Mass Balance Studies of Mercury and Methyl Mercury in Small Temperate/Boreal Lakes of the Northern Hemisphere

Watras, Carl J.; Morrison, K. A.; Back, Richard C.

doi:10.1007/978-94-009-1780-4_17

Cited by 18 publications

(14 citation statements)

References 31 publications

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“…3b, 4) has been observed in other lakes (Verta et al 1994;Watras et al 1994;Henry et al 1995;Regnell et al 1997;Herrin et al 1998). The main difference between Lake 240 and these other lakes is that there was very little anoxia in the water column of Lake 240.…”

Section: Discussionsupporting

confidence: 63%

“…3b), especially because hypolimnetic samples collected on this date contained abundant phytoplankton particles. Watras et al (1996) also observed an MeHg maximum in their study lake, which was near the top of the anoxic hypolimnion and associated with a particle phase. They concluded that this was due to new MeHg production by methylating bacteria that thrive just below the oxic-anoxic interface.…”

Section: Discussionmentioning

confidence: 68%

“…3b). This could be MeHg that was produced in the hypolimnetic sediments from methylation of inorganic mercury (Ramlal et al 1993) and subsequently diffused across the sediment-water interface, or MeHg released from particles decomposing on the sediment surface (Hurley et al 1994;Watras et al 1996). Regardless of mechanism, water-column MeHg in the hypolimnion was likely from in-lake production because the total water-column accumulation (Table 3) was much greater than external inputs (Table 2).…”

Section: Discussionmentioning

confidence: 99%

“…To date, there have been only a few studies of MeHg fluxes in whole-lake ecosystems (Hultberg et al 1994;Watras et al 1994;Henry et al 1995). Photodegradation of MeHg in lakes (Sellers et al 1996) was unknown at the time of these studies.…”

mentioning

confidence: 99%

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Fluxes of methylmercury to the water column of a drainage lake: The relative importance of internal and external sources

Sellers

Kelly

Rudd³

2001

Limnology & Oceanography

107

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We studied fluxes of methylmercury (MeHg) through a Precambrian Shield lake using a mass balance approach. The primary goal of the study was to determine the importance of various sources of MeHg to the water column of the lake. The relative importance of all sources was: in-lake production ϾϾϾ inflow from a brown-water lake with riparian wetlands ϾϾϾ wet deposition Ͼ inflow from an upstream oligotrophic lake Ͼ direct inflow from uplands surrounding the lake. MeHg accumulated in the hypolimnion of Lake 240 when oxygen was present. Watercolumn sinks for MeHg included photodegradation of MeHg, which was about 3.5 times greater than the loss of MeHg through outflow. At present, there are few studies available on mass balance fluxes of MeHg in lakes, and this is the first study that includes losses of MeHg by photodegradation. The inclusion of photodegradation in this study results in a clear demonstration that in-lake production of MeHg is very important. In drainage lakes, the relative importance of in-lake production versus inflow of MeHg from wetlands will vary according to the extent of wetlands in the drainage basin, as well as the volume of precipitation, which produces runoff and transports MeHg from wetlands to downstream lakes.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Fluxes of methylmercury to the water column of a drainage lake: The relative importance of internal and external sources

Sellers

Kelly

Rudd³

2001

Limnology & Oceanography

107

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“…Evasion, on the other hand, could be a significant flux and might vary among lakes depending on water chemistry and other factors. For example, evasion estimates for a geographically comparable set of Wisconsin lakes range from 7% to 51% of annual Hg deposition Vandal et al 1991;Watras et al 1996), while whole-lake additions of stable 202 Hg in the METAALICUS experiment indicate evasion of about 45% of the isotopic spike (Southworth et al 2007). Add to this the variability among cores caused by sediment focusing (a factor of two) (Engstrom et al 1994), and the comparability of Hg fluxes among sediment cores from 55 lakes might appear problematic.…”

Section: Discussionmentioning

confidence: 99%

History of mercury inputs to Minnesota lakes: Influences of watershed disturbance and localized atmospheric deposition

Engstrom

Balogh

Swain

2007

Limnology & Oceanography

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The history of mercury (Hg) inputs to 55 Minnesota (U.S.A.) lakes was reconstructed from 210 Pb (lead-210)-dated sediment cores to determine if erosion of soils from agriculture and urbanization contributes a significant loading of Hg to lakes, and whether lakes near Hg-emitting facilities receive appreciable local atmospheric deposition. Modern (1994Modern ( -1997 Hg accumulation and Hg flux ratios (modern : preindustrial) increase significantly with the percentage of watershed area under urban or agricultural land-use. Both past and modern Hg accumulation rates are strongly correlated with the flux of total aluminum (Al), a tracer for soil erosion. Modern Hg accumulation rates are substantially higher in the Minneapolis-St. Paul metropolitan area and in agriculturally dominated south-central Minnesota than in the forested northeastern part of the state, largely because of erosional inputs of soil-bound Hg from disturbed catchments. Modern Hg loading from direct atmospheric deposition is also greater in the metropolitan region than in the rural areas of south-central or northeastern Minnesota. However, some of the excess loading to urban lakes may also be a legacy of formerly high Hg deposition to urban watersheds. A decline in local Hg emissions from peak levels in the 1970s coupled with reduced erosional inputs has cut Hg loading to many metro-area lakes by more than half.

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Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species

Lescord

Johnston

Branfireun

et al. 2018

Enviro Toxic and Chemistry

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It is commonly assumed that most (>95%) of the mercury (Hg) found in fish muscle is the toxic form, methylmercury (MeHg), due to its efficient assimilation and retention in biotic tissue. However, this assumption is largely based on studies examining the percentage of MeHg (%MeHg [the fraction of total Hg as MeHg]) in muscle from mostly large-bodied predatory fish; less is known about the %MeHg in smaller bodied individuals or those of different trophic guilds. The present study analyzed MeHg and total Hg concentrations in the muscle of 2 large-bodied piscivores (walleye and northern pike), one large-bodied benthivore (white sucker), and 2 small-bodied forage fish (sculpins and shiners) across a broad size range. We found substantially lower %MeHg than the commonly assumed 95% in several fish (e.g., 17 individuals had <70% MeHg). Muscle %MeHg significantly increased with size and age in all species except walleye, which had significantly higher %MeHg than pike or suckers, particularly in smaller and younger fish (e.g., 18-21% higher at 10 g; 5-11% higher at 500 g). Results of predictive modeling suggest that muscle %MeHg is higher in pelagic-feeding fish and those with lower lipid content, although model results varied significantly among species. According to our findings, total Hg measurement in muscle is not an appropriate proxy for MeHg in smaller fish from all species, an important consideration for future piscine Hg studies and monitoring. Environ Toxicol Chem 2018;37:2682-2691. © 2018 SETAC.

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Mass Balance Studies of Mercury and Methyl Mercury in Small Temperate/Boreal Lakes of the Northern Hemisphere

Cited by 18 publications

References 31 publications

Fluxes of methylmercury to the water column of a drainage lake: The relative importance of internal and external sources

Fluxes of methylmercury to the water column of a drainage lake: The relative importance of internal and external sources

History of mercury inputs to Minnesota lakes: Influences of watershed disturbance and localized atmospheric deposition

Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species

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