Semivolatile Organic Compounds (SOCs) in Fine Particulate Matter (PM2.5) during Clear, Fog, and Haze Episodes in Winter in Beijing, China.

Few efforts have been made to elucidate the influence of weather conditions on the fate of semivolatile organic compounds (SOCs). Here, daily fine particulate matter (PM2.5) during clear, haze, and fog episodes collected in the winter in Beijing, China was analyzed for polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants (BFRs), and organophosphate flame retardants (OPFRs). The total concentrations of PAHs, OPFRs, and BFRs had medians of 45.1 ng/m3 and 1347 and 46.7 pg/m3, respectively. The temporal pattern for PAH concentrations was largely dependent on coal combustion for residential heating. OPFR compositions that change during colder period were related to enhanced indoor emissions due to heating. The mean concentrations of SOCs during haze and fog days were 2-10 times higher than those during clear days. We found that BFRs with lower octanol and air partition coefficients tended to increase during haze and fog episodes, be removed from PM2.5 during clear episodes, or both. For PAHs and OPFRs, pollutants that are more recalcitrant to degradation were prone to accumulate during haze and fog days. The potential source contribution function (PSCF) model indicated that southern and eastern cities were major source regions of SOCs at this site.

Assessment of exposure to polybrominated diphenyl ethers associated with consumption of market hens in Guangzhou.

To evaluate contamination by polybrominated diphenyl ethers (PBDEs) in market hens and human PBDE exposure via hen consumption in Guangzhou, hens were collected and their muscle, liver, fat, blood, yolk, and ingluvies tissues were analyzed for 13 PBDE congeners. The median highest concentration of ∑PBDEs was found in the ingluvies (5.30 ng/g lw), followed by the muscle (2.53 ng/g lw), with the lowest located in the yolk (0.09 ng/g lw). The concentrations of PBDEs in the muscle tissue of market hens in Guangzhou were at medium levels compared to others reported around the world. BDE-47, -153, -99, and -183 were the predominant congeners. The daily intake concentrations of PBDEs from hen muscle were estimated to range from 0.08 to 0.31 ng/kg/day in this study, with a Hazard Quotient (HQ) below 1.0. These results suggest that the health risk of PBDEs for the general population, through the consumption of market hens in Guangzhou, was generally low. However, the intake of PBDEs via food consumption may be one major exposure pathway for the general population of Guangzhou.

[Light Absorption Properties of Water-Soluble Organic Carbon (WSOC ) Associated with Particles in Autumn and Winter in the Urban Area of Guangzhou].

Light absorption properties of water-soluble organic carbon (WSOC) were investigated in the urban area of Guangzhou. The fine particulate matter (PM2.5) and size-segregated samples were collected in September and December of 2014 and January of 2015. The variation of absorption with wavelength of WSOC was characterized by the absorption Angström exponent (AAEabs). The AAE values of WSOC in PM2.5 were 3.72 ± 0.41 in autumn and 3.91 ± 0.70 in winter, which were lower than those in Beijing and north America. The mass absorption efficiency (MAE) of WSOC at 365 nm wavelength was 0.52 m² · g⁻¹ in autumn and 0.92 m² · g⁻¹ in winter, exhibiting distinct variations between autumn and winter. In winter, the MAEwsoc values exhibited a decreasing trend with increasing particle size, and all size-segregated MAE(WSOC) values in autumn were lower than those in winter, particularly for the particles < 0.95 µm, suggesting more contribution of the secondary formation to WSOC. Comparing the MAE values of elemental carbon (EC) and WSOC, it could be found that the contribution of WSOC to the light extinction of particles couldn't be ignored when the particles were mainly emitted from primary sources.

Development of a compound-specific carbon isotope analysis method for 2-methyltetrols, biomarkers for secondary organic aerosols from atmospheric isoprene.

The stable carbon isotope compositions of 2-methyltetrols, biomarker compounds for secondary organic aerosols formed from isoprene in the atmosphere, have been determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In this work, isoprene with various delta(13)C values was used to produce 2-methyltetrols via an oxidation reaction with hydrogen peroxide in sulfuric acid under direct sunlight. The target compounds with different stable carbon isotope compositions were then derivatized by methylboronic acid with a known delta(13)C value and measured by GC/C/IRMS. With delta(13)C values of 2-methyltetrols and methylboronic acid predetermined, isotopic fractionation is evaluated for the derivatization process. Through reduplicate delta(13)C measurements, the carbon isotope analysis achieved excellent reproducibility and high accuracy with an average error of <0.3 per thousand. The differences between the predicted and measured delta(13)C values range from -0.10 to 0.29 per thousand, indicating that the derivatization process does not introduce isotopic fractionation. The delta(13)C values of 2-methyltetrols could be calculated on the basis of the stoichiometric mass balance equation among 2-methyltetrols, methylboronic acid, and methylboronate derivatives. Preliminary tests of 2-methyltetrols in PM(2.5) aerosols at two forested sites were conducted and revealed significant differences in their isotope compositions, implying possible application of the method in helping us understand the primary emission, photochemical reaction, or removal processes of isoprene in the atmosphere.

[PBDEs pollution in the atmosphere of a typical E-waste dismantling region].

