title: Heavy metals of the Tibetan top soils: level, source, spatial distribution, temporal variation and risk assessment.
abstract: OBJECTIVE
  Due to its high elevation, rare human activities and proximity to south Asia where industries are highly developed, it is required to investigate the fragile environment of the Tibetan Plateau. We are aiming to obtain the concentration level, source, spatial distribution, temporal variation and potential environmental risk of Tibetan soils.
  
  
  METHODS
  A total of 128 surf ace soil samples were collected and analyzed f or V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb, and an additional 111 samples were analyzed f or Hg and total organic carbon. Concentration comparisons coupled with multivariate statistics were used to analysis the sources of elements of soils. We also carried out Risk assessment on the soils.
  
  
  RESULTS
  Concentrations of Hg, Cr, Ni, Cd and Pb are slightly higher than those of the late 1970s. Concentrations of Cr and Ni are higher than averaged world background values. Tibetan soils present a high natural As concentration level.
  
  
  CONCLUSIONS
  Anthropogenic sources may partly contribute to the elevated Hg, Cd and Pb concentrations. Cr and Ni are mainly originated from soil parent materials. Soil elements in Anduo and Qamdo regions may threaten the health of local people.
  
  
  CONCLUSIONS
  Heavy metal elements of Tibetan Plateau are mainly from the natural source. Arsenic present a high background level. Soil elements in Anduo and Qamdo regions may threaten the health of local people, which should be of concern to scientists and the government.
authors.affiliation: Key laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jiujiang
authors.initials: J
authors.lastname: Sheng
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Gong
authors.forename: Lide
authors.initials: L
authors.lastname: Tian
authors.forename: Tandong
authors.initials: T
authors.lastname: Yao
mesh_terms: D001151:Arsenic / Q000032:analysis; D004784:Environmental Monitoring; D019216:Metals, Heavy / Q000032:analysis*; D018570:Risk Assessment; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D018609:Tibet
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D001151:Arsenic