No abstract

No abstract

Abstract. Beijing has suffered from heavy local emissions as well as regional transport of air pollutants, resulting in severe atmospheric fine-particle (PM2.5) pollution. This study developed a combined method to investigate source types of PM2.5 and its source regions during winter 2016 in Beijing, which include the receptor model (positive matrix factorization, PMF), footprint and an air quality model. The PMF model was performed with high-time-resolution measurements of trace elements, water soluble ions, organic carbon and elemental carbon using online instruments during the wintertime campaign of the Air Pollution and Human Health in a Chinese Megacity – Beijing (APHH-Beijing) program in 2016. Source types and their contributions estimated by PMF model using online measurements were linked with source regions identified by the footprint model, and the regional transport contribution was estimated by an air quality model (the Nested Air Quality Prediction Model System, NAQPMS) to analyze the specific sources and source regions during haze episodes. Our results show that secondary and biomass-burning sources were dominated by regional transport, while the coal combustion source increased with local contribution, suggesting that strict control strategies for local coal combustion in Beijing and a reduction of biomass-burning and gaseous precursor emissions in surrounding areas were essential to improve air quality in Beijing. The combination of PMF with footprint results revealed that secondary sources were mainly associated with southern footprints (53 %). The northern footprint was characterized by a high dust source contribution (11 %), while industrial sources increased with the eastern footprint (10 %). The results demonstrated the power of combining receptor model-based source apportionment with other models in understanding the formation of haze episodes and identifying specific sources from different source regions affecting air quality in Beijing.

Beijing, the capital of China, frequently suffers from the high levels of ozone in summer. A 3-D regional chemical transport model, the Comprehensive Air Quality Model with extensions (CAMx), has been used to simulate a heavy O 3 pollution episode in Beijing during June 26-July 2, 2000. Ozone Source Apportionment Technology (OSAT) and Geographic Ozone Assessment Technology (GOAT) were applied to quantify the contributions of the precursor emissions from different regions to O 3 concentrations in Beijing, to identify the relative importance of different ways by which regional sources affected the O 3 levels in Beijing urban areas, and to investigate the sensitivity of O 3 formation to the precursors during the episode. The O 3 pollution in Beijing showed a significant spatial distribution with strong regional contribution. The results suggested that the plume originating from Beijing urban areas greatly affected the O 3 concentrations at the Dingling site, accounting for 55% of elevated O 3 there, while O 3 pollution in the Beijing urban areas resulted from both local emissions and those from Tianjin and the south of Hebei Province. Transport of O 3 was responsible for about 70% of the regional O 3 contribution to Beijing urban areas, while transport of O 3 precursors accounted for the remainder. The formation of O 3 was limited by volatile organic compounds (VOCs) in the urban areas of Beijing, while being more sensitive to NO x levels in the suburban and more remote areas. Therefore, it is necessary to consider a large number of factors, including impacts of emissions from different regions, the two modes of regional contribution as well as the sensitivity of O 3 formation to precursors, in the design of emissions control strategies for O 3 reduction in Beijing.Beijing, ozone, source apportionment, emission

No abstract