The vapor-phase and particulate-phase samples were collected from the E-waste dismantling region (E) and a reference region (S), which is located in the upwind direction of the E and where the costume industry is developed. The aim was to acquire information about the concentrations, gas/particle partitioning and distribution of polybrominated diphenyt ethers (PBDEs). 11 congeners PBDEs were detected with GC-NCI-MS. The results showed that E-waste dismantling has resulted in serious pollution and the PBDE concentrations (from tri-to deca-BDE) ranged from 51.1 pg x m(-3) to 2685 pg x m(-3) (mean:830 pg x m(-3)), while the PBDE concentrations (from tri-to deca-BDE) in S were in the range of 1.00 pg x m(-3) to 98.9 pg x m(-3) (mean: 28.7 pg x m(-3)). The gas/particle partitioning of PBDEs exhibited a strong dependence on bromine number. Low-brominated PBDEs tend to have a higher concentration in the gas-phase while highly brominated PBDEs are mostly associated with the particulate. The mass distribution of PBDEs in E (including vapor-phase and particulate-phase) was dominated by penta-BDE, accounting for 54.3% of the total PBDEs, followed by deca-BDE, accounting for 23.8%. This pollution characters validated that the E-waste did not only come from Asia, but also from North America and Europe.

[Physicochemistry and bioreactivity characterization of fine particles (PM(2.5)) in Shanghai air].

PM(2.5) was collected at Shanghai urban and suburban sites during spring and autumn. PIXE (Proton Induced X-ray Emission) was used to investigate mass concentration of 15 elements (S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Sr, Pb) in Shanghai PM(2.5). The total mass concentration of the 15 chemical elements was higher in spring (5 038.6 ng x m(-3)) than in summer (3 810.6 ng x m(-3)). In spring, mass concentrations of these elements in urban and suburban samples were in the same level. In summer, concentration of the elements in urban samples were lower than in suburban samples, however, the elements which were originated from anthropogenic resources were in higher level in urban samples. The results of FESEM showed that Shanghai PM(2.5) was consisted of soot aggregates, coal fly ashes, minerals, bio-particles and unidentified particles. The result of Plasmid DNA assay demonstrated bioreactivity of urban PM(2.5) was more reactive than that of suburban PM(2.5), this phenomenon probably was explained by higher mass level of heavy metals and more proportion of soot aggregates in urban PM(2.5).

[Stable carbon isotope analysis method for the atmospheric formaldehyde].

A method of compound-specific stable carbon isotopic analysis for the research about the sources of atmospheric formaldehyde was preliminary studied using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) via 2, 4-dinitrophenylhydrazine (DNPH) derivatization. In order to evaluate the reproducibility, the accuracy and the carbon isotope effects of the method, formaldehyde with different delta 13C values were used to simulate the sampling procedure. The results show that the maximal analytical deviation for all formaldehyde 2, 4-dinitrophenylhydrazone is 0.3 per thousand and the average deviations between the determined and theoretical delta 13C values of them are 0.24 per thousand +/- 0.14per thousand (ranged from 0.03 per thousand to 0.35 per thousand), less than 0.5 per thousand the technical specifications of the GC/C/IRMS system. These mean that no carbon isotopic fractionation occurred during the procedure. The study for the indoor and outdoor atmospheric formaldehyde in the restaurant show that the stable carbon isotopic compositions are significant different for different sources of formaldehyde. The present method could provide valuable information about the sources of atmospheric formaldehyde.

[Size distribution of polycyclic aromatic hydrocarbons (PAHs) in different function zones of Guangzhou in autumn, China].

Size distribution of aerosol samples collected from two urban locations (Liwan and Wushan) and a suburban location (Xinken) in Guangzhou (South China) in autumn using Micro-Orifice Uniform Deposit Impactor (MOUDI) were analyzed for 13 polycyclic aromatic hydrocarbons (PAHs) by gas chromatography with mass selective detection (GC-MS). Bimodal distribution was found for 3- and 4-ring PAHs and unimodal for 5-, 6- and 7-ring PAHs. Different PAH size distribution models were found for urban and suburban. PAHs associated with larger particles in suburban than in urban, and different aging processes of aerosols can account for it. Adsorption behavior may be the main mechanism controlled the size distribution of PAHs in urban, and adsorption, absorption and multilayer adsorption may all play a part in suburban. For the diagnostic ratios of PAHs with the same molecular weight, large differences were found between the range of 1-2.5 microm and 0.1-0.56 microm. The concentrations of 13 PAHs were 39 ng/m3 in Xinken, 71-94 ng/m3 in Wushan and 32-154 ng/m3 in Liwan, and 5-7 ring PAHs were the most abundant.

Concentration levels, compositional profiles, and gas-particle partitioning of polybrominated diphenyl ethers in the atmosphere of an urban city in South China.

Air samples were collected in June of 2004 from four sites in the city of Guangzhou, a typical urban center in South China, to determine the levels, compositional profiles, and gas-particle distribution of 11 polybrominated diphenyl ether (PBDE) congeners (BDE-28, -47, -66, -100, -99, -85, -154, -153, -138, -183, and -209). The arithmetic mean atmospheric concentrations of sigmaPBDEs (sum of all target PBDE congeners except for BDE-209) in samples from the urban and city background sites were comparable to or slightly higher than those from other places around the world. The arithmetic mean atmospheric concentrations of BDE-209, however, were higherthan those in North America and Europe, and similar to the values from Japan. Congener compositions were dominated by BDE-209 in all (>70%) but an industrial site, with an average abundance of 48% for BDE-209. The PBDE patterns were generally similar to that in the technical penta-BDE mixture, Bromkal 70-5DE. Partitioning of PBDEs between the gas and particle phases (Kp) was well correlated with the subcooled liquid vapor pressure (PLO) for all of the samples, but the relationship differed between samples from different sites. The measured fractions of PBDEs in the particulate phase were compared to the predictions from the Junge-Pankow adsorption and KOA-based absorption models. The results indicated that the KOA-based model worked better than the Junge-Pankow model that tended to overestimate the particulate fractions for most PBDE congeners.