Influence of Dissolved Organic Carbon, pH, and Microbial Respiration Rates on Mercury Methylation and Demethylation in Lake Water

1992 ◽  
Vol 49 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Brenda M. Miskimmin ◽  
John W. M. Rudd ◽  
Carol A. Kelly
Keyword(s):  
Lake Water ◽  
Methyl Mercury ◽  
Microbial Respiration ◽  
Inorganic Mercury ◽  
Mercury Methylation ◽  
Ph Change ◽  
Respiration Rates ◽  
Terrestrial Inputs ◽  
High Mercury ◽  
High Fish

Effects of changes in DOC concentrations, pH, and microbial respiration rates on specific rates of mercury methylation and demethylation in lake water were studied using radioisotopic techniques. Increased concentrations of DOC resulted in decreased specific rates of net methylation, possibly as a result of complexation of inorganic mercury with DOC. A reduction in pH from 7.0 to 5.0 had the greatest effect, causing large to moderate increases in net methylation rate at both low and high DOC concentrations (500–2600 μM). Rates of respiration (indicative of general rates of microbial activity), which were insensitive to pH change over the range tested (5.0–7.0), had the smallest effect on net methyl mercury production rates. We propose the following explanations for three situations in which high mercury concentrations are commonly found in fish. (1) in acidified dilute clear-water lakes, high fish mercury concentrations may be a result of enhanced in-lake methylation; (2) in brown-water circumneutral lakes, where in-lake methylation is inhibited by high DOC concentrations, terrestrial inputs of methyl mercury may be most important; and (3) in brown-water, low-pH lakes, both in-lake and terrestrial sources of methyl mercury may contribute to elevated mercury concentrations in fish.

scholarly journals Why the English–Wabigoon river system is still polluted by mercury 57 years after its contamination

FACETS ◽  
2021 ◽  
Vol 6 ◽  
pp. 2002-2027
Author(s):  
John W.M. Rudd ◽  
Carol A. Kelly ◽  
Patricia Sellers ◽  
Robert J. Flett ◽  
Bruce E. Townsend
Keyword(s):  
Surface Sediment ◽  
Methyl Mercury ◽  
Total Mercury ◽  
Inorganic Mercury ◽  
River System ◽  
Lake Surface ◽  
Riverbank Erosion ◽  
Plant Site ◽  
High Mercury ◽  
Mercury Production

Between 1962 and 1969, 10 tonnes of mercury were discharged from a chlor-alkali plant in Dryden, Ontario, to the English–Wabigoon River. Present-day fish mercury concentrations are amongst the highest recorded in Canada. In 2017, the Grassy Narrows Science Team found no evidence of ongoing discharges from the plant site to the river water, even though large quantities of mercury remain at the site. Instead, our data suggest that ongoing erosion of high mercury particles by the river, as it meanders through contaminated floodplains, is responsible for present-day transport of mercury to Clay Lake and to Ball Lake, located 154 km downstream. In Clay Lake, surface sediment total mercury concentrations and inflow water concentrations are still about 15 times above background (86 km downstream), and in Ball Lake mercury concentrations in sediments appeared to be still increasing. The remobilization of legacy inorganic mercury from riverbank erosion between Dryden and Clay Lake stimulates methyl mercury production there, in Clay Lake, and in Ball Lake. The large quantities of methyl mercury produced between Dryden and Clay Lake are mostly dissolved in water and are swept downstream, elevating concentrations in water and biota throughout the system. Several options for remediating the ongoing contamination are discussed.

The Effect of pH on Methyl Mercury Production and Decomposition in Lake Sediments

1985 ◽  
Vol 42 (4) ◽  
pp. 685-692 ◽  
Author(s):  
P. S. Ramial ◽  
John W. M Rudd ◽  
Akira Furutam ◽  
Luying Xun
Keyword(s):  
Lake Sediments ◽  
Methyl Mercury ◽  
Inorganic Mercury ◽  
Mercury Methylation ◽  
Surficial Sediments ◽  
Experimental Lakes Area ◽  
Effect Of Ph ◽  
Northwestern Ontario ◽  
Acidified Lakes ◽  
Mercury Production

