title: Combine the soil water assessment tool (SWAT) with sediment geochemistry to evaluate diffuse heavy metal loadings at watershed scale.
abstract: Assessing the diffuse pollutant loadings at watershed scale has become increasingly important when formulating effective watershed water management strategies, but the process was seldom achieved for heavy metals. In this study, the overall temporal-spatial variability of particulate Pb, Cu, Cr and Ni losses within an agricultural watershed was quantitatively evaluated by combining SWAT with sediment geochemistry. Results showed that the watershed particulate heavy metal loadings displayed strong variability in the simulation period 1981-2010, with an obvious increasing trend in recent years. The simulated annual average loadings were 20.21 g/ha, 21.75 g/ha, 47.35 g/ha and 21.27 g/ha for Pb, Cu, Cr and Ni, respectively. By comparison, these annual average values generally matched the estimated particulate heavy metal loadings at field scale. With spatial interpolation of field loadings, it was found that the diffuse heavy metal pollution mainly came from the sub-basins dominated with cultivated lands, accounting for over 70% of total watershed loadings. The watershed distribution of particulate heavy metal losses was very similar to that of soil loss but contrary to that of heavy metal concentrations in soil, highlighting the important role of sediment yield in controlling the diffuse heavy metal loadings.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiao
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: wei@itc.nl.
authors.forename: Wei
authors.initials: W
authors.lastname: Ouyang
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Fanghua
authors.initials: F
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Haobo
authors.initials: H
authors.lastname: Huang
authors.affiliation: Taihu Basin Authority, Ministry of Water Resources, Shanghai 200434, China.
authors.forename: Yushu
authors.initials: Y
authors.lastname: Shan
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Geng
mesh_terms: D000383:Agriculture; D002681:China; D019015:Geologic Sediments / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis*; D045483:Rivers; D012987:Soil / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis
chemical_list: D019216:Metals, Heavy; D012987:Soil; D014874:Water Pollutants, Chemical
keywords: Diffuse pollution; Heavy metal; SWAT; Sediment; Watershed water management