title: A reactive transport model for mercury fate in contaminated soil--sensitivity analysis.
abstract: We present a sensitivity analysis of a reactive transport model of mercury (Hg) fate in contaminated soil systems. The one-dimensional model, presented in Leterme et al. (2014), couples water flow in variably saturated conditions with Hg physico-chemical reactions. The sensitivity of Hg leaching and volatilisation to parameter uncertainty is examined using the elementary effect method. A test case is built using a hypothetical 1-m depth sandy soil and a 50-year time series of daily precipitation and evapotranspiration. Hg anthropogenic contamination is simulated in the topsoil by separately considering three different sources: cinnabar, non-aqueous phase liquid and aqueous mercuric chloride. The model sensitivity to a set of 13 input parameters is assessed, using three different model outputs (volatilized Hg, leached Hg, Hg still present in the contaminated soil horizon). Results show that dissolved organic matter (DOM) concentration in soil solution and the binding constant to DOM thiol groups are critical parameters, as well as parameters related to Hg sorption to humic and fulvic acids in solid organic matter. Initial Hg concentration is also identified as a sensitive parameter. The sensitivity analysis also brings out non-monotonic model behaviour for certain parameters.
authors.affiliation: Performance Assessments, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400, Mol, Belgium. bleterme@sckcen.be.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Leterme
authors.affiliation: Performance Assessments, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400, Mol, Belgium. djacques@sckcen.be.
authors.forename: Diederik
authors.initials: D
authors.lastname: Jacques
mesh_terms: D000327:Adsorption; D000393:Air Pollutants / Q000032:analysis*; D008627:Mercuric Chloride / Q000032:analysis; D008628:Mercury / Q000032:analysis*; D017669:Mercury Compounds / Q000032:analysis; D008956:Models, Chemical; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014835:Volatilization; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D017669:Mercury Compounds; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D008627:Mercuric Chloride; D008628:Mercury; C034211:cinnabar
keywords: HP1; Hg; Mercury; Morris; Reactive transport modelling; Sensitivity analysis; Vadose zone