Size distribution and chemical characteristics of particles from crop residue open burning in North China.

Crop residue open burning is an important emission source of ambient particles in China. This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China (corn, wheat, and rice). Particle samples size ranging from 0.006-9.890 µm were collected by an Electrical Low Pressure Impactor plus, a high size-resolution instrument capable of dividing particles into 14 size stages. The size distributions of organic carbon (OC), elemental carbon (EC), water-soluble ions, and elements were analyzed, and source chemical profiles were constructed for PM0.1, PM1, PM2.5, and PM10. The number concentration of particles was concentrated in the Aiken nuclei mode (0.006-0.054 µm), accounting for 75% of the total number, whereas the mass concentration was concentrated in the accumulation mode (0.054-0.949 µm), accounting for 85.43% of the mass loading. OC, EC, Cl-, and K(include total K and water-soluble K) were the major chemical components of the particles, whose mass percentage distributions differed from those of other components. These five main components exhibited a bell-shaped size distribution in the 0.006-9.890 µm range, whereas the other components exhibited a U-shaped distribution. Among the chemical profiles for PM0.1-PM10, OC was the most important component at 10-30%, followed by EC at 2%-8%. The proportions of K+, Cl-, and K varied substantially in different experimental groups, ranging from 0-15%, and K+ and Cl- were significantly correlated (r = 0.878, α = 0.000).

Comprehensive performance evaluation of coordinated development of industrial economy and its air pollution control.

Exploring coordinated pathways that can promote not only the sustainable development of the industrial economy but also air quality is of great significance for the prevention and control of air pollution in China. Currently, the joint development pathways of the industrial economy-environment nexus remain unclear and poorly evaluated. In this study, we proposed a comprehensive performance evaluation combining objective and subjective weighting to identify industrial enterprises' economic-environment nexus benefits. It would be one of the most important steps to explore the coordinated pathways. Based on data envelopment analysis (DEA), the proposed method integrated with the index integration was used to evaluate the comprehensive performances of 41 industrial sectors in China's 13th five-year plan (2016-2020). Evaluation results showed that the comprehensive performances of the economy-environment nexus of the industrial sectors varied significantly, with the five-year average comprehensive technical efficiency (TE) of 0.11-1. Overall, the best two performances were realized by the industries of equipment manufacturing and living consumption, whereas the worst one belonged to the industry of bulk raw materials, with average comprehensive TE values of 0.50, 0.43, and 0.19, respectively. The results of the quantitative evaluation were consistent with those of the qualitative analysis in terms of the developmental status of the industrial sectors. According to the analyses of pure technical efficiency and scale effect, the proposed method identified the industrial sectors with the highest developmental value and with the highest need to control air pollution. Compared with those of the original DEA model, the results of the proposed method showed pronounced differences in terms of the performances of industrial sectors with high energy consumption and high particulate matter (PM) emissions and with low energy consumption and low PM emissions. The proposed evaluation method combining the weighting was suitable for identifying the comprehensive performance of the industrial economy-environment nexus and provides the basis for the prevention and control of air pollution.

[Main Problems and Refined Solutions of Urban Fugitive Dust Pollution in China].

Fugitive dust poses an important contribution to urban air particulate matter in China. To further improve the level of dust pollution prevention and control, the emission and contribution characteristics of urban fugitive dust were summarized; the main causes of dust pollution were analyzed; and the key links, key indicators, and main measures for prevention and control were clarified, so as to further improve the concept of "accurate dust control." Among all types of fugitive dust sources, road dust and construction dust were the main emission and contribution sources, among which road dust was more prominent. Production activities, vehicle disturbances, and wind erosion were the main dust-generating links of various dust sources. Silt loading was taken as the key control index for road dust prevention and control, whereas silt loading and bare soil (or material) areas were taken as the key control index for construction and other dust sources. Around the key indicators, three main ways to control the road dust and six main measures to control the construction and other dust sources were defined. In addition, some suggestions on the necessary supporting measures for dust control were put forward, so as to provide a comprehensive and beneficial reference for the practical application of dust control in Chinese cities.

Optimized approach for developing soil fugitive dust emission inventory in "2+26" Chinese cities.

Based on the wind erosion equation and the use of moderate resolution imaging spectroradiometer (MODIS) satellite remote sensing data combined with parameter normalization processing, an optimized high spatial-temporal resolution soil fugitive dust (SFD) emission inventory compiling method was proposed in this study. The "2 + 26" cities in northern China, where heavy pollution frequently occurs, were used as a case study. Using the optimized method, we estimated that the PM50, PM10, and PM2.5 emissions from SFD of "2 + 26" cities in 2018 were 2,014,927, 1,007,463, and 151,120 tons, respectively. The dust emissions and emission factors of each city presented significant differences and were generally of a greater level in high-latitude areas (such as cities in Hebei Province) than in low-latitude areas (such as cities in Henan and Shandong Province). Moreover, with an increase in latitude, vegetation cover factors generally exhibit an upward trend, while temperature and rainfall exhibit a downward trend. The dust emissions in the different months showed significant differences. The total dust emission reached the highest level in "late winter-early spring" season (February to April), and the monthly emission accounted for 15-17% of the annual emissions. While in the "summer-autumn" season (July to November), it is the lowest level of the whole year, monthly emissions accounted for 3-5% of the annual emissions. The emission inventory method proposed in this study can provide a reference for dust emission assessment and further pollution prevention and control work.

