Minnesota's Mercury Risk Estimation Method (MMREM) for the Fish Consumption Pathway: A Comparison Against the Methodology Described in USEPA's Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities (HHRAP)

摘要

The minnesota mercury risk estimation method (MMREM) was developed in response to the observation that mercury concentrations in Minnesota lakes varied a great deal in top predators despite a relatively uniform atmospheric deposition of mercury across the state. This is not entirely surprising given the complexity of the aquatic fate and transport of deposited mercury and the unique characteristics of individual water bodies. The MMREM relies on empirical fish contamination data combined with the principle of proportionality between mercury concentrations in fish and atmospheric mercury deposition. Specifically, the MPCA has developed a statewide estimate of ambient annual mercury deposition based on a series of sediment core measurements. Mass mercury input to a given water body is approximated from direct atmospheric deposition plus loading from the watershed using the statewide deposition value. This ambient mercury loading is then correlated with fish tissue mercury concentrations in that water body using data collected by the DNR. Once this baseline correlation has been developed, the potential impact from any new source can be estimated using air dispersion /deposition results for the source to determine the incremental increase in water body loading of mercury. Under the principle of proportionality, the increase in fish tissue mercury for that water body will be proportional to the increase in mercury loading. In the current study, a site was selected for evaluation using the MMREM and the results compared against the results for that same site evaluated using the more complex methodology described in USEPA's HHRAP.