title: Sources and environmental processes of polycyclic aromatic hydrocarbons and mercury along a southern slope of the Central Himalayas, Nepal.
abstract: Semi-volatile pollutants can undergo long-range atmospheric transport from low-altitude source regions to high-altitude regions and then accumulate in surface matrices (soil and plants). The Himalayas is the highest mountain range worldwide, but there have been limited studies on the source, transport, and deposition of polycyclic aromatic hydrocarbons (PAHs) and mercury (Hg) in the region. In this study, atmospheric PAHs, and the PAHs and Hg in soil and foliage were determined along a transect on a southern slope of the Himalayas, Nepal. The study showed anthropogenic emissions of PAHs and Hg occurred in the lowland areas of Nepal, and upslope transport to the high-altitude regions happened for both pollutants. During the upslope transport, forest filter effect and snow scavenging may be the important factors that enhance the deposition of PAHs, contributing to the negative pattern between concentrations of PAHs and altitudes. On the contrary, more Hg accumulated in the high Himalayas, relating to the enhanced deposition in the high altitude caused by the higher input from upper atmosphere. Graphical abstract Distribution and environmental processes of PAHs and Hg along the southern slope of Himalayan mountain.
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.|School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Balram
authors.initials: B
authors.lastname: Pokhrel
authors.affiliation: 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.
authors.forename: Ping
authors.initials: P
authors.lastname: Gong
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China. wangxp@itpcas.ac.cn.|CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China. wangxp@itpcas.ac.cn.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Shaopeng
authors.initials: S
authors.lastname: Gao
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Chuanfei
authors.initials: C
authors.lastname: Wang
authors.affiliation: 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.
authors.forename: Tandong
authors.initials: T
authors.lastname: Yao
mesh_terms: D000531:Altitude; D001272:Atmosphere; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry*; D009390:Nepal; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*
chemical_list: D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D008628:Mercury
keywords: Deposition; Emission sources; Forest filter effect; Himalayas; Persistent toxic substances; Snow scavenging; Upslope transport