title: Simulation of the transfer and fate of γ-HCH in epikarst system.
abstract: The thin surface soil layer and karst features in karst terrains lead to poor filtration, poor pre-purification and rapid infiltration, so that karst groundwater systems are particularly vulnerable to contamination. Due to its extensive use in past, gamma-hexachlorocyclohexane (γ-HCH) is ubiquitous in various environmental compartments of China, even though it has been prohibited since 1984. However, very little is known about its movement and behavior in special karst system. In this study, a dynamic fugacity model was established for γ-HCH in epikarst system via dividing the karst soil into multiple layers coupled with the physical-chemical properties of γ-HCH. The simulated results in soil profile were in good agreement with the measured values of γ-HCH. The modeled results predict that only 18 g γ-HCH will be left in the studied area in 2020, which is only 0.4% of the largest reserves in 1983, and about 99.99% of γ-HCH will remains in soil. The concentrations of γ-HCH in air, plant and 0-20 cm layer soil in the studied area descended quickly after HCHs was prohibited in 1984, while its concentration in soil layer deeper than 20 cm (deeper soil) increased continuously till 1997. The dominant transfer process of γ-HCH between the adjacent compartments in the studied area was from 0-20 cm layer to the deeper soil. Sensitivity analysis results showed that emission rate, infiltration coefficient, total organic carbon of soil, degradation rate in soil, compartment area and volume were the top six influential parameters for predicting γ-HCH concentration.
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Karst Dynamics Laboratory, Ministry of Land and Resources, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China; Field Scientific Observation & Research Base of Karst Eco-environments at Nanchuan in Chongqing, Ministry of Land and Resources of China, Chongqing 40843, China. Electronic address: sunyc@swu.edu.cn.
authors.forename: Yuchuan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Geographical Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Zuobing
authors.initials: Z
authors.lastname: Liang
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Geographical Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Xiang
authors.affiliation: Institute of South China Karst, Guizhou Normal University, Guiyang 550001, China.
authors.forename: Jiacheng
authors.initials: J
authors.lastname: Lan
authors.affiliation: Karst Dynamics Laboratory, Ministry of Land and Resources, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Karst Dynamics Laboratory, Ministry of Land and Resources, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China.
authors.forename: Daoxian
authors.initials: D
authors.lastname: Yuan
mesh_terms: D000388:Air / Q000032:analysis; D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D060587:Groundwater / Q000737:chemistry; D001556:Hexachlorocyclohexane / Q000032:analysis*; D008962:Models, Theoretical; D010944:Plants / Q000737:chemistry; D011891:Rain / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D014872:Water Movements
chemical_list: D004785:Environmental Pollutants; D012987:Soil; D001556:Hexachlorocyclohexane
keywords: Epikarst system; Fate; Fugacity model; Transfer flux; γ-HCH