Based on anthropogenic source activity data and emission factors for the Sichuan Province, the 1 km×1 km-gridded atmospheric air pollutant emission inventory of 2015 was developed in combination with GIS technology and the combined "bottom-up" and "top-down" construction method. The results show that the total emission of SO2, NOx, CO, PM10, PM2.5, BC, OC, VOCs, and NH3 in Chengdu is 444.9×103, 820.0×103, 3773.1×103, 1371.6×103, 537.5×103, 28.7×103, 53.1×103, 923.6×103, and 988.0×103 t, respectively. Power plants and other industrial combustion boilers contribute more than 95% of the SO2 emissions. Mobile, fossil fuel combustion, and industrial process sources contribute 54%, 23%, and 20% of the NOx emissions, respectively. The industrial process of steel production and building materials manufacturing contribute 20% PM10 of the emissions and take up 34% PM2.5 of the emissions. Fugitive dust and road fugitive dust contributes 60% PM10 and 35% PM2.5 of the emissions, respectively. Biomass combustion contributes 33% BC and 51% OC of the emissions, respectively. The solvent use of mechanical processing, building decoration, electronic equipment manufacturing, and printing and furniture industry contribute 46% of the VOCs of the emissions. The NH3 emissions mainly orginate from the sources of livestock feeding and nitrogen fertilizers, accounting for 70% and 25% of the NH3 emissions, respectively. The spatial distribution of the emissions shows that high emissions are mainly distributed in the most densely populated, agricultural, and industrial more developed areas in Panzhihua and the Sichuan Basin. The urban agglomerations of the Chengdu Plain, represented by Chengdu, Deyang, and Mianyang, are the areas with emission concentration in the Sichuan Basin. The emissions inventory in this study has uncertainties. More fundamental studies on activity data should be conducted and the emission factors of typical emission sources should be further localized to improve the emission inventory and prevention and control of complex air pollution in the Sichuan Province and provide scientific support.
Abstract This study improved the computation theory “Ozone Weekend Effect Method” (OWEM) and analyzed the 2016 observation data from the state-controlled ambient air quality monitoring sites in Chengdu using the OWEM theory. The improved OWEM theory is then applied to processing large sample data and making a judgment on photochemical reaction sensitivity in Chengdu. The result of applying the OWEM theory to Chengdu shows 1) that the VOCs-limited period, the NOx-limited period and the photochemical reaction steady-state period, R t , accounted for 66.06%, 33.64% and 0.30%, respectively; 2) that on a seasonal basis, i.e. in the ozone photochemical reaction occurring in spring, summer, autumn and winter 2016 in Chengdu, the VOCs-limited period accounted for 59.40%, 72.49%, 63.85% and 68.49% of the 2016 observed data, respectively, and the NOx-limited period accounted for 39.70%, 27.51%, 36.15% and 31.19%respectively; 3) that in the VOCs-limited period and the NOx-limited period of August 2016, the month when the most serious ozone pollution of that year occurred in Chengdu, R t accounted for 70.0% and 30.0%, respectively, and that there was no photochemical reaction steady-state zone period that month; 4) and that through estimation, it is suggested that as for the ozone pollution control of Chengdu, the ratio of VOCs emission reduction to NOx emission reduction should be around 3:1.
The volatile organic compound (VOC) emission characteristics of various production procedures were analyzed through GC-MS after the emissions of typical enterprises such as automobile manufacturing, petrochemical, and other industries had been sampled with SUMMA canisters. Each production procedure in the automobile manufacturing and petrochemical industries was considered. The results showed that each automobile manufacturing procedure had its own dominant species, and alkanes (32%) and aromatics (35%) were the main emission species of coating spraying. The emission characteristics of furniture manufacturing were highly correlated with the raw materials, and the VOC emission species were mainly composed of aromatics (50%) and oxygenated VOCs (OVOCs) (38%). As for the petrochemical industry, VOC concentrations in various process plant areas ranged from 49 μg·m-3 to 1387 μg·m-3. As the main products of the refining area were C5-C9 gasoline and benzene series, whereas comparatively more solvents were used in the chemical area, which would generate alkene products, VOC concentrations greatly differed in the various process plant areas. In terms of electronic manufacturing, OVOCs were the main emission species, accounting for more than 50% of total VOCs. Alkanes and OVOCs were the main contributors to VOC emissions in shoemaking, accounting for 52% and 36% on average, respectively, which was strongly related to the species of the used solvents. The VOC emission species of automobile manufacturing were quite different, predominantly including n-dodecane and 2-butanone. The emission species of furniture manufacturing mainly included styrene, ethyl acetate, m/p-xylene, etc., which are typical species of coatings and diluents. As for the differences in the emission species of process plant areas in the petrochemical industry, styrene was the main species in the refining area, 1,3-butadiene in the chemical area, C3-C5 alkanes in the storage area, and C6-C8 alkanes in the wastewater treatment area. The main emission species of electronic manufacturing were ethanol, acetone, and other aldehyde ketone species. The emission species of shoemaking enterprises are mainly C5 and C6 alkanes. According to the results of ozone formation potential (OFP), alkenes and aromatics were the main VOC emission species that contribute significantly to the OFP in the automobile manufacturing and petrochemical industries, with relatively high pollution source reaction activity. The results showed that the emission ratio (17%-96%) and OFP contributions of OVOCs were significant in various industries. Therefore, for VOC emission control, in addition to focusing on the control of aromatics and alkenes, attention should also be paid to OVOCs.
The characteristics of volatile organic compound (VOCs) species from various production procedures of wood-based panel production and other industrial processes in Chengdu were analyzed through gas chromatography-mass spectrometry (GC-MS) and other methods specified in national standards after the emissions of typical enterprises of wood-based panel production, pharmaceutical manufacturing, chemical production and other industrial processes in Chengdu had been sampled using sampling bottles and SUMMA canisters. Generally, the process of wood-based panel production includes glue making, glue mixing, sorting, and hot pressing, whereas the process of pharmaceutical manufacturing includes workshop production and wastewater treatment. The results showed that the main contribution species of VOCs in wood-based panel production and pharmaceutical manufacturing is oxygenated VOCs (OVOCs), accounting for more than 50% of the total VOCs emitted. The species from organized and unorganized emissions of formaldehyde manufacturing differed significantly. The main species of organized emissions was OVOCs, and that of unorganized emissions was halohydrocarbons. Emissions of VOCs from coating manufacturing were strongly correlated with the raw materials, and the corresponding emission species were composed mainly of aromatics and OVOCs. Except for glue mixing, the main species of VOCs in other process procedures of wood-based panel production was formaldehyde, with emission proportion of more than 50%. The primary species of VOCs in various processes of pharmaceutical manufacturing was ethanol; however 1,4-dioxane, ethyl acetate, and toluene were also important species. Moreover, the main VOCs from formaldehyde manufacturing were composed mainly of acetone and ethanol, and those of coating manufacturing were aromatic hydrocarbons such as p-xylene. The ozone formation potential was to characterize the reactivity of pollution sources in VOCs from wood-based panel production, pharmaceutical manufacturing, and chemical production. The results showed that the species of VOCs in different industries contributed similarly to the reactivity and that these species were mainly high-activity species such as formaldehyde, ethanol, and other OVOCs as well as some aromatic hydrocarbons. Therefore, supervision and regulation of enterprises of industrial processes is required with a focus on species with relatively large ozone formation potential. In addition, it is necessary to analyze the emission characteristics and chemical mechanism of various industries and to control O3 generation from the sources.
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