Characterization Of Local Emission Sources And Regional Transport Of Fine Particulate Matter In A City

Hazy days, which is characterized as deterioration of visibility due to high concentrations of fine particulate matter(PM2.5), is one of the most prominent regional atmospheric issues. High concentrations of fine particulate matter in the atmosphere inevitably damage public health, boost the frequency of acid precipitation and even change the global climate. Formation of fine particulate matter is complex since primary emission source and secondary sources are involved. Therefor, researching on the sources of fine particulate matter pollution and clearly indentifying local emission sources and regional transport are of great scientific value in development of effective air quality management strategy and improvement of regional air quality.In this study, a methodological framework for source apportionment of PM2.5 was established which associated with emission inventory developing, model system assessing and development of particulate matter source apportionment technology(PSAT). Meanwhile, a city in PRD was carried out as a case to investigating the characteristics of anthropogentic emission, contributions from regional transport and different local emission sources to ambient PM2.5 and its precursors by developing emission inventory and WRF/SMOKE-PRD/CAMX modeling system combined with PSAT.Based on the framework, a 2012-based emission inventory with the horizontal resolution of 1km * 1km was developed for the case city by using appropriate emission estimation method. The total emissions of SO2, NOX, CO, PM10, PM2.5, VOCs and NH3 for case city were 17.7kt, 40.5kt, 585.0kt, 53.1kt, 21.7kt, 40.1kt and 52.0kt, respectively. Results showed that stationary combustion source was the largest contributor to SO2, NOX and CO, while fugitive dust and industrial process source were the largest contributors for PM10 and PM2.5 emissions, respectively. VOCs emission was dominated by on-road mobile source and industrial process source, while NH3 mainly derived from livestock feeding and N-fertilizer application source. Spatial distributions showed that NH3 emissions mainly distributed in mountainous areas while emissions of other pollutants were concentrated in economically developed areas wherer there were dense populations, heavy traffic flows and intensive road networks.Meanwhile, modeling studies were conducted to quantify the contribution of regional transport and local emission sources to atmopherical PM2.5 of case city in November 2013 with the aid of the modeling system(WRF/SMOKE-PRD/CAMX-PSAT). Results showed that PM2.5 concentratoin initiated by local emissions accounted for 56% of the totol ambient PM2.5 in case city. Among the local emission sources, industry process source, stationary combustion source, farming activities and fugitive dust were the most important contributors. In terms of SO2, NOX and PM10, the contribution of local emissions was approximately 77%, 81% and 60%, respectively, mainly originated from stationary combustion source. Besides, contribution from industry process source and fugitive dust to PM10 could not be negligible.Finally, to reduce PM2.5 in case city, control of local emission sources including industry process source, stationary combustion source and farming activities should be priorly taken into consideration based on the results of emission inventory and PSAT modeling system. In the meantime, considering the impact of the regional transport, joint efforts should be taken to prevent regional air pollution and protect regional air quality.