Effect of Loading Rate on the Fate of Mercury in Littoral Mesocosms

Orihel, Diane M.; Paterson, Michael; Gilmour, Cynthia C.; Bodaly, R. A.; Blanchfield, Paul J.; Hintelmann, Holger; Harris, R. O.; Rudd, John W. M.

doi:10.1021/es060823+

Cited by 64 publications

(45 citation statements)

References 36 publications

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“…The calculation of relevant numbers for these parameters requires that the quantities of MeHg formed and bioaccumulated in the mesocosms are proportional to the amount of added tracer. This has been convincingly demonstrated in previous lake mesocosm experiments where the loading rate of a Hg II tracer to the water column was varied more than one order of magnitude 38,47 and yielded proportional amounts of formed and bioaccumulated MeHg. We used the BSAF to quantify bioaccumulation in order to facilitate a transparent comparison of accumulation of the different tracers in all the biota species (benthic invertebrates, amphipods and plankton).…”

Section: Discussionsupporting

confidence: 72%

Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota

et al. 2014

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Neurotoxic methylmercury (MeHg) formed from inorganic divalent mercury (Hg II ) accumulates in aquatic biota and remains at high levels worldwide. It is poorly understood to what extent different geochemical Hg pools contribute to these levels. Here we report quantitative data on MeHg formation and bioaccumulation, in mesocosm water-sediment model ecosystems, using five Hg II and MeHg isotope tracers simulating recent Hg inputs to the water phase and Hg stored in sediment as bound to natural organic matter or as metacinnabar. Calculations for an estuarine ecosystem suggest that the chemical speciation of Hg II solid/adsorbed phases control the sediment Hg pool's contribution to MeHg, but that input of MeHg from terrestrial and atmospheric sources bioaccumulates to a substantially greater extent than MeHg formed in situ in sediment. Our findings emphasize the importance of MeHg loadings from catchment runoff to MeHg content in estuarine biota and we suggest that this contribution has been underestimated.

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Section: Discussionsupporting

confidence: 72%

Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota

et al. 2014

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“…3). Previous studies have shown that, on the short term, there is a proportional response of rates of production (24,25) and bioaccumulation (26) of new methylmercury to new additions of inorganic mercury. However, when new mercury is added to a system that already contains older inorganic mercury, both the new and older mercury contribute to methylation (although not necessarily equally), so on the short term the overall rate of mercury methylation (new ϩ old) does not respond in direct proportion to the amount of new mercury added.…”

Section: Resultsmentioning

confidence: 99%

Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

Harris

Rudd²,

Amyot

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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409

333

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Methylmercury contamination of fisheries from centuries of industrial atmospheric emissions negatively impacts humans and wildlife worldwide. The response of fish methylmercury concentrations to changes in mercury deposition has been difficult to establish because sediments/soils contain large pools of historical contamination, and many factors in addition to deposition affect fish mercury. To test directly the response of fish contamination to changing mercury deposition, we conducted a whole-ecosystem experiment, increasing the mercury load to a lake and its watershed by the addition of enriched stable mercury isotopes. The isotopes allowed us to distinguish between experimentally applied mercury and mercury already present in the ecosystem and to examine bioaccumulation of mercury deposited to different parts of the watershed. Fish methylmercury concentrations responded rapidly to changes in mercury deposition over the first 3 years of study. Essentially all of the increase in fish methylmercury concentrations came from mercury deposited directly to the lake surface. In contrast, <1% of the mercury isotope deposited to the watershed was exported to the lake. Steady state was not reached within 3 years. Lake mercury isotope concentrations were still rising in lake biota, and watershed mercury isotope exports to the lake were increasing slowly. Therefore, we predict that mercury emissions reductions will yield rapid (years) reductions in fish methylmercury concentrations and will yield concomitant reductions in risk. However, a full response will be delayed by the gradual export of mercury stored in watersheds. The rate of response will vary among lakes depending on the relative surface areas of water and watershed.bioaccumulation ͉ mercury methylation ͉ stable isotopes ͉ whole-ecosystem experimentation ͉ methylmercury

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“…4). By comparison, Butler et al (2008) , and mosquitoes (Hammerschmidt and Fitzgerald 2005), and directly with MeHg production (Orihel et al 2006;). reported that Hg wet deposition between 1992 and 2004 accounted for about two-thirds of Hg variation in largemouth bass between 1990 and 1995. suggested that reductions in anthropogenic Hg emissions could result in proportionally lower levels of Hg concentrations in fish, but that the magnitude and timing of the response are unclear.…”

Section: Comparison To Wet Depositionmentioning

confidence: 99%

Mercury trends in fish from rivers and lakes in the United States, 1969–2005

Chalmers

Argue

Brigham

et al. 2010

Environ Monit Assess

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A national dataset on concentrations of mercury in fish, compiled mainly from state and federal monitoring programs, was used to evaluate trends in mercury (Hg) in fish from US rivers and lakes. Trends were analyzed on data aggregated by site and by state, using samples of the same fish species and tissue type, and using fish (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) were compared to wet Hg deposition data from the Mercury Deposition Network (MDN) over the same period. Downward trends in Hg concentrations in fish from data collected during 1969-1987 exceeded upward trends by a ratio of 6 to 1. Declining Hg accumulation rates in sediment and peat cores reported by many studies during the 1970s and 1980s correspond with the period when the most downward trends in fish Hg concentrations occurred. Downward Hg trends in both sediment cores and fish were also consistent with the implementation of stricter regulatory controls of direct releases of Hg to the atmosphere and surface waters during the same period. The southeastern USA had more upward Hg trends in fish than other regions for both site and state aggregated data. Upward Hg trends in fish from the southeastern USA were associated with increases in wet deposition in the region and may be attributed to a greater influence of global atmospheric Hg emissions in the southeastern USA. No significant trends were found in 62% of the fish species from six states from 1996 to 2005. A lack of Hg trends in fish in the more recent data was consistent with the lack of trends in wet Hg deposition at MDN 176 Environ Monit Assess (2011) 175:175-191 sites and with relatively constant global emissions during the same time period. Although few significant trends were observed in the more recent Hg concentrations in fish, it is anticipated that Hg concentrations in fish will respond to changes in atmospheric Hg deposition, however, the magnitude and timing of the response is uncertain.

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Effect of Loading Rate on the Fate of Mercury in Littoral Mesocosms

Cited by 64 publications

References 36 publications

Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota

Differentiated availability of geochemical mercury pools controls methylmercury levels in estuarine sediment and biota

Whole-ecosystem study shows rapid fish-mercury response to changes in mercury deposition

Mercury trends in fish from rivers and lakes in the United States, 1969–2005

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