. However, pollution distribution was spatially heterogeneous inside the city. The most polluted sites located in the southeast of the city. Unlike previous studies, fluoranthene was the most abundant component quantified, which could be associated with increasing use of natural gas as clean energy. Compositional analysis and principal component analysis (PCA) suggested that different kinds of combustion were the main source of the PAHs in PM, though contribution of coal was still evident.

Determination of triclosan, triclocarban and methyl-triclosan in aqueous samples by dispersive liquid–liquid microextraction combined with rapid liquid chromatography

In this study, dispersive liquid-liquid microextraction (DLLME) combined with ultra-high-pressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV), has been developed for pre-concentration and determination of triclosan (TCS), triclocarban (TCC) and methyl-triclosan (M-TCS) in aqueous samples. The key factors, including the kind and volume of extraction solvent and dispersive solvent, extraction time, salt effect and pH, which probably affect the extraction efficiencies were examined and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.0500-100 microg L(-1) for TCS, 0.0250-50.0 microg L(-1) for TCC, and 0.500-100 microgL(-1) for M-TCS, respectively, with correlation coefficients (r(2))>0.9945. The limits of detection (LODs) ranged from 45.1 to 236 ng L(-1). TCS in domestic waters was detected with the concentration of 2.08 microg L(-1). The spiked recoveries of three target compounds in river water, irrigating water, reclaimed water and domestic water samples were achieved in the range of 96.4-121%, 64.3-84.9%, 77.2-115% and 75.5-106%, respectively. As a result, this method can be successfully applied for the rapid and convenient determination of TCS, TCC and M-TCS in real water samples.

Diffusion of polybrominated diphenyl ether (PBDE) from an e-waste recycling area to the surrounding regions in Southeast China

Using Cinnamomum camphora (C. camphora) leaves as biomonitors, we investigated that the diffusion of polybrominated diphenyl ethers (PBDEs) from an e-waste recycling area to the surrounding regions. Variance in sigma(32)PBDEs concentrations (0.46-399.93 ng g(-1) dry weight) in the leaves showed that PBDEs from the e-waste recycling area diffused into the surrounding regions, and resulted in a halo of PBDEs contamination, at least 74 km in radius. The attenuation of sigma(32)PBDEs in the diffusing process fitted in log-linear regression. The difference in the attenuating slopes of linear equations among different directions can be explained by terrain and wind direction. The attenuation of PBDE congeners also fitted well in log-linear regression. The findings that similar attenuating slopes and characteristic travel distance among congeners suggest that the transport behavior of lower brominated congeners might not differ from that of higher brominated congeners in short-range scale.

Dual body burdens of polychlorinated biphenyls and polybrominated diphenyl ethers among local residents in an e-waste recycling region in Southeast China

E-waste recycling resulted in serious pollution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Taizhou of Zhejiang Province, China. The aims of this study were to assess dual body burdens of the two pollutants and potential health risk for local residents. Blood samples were collected from two e-waste recycling sites, Luqiao (where PCBs-containing e-wastes were recycled) and Wenling (where PBDEs-containing e-wastes were recycled). The mean summation SigmaPCBs (CB-105, 118, 153, 183, and 180) and summation SigmaPBDEs (BDE-28, 47, 99, 100, 153, 154, 180, and 209) were 204.20 and 117.58 ng g(-1) lipid in the blood from Luqiao, respectively, while they were 83.80 and 357.44 ng g(-1) lipid from Wenling, respectively. The PCBs levels among Luqiao residents were comparable to the values reported for US populations, while the PBDEs levels among two study populations were higher than the values from US populations. This is the first report to present dual body burdens of PCBs and PBDEs at so high levels. Based on previous epidemiologic data, it is suggested that dual burdens of PCBs and PBDEs at so high levels might pose health risk for local residents. In addition, no correlation between PCBs or PBDEs concentrations and the ages of the volunteers was observed in the two populations, which was explained by similar exposure time. No correlation of PBDEs with PCBs concentrations suggested different pathways of human exposures to PCBs and PBDEs. Our findings have raised concern about human health risk of dual exposure to PCBs and PBDEs resulting from e-waste recycling.

Degradation pathways of PCBs upon UV irradiation in hexane

The photodegradations of eight individual PCB congeners (5, 31, 52, 77, 87, 126, 138, 169) in hexane have been investigated employing a mercury lamp. All degradation reactions of the above mentioned PCB congeners are of the pseudo first order. The principal products of PCB decomposition are the less chlorinated biphenyls, and no PCB-solvent adducts are found. Symmetrical and coplanar PCB congeners show lower photoreactivities. The reactivities of the chlorine atoms at various positions of PCB rings are generally in the order: ortho > meta > para. Photodechlorinations occur mainly on the more substituted rings, when the numbers of chlorine atoms on the two phenyl rings are unequal. During photodegradation, some coplanar PCB congeners are formed, which make the TEQ of solutions to decrease slowly or even to increase.

