| A third generation air quality model (CAMx) is used to simulate the distribution of air pollutants in East Asia. Source-relationships are established for ozone, sulfur, nitrate, and elemental carbon in East Asia, using reactive tracer methods including PSAT and OSAT provided by CAMx.3regions (northern, central and southern Japan) of Japan main islands, Korea mainland, Cheju island of Korea, Okinawa islands of Japan, Seoul, and Tokyo are set as receptors. The modle domin is divided into43areas as the source regions including33chinese regions according the administration division.The largest contribution to the sulfur oxides in northern, central and southern Japan main islands is from the emission of Japan itself, accounting for73.8%,77.1%and65.9%respectively.67.8%of the sulfur oxides in Korea mainland come from Korea. The trend of seasonal variations of trans-boundary sulfur oxides’contribution in these receptors are various from north to south. The strongest contribution of trans-boundary sulfur oxides in Korea and southern Japan happenes in January, and the weakest happened in July; in northern and central Japan the strongest happened in April and the weakest happened in January. The concentration of trans-boundary sulfur oxides in Japan and Korea is low:it is less than1.5μg/m3in Japan and less than2.5μg/m3in Korean mainland.The largest contribution to the nitrate in Japan and Korea is the local emission, accounting for36.7%-69.3%, which is10%-27%lower than the figure of sulfate we got in the previous work. The.seasonal variation of the nitrate concentration in East Asia, as well as the Asian monsoon, lead to that the amount of nitrate attributed to long range transport is the largest in winter (larger than54%) and the least in summer (less than27%). The distribution of degree of sulfate neutralization (DSN) and the adjusted gas ratio (AdjGR) in East Asia suggests that the particle nitrate concentration is most sensitive to changes in the total ammonia in most parts of Japan and some regions in Korea during the time excluding the winter, which is different from most parts of East Asia where there is enough ammonia. The ammonia contributed by the local emissions should be responsible for some particulate nitrate transformed from trans-boundary gas nitric, which means the local emissions of ammonia enlarges the contribution of China to the nitrate concentration in Japan and Korea.The domestic emissions are the primary contributions to the elemental carbon over Japan and Korea. The local emissions are responsible for42.3%,77.4%, and53.0%of the elemental carbon concentrations in northern, central, and southern Japan respectively, and the figure in Korea is62%. There are still significant contributions of trans-boundary elemental carbon, but the average concentration contributed by trans-boundary pollutants to the receptors is less than0.8μ g/m3. The seasonal variation of trans-boundary contribution to the receptors of elemental carbon is similar to aerosol nitrate.The transport of ozone from outside of model domain is the largest contributor of ozone in Japan and Korea, supplying with65-80%. The magnitude of ozone photochemical formation is lager in July than other three selected months. The formation of ozone in July doesn’t lead to the large transport of ozone to western pacific because of the summer monsoon, while April holds a larger transport due to the prevailing westerlies. The concentration of ozone in Japan and Korea in April is less than in July, which is different from other regions in East Asia. That should be attributed to the larger depletion of ozone from outside of our model domain in the transport process in July.The contribution of Japan and Korea to Chinese east coastland is lower than4%. There are significant contributions of South and Southeast Aisa to Tibet and southern of Yunan province of China. The mutual influence between different regions among china is significant, especially for Northern China and Central China. |
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