title: A review of current knowledge and future prospects regarding persistent organic pollutants over the Tibetan Plateau.
abstract: Since the turn of the century, our understanding of the quantities, transport pathways, and fate of persistent organic pollutants (POPs) over the Tibetan Plateau (TP), the largest and highest plateau on Earth, has greatly enhanced. We begin in this article by reviewing the available literature on the levels of POPs over the TP. In general, the levels of most POPs are similar or lower than values reported for other background regions. However, dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) levels in air and soil far exceed those measured in other mountainous areas. The East Asian monsoon, Indian Monsoon and westerly winds are responsible for the long-range atmospheric transport (LRAT) and arrival of POPs over the TP. Surface soil and vegetation act as "final sinks" for DDTs and other high molecular weight POPs. Linked to the continuous use of POPs in surrounding counties, LRAT and "cold trapping" by the TP can happen following emission-transport-deposition events, leading to the enrichment of POPs in the TP environment. Bioaccumulation of DDTs and high chlorinated PCBs have been found in Tibetan terrestrial and aquatic food chains, and newly emerging compounds such as polyfluoroalkyl substances and hexabromocyclododecanes have been widely detected in wild fish species. The corresponding ecological risks should be of great concern. Climate change, such as increased temperatures and changing coverage of snow and glaciers, has the potential to affect the behavior and distribution of POPs. Therefore, long-term monitoring data are required. Ineffective regulation regarding POPs has been reported for countries in South Asia, emissions patterns, the outflow of POPs, and their seasonal and inter-annual variability should therefore be clarified. Estimating the loading of POPs, as well as how they move, within the TP, especially under the impact of glacial melt and global warming, should be a priority.
authors: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China. Electronic address: wangxp@itpcas.ac.cn.
authors: Xiaoping
authors: X
authors: Wang
authors: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China.
authors: Ping
authors: P
authors: Gong
authors: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China.
authors: Chuanfei
authors: C
authors: Wang
authors: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Jiao
authors: J
authors: Ren
authors: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China.
authors: Tandong
authors: T
authors: Yao
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D057231:Climate Change; D003634:DDT / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005544:Forecasting; D001556:Hexachlorocyclohexane / Q000032:analysis*; D018609:Tibet; D014919:Wind
chemical_list: D000393:Air Pollutants; D001556:Hexachlorocyclohexane; D003634:DDT
keywords: Climate change; Persistent organic pollutants; Sink; Source; Tibetan Plateau