title: Polycyclic aromatic hydrocarbons in soils from the Central-Himalaya region: Distribution, sources, and risks to humans and wildlife.
abstract: The Central Himalayas are not only a natural boundary between China and Nepal but also a natural barrier for transport of air masses from South Asia. In this study, 99 samples of surface soil were collected from five regions of Nepal on the southern side of the Central Himalayas, and 65 samples of surface soil were obtained from the northern side on the edge of the Tibetan Plateau, China (TPC). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in soils were measured to determine their distribution, potential for accumulation, and sources, as well as risks to humans and the environment. Mean concentrations of Σ16PAHs were 2.4×10(2) and 3.3×10(2)ng/g dry mass (dm) in soils collected from the TPC and Nepal, respectively. Significant correlations between concentrations of lower molecular weight PAHs (LMW-PAHs) in soils and altitude were found. Total organic carbon (TOC) in soil was positively but weakly correlated with concentrations of PAHs in the study area, which suggested little role of TOC in adsorption of PAHs. The cities of Kathmandu and Pokhara in Nepal and Nyemo (especially Zhangmu Port), Shigatse, and Lhasa on the TPC, were areas with relatively great concentrations of PAHs in soils. The main sources of PAHs identified by positive matrix factorization were emissions from motor vehicles and combustion of coal and biomass in the Central Himalayas. Calculated total benzo[a]pyrene potency equivalents of 0.23-44ng/gdm and index of additive cancer risk of 3.8×10(-3)-9.2×10(-1) indicated that PAHs in almost all soils investigated posed de minimis risk of additional cancer to residents via direct contact and had no significant risk of additional cancers through consumption of potable water. Mean risk quotient values indicated that 39% of soils had a slight risk to wildlife and the ambient environment of the Central Himalayas.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Graduate University of Chinese Academy of Sciences, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Bi
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: luow@rcees.ac.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Tibet Climatic Center, Lhasa 850001, China.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Xu
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100085, China.
authors.forename: Junming
authors.initials: J
authors.lastname: Guo
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100085, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Qianggong
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science and Engineering, School of Science, Kathmandu University, Kathmandu 6250, Nepal.
authors.forename: Kumar Y
authors.initials: KY
authors.lastname: Romesh
authors.affiliation: Department of Veterinary Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, Canada.
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
authors.affiliation: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Shichang
authors.initials: S
authors.lastname: Kang
authors.affiliation: Institute for Environmental Studies, VU University, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.
authors.forename: Jacob
authors.initials: J
authors.lastname: de Boer
mesh_terms: D002681:China; D004784:Environmental Monitoring; D009390:Nepal; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D018570:Risk Assessment; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants
keywords: China; Mountain; Nepal; PMF model; Tibetan Plateau; Toxicity assessment