title: Heavy Metals in Surface Soils in the Upper Reaches of the Heihe River, Northeastern Tibetan Plateau, China.
abstract: The upper reaches of the Heihe River have been regarded as a hotspot for phytoecology, climate change, water resources and hydrology studies. Due to the cold-arid climate, high elevation, remote location and poor traffic conditions, few studies focused on heavy metal contamination of soils have been conducted or reported in this region. In the present study, an investigation was performed to provide information regarding the concentration levels, sources, spatial distributions, and environmental risks of heavy metals in this area for the first time. Fifty-six surface soil samples collected from the study area were analyzed for Cr, Mn, Ni, Cu, Zn, As, Cd and Pb concentrations, as well as TOC levels. Basic statistics, concentration comparisons, correlation coefficient analysis and multivariate analyses coupled with spatial distributions were utilized to delineate the features and the sources of different heavy metals. Risk assessments, including geoaccumulation index, enrichment factor and potential ecological risk index, were also performed. The results indicate that the concentrations of heavy metals have been increasing since the 1990 s. The mean values of each metal are all above the average background values in the Qinghai Province, Tibet, China and the world, except for that of Cr. Of special note is the concentration of Cd, which is extremely elevated compared with all background values. The distinguished ore-forming conditions and well-preserved, widely distributed limestones likely contribute to the high Cd concentration. Heavy metals in surface soils in the study area are primarily inherited from parent materials. Nonetheless, anthropogenic activities may have accelerated the process of weathering. Cd presents a high background concentration level and poses a severe environmental risk throughout the whole region. Soils in Yinda, Reshui daban, Kekeli and Zamasheng in particular pose threats to the health of the local population, as well as that of livestock and wildlife.
authors.affiliation: Geological Survey, China University of Geosciences, Wuhan 430074, China. jangous@163.com.|Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences, Wuhan 430074, China. jangous@163.com.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Bu
authors.affiliation: Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences, Wuhan 430074, China. ziyong.sun@cug.edu.cn.|School of Environmental Studies, China University of Geosciences, Wuhan 430074, China. ziyong.sun@cug.edu.cn.
authors.forename: Ziyong
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Geological Survey, China University of Geosciences, Wuhan 430074, China. aiguozhou@cug.edu.cn.|Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences, Wuhan 430074, China. aiguozhou@cug.edu.cn.|School of Environmental Studies, China University of Geosciences, Wuhan 430074, China. aiguozhou@cug.edu.cn.
authors.forename: Aiguo
authors.initials: A
authors.lastname: Zhou
authors.affiliation: Xi'an Center of Geological Survey, China Geological Survey, Xi'an 710054, China. ksdzhj@sohu.com.
authors.forename: Youning
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences, Wuhan 430074, China. rma@cug.edu.cn.|School of Environmental Studies, China University of Geosciences, Wuhan 430074, China. rma@cug.edu.cn.
authors.forename: Rui
authors.initials: R
authors.lastname: Ma
authors.affiliation: Geological Survey, China University of Geosciences, Wuhan 430074, China. weiwenhao048@outlook.com.
authors.forename: Wenhao
authors.initials: W
authors.lastname: Wei
authors.affiliation: Geological Survey, China University of Geosciences, Wuhan 430074, China. lethelm@126.com.|Faculty of Mechanical &amp; Electronic Information, China University of Geosciences, Wuhan 430074, China. lethelm@126.com.
authors.forename: Meng
authors.initials: M
authors.lastname: Liu
mesh_terms: D002681:China; D004784:Environmental Monitoring; D019216:Metals, Heavy / Q000032:analysis*; D015999:Multivariate Analysis; D018570:Risk Assessment; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D018609:Tibet
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants
keywords: Heihe River; Tibetan Plateau; heavy metals; multivariate statistics; risk assessment; soil