Wu Po-Chao, Huang Kuo-Fang
Earth System Science Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei, Taiwan.
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan.
Sci Rep. 2021 Apr 7;11(1):7593. doi: 10.1038/s41598-021-87051-y.
Central Taiwan is among the most heavily polluted regions in Taiwan because of a complex mixing of local emissions from intense anthropogenic activities with natural dust. Long-range transport (LRT) of pollutants from outside Taiwan also contributes critically to the deterioration of air quality, especially during the northeast monsoon season. To identify the sources of particulate matter < 10 μm (PM) in central Taiwan, this study performed several sampling campaigns, including three local events, one LRT event, and one dust storm event, during the northeast monsoon season of 2018/2019. The PM samples were analyzed for water-soluble ion and trace metal concentrations as well as Pb isotope ratios. Local sediments were also collected and analyzed to constrain chemical/isotopic signatures of natural sources. The Pb isotope data were interpreted together with the enrichment factors and elemental ratios of trace metals in PM, and reanalysis data sets were used to delineate the sources of PM in central Taiwan. Our results suggested that Pb in PM was predominantly contributed by oil combustion and oil refineries during the local events (48-88%), whereas the lowest contributions were from coal combustion (< 21%). During periods of high wind speed, the contribution from natural sources increased significantly from 13 to 31%. Despite Pb represented only a small portion of PM, a strong correlation (r = 0.89, p < 0.001, multiple regression analysis) between PM mass and the concentrations of Pb, V, and Al was observed in the study area, suggesting that the sources of PM in central Taiwan can be possibly tracked by using chemical characteristics and Pb isotopes in PM. Moreover, the Pb isotopic signals of PM collected during the LRT event confirmed the impact of LRT from Mainland China, and the chemical characteristics of the PM significantly differed from those of the PM collected during local events. This study demonstrates the robustness of using a combination of Pb isotopic compositions and chemical characteristics in PM for source tracing in complex and heavily polluted areas.
由于强烈的人为活动产生的本地排放与自然沙尘复杂混合，台湾中部是台湾污染最严重的地区之一。来自台湾岛外污染物的长距离传输（LRT）也对空气质量恶化起到关键作用，尤其是在东北季风季节。为了确定台湾中部小于10微米颗粒物（PM）的来源，本研究在2018/2019年东北季风季节开展了几次采样活动，包括三次本地事件、一次长距离传输事件和一次沙尘暴事件。对PM样本进行了水溶性离子、痕量金属浓度以及铅同位素比率分析。还收集并分析了本地沉积物，以确定自然源的化学/同位素特征。结合PM中痕量金属的富集因子和元素比率解读铅同位素数据，并使用重新分析数据集来划定台湾中部PM的来源。我们的结果表明，在本地事件期间，PM中的铅主要来自石油燃烧和炼油厂（48 - 88%），而煤炭燃烧的贡献最小（<21%）。在高风速时期，自然源的贡献从13%显著增加到31%。尽管铅仅占PM的一小部分，但在研究区域内观察到PM质量与铅、钒和铝浓度之间存在很强的相关性（r = 0.89，p < 0.001，多元回归分析），这表明可以利用PM中的化学特征和铅同位素来追踪台湾中部PM的来源。此外，在长距离传输事件期间收集的PM的铅同位素信号证实了来自中国大陆的长距离传输的影响，并且该PM的化学特征与本地事件期间收集的PM有显著差异。本研究证明了在复杂和污染严重的地区使用PM中铅同位素组成和化学特征相结合进行源追踪的有效性。