Mercury methylation was measured in surficial sediments taken from unacidified and experimentally acidified lakes in the Experimental Lakes Area, northwestern Ontario. A reduction in the pH of sediments lowered the rate of 203Hg methylation. Methylation was undetectable at pH <5.0. This decrease in mercury methylation was probably related to a shortage of available inorganic mercury when the pH of the sediment porewater was reduced. Below pH 6.0, inorganic mercury concentrations in porewater, measured with 203Hg, were reduced to less than 20% of that found at unaltered pH. A comparison of methylation and demethylation rates was made at various pH's. The rate of demethylation decreased to a lesser extent than methylation as the pH was lowered. This research indicates that enhanced mercury methylation in the sediment is not responsible for the observed increase in mercury levels in fish from acidified lakes.

scholarly journals Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

2021 ◽  
Author(s):  
Jon R. Hawkings ◽  
Benjamin S. Linhoff ◽  
Jemma L. Wadham ◽  
Marek Stibal ◽  
Carl H. Lamborg ◽  
...  
Keyword(s):  
Natural Waters ◽  
Inorganic Mercury ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Annual Runoff ◽  
Arctic Ecosystems ◽  
High Mercury ◽  
Southwestern Margin ◽  
High Concentrations ◽  
Dissolved Mercury

AbstractThe Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

scholarly journals Determination of methyl mercury and total mercury in sediment samples collected from canals in HoChiMinh city

2016 ◽  
Vol 19 (4) ◽  
pp. 123-136
Author(s):  
Hien Thai Hoang ◽  
Dong Van Nguyen
Keyword(s):  
Reference Material ◽  
Analytical Method ◽  
Methyl Mercury ◽  
Total Mercury ◽  
Inorganic Mercury ◽  
Absorption Spectrometry ◽  
Internal Reference ◽  
Atomic Fluorescence ◽  
Sediment Samples ◽  
Cold Vapour

In this study, the analysis of methyl mercury (MeHg) and total mercury (T-Hg) was studied using gas chromatographic separation/atomic fluorescence spectrometric detection and cold vapour atomic absorption spectrometry respectively. MeHg was extracted from sediment matrix using HNO3/KCl/CuSO4 into dichloromethane followed ethylation with NaB(C2H5)4 in hexane. Total mercury was digested using three different procedures: EPA 245.1, AOAC 971.21 and our proposed one. The reliability of the analytical method for MeHg was evaluated by the use of the certified reference material ERM CC-580. In addition, the analytical method for total merury was evaluated using a fresh water sediment as an internal reference material, spiked with inorganic mercury, methyl mercury and phenyl mercury. The method detection limits for MeHg and total mercury were 0.08 and 0.15 ng/g (as Hg), respectively. The established analytical methods were applied to analyse MeHg and total mercury in sediment samples collected from canals and rivers in Hochiminh City. The concentrations of methyl mercury and total mercury in sediment samples were 0.08–2.87 ng/g và 14 – 623 ng/g (as Hg, dw). [MeHg]/Σ[Hg] respectirely were in a range of 0.1–2.3 %, which was in good agreement with the published ratios in sediment samples. A good correlation between the concentration of MeHg with total mercury and total organic carbon contents in the studied sediment samples was found.

Greenhouse Characterization of Inorganic Mercury, Methyl Mercury and Ethyl Mercury Migration and Transformation in Indian Mustard and Chinese Pakchoi

2021 ◽  
pp. 1-15
Author(s):  
Wen Sun ◽  
Yuyan Zhao ◽  
Zeyu Zhang ◽  
Bing Li ◽  
Zhenghe Li ◽  
...  
Keyword(s):  
Methyl Mercury ◽  
Inorganic Mercury ◽  
Indian Mustard ◽  
Ethyl Mercury

METHYL MERCURY AND INORGANIC MERCURY: UPTAKE, DISTRIBUTION, AND EFFECT ON OSMOREGULATORY MECHANISMS IN FISHES

1974 ◽  
pp. 101-122 ◽  
Author(s):  
J. LARRY RENFRO ◽  
BODIL SCHMIDT-NIELSEN ◽  
DAVID MILLER ◽  
DALE BENOS ◽  
JONATHAN ALLEN
Keyword(s):  
Methyl Mercury ◽  
Inorganic Mercury ◽  
Mercury Uptake

scholarly journals Mercury Methylation and Demethylation in Anoxic Lake Sediments and by Strictly Anaerobic Bacteria

1998 ◽  
Vol 64 (3) ◽  
pp. 1013-1017 ◽  
Author(s):  
K.-R. Pak ◽  
R. Bartha
Keyword(s):  
Organic Matter ◽  
Anaerobic Bacteria ◽  
Mercury Methylation ◽  
Strictly Anaerobic ◽  
Anoxic Sediment ◽  
Acetogenic Bacteria ◽  
High Potentials ◽  
High Mercury ◽  
Pure Cultures ◽  
Sediment Ph

ABSTRACT After spiking anoxic sediment slurries of three acidic oligotrophic lakes with either HgCl2 at 1.0 μg/ml or CH3HgI at 0.1 μg/ml, both mercury methylation and demethylation rates were measured. High mercury methylation potentials were accompanied by high demethylation potentials in the same sediment. These high potentials correlated positively with the concentrations of organic matter and dissolved sulfate in the sediment and with mercury levels in fish. Adjustment of the acidic sediment pH to neutrality failed to influence either the methylation or the demethylation rate of mercury. The opposing methylation and demethylation processes converged to establish similar Hg2+-CH3Hg+equilibria in all three sediments. Because of their metabolic dominance in anoxic sediments, mercury methylation and demethylation in pure cultures of sulfidogenic, methanogenic, and acetogenic bacteria were also measured. Sulfidogens both methylated and demethylated mercury, but the methanogen tested only catalyzed demethylation and the acetogen neither methylated nor demethylated mercury.

Total Mercury, Inorganic Mercury and Methyl Mercury Determination in Red Wine

2011 ◽  
Vol 5 (3) ◽  
pp. 505-511 ◽  
Author(s):  
Valderi Luiz Dressler ◽  
Clarissa Marques Moreira Santos ◽  
Fabiane Goldschmidt Antes ◽  
Fabrina Regia Stum Bentlin ◽  
Dirce Pozebon ◽  
...  
Keyword(s):  
Methyl Mercury ◽  
Total Mercury ◽  
Red Wine ◽  
Inorganic Mercury ◽  
Mercury Determination

Determination of Methyl Mercury in Fish by Flameless Atomic Absorption Spectroscopy and Comparison with an Acid Digestion Method for Total Mercury

1976 ◽  
Vol 59 (1) ◽  
pp. 153-157
Author(s):  
Jurgen L Kacprzak ◽  
Ramon Chvojka
Keyword(s):  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Methyl Mercury ◽  
Total Mercury ◽  
Inorganic Mercury ◽  
Flameless Atomic Absorption ◽  
Flameless Atomic Absorption Spectroscopy ◽  
The Difference

Abstract A method for the concurrent determination of methyl mercury and inorganic mercury by flameless atomic absorption spectroscopy (AAS) is described. Fifty-seven samples of juvenile black marlin fish were analyzed for inorganic and methyl mercury, and total mercury was calculated by addition of the 2 values. The sensitivity of the method was estimated to be 0.029 μg for inorganic mercury and 0.033 μg for methyl mercury. The detection limit of the method was about 0.02 μg inorganic mercury or methyl mercury and the error of the method was found not to exceed 10% for samples giving about 10% deflection on the absorbance scale. Samples from the same fish were analyzed by a commonly accepted flameless AAS method for the determination of total mercury. When the results for total mercury from the 2 methods were statistically compared, using a paired t-test, the difference between the results obtained by the 2 methods was found to be insignificant at the 95% confidence level.

The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.)

2017 ◽  
Vol 223 ◽  
pp. 11-18 ◽  
Author(s):  
Xiaohang Xu ◽  
Bo Meng ◽  
Chao Zhang ◽  
Xinbin Feng ◽  
Chunhao Gu ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Power Plant ◽  
Methyl Mercury ◽  
Oryza Sativa L ◽  
Inorganic Mercury ◽  
Mercury Distribution ◽  
Local Impact
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