Absence of fractionation of mercury isotopes during trophic transfer of methylmercury to freshwater fish in captivity

Sae Yun Kwon, Joel D. Blum, Michael J. Carvan, Niladri Basu, Jessica A. Head, Charles P. Madenjian, Solomon R. David

Research output: Contribution to journalArticlepeer-review

112 Scopus citations

Abstract

We performed two controlled experiments to determine the amount of mass-dependent and mass-independent fractionation (MDF and MIF) of methylmercury (MeHg) during trophic transfer into fish. In experiment 1, juvenile yellow perch (Perca flavescens) were raised in captivity on commercial food pellets and then their diet was either maintained on unamended food pellets (0.1 μg/g MeHg) or was switched to food pellets with 1.0 μg/g or 4.0 μg/g of added MeHg, for a period of 2 months. The difference in λ202Hg (MDF) and δ199Hg (MIF) between fish tissues and food pellets with added MeHg was within the analytical uncertainty (λ202Hg, 0.07 %; δ199Hg, 0.06 %), indicating no isotope fractionation. In experiment 2, lake trout (Salvelinus namaycush) were raised in captivity on food pellets and then shifted to a diet of bloater (Coregonus hoyi) for 6 months. The λ202Hg and δ199Hg of the lake trout equaled the isotopic composition of the bloater after 6 months, reflecting reequilibration of the Hg isotopic composition of the fish to new food sources and a lack of isotope fractionation during trophic transfer. We suggest that the stable Hg isotope ratios in fish can be used to trace environmental sources of Hg in aquatic ecosystems.

Original languageEnglish (US)
Pages (from-to)7527-7534
Number of pages8
JournalEnvironmental Science and Technology
Volume46
Issue number14
DOIs
StatePublished - Jul 17 2012
Externally publishedYes

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