Atmospheric PM2.5 and PCDD/Fs have received much more attention in recent years due to their harmful properties. In this study, the PM2.5 and PCDD/Fs in the ambient air and the atmospheric dry and wet depositions were investigated in a coastal area of central Taiwan. During 2014, 2015 and 2016, the mean PM2.5 concentrations in Yunlin were 29.6, 26.6 and 26.3 µg m–3, respectively. The mean values of PM2.5/PM10 ratios were in an order of Lunbei (averaged at 0.55) > Taisi (averaged at 0.54) > Mailiao (averaged at 0.363). The modeled PCDD/Fs concentration at Yunlin were 0.0380, 0.0346 and 0.0324 pg WHO2005-TEQ m–3 during 2014 to 2016. The observed concentration of total-PCDD/Fs-WHO2005-TEQ at Yunlin in January and August were 0.089 and 0.00538 pg WHO2005-TEQ m–3, and the modeled concentration were 0.0598 and 0.0176 pg WHO2005-TEQ m–3. From 2014 to 2016, the annual average dry deposition, wet deposition and total deposition in Yunlin were 4,955, 254 and 5,209 pg WHO2005-TEQ m–2 year–1 in 2014; 4,524, 348 and 4,872 pg WHO2005-TEQ m–2 year–1 in 2015; 4,224, 518 and 4,742 pg WHO2005-TEQ m–2 year–1 in 2016. Among these three areas, the dry deposition fluxes were highest at Mailiao, followed by Lunbei, and the lowest at Taisi. The scavenging ratios (Stot) of total-PCDD/Fs-WHO2005-TEQ in Yunlin were 14,600, 13,800 and 13,300 in 2014, 2015 and 2016, respectively, and with an average of 13,900. The scavenging ratios (Stot) indicated a distinctive seasonal variation, and the values in spring, summer, autumn and winter were 13,700, 6,330, 12,100 and 23,500 in Yunlin, respectively. This is due to the fact that a higher temperature will cause more fraction of PCDD/Fs in the gas phase in summer and the gas phase scavenging ratio is less than that of particle phase. The results of this work provide useful information for both further studies and environmental control strategies aimed at persistent organic compounds (POPs).
All Science Journal Classification (ASJC) codes
- Environmental Chemistry