Movement and Retention of Polychlorinated Biphenyls in a Paddy Field of WenTai Area in China

Polychlorinated biphenyls (PCBs) are classified as priority pollutants by environmental agencies. A field investigation on polychlorinated biphenyls movement and retention in paddy field was conducted during 1993, 1997 and 1999 at the WenTai area. Soil, air and rice samples were analyzed. PCB concentrations in the soil showed a reducing trend with respect to time and depth. Most of the di-, tri-, and tetra-chlorinated PCB congeners showed significant decreases during the period, while the more highly chlorinated PCBs were more persistent in soil. The results of field investigation data showed that even though 6 years the PCB concentrations in two fields were far from reaching uniform. In addition, rice grown in the field appeared somewhat contamination by PCBs, but it was not likely subjected to concentrating PCBs from contaminated soil significantly. It was shown that the PCB concentrations in rice samples were not directly proportional to their concentrations in soil. Principal component analysis was performed with the standardized relative abundance of PCBs in the samples. All these observations indicated that the pattern of PCBs in soil cannot be considered to reflect the original pollution source.

Levels and distribution of polybrominated diphenyl ethers in various tissues of foraging hens from an electronic waste recycling area in South China

Levels and distribution of polybrominated diphenyl ethers (PBDEs) in various tissues of hens foraging near an electronic wastes stack spot in Taizhou, China, were studied. With high-resolution gas chromatography/negative chemical ionization mass spectrometry analysis, 37 PBDE congeners from di- to hepta-brominated and BDE 209 were identified and quantified in the liver, heart, skin, fat, intestine, muscle, blood, oviduct, ovum, gizzard, spleen, and kidney tissues of hens. Based on lipid weight in all analyzed tissues, muscle exhibited the highest PBDE concentrations (17,977 ng/g lipid wt), BDE 209 was the dominant congener, and the sum of quantified PBDEs followed the order muscle > fat > intestine > heart > liver > oviduct > gizzard > blood > skin > ovum. Principal component analysis results indicated that the hen muscle tissue was characterized by BDE 32, 209, 28, and 75 congeners; hen intestine, heart, and blood tissues were characterized by BDE 153, 99, 183, 138, 154, 47, and 100 congeners; and hen skin, liver, oviduct, ovum, gizzard, spleen, kidney, and fat tissues had a similar PBDE congener profile. The present study also indicated that the PBDE congeners were persistent enough to accumulate through the human food chain and that deca-BDE might be potential risk to ecoenvironment.

Phototransformation of polychlorinated dibenzo-p-dioxins from photolysis of pentachlorophenol on soils surface

The phototransformation of polychlorinated dibenzo-p-dioxins (PCDDs) by photolysis of pentachlorophenol (PCP) on soil surface under irradiation of UV light in the laboratory has been investigated. Octachlorodibenzo-p-dioxin (OCDD) and heptachlorodibenzo-p-dioxin (H7CDD) were detected from the products of the photoreactions. The effects of soil types with different basic soil physicochemical properties were varied from silt loam, silt clay and clay soil on the formation of PCDDs by irradiation of PCP on soils surface. Fulvic acids can prevent phototransformation of PCDDs by photolysis of PCP on soil surface.

Levels and distribution of organochlorine pesticides in various media in a mega-city, China

As one of Chinas great metropolises, Taiyuan is generally recognized to be one of the most polluted cities in the world. It is affected by pollution from heavy industries, and from organochlorine pesticides (OCPs). In this study, we measured the concentrations of OCPs in various environmental media in Taiyuan. We measured the levels of OCPs in 15 soil samples and 34 samples of respirable particulate matter (PM) (17 of PM(2.5) and 17 of PM(10)) from urban areas of Taiyuan. Analysis of the composition ratios of OCP residues revealed that dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) were the predominant compounds in soil, PM(2.5) and PM(10). The total DDT concentrations were 1.8-1.0x10(2)ngg(-1) in soil, 6.5-1.0x10(3)pgm(-3) in PM(2.5), and 8.5-1.5x10(3)pgm(-3) in PM(10). The total HCH concentrations were 1.4-45ngg(-1) in soil, 5.2-8.0x10(2)pgm(-3) in PM(2.5), and 9.6-8.7x10(2)pgm(-3) in PM(10). Furthermore, source analysis indicated that there was new input of OCPs at some sites. Finally, analysis of the individual OCPs revealed that new OCP contamination was the major problem in Taiyuan. This study suggests that measures should be taken to reduce the levels of OCP residues in order to improve the environmental quality in Taiyuan.