Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China.
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2018 May 15;624:241-249. doi: 10.1016/j.scitotenv.2017.12.140. Epub 2017 Dec 15.
Long-term monitoring in remote regions is essential for revealing pollution trends at the global scale but relevant studies remain limited. In the present study, a six-year continuous monitoring of atmospheric persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) was carried out at Lulang in the southeastern Tibetan Plateau (TP). Average concentrations of hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethanes (DDTs), polychlorinated biphenyls (PCBs) and PAHs were 13.5, 8.9, 41.7, 1.8pg/m and 6.2ng/m, respectively. Obvious seasonality was found for all the target compounds. HCHs, DDTs and PCBs had their highest concentrations in summer (monsoon season) and lowest in winter, which is consistent with the fluctuation of the Indian monsoon. Meanwhile, HCB and 5-6-ring PAHs showed opposite variations, possibly induced by local sources and the westerly flow in winter. Declining trends were observed for most of the chemicals, except o,p'-DDE, HCB and PCBs. A declining trend in the α/γ-HCH ratio indicated a shift from technical HCHs to lindane. An increasing trend in the o,p'/p,p'-DDT ratio suggested a likely shift from technical DDTs to dicofol. For PAHs, the contribution from high-temperature combustion has increased recently. The half-lives of α-HCH, γ-HCH, o,p'-DDT, p,p'-DDT were 6.1, 108, 77.6 and 14.2years, respectively. The half-lives of γ-HCH, o,p'-DDT and p,p'-DDT were higher than those in the Arctic, indicating these compounds will persist in the TP for a longer period. The temporal trends in atmospheric POPs were possibly induced by emissions in India and likely driven by wind speed in Lulang. This study contributes toward a better understanding of the behavior and transport of POPs in the TP region.
在偏远地区进行长期监测对于揭示全球范围内的污染趋势至关重要，但相关研究仍然有限。本研究在青藏高原东南部的鲁朗进行了为期六年的大气持久性有机污染物（POPs）和多环芳烃（PAHs）的连续监测。六氯环己烷（HCHs）、六氯苯（HCB）、滴滴涕（DDTs）、多氯联苯（PCBs）和 PAHs 的平均浓度分别为 13.5、8.9、41.7、1.8pg/m 和 6.2ng/m。所有目标化合物均表现出明显的季节性。HCHs、DDTs 和 PCBs 的浓度在夏季（季风季节）最高，冬季最低，这与印度季风的波动一致。同时，HCB 和 5-6 环 PAHs 的变化相反，可能是由当地源和冬季西风引起的。除了 o,p'-DDE、HCB 和 PCBs 外，大多数化学物质的浓度呈下降趋势。α/γ-HCH 比值的下降表明技术 HCHs 向林丹的转变。o,p'/p,p'-DDT 比值的上升表明技术 DDTs 向三氯杀螨醇的转变。对于 PAHs，高温燃烧的贡献最近有所增加。α-HCH、γ-HCH、o,p'-DDT、p,p'-DDT 的半衰期分别为 6.1、108、77.6 和 14.2 年。γ-HCH、o,p'-DDT 和 p,p'-DDT 的半衰期高于北极，表明这些化合物将在青藏高原上持续更长时间。大气 POPs 的时间趋势可能是由印度的排放引起的，可能是由鲁朗的风速驱动的。本研究有助于更好地了解青藏高原地区 POPs 的行为和传输。
