Identification of the determinants of fish tissue mercury concentrations in temperate lakes: Factors to be considered in the establishment or revision of fish consumption advisories
PI's: Aria Amirbahman, Stephen Norton - University of Maine; Linda Bacon - Maine DEP
Mercury (Hg) is number two on the Agency for Toxic Substances and Disease Registry’s (ATSDR) priority pollutant list and a global contaminant of major concern because exposure to this neurotoxin poses risk to
human and wildlife health. The threat of this toxin to human health has resulted in the establishment of
consumption advisories of marine and freshwater fish in 44 states in the U.S. and all of the eastern Canadian
provinces. Maine is one of only two states with a blanket fish consumption advisory for all inland waters.
Given the policy’s economic and social costs, the Maine Department of Environmental Protection (DEP) is
interested in supporting scientific research to better understand mercury dynamics in watersheds, which would
allow consideration of alternative approaches. We have analyzed the existing DEP and UMaine lake databases
for Hg and other physical, chemical, and biological parameters that control fish Hg bioaccumulation, with a
goal to identify mechanistic relationships, formulate testable hypotheses, and prioritize future empirical and
statistical analyses that will be used as a basis for revising the current fish advisory. Our statistical analysis to
date shows that a) trophic status, b) dissolved organic carbon (DOC) concentration, and c) lake depth explain
most of variability in fish Hg concentration in lakes across Maine. However, there are gaps in the existing data
and, thus, there is a need to collect more data to better explain the observed variability in fish Hg
concentration in Maine lakes. We propose to analyze relevant parameters in fish, sediment, and water column
from 100 targeted lakes that cover a wide continuum of conditions within each of the above three indicators.
Analysis of data from these lakes will allow us to rigorously assess the factors that control fish Hg
bioaccumulation in Maine lakes, and likely other regions, and formulate a scientific basis for the refinement of
fish consumption advisories to exempt lakes where Hg is unlikely to bioaccumulate.
Aria Amirbahman, Ph.D., P.E.
Professor of Environmental Engineering
Department of Civil and Environmental Engineering
University of Maine, Orono, ME 04469