Assessment of Co-benefits of vehicle emission reduction measures for 2015–2020 in the Pearl River Delta region, China

Signal enhancement technology (sub-pixel interpolation) is used to obtain SO2 column concentrations for Guangdong Province in China from 2005 to 2016. The high resolution (2 km × 2 km) data used was obtained via a remote sensing satellite (Ozone Monitoring Instrument) and verified by comparing it with average annual SO2 data recorded in ground monitoring stations. The correlation was found to be up to 0.95. Moreover, the data was cross-correlated with national and regional inventories of pollution sources. The results show that the regional characteristics of the spatial distribution obtained are consistent and the detailed characteristics are highly coincidental. Based on this, the new and detailed spatiotemporal variation was analyzed and the effect of emission reduction in urban agglomerations on the SO2 concentration in the Pearl River Delta (PRD) region of China investigated. The results demonstrate that the distribution of SO2 pollution in the PRD has been transformed over the period studied. In the early stages, it had a traditional high-concentration type of distribution (with agglomeration areas like Guangzhou and Foshan as high-concentration pollution centers) and this has changed to the currently-observed low-concentration decentralized type of distribution (mainly distributed along administrative boundaries). In the last 10 years, significant SO2 emission reduction has occurred in prefecture-level cities, e.g., Foshan, Zhongshan, and Guangzhou (with emission-reduction amplitudes of 71%, 65%, and 57%, respectively). Foshan and Zhongshan are the top two prefecture-level cities in the PRD region in terms of significant reduction in rate of SO2 contribution. The SO2 contribution rate fell from 17% to 13% in Foshan and from 16% to 10% in Zhongshan. However, the relative contribution rates in Zhaoqing and Huizhou increased from 7% to 11% and from 6% to 10%, respectively. The size of the emission reduction and changes in SO2 contribution rates in the prefecture-level cities in the PRD region show that the government’s efforts to improve air quality have had a significant effect.

CO2 synergistic emission reduction and health benefits of PM2.5 reaching WHO-III level in Pearl River Delta

Reduction measures for air pollutants and greenhouse gas in the transportation sector: A cost-benefit analysis

Contribution of anthropogenic emission changes to the evolution of PM2.5 concentrations and composition in the Pearl River Delta during the period of 2006–2020

Modeling study of ozone source apportionment over the Pearl River Delta in 2015

The characteristics of hourly wind field and its impacts on air quality in the Pearl River Delta region during 2013–2017

Insights into the source-specific health risk of ambient particle-bound metals in the Pearl River Delta region, China

Effects of Southeast Asia biomass burning on aerosols and ozone concentrations over the Pearl River Delta (PRD) region

Application of air parcel residence time analysis for air pollution prevention and control policy in the Pearl River Delta region

Modulation of synoptic circulation to dry season PM2.5 pollution over the Pearl River Delta region: An investigation based on self-organizing maps

The variation in the urban spatial structure (USS) has profound impacts on carbon emissions. Studying the relationship between the two can provide guidance for carbon neutrality strategies and the construction of low-carbon cities in China. However, there is currently a lack of comparative research on the different regions within a province. In this paper, the spatiotemporal evolution of the USS and carbon emissions, at five-year intervals from 2000 to 2020, is investigated in 21 prefecture-level cities in Guangdong Province, China, and the overall relationship of the USS to carbon emissions and their spatiotemporal variations are analyzed by using a two-way fixed-effects model and a geographically and temporally weighted regression model, respectively. The results show that, first, over the past twenty years, the scale of cities has continued to expand, with increasing continuity and aggregation in the built-up areas, while the complexity and fragmentation of their shapes have gradually decreased. Second, the gap in carbon emissions between the Pearl River Delta and other regions in Guangdong shows a trend of first decreasing and then increasing, with high values concentrated in the Pearl River Delta region and the city of Shantou in the east. Third, compared to socio-economic factors, the USS has a more direct and pronounced impact on carbon emissions. Urban expansion and the increased complexity of land patches promote carbon emissions, whereas improving urban spatial continuity and compactness can reduce carbon emissions. Fourth, the dominant spatial structure indicators of carbon emissions differ among the regions of eastern, western, and northern Guangdong and the Pearl River Delta. This study proposes spatial optimization strategies for the low-carbon development of cities in Guangdong Province, providing a new perspective for integrating urban layout and emission reduction policies.

