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Chemical and Physical Controls on Mercury Source Signatures in Stream Fish from the Northeastern United States
journal contribution
posted on 2019-08-20, 13:33 authored by Sarah E. Janssen, Karen Riva-Murray, John F. DeWild, Jacob M. Ogorek, Michael T. Tate, Peter C. Van Metre, David P. Krabbenhoft, James F. ColesStreams
in the northeastern U.S. receive mercury (Hg) in varying
proportions from atmospheric deposition and legacy point sources,
making it difficult to attribute shifts in fish concentrations directly
back to changes in Hg source management. Mercury stable isotope tracers
were utilized to relate sources of Hg to co-located fish and bed sediments
from 23 streams across a forested to urban-industrial land-use gradient
within this region. Mass-dependent isotopes (δ202Hg) in prey and game fish at forested sites were depleted (medians
−0.95 and −0.83 ‰, respectively) in comparison
to fish from urban-industrial settings (medians −0.26 and −0.38
‰, respectively); the forested site group also had higher prey
fish Hg concentrations. The separation of Hg isotope signatures in
fish was strongly related to in-stream and watershed land-use indicator
variables. Fish isotopes were strongly correlated with bed sediment
isotopes, but the isotopic offset between the two matrices was variable
due to differing ecosystem-specific drivers controlling the extent
of MeHg formation. The multivariable approach of analyzing watershed
characteristics and stream chemistry reveals that the Hg isotope composition
in fish is linked to current and historic Hg sources in the northeastern
U.S. and can be used to trace bioaccumulated Hg.
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watershed characteristicsisotope tracersNortheastern United States Streamsmultivariable approachHg isotope signaturesPhysical Controls23 streamsfish concentrationsecosystem-specific driversHg sourcesStream FishHg source managementbed sedimentsstream chemistryHg isotope compositionbed sediment isotopesurban-industrial land-use gradientco-located fishMercury Source Signaturesurban-industrial settingsfish isotopesforested site groupprey fish Hg concentrationswatershed land-use indicator variablesgame fishMeHg formationtrace bioaccumulated HgU.Sforested siteslegacy point sources
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