Mathematical Modeling of Fate and Transport of Dissolved and Particulate Mercury in Riverine Systems

Mercury is a hazardous metal in the environment that in many cases is concentrated in riverine and estuarine bed sediments, from which mercury can be mobilized due to erosion of the top layer. In this research, a one-dimensional flow and transport sub-model representing the transport of mercury in the river is coupled with several one-dimensional sub-models incorporating diffusive transport, transformation and sorption of mercury species in the bed sediments. Transport of dissolved and particle-associated mercury in the water, and thus the effect of erosion and resuspension of particles on the transport process, is taken into consideration. A set of one-dimensional reactive transport sub-models are utilized to represent the release, adsorption, and burial of mercury species to the bed sediments. This transport model is coupled with a detailed biochemical reaction network that includes main mercury species as well as major components which are effective in production of Methyl-Mercury. The goal of this coupling is to quantify methylmercury production using basic principles. Model parameters are obtained using available literature data and by calibration of the one dimensional-reactive transport model to available column and batch study data. The model can be used for simulating transport of mercury and production of methylmercury, examining various remediation scenarios, and evaluating the effect of anthropogenic activities on resuspension or burial of mercury species in water systems after doing appropriate calibrations.