Taiwan is located in the downwind region of the Asian circulation system. Air pollutants emitted in the upwind regions, such as the East Asia continent and the Indochina peninisula, can thus be transported to Taiwan via prevailing monsoon and high-altitude westerlies to influence air quality, environment, ecosystems, and human health. Accordingly, Taiwan EPA drew up this project to achieve the following goals: (1) to participate regional background air quality monitoring and establish a platform for international collaboration in monitoring; (2) to replenish monitoring information of long-range transported air pollutants and assess its influence to Taiwan. Dongsha Experiment, the preliminary monitoring study of 7-SEAS led by Taiwan, was one of the major tasks of this project. Dongsha Island was the principal experimental site. Overall, there were 15 domestic research groups, led by National Central University and Taiwan EPA, participating this experiment. U.S. NASA and Naval Research Lab (NRL), Vietnam, and Thailand were the main foreign participants. During March and June, a Taiwan EPA mobile monitoring vehicle and a NASA COMMIT were placed in Dongsha to conduct continuous monitoring. Additionally, two IOPs (3/13-20 and 4/10-20) were operated with all participating research groups conducting measurements simultaneously. Parameters monitored include meteorology, sounding, radiation, atmospheric aerosol physic and chemistry, common air pollutants (e.g. CO, SO2, O3), hazardous air pollutants (e.g. Hg, dioxins, PAHs), VOCs, and greenhouse gases. A data workshop was held in mid-June to discuss preliminary results of the Dongsha Experiment. Another important task of this project was to monitor hazardous air pollutants (atmospheric Hg and dioxins) at background sites in Taiwan and remote islands, including Mazu, Mt. Bamboo, Mt. Lulin, Hengchun, Dongsha, and Nansha. A total of 21 IOPs were conducted and each IOP lasted for at least 7 days. Concentrations of atmospheric Hg and dioxins were 1.09-4.34 ng m-3 and 0.22 and 184 fg-I-TEQ m-3, respectively. Concentrations of both pollutants showed seasonal variations, usually lower in summer but higher in winter and spring. The seasonal variation in pollutant concentrations was related to the seasonal variation in air mass origins. In summer, the prevailing southwest monsoon brought clean marine air masses with lower concentrations of mercury and dioxins. On the other hand, in winter and spring the prevailing northeast monsoon brought continental air masses, which contained higher HAPs concentrations, indicating the influence of long-range transport. This project also investigated the chemical composition, including water-soluble ions and metal elements, of Mt. Lulin aerosol samples (PM2.5 and PM2.5-10). In 2010, SO42- and NO3- were the major anions, while NH4+ was the major cation. Fe, Al, and Mg were the major metal elements. Pb was the most frequently detected hazardous metal element. Concentrations of K+ increased significantly during the Southeast Asian biomass burning season in spring.

long-range transport, atmospheric mercury, dioxins, aerosol, water-soluble ions, metal elements.