Enhanced Two Dimensional Hydrodynamic and Water Quality Model (CE-QUAL-W2) for Simulating Mercury Transport and Cycling in Water Bodies

Abstract

CE-QUAL-W2 (W2) is a widely-used two-dimensional, laterally averaged, longitudinal/vertical, hydrodynamic and water quality model. This model was modified and enhanced to include a mercury (Hg) simulation module for simulating Hg transport and cycling in water bodies. The Hg simulation module in W2 is able to model the physical and biochemical processes including adsorption and desorption of Hg species on multi-solids, settling and resuspension, sediment burial of adsorbed Hg, diffusive exchange between water column and sediment layer, volatilization, and biogeochemical transformations among Hg species. This paper describes the Hg simulation module, W2 model validation and its application to the Xiaxi River, China, a historical Hg contaminated water body. The W2 model was evaluated using the Xiaxi River data collected in 2007 and 2008. Model results show that W2 was able to predict the total Hg and methylmercury concentrations observed for the Xiaxi River. The Xiaxi River W2 model also provides a foundation for the future investigations of Hg contamination in the Xiaxi River. This application demonstrated the W2 model capability in predicting complex transport and cycling of Hg species in water bodies.

Keywords

• CE-QUAL-W2
• Mercury
• Methylmercury
• cycling
• Mercury simulation module