MODELING THE TRANSPORT AND FATE OF MERCURY IN AN URBAN LAKE (ONONDAGALAKE, NY)

A mass balance model was developed to simulate mercury (Hg) cycling in Onondaga Lake, New York. MERC4, a U.S. Environmental Protection Agenc y model of the physical and biogeochemical transport and transformatio n of Bg, was modified by the addition of input from two supporting mod els (Fish Bioenergetics Model 2 and a lake eutrophication model) to mo del the transport of Hg into and out of plankton and fish. The model c alculates the concentrations of total Hg, methylmercury, elemental Pig , and ionic Hg in both dissolved and particulate forms in the water co lumn. The model was calibrated to an extensive data set of temporally and spatially variable Hg concentrations in Onondaga Lake in 1992. In addition to standard transport processes of advection and dispersion i ncluded in MERC4, the Onondaga Lake Mercury Model includes remineraliz ation to simulate release of Hg from settling particulates before inco rporation into sediment. The model provides an analytical framework fo r understanding and predicting the behavior of Hg in Onondaga Lake and has potential use in evaluating the relative impact of different sour ce, control and remedial alternatives.