Predicting mercury concentrations and fluxes in the water column and sediment of lakes with a limited dataset

Abstract

The purpose of the present study was to evaluate the mercury (Hg) Environmental Ratios Multimedia Ecosystem Sources (HERMES) model on two Ontario, Canada lakes (Harp and Dickie) and to include modifications to enable the model to estimate the major model input variables that tend to be missing for lakes with limited datasets. No significant differences were found for either sediment solid or bulk water total mercury (THg) when the HERMES model was applied to the two Ontario lakes, regardless of whether all available data were altered during application or only the 10 variables that tend to cause the most variation in model output (i.e., concentration of THg in atmosphere, water inflow THg concentration, water inflow rate, water volume, surface area, mean depth, suspended particulate matter concentration, settling rate of solids in water column, water temperature, and precipitation rate). Since measured sediment and water THg values do not exist for most lakes removed from industrial activities, empirical relationships were incorporated into the HERMES model framework to provide a method to double-check model output for lakes where this information is unavailable.

Methylmercury screening models for surface water habitat restoration : a case study in Duluth-Superior Harbor

“…Therefore, it is helpful to utilize existing mathematical models, designed for Hg, to assess the multiple potential processes occurring in the cove that affect Hg fate and transport. Three models were investigated for understanding Hg in surface water and sediments: the Hg Environmental Ratios Multimedia Ecosystem Sources (HERMES) model (Ethier et al 2010); the Water quality Analysis Simulation Program (WASP 7.3) with the Hg module (Wool et al 2001); and the Spreadsheet-based Ecological Risk Assessment for the Fate of Mercury (SERAFM) model (Knightes 2008). Both WASP and SERAFM are U.S. Environmental Protection Agency (USEPA) models.…”

“…Changing parameter inputs to the HERMES model (Ethier et al 2010) as a result of the creation of shallow-water vegetated habitat was explored. HERMES is a mass balance model intended for lakes (Ethier 2009).…”

“…Table 1 provides inputs that were held constant in the HERMES model for both the "no-action" and "restoration" scenarios. The concentration of Hg in the air and the precipitation rate were set as default values designed for Ontario, Canada, lakes (Ethier et al 2010).…”

“…Therefore, the rate of settling may be similar before and after restoration. A value of 1 g/m2/day was obtained using a method by Ethier et al (2010) and an average water depth of 1.2 meters. Table 2 provides varied inputs to predict changes in Hg in the cove as a result of restoration.…”

“…The MeHg to total Hg ratio in the surface water was set to a measured value for the estuary of about 0.03 3 . The ratio in the air was left at the default value of 0.005 (Ethier et al 2010).…”