Xinhui Bi

Pollution characterization and diurnal variation of PBDEs in the atmosphere of an E-waste dismantling region.

Diurnal air samples were collected from the E-waste dismantling region Guiyu and the underwear industry region Chendian. This was the first report to present the diurnal variation of PBDEs in the atmosphere. The average concentrations of 11 PBDE congeners were 11,742 pgm(-3) in the daytime, and 4830 pgm(-3) at night in Guiyu, while the concentrations were lower in Chendian with 376 pgm(-3) in the daytime, and 237 pgm(-3) at night. BDE-209 accounted for 22% and 31.3% of the total PBDEs in Guiyu and Chendian, respectively. The diurnal variation trends of BDE-47, -99, -153, -183, and -209 were also analyzed in detail in the two regions.

Phase partitioning, concentration variation and risk assessment of polybrominated diphenyl ethers (PBDEs) in the atmosphere of an e-waste recycling site

The daytime and nighttime air samples were collected from an e-waste recycling site in Guiyu (GY) and its upwind and downwind direction sites in Chendian (CD) and Gurao (GR), respectively, during September and December 2005 to determine the phase partitioning, seasonal and diurnal variation of polybrominated diphenyl ethers (PBDEs). The three sites showed similar congener compositions with BDEs-28, -47, -99, -207 and -209 as the dominant congeners. The gas phase contribution ranged from 42.1% ± 17.1% of the total PBDEs in summer to 9.0% ± 8.6% in winter. Partitioning of PBDEs between gas and particulate phases was well correlated with the subcooled liquid vapor pressure (P(L)(0)) for all samples. Both Junge-Pankow adsorption model and K(OA)-based absorption model fitted well the PBDEs data in winter but overestimated the sorption of PBDEs in summer. The mean atmospheric concentrations of BDEs-47 (2748 pg m(-3) in summer and 6146 pg m(-3) in winter) and -99 (1656 pg m(-3) in summer and 4911 pg m(-3) in winter) in GY were much higher than those from other places around the world. Additionally, the time series of PBDEs in GY demonstrated a pronounced diurnal variation pattern, but not CD and GR, where PBDEs appeared partly associated with regional accumulation. Source characterization from local emissions may be the major factor controlling the diurnal variation of PBDEs in GY air. The risk assessment showed that the total daily intakes of BDE-99 in GY was 9.0-34.9 ng kg(-1)-bwd(-1), which is higher than the maximal allowed intake level (0.26 ng kg(-1)-bwd(-1)) with factors of 35-135, indicating possible health risk for GY residents with exposure to PBDEs.

Heavy metals and organic compounds contamination in soil from an e-waste region in South China

Heavy metals and persistent organic pollutants polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were analyzed in 34 surface soil samples collected from farmland and 7 soil or dust samples collected from the workshops in South China, where e-waste was dismantled using primitive techniques. The results show that Cd, Cu and Hg were the most abundant metals, in particular Cd pollution was serious in farmland soils, and the median concentrations in farmland soils were beyond the environmental quality standard for soils (China Grade II). A correlation between Cd, Cu, Zn, Pb and PCBs or PBDEs was significant indicating similar sources. Among the PCB congeners, high relative similarity was observed between the e-waste dump site soil (EW1) and Aroclor 1254, implying that the technical product Aroclor 1254 was one of the major sources of PCB contamination. High concentrations of PCBs in workshop dusts (D2 and D3) (1958 and 1675 μg kg(-1)) demonstrated that the workshops dismantling electrical wires and cables, electrical motors, compressors and aluminum apparatus containing PCBs in lubricants represent strong PCB emission sources to this area. Principal component analysis (PCA) and PBDE homologue patterns verify that farmland soils surrounding the e-waste recycling sites were enriched with lower brominated congeners, and the major source of PBDEs in dust samples might potentially be associated with the extensive use of deca-mix technical products as a flame retardant. The difference between e-waste soils, dusts and farmland soils can be observed in the PCA score plot of PCBs and PBDEs, and E-waste soils and dusts exhibited more diversity than farmland soils. Furthermore, a prediction of the particular kinds of pollution from different recycling activities through the analysis of each contamination and the connections between them was investigated.

Separation of PAHs in aerosol by thin layer chromatography for compound-specific stable carbon isotope analysis

A method using a thin layer chromatography (TLC) for compound-specific stable carbon isotope analysis of polycyclic aromatic hydrocarbons (PAHs) with four to seven rings was developed in this study. Five aerosol samples were used as test samples. Two stationary phases and eight developing systems were tested. The results indicated: (1) silica gel is superior to aluminum oxide and the silica gel precoated plate developed with hexane:chloroform (45:5, v/v) can give the best separation effect; (2) individual PAHs associated with aerosols can be effectively separated from unresolved complex mixture (UCM) by this procedure. The carbon isotope composition of PAHs can be measured with a standard deviation (S.D.)<0.5 per thousand, n=4. No significant isotopic fractionation was observed during the TLC procedure. And this technique can be used as a potential tool for source identification of PAHs in the aerosols.

