- Thesis topic:  Deposition Fluxes of PCDD/Fs and PCBs through Cloud/Fog Water in Mt. Bamboo, Taiwan during Northeastern Monsoon Season

- Doi: https://doi.org/10.6840/cycu202200079

- Abstract: 

        During the northeastern monsoon, airborne pollutants from eastern and central Asia were transported to Taiwan. As a result of the cloudy weather in northern Taiwan, the pollution may have been scavenged by the cloud. In this study, the cloud/fog water samplings were conducted in Mountain Bamboo, northern Taiwan, using passive and active fog collectors to investigate the amount, scavenging mechanism, and deposition flux of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) and polychlorinated biphenyls (PCBs). The average PCDD/F concentrations in cloud/fog water samples were 0.861 pg WHO-TEQ/L for passive samples and 1.30 pg WHO-TEQ/L for active samples, while PCB concentrations were 0.0213 pg WHO-TEQ/L and 0.0462 pg WHO-TEQ/L, respectively. The PCDD/Fs TEQ values of cloud/fog water are three orders higher than the TEQ values of PCDD/Fs in the rain of urban Taipei. Backward trajectory modeling revealed that high concentration events originated from eastern and central Asia. The scavenging coefficient and scavenging ratio of particle-phase PCDD/Fs and PCBs were higher than the gas-phase demonstrating particulate matter (PM) scavenging by cloud/fog water. The average deposition flux of PCDD/Fs through the fog was 1.12 pg TEQ WHO m-2 h-1, while that of PCBs was 0.0364 pg TEQ WHO m-2 h-1. The PCDD/Fs deposition flux through fog is one order of magnitude greater than the total PCDD/Fs atmospheric deposition flux (dry + wet deposition) reported in previous studies. Higher deposition flux might result in elevated pollutant contents in the environmental compartment nearby Mountain Bamboo.

Keywords: PCDD/Fs, PCBs, Cloud, Deposition Flux