Isotopic fractionation during the uptake and elimination of inorganic mercury by a marine fish

Isotopic and chemical characteristics of mercury in organs and tissues of fish in a mercury‐polluted lake: Evidence for fractionation of mercury isotopes by physiological processes

“…The disparity between the 2 species and the anomalous isotope signature of the whitefish kidneys are consistent with previously published evidence showing that whitefish have a special physiological mechanism for the elimination of CH 3 Hg þ [9,52]. These results do not accord with previously published reports that Hg isotopes ingested by fish in experiments performed under artificial conditions underwent little or no fractionation by metabolic processes of the fish [44][45][46][47].…”

“…There have been many studies of Hg in general, and CH 3 Hg þ and inorganic Hg in particular, in different body parts of fish in experimental and natural environments [36][37][38][39][40][41][42][43]. In addition, there have been a few experimental studies of Hg isotopes in body parts of fish that were fed Hg-bearing food [44][45][46][47], but only one of these investigations differentiated between the isotope signatures of CH 3 Hg þ and inorganic Hg [46], and none of them included analyses of fish collected from natural waters. The studies either yielded no evidence for isotope fractionation by physiological processes of the fish or revealed measurable MDF during excretion of Hg or metabolic transformation of Hg in the liver but gave no indication that MIF had occurred in the fish.…”

Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers

“…3 ). Since results from previous studies did not support Hg MIF during trophic transfer and in vivo processes 11 12 13 44 45 48 49 50 51 , the observed Δ 199 Hg enrichment with trophic level was attributed to the efficient biomagnification of MHg, the varying percentage in MHg among trophic levels, and the great differences in isotopic signatures between IHg and MHg 2 3 4 9 10 15 16 17 18 . Biotic δ 202 Hg enriched approximately 3% from the sediment to the fish in both lakes, which were much higher than <1.0% in the estuarine ecosystems 15 and <1.5% in the Florida lakes 16 .…”

“…Bergquist and Blum 5 discussed the importance of photochemical reduction in mass dependent (MDF) and independent fractionation (MIF) of aqueous Hg, and suggested to use Hg isotopes to study its biogeochemical pathways. Kwon et al 11 12 and Xu & Wang 13 then studied the isotopic fractionations of different Hg species during feeding experiments, and found no evidence of Hg MIF in either metabolic processes or during trophic transfer, thereby identifying the possibility of tracking sources with Hg isotopes in fish and other biological species. Mercury isotopic compositions in diverse samples such as sediment, soil, snow, and biota from marine, estuarine, freshwater, Arctic, and terrestrial ecosystems were analyzed to identify their multiple external sources, explore MHg exposure pathways, and determine the degree of photoreduction before MHg is incorporated into the trophic webs 6 7 8 9 10 11 12 13 14 15 16 17 18 19 .…”

Methylmercury degradation and exposure pathways in streams and wetlands impacted by historical mining

“…[42][43][44] Fish feeding studies show essentially no isotopic fractionation of MMHg during trophic transfer, [45][46][47][48][49] and therefore the estimated isotopic composition of MMHg provides insight into MMHg biogeochemical transformations in the environment prior to bioaccumulation. For example, changes in Δ 199 Hg values of MMHg have been used to identify spatial changes in the extent of MMHg photodegradation between different environments (streams, forests, etc.).…”