Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in paired ambient and surface air fugacity samples were measured in the Tibetan Plateau (TP) from 2019 to 2022. The air concentrations of previously intention-ally produced chemicals like dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) declined. Their soil-air exchange direction ranged from equilibrium to volatilization, suggesting that the TP is acting as a sec-ondary source of most OCPs and PCBs with the pollution alleviation. However, considerably high atmospheric levels of PCB-11, an indicator of unintentionally produced PCBs (UP-PCBs), were recorded in the southern TP. Strong episodic long-range atmospheric transport (LRAT) and deposition of PCB-11 events took place mostly in summer. Those events associated with winds from potential sources and less rainfall interception along the air mass transport routes accounted for a significant fraction of overall atmospheric deposition in the TP. Meanwhile, cryoturbation and plowing are suspected to be important factors contributing to the reemission of PCB-11 from surface soil. The high abundance of PCB-11 and strong deposition/evaporation events highlights potential environmental and health risks of UP-POPs in the TP.

Publication name	SCIENCE OF THE TOTAL ENVIRONMENT, Volume 873, Article Number 162453, DOI 10.1016/j.scitotenv.2023.162453, Published MAY 15 2023, Early Access FEB 2023
Author(s)	Xu, Yue; Wang, Yan; Yang, Chenmeng; Zhao, Shizhen; Zhang, Haiyan
Corresponding author(s)	Xu, Yue  xu-yue@mail.gyig.ac.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Peoples R China
Author(s) from IGCAS	Xu, Yue; Yang, Chenmeng