Determination of tobacco smoking influence on volatile organic compounds constituent by indoor tobacco smoking simulation experiment

Tobacco smoking simulation experiment was conducted in a test room under different conditions such as cigarette brands, smoking number, and post-smoke decay in forced ventilation or in closed indoor environments. Thirty-seven chemical species were targeted and monitored, including volatile organic compounds (VOCs) and environmental tobacco smoke (ETS) markers. The results indicate that benzene, d-limonene, styrene, m-ethyltoluene and 1,2,4/1,3,5-trimethylbenzene are correlated well with ETS markers, but toluene, xylene, and ethylbenzene are not evidently correlated with ETS markers because there are some potential indoor sources of these compounds. 2,5-dimethylfuran is considered to be a better ETS marker due to the relative stability in different cigarette brands and a good relationship with other ETS markers. The VOCs concentrations emitted by tobacco smoking were linearly associated with the number of cigarettes consumed, and different behaviors were observed in closed indoor environment, of which ETS markers, d-limonene, styrene, trimethylbenzene, etc. decayed fast, whereas benzene, toluene, xylene, ethylbenzene, etc. decayed slowly and even increased in primary periods of the decay; hence ETS exposure in closed environments is believed to be more dangerous. VOCs concentrations and the relative percentage constituent of ETS markers of different brand cigarettes emissions vary largely, but the relative percentage constituent of ETS markers for the same brand cigarette emissions is similar.

Increase in polycyclic aromatic hydrocarbon (PAH) emissions due to briquetting: A challenge to the coal briquetting policy

Both China and UNEP recommend replacing raw coal chunks with coal briquettes in household sector as clean coal technology (CCT), which has been confirmed by the decreased emissions of particulate matter and black carbon. However, the clean effect has never been systematically checked by other pollutants like polycyclic aromatic hydrocarbons (PAHs). In this study, 5 coals with different geological maturities were processed as both chunks and briquettes and burned in 3 typical coal stoves for the measurement of emission factors (EFs) of particle-bound PAHs. It was found that the EFs of 16 parent PAHs, 26 nitrated PAHs, 6 oxygenated PAHs, and 8 alkylated PAHs for coal briquettes were 6.90 ± 7.89, 0.04 ± 0.03, 0.65 ± 0.40, and 72.78 ± 18.23 mg/kg, respectively, which were approximately 3.1, 3.7, 1.9, and 171 times those for coal chunks, respectively. Such significant increases in PAH emissions increased human health risk and challenged the policy of CCT.

Source and mixing state of iron-containing particles in Shanghai by individual particle analysis.

Bioavailable iron (Fe) is an essential nutrient that can control oceanic productivity, thereby impacting the global carbon budget and climate. Therefore it is of vital importance to identify chemical species and mixing state of Fe-containing particles in the air, which are demonstrated to pose substantial impact on bioavailability of Fe. Using a single particle aerosol mass spectrometer (SPAMS), ~2,000,000 individual particles with mass spectra were collected in Shanghai for nearly 22d during the winter of 2011. Number fraction of Fe-containing particles (NfFe) varied in a wide range (<1-15%) throughout the measurement. Fe-containing particles were mainly clustered into four chemical groups, comprising of Fe-rich, K-rich, Dust and V-containing particle types. Analysis of mass spectra and mixing state suggests that Fe-containing particles correspond to various sources in Shanghai, especially anthropogenic sources iron/steel industrial activities, and fly ashes from both biomass burning and coal combustion, accounting for ~55% and ~18%, respectively. However, invasion of dust from northern desert areas is suspected to be more responsible for the spikes of NfFe (>10%), when Dust particle type contributed to >50% of Fe-containing particles. It is also revealed that Fe-containing particles were internally mixed with secondary species (e.g., sulfate and nitrate). Anthropogenic K-rich and Fe-rich particles tended to associate with both sulfate and nitrate, and thus might lead to more fraction of soluble Fe, compared to Dust particles. These results imply that atmospheric processing of Fe-containing particles from various sources might vary and thus would change the bioavailability of atmospheric Fe.