Application and validation of the fugitive dust source emission inventory compilation method in Xiong'an New Area, China.

The development of a refined fugitive dust emission inventory is vital for prevention and control of air pollution. In this study, a fugitive dust emission inventory of soil dust (SD), road dust (RD), and construction dust (CD) in Xiong'an New Area (XANA) for 2020 was developed by collecting activity data and combining remote sensing and field investigation data based on a popular compilation technology in China. The CALPUFF model was used to elucidate the contribution characteristics of dust sources to ambient particulate matter (PM), and the accuracy of the dust emission inventory compilation method was verified. The results show that the total emissions of PM10 and PM2.5 were 43,081.14 tons and 9701.69 tons, respectively. Meanwhile, RD and CD were the main emission sources, accounting for over 98.49% of the total emissions. The total contribution from the different types of dust sources to the ambient PM10 was 42.59 µg/m3 (29.38%), with the contribution of RD (32.63 µg/m3, 22.51%) being approximately three times that of CD (9.78 µg/m3, 6.74%). Roads were the main source of fugitive dust, but large-scale infrastructure construction was the main cause of the high emission and high contribution of RD. The results show that the emission inventory compilation method can be used to estimate the emissions of dust sources, while the method used to calculate the emission of SD may be more suitable for dry and semi-dry areas with less rainfall. It was also found that when the dust emissions stay stable, the contribution of dust sources to the ambient PM10 in different seasons can vary by 3-4 times. Therefore, under adverse meteorological conditions, it is necessary to strengthen the control of various dust sources and reduce the influence of human factors on them.

[Emission Performance Quantitative Evaluation and Application of Industrial Air Pollution Sources].

Treatment of industrial atmospheric emission sources is an important way to improve air quality, but accurate pollution control remains still an urgent challenge. Taking Xiqing District of Tianjin as an example, based on the second national pollution source census, this study carried out a quantitative evaluation of the pollutant emission performance of industrial enterprises and explored the significance, feasibility, and challenges facing emission performance evaluation. The results show that the emission performance of various industries in Xiqing District vary greatly. The pollutant emission performance level is closely related to an industry's own attributes, development scale, and management level. On the whole, the emission performance level of industries with high production process emission coefficients and a high proportion of small and medium-sized enterprises (such as furniture manufacturing, the metal products industry, ferrous metal smelting, and the rolling processing industry) is worse, while the emission performance of high-end industries represented by computer communication and other electronic equipment manufacturing and automobile manufacturing is generally better. The emission performance of different enterprises in the same industry also varies greatly. For example, the 11 enterprises with the worst performance in the metal machinery manufacturing industry only contributed 0.06% of industrial output yet their PM emission contribution reached 8.50%. The 19 worst-performing enterprises in the rubber and plastic industry contributed 4.76% of industrial output yet their VOCs emissions accounted for 43.59% of the total. At the same time, this study presents an emissions reduction plan according to the relevant technical guidelines of the Ministry of Ecology and Environment. Based on this, the cost of emissions reduction could be cut by as much as 90% when the pollutant emissions reductions of the same scale are reduced. The gap in the pollutant emissions performance of various industries and enterprises, the incongruity between economic benefits and environmental costs, and the important guiding role of emission performance evaluation for emissions reductions demonstrate the necessity of performance evaluation. Overall, this research shows that pollutant emission performance evaluation can effectively support macro-industrial structure adjustment and the environmental governance of meso-micro industrial enterprises, providing an important reference for pollution control interventions.

Source apportionment and a novel approach of estimating regional contributions to ambient PM2.5 in Haikou, China.

A novel approach was developed to estimate regional contributions to ambient PM2.5 in Haikou, China. In this paper, the investigation was divided into two main steps. The first step: analysing the characteristics of the chemical compositions of ambient PM2.5, as well as the source profiles, and then conducting source apportionments by using the CMB and CMB-Iteration models. The second step: the development of estimation approaches for regional contributions in terms of local features of Haikou and the results of source apportionment, and estimating regional contributions to ambient PM2.5 in Haikou by this new approach. The results indicate that secondary sulphate, resuspended dust and vehicle exhaust were the major sources of ambient PM2.5 in Haikou, contributing 9.9-21.4%, 10.1-19.0% and 10.5-20.2%, respectively. Regional contributions to ambient PM2.5 in Haikou in spring, autumn and winter were 22.5%, 11.6% and 32.5%, respectively. The regional contribution in summer was assumed to be zero according to the better atmospheric quality and assumptions of this new estimation approach. The higher regional contribution in winter might be mainly attributable to the transport of polluted air originating in mainland China, especially from the north, where coal is burned for heating in winter.