Abstract. Vehicle emissions are a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce vehicle emissions. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emissions in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicle emissions, the emission factors of PM2.5 mass, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSII), metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang tunnel of Guangzhou, in the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC and WSOC were 92.4, 16.7, 16.4 and 1.31 mg vehicle−1 km−1 respectively. Emission factors of WSII were 0.016 (F-) ~ 4.17 (Cl−) mg vehicle−1 km−1, contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle−1 km−1. Emission factors of organic compounds including n-alkanes, polycyclic aromatic hydrocarbons, hopanes and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle−1 km−1, respectively. Stable carbon isotopic composition δ13C value was −25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared to a previous study in Zhujiang tunnel in 2004, emission factors of PM2.5mass, EC, OC, WSII except Cl- and organic compounds decreased by 16.0 ~ 93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle conditions. There are no mandatory national standards to limit metal content from vehicle emissions, which should be a concern of the government. A snapshot of the 2013 characteristic emissions of PM2.5 and its constituents from the on-road vehicular fleet in the PRD region retrieved from our study would be helpful for the assessment of past and future implementations of vehicle emission control policy.

Despite a downward trend in pollutant levels because of a series of emission control policies, the Pearl River Delta (PRD) region continues to suffer from a high number of fine particulate matter (PM2.5) events and the resultant public health impacts. To effectively control PM2.5 in the region, a comprehensive understanding of source contribution and PM2.5 responses to various emission species is critical. We applied the Community Multiscale Air Quality Modeling System together with the high-order decoupled direct method, to simulate air quality and PM2.5 sensitivity and examined PM2.5 responses to emission species in the PRD region in the four seasons of 2010. We employed a concentration-response function to quantify the resultant number of premature mortalities attributable to outdoor PM2.5. We estimated that local and transboundary air pollution (TAP) contributed 27% and 73%, respectively, of the region’s PM2.5. In absolute terms, the largest impacts from local and TAP occurred in winter. With respect to relative contributions among the different sources, regional TAP (between cities in the region) (R-TAP) and local contributions had the largest effect in summer, whereas superregional TAP (from outside of the region) contributed the most in fall and winter. Outdoor PM2.5 pollution caused 20 160 (95% confidence interval: 5100–39 310) premature mortalities every year in the PRD region. Averaging among cities, 50%, 20%, and 30% of these deaths were attributable to S-TAP, R-TAP, and local contributions, respectively. Precursor gas emissions (i.e. NH3, volatile organic compounds, SO2, and NOx) affect PM2.5 level in a nonlinear manner; thus, individual pollutant control strategies are less effective for improving PM2.5 pollution than an integrated strategy. On the basis of our findings, we recommend that controls for multiple emission species should be implemented to control PM2.5 pollution in the region.

This study focuses on the influences of a warm high-pressure meteorological system on aerosol pollutants, employing the simulations by the Models-3/CMAQ system and the observations collected during October 10–12, 2004, over the Pearl River Delta (PRD) region. The results show that the spatial distributions of air pollutants are generally circular near Guangzhou and Foshan, which are cities with high emissions rates. The primary pollutant is particulate matter (PM) over the PRD. MM5 shows reasonable performance for major meteorological variables (i.e., temperature, relative humidity, wind direction) with normalized mean biases (NMB) of 4.5–38.8% and for their time series. CMAQ can capture one peak of all air pollutant concentrations on October 11, but misses other peaks. The CMAQ model systematically underpredicts the mass concentrations of all air pollutants. Compared with chemical observations, SO2 and O3 are predicted well with a correlation coefficient of 0.70 and 0.65. PM2.5 and NO are significantly underpredicted with an NMB of 43% and 90%, respectively. The process analysis results show that the emission, dry deposition, horizontal transport, and vertical transport are four main processes affecting air pollutants. The contributions of each physical process are different for the various pollutants. The most important process for PM10 is dry deposition, and for NOx it is transport. The contributions of horizontal and vertical transport processes vary during the period, but these two processes mostly contribute to the removal of air pollutants at Guangzhou city, whose emissions are high. For this high-pressure case, the contributions of the various processes show high correlations in cities with the similar geographical attributes. According to the statistical results, cities in the PRD region are divided into four groups with different features. The contributions from local and nonlocal emission sources are discussed in different groups.Implications: The characteristics of aerosol pollution episodes are intensively studied in this work using the high-resolution modeling system MM5/SMOKE/CMAQ, with special efforts on examining the contributions of different physical and chemical processes to air concentrations for each city over the PRD region by a process analysis method, so as to provide a scientific basis for understanding the formation mechanism of regional aerosol pollution under the high-pressure system over PRD.

Spatio-seasonal characterization and emissions estimation of ozone-depleting substances in the Pearl River Delta, China