Chemical composition, diurnal variation and sources of PM2.5 at two industrial sites of South China

Abstract Diurnal PM 2.5 samples were collected during summer and winter at an industrial complex site (site A) and an electronic waste (e–waste) recycling site (site B) in Qingyuan, South China. The concentration of organic carbon (OC), elemental carbon (EC), water soluble ions (WSI) and elements were investigated for their seasonal and diurnal variations. Organic matter (OM) was the most abundant specie in winter, accounting for 40.2% and 48.8% of PM 2.5 in sites A and B, respectively; while in summer, excluding the elemental portion, WSI was the biggest part, which accounted for 37% and 49.4% of PM 2.5 mass in sites A and B, respectively. Significantly higher concentrations were observed for most of the analyzed chemical species in winter. Average acidity of PM 2.5 at both sites was significantly higher in summer. Diurnal variation with elevated concentrations of PM 2.5 in nighttime samples was found at site B. Secondary inorganic aerosols (NH 4 + , NO 3 − and SO 4 2− ) exhibited clear day–to–night variation. Concentration of SO 4 2− was about 15% higher in daytime samples. NH 4 + and NO 3 − co–varied in winter, but were weakly associated with each other in summer. Sites A and B samples were almost all ammonium–rich in winter, whereas the summer samples were ammonium–poor during the daytime but ammonium–rich in the night. Positive matrix factorization (PMF) model analysis showed that secondary formation, biomass burning, regional industries, coal combustion and dust had significant contribution to PM 2.5 . Among them, secondary formation and biomass burning together contributed approximately 50% of PM 2.5 mass at both sites. Additionally e–waste recycling activities resulted in high pollution of Cu at Site B.

Changes in visibility with PM2.5 composition and relative humidity at a background site in the Pearl River Delta region.

In fall-winter, 2007-2013, visibility and light scattering coefficients (bsp) were measured along with PM2.5 mass concentrations and chemical compositions at a background site in the Pearl River Delta (PRD) region. The daily average visibility increased significantly (p<0.01) at a rate of 1.1 km/year, yet its median stabilized at ~13 km. No haze days occurred when the 24-hr mean PM2.5 mass concentration was below 75 μg/m(3). By multiple linear regression on the chemical budget of particle scattering coefficient (bsp), we obtained site-specific mass scattering efficiency (MSE) values of 6.5 ± 0.2, 2.6 ± 0.3, 2.4 ± 0.7 and 7.3 ± 1.2m(2)/g, respectively, for organic matter (OM), ammonium sulfate (AS), ammonium nitrate (AN) and sea salt (SS). The reconstructed light extinction coefficient (bext) based on the Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithm with our site-specific MSE revealed that OM, AS, AN, SS and light-absorbing carbon (LAC) on average contributed 45.9% ± 1.6%, 25.6% ± 1.2%, 12.0% ± 0.7%, 11.2% ± 0.9% and 5.4% ± 0.3% to light extinction, respectively. Averaged bext displayed a significant reduction rate of 14.1/Mm·year (p<0.05); this rate would be 82% higher if it were not counteracted by increasing relative humidity (RH) and hygroscopic growth factor (f(RH)) at rates of 2.5% and 0.16/year(-1) (p<0.01), respectively, during the fall-winter, 2007-2013. This growth of RH and f(RH) partly offsets the positive effects of lowered AS in improving visibility, and aggravated the negative effects of increasing AN to impair visibility.

Variations and Origins of Aliphatic Hydrocarbons in Sediment Cores from Chini Lake in Peninsular Malaysia

Over the past decade, Chini Lake has experienced tremendous changes due to land conversions from forest to agriculture such as oil palm and rubber plantations and also construction of a small barrage downstream of the Chini River. This land conversion has caused changes to the plant community and increased sedimentation rates in the lake. Consequently, this study was carried out to investigate the distribution patterns and sources of n-alkanes in four sediment core samples from Chini Lake and to evaluate the relative changes in organic matter inputs from land and lake flora. In the long-chain n-alkanes (LHC > C23)region, carbon preference index (CPI) values ranged from 1–1.52 in the sediment cores. Most lake sediments analyzed did not contain an unresolved complex mixture (UCM). The average nC17/pristane ratios (nC17/Pr) were 5.34 ± 1.99 and the average nC18/phytane (nC18/Ph) ratios were 1.27 ± 0.25 for the sediment profiles. The n-alkane average chain length (ACL) was 29.68 ± 0.15in the study area. There was significant positive correlation between ACL and CPI in the sediment cores at station B (r = 0.769, p = 0.003), station C (r = 0.735, p = 0.015), station D (r = 0.737, p = 0.006), and station E (r = 0.741, p = 0.006). Positive correlations between diploptene and long-chain n-alkanes (nC25−nC33) were found for sediment core B (r = 0.976, p<0.001), sediment core C (r = 0.836, p = 0.003), sediment core D (r = 0.824, p = 0.001) and sediment core E (r = 0.865, p < 0.001). Terrigenious to aquatic ratio for hydrocarbons (TARHC) and total n-alkanes (∑HC) concentrations increased with depth a pattern that contrast with short chain n-alkanes/total organic carbon (SHC/TOC) ratios. It can be concluded that the petrogenic hydrocarbon contamination in the sediment cores is minimal and that the n-alkanes preserved in Chini Lake sediments are influenced by higher plant waxes and bacteria.