title: Modeling the dynamic changes in concentrations of gamma-hexachlorocyclohexane (gamma-HCH) in Tianjin region from 1953 to 2020.
abstract: A level IV fugacity model was used to simulate the dynamic changes of gamma-hexachlorocyclohexane (gamma-HCH) concentrations in environmental media in Tianjin, China. A similar model (level III) was previously used and validated under steady state conditions; this paper explores its dynamic behavior. Application of the level IV fugacity model has been validated using independently observed gamma-HCH concentrations in various media during the early 1980s and during 2001. Sensitivity analysis was conducted using coefficient-of-variation normalized sensitivity coefficients. The model was also subject to uncertainty analysis using Monte Carlo simulation. It was found that concentrations of gamma-HCH reached within 95% of their steady-state levels in all media after less than 15 years. Around one order-of-magnitude decreases in gamma-HCH concentrations in various media occurred between 1993 and 2001. We project that gamma-HCH concentrations will decrease another 1.7-1.9 orders of magnitude to reach 1.1 (0.9-1.2) x 10(-14), 2.7 (2.5-3.0) x 10(-10), 1.2 (1.1-1.3) x 10(-7), and 6.1 (5.4-6.8) x 10(-8) mol/m(3), in air, water, soil, and sediment, respectively, by 2020. The sensitivities and true uncertainty of the model are discussed.
authors.affiliation: Laboratory for Earth Surface Processes, College of Environmental Sciences, Peking University, Beijing 100871, China. taos@urban.pku.edu.cn
authors.forename: S
authors.initials: S
authors.lastname: Tao
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: H Y
authors.initials: HY
authors.lastname: Cao
authors.forename: W X
authors.initials: WX
authors.lastname: Liu
authors.forename: R M
authors.initials: RM
authors.lastname: Coveney
authors.forename: F L
authors.initials: FL
authors.lastname: Xu
authors.forename: J
authors.initials: J
authors.lastname: Cao
authors.forename: B G
authors.initials: BG
authors.lastname: Li
authors.forename: X J
authors.initials: XJ
authors.lastname: Wang
authors.forename: J Y
authors.initials: JY
authors.lastname: Hu
authors.forename: J Y
authors.initials: JY
authors.lastname: Fang
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D002681:China; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D019015:Geologic Sediments; D006256:Hazardous Waste / Q000032:analysis; D001556:Hexachlorocyclohexane / Q000032:analysis*; D007306:Insecticides / Q000032:analysis*; D008956:Models, Chemical; D009010:Monte Carlo Method; D015203:Reproducibility of Results; D012989:Soil Pollutants / Q000032:analysis; D035501:Uncertainty; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000393:Air Pollutants; D004785:Environmental Pollutants; D006256:Hazardous Waste; D007306:Insecticides; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D001556:Hexachlorocyclohexane