The underappreciated role of fugitive VOCs in ozone formation and health risk assessment emitted from seven typical industries in China

Fugitive emission from industrial sources may result in ozone formation and health risk, while the exact contribution of this source remains incompletely understood. In this study, emission characteristics, ozone formation potential (OFP) and health risk of fugitive VOCs in 7 representative industries were investigated. Chemical material industry was the dominant contributor to VOCs of fugitive emission in comparison with other industries. The OFP of VOCs from fugitive emission was in the range of 1.45 × 103-3.98 × 105 µg/m3, with a higher value than that of organized emission in seven industries except for the coking industry and the chemical material industry, suggesting that fugitive VOCs should be taken into account while developing control strategies. Acetaldehyde, m,p-xylene, n-nonane, ethylene, vinyl chloridethe and other high OFP-contributing species were the major reactive species that should be targeted. Health risk assessment investigated non-cancer and cancer risks of fugitive VOCs in 7 industries were all above safe level (HR > 1 and LCR > 1 × 10-4), posing remarkable health threats to human health. OVOCs were the main contributor to non-cancer risk, while halohydrocarbons and aromatics contributed most to cancer risks, posing remarkable health threat on human health. Our findings highlighted the contribution of fugitive VOCs on ozone formation and health risk was underestimated, indicating which should be considered in emission control strategies of industrial sources.

Influence of atmospheric conditions on sulfuric acid-dimethylamine-ammonia-based new particle formation

A recent quantitative measurement of rates of new particle formation (NPF) in urban Shanghai showed that the high rates of NPF can be largely attributed to the sulfuric acid (SA)-dimethylamine (DMA) nucleation due to relatively high DMA concentration in urban atmosphere (Yao et al., Science. 2018, 361, 278). In certain atmospheric conditions, the release of DMA is accompanied with the emission of high concentration of ammonia. As a result, the ammonia (A) may participate in SA-DMA-based NPF. However, the main sources of DMA and A can be different, thereby leading to different mechanism for the SA-DMA-A-based nucleation under different atmospheric conditions. Near industrial sources with relatively high DMA concentration of 10⁸ molecules cm^-3, the contribution of binary SA-DMA nucleation to cluster formation is 61% at 278 K, representing a dominant pathway for NPF. However, in the region not too close to major source of DMA emission, e.g., near agriculture farmland, the routes involving ternary SA-DMA-A nucleation make a 64% contribution at 278 K with DMA concentration of 10⁷ molecules cm^-3, showing that A has marked impact on the cluster formation. Under such a condition, we predict that coexisting DMA and A could be detected in the process of NPF. Moreover, at winter temperatures or at higher altitudes, our calculations suggest that the clustering of initial clusters likely involve ternary SA-DMA-A clusters rather than binary SA-DMA clusters. These new insights may be helpful to analyze and predict atmospheric-condition-dependent NFP in either urban or rural regions and/or in different season of the year.

Fine particles sampled at an urban background site and an industrialized coastal site in Northern France - Part 1: Seasonal variations and chemical characterization

The chemical composition of particulate matter sampled at two French Northern sites (Douai, DO - urban background; Grande-Synthe, GS - industrialized coastal site) was investigated during two summer and winter field campaigns at each site. Measurements of the major chemical species (organic, sulfate, nitrate, ammonium, chloride) in the non-refractory submicron aerosols (NR-PM₁) were carried out by a High Resolution Time-of-Flight Aerosol Mass Spectrometer. Black Carbon in PM_2.5 was monitored using an Aethalometer, while the OC and EC fractions and some targeted chemical organic families (polycyclic aromatic hydrocarbons, PAHs; dicarboxylic acids, DCAs) were quantified by the simultaneous collection of PM_2.5 on filters followed by offline analyses. The seasonal trends and winter-to-summer (W/S) concentration ratios are discussed in this paper. Results indicate that the total average mass concentrations of PM_2.5 varied between 20.5μgm^-3 and 32.6μgm^-3 in DO and between 10.6μgm^-3 and 29.9μgm^-3 in GS during summer and winter, respectively. Similar concentration patterns were found for PAHs and Organic Carbon (OC, representing ~80% of the total carbon) with highest concentrations in winter at the urban site. DCA concentrations showed less seasonal variations, although the highest value also appeared during winter. Total NR-PM₁ presented concentrations in summer lower by a factor of 4 (for DO) and 10 (for GS) than those observed in winter. Organics and nitrates dominated the NR-PM₁ in DO for both seasons and during winter in GS while sulfates and nitrates were the most dominant species in summer in GS. Average chloride concentrations were slightly more important in GS than those in DO related to its use in industrial processes and no significant seasonal trend was observed. The size-resolved chemical composition showed that aerosols sampled in DO in winter are more aged than those collected in GS where fresh emissions of sulfate from the industrial sector were observed.

Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model

China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China.