The randomness of firecracker-burning site and the overlapping impact of multi-sources makes the source apportionment of PM 2.5 during the firecracker burning events more difficult. To investigate the influences of the downwind distance to the firecracker-burning site on the temporospatial distribution of PM 2.5 and public health risk, PM 2.5 were sampled at three sites adjacent to a fixed firecracker-burning route accompanied with annual pilgrimage activity during the Lantern Festival in Taitung, Taiwan, which had a low background PM 2.5 concentration. The metallic elements, water-soluble ions, carbonaceous contents were analyzed. The potential sources were identified using positive matrix factorization. Finally, the health risks were assessed by calculating the hazard quotient and incremental lifetime carcinogenic risk, respectively. The results showed that the average concentration of PM 2.5 on the event days increased by approximately five-fold compared to the non-event days. The increase of chemical components varied significantly from the distance to the burning site. The concentrations of K, Fe, Al, Mg, K + , Cland OC rose by 6-14 times at one site close to a site with intensive firecracker burning, while increased by 2-6 times at one site far away from the firecracker burning sites. The PM 2.5 increment on the event days was mostly attributed to firecracker burning, kitchen fumes, and mobile sources. The health risk assessment results showed that the hazard index differed between the sampling sites. Furthermore, the cancer risk of one site close to the firecracker burning site was over the threshold, while that far away from the site was below the threshold.

No abstract

Indicators of (Fe/Cd) are approximately applied to observe the effects of ADEs. Local governments could realize the mechanisms of S- and NW-type aeolian dust episodes (ADEs). They can cause deterioration in different ways for the regional air quality surrounding Kaoping River Valley. Residents who have been living in the influenced areas can take precautions to prevent damage from aeolian dust. Strategies for curbing ADEs must reduce the area of bare lands by artificial measures in the long period of the sunny days during the rainy season. Future research should examine physical conditions of topsoils and other chemical composition in aeolian dust.

Aeolian dust episodes (ADEs) frequently occurred at the bare lands of the riverbeds in Kaoping River are emerging disasters in Southern Taiwan in the past few years. However, their influences on ambient particulate air quality due to the outflow circulation of typhoons have not been addressed in such a subtropical region. This study aims to investigate the association between typhoons and ADEs and their influences on the ambient particulate air quality, which might occur in East Asia. Four sites along the Kaoping River were selected to collect PM 10 with high-volume samplers during and after the ADE accompanying with Typhoon Doksuri on June 29, 2012. During the ADE, PM 10 concentration rose as high as 30-40 folds higher than those on regular days. Chemical composition of PM 10 was further analyzed to verify several valuable indicators including the molar ratios of [Cl -]/[Na + ] (0.95-1.02), the mass ratios of Fe/Cd (211.6-3957), and the mass ratios of OC/EC (1.18-1.35). Nevertheless, the chloride deficit phenomenon was not favorable during the ADE. Moreover, CMB receptor modeling results showed that aeolian dust and sea-salts were major contributors of PM 10 during the ADE. Along the Kaoping River, the contribution of aeolian dust to PM 10 ranged from 11.5 to 33.1% during the ADE, and reduced to 7.2-23.0% after the ADE. However, a small amount of finer aeolian dust could be still suspended in the ambient air after the ADE. Moreover, integrating SURFER software and WRF model was appropriate to locate the hot spots influenced by the ADE.

Aeolian dust episode (ADE) is an emerging disaster occurred from the bare lands of the Kaoping River Valley in southern Taiwan because of typhoons. Four manual sampling sites located along the Kaoping River Valley conducted to collect PM 10 (aerodynamic diameter ≤ 10 μm) with high-volume samplers during the ADE occurred by Typhoon Doksuri, and on regular days. Mass percentages of sea-salt particles (SSs) in PM 10 accounted for 5.47-8.91% on regular days and 11.66-14.05% in phase II. Average mass percentage of Ca 2+ in phase I increased twice than those on regular days. Cl − deficit percentages were much lower during the ADE (7.37-14.13%) than on regular days (31.69-42.78%), indicating acidic particles mainly produced by chemical reactions of acidic aerosols with aeolian dust and SSs. Even alkaline aeolian dust is a dominant source of the ADE, the atmospheric particles are attributable to acidic particles in the air. Hence, anthropogenic sources play a key role for the worst air quality during typhoon season. K E Y W O R D Saeolian dust episode, particulate air quality, sea-salt particles, typhoon, water-soluble ionic species