Source Apportionment of Size-classified Particle Matter Collected by the National Air Surveillance Network in Japan
Abstract
Due to the adverse effects of fine particulate matter (PM2.5) for human health, monitoring studies have been widely conducted in many counties. In Japan, environmental standards for PM2.5 were established in 2009 (15 μg/m3 for annual average and 35 μg/m3 for daily average) and continuous monitoring has been carried out at 1,872 stations (as of 2017). For making policy to improve the serious pollution, source apportionment study by using receptor model is required.
In PMF (Positive Matrix Factorization) model, variations in the dataset (e.g. temporal, spatial, and particle size distributions) play an important role in extracting factors. Long term monitoring of chemical species in size-classified PM was conducted as the National Air Surveillance Network (NASN) in Japan and its results were published as annual reports. In this study, source apportionment was carried out by using PMF (EPA PMF 5.0) with the dataset by NASN. The dataset consists of 26 components in 5 particle size factions (D1: Dp <0.43 μm, D2: Dp = 0.43-0.65 μm, D3: Dp = 0.65-1.1 μm, D4: Dp = 1.1-2.1 μm, D5: Dp = 2.1-3.3 μm) collected at 8 sites (including 5 residential sites and 3 roadside sites) from 2002 to 2009. PMF model resolved an eight-factor solution. Each of these factors has a distinctive grouping of species that can be associated with specific source sectors as follows (F1: Secondary sulfate, F2: Sea salt, F3: Secondary nitrate, F4: Vehicle exhaust, F5: Industry, F6: Brake wear particle, F7: Soil, F8: Heavy oil combustion). Combustion related factors (F4 and F8) were largely apportioned in the D1 fraction. Contributions of secondary aerosols (F1 and F3) and industry (F5) were typically observed in D3 fraction. On the other hand, Natural aerosols (F2 and F7) and brake wear particle (F6) were mainly contributed in D5 fraction. Vehicle related factors (F4 and F6) showed reasonably high contributions in the results in roadside sites as compared to the residential sites. By focusing on the temporal variation, the contribution of F4 tended to decrease in the monitoring period, indicating that the tightening of regulations for vehicle exhaust was effective to improve the fine PM pollution in Japan. In the presentation, we will also discuss about the characteristics of source apportionment in terms of seasonal change and spatial distribution.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A51L2326O
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES