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Mercury methylation in the hypolimnetic waters of lakes with and without connection to wetlands in northern Wisconsin

Eckley, CS; Watras, CJ; Hintelmann, H; Morrison, K; Kent, AD and Regnell, Olof LU (2005) In Canadian Journal of Fisheries and Aquatic Sciences 62(2). p.400-411
Abstract
Rates of Hg methylation and demethylation were measured in anoxic hypolimnetic waters of two pristine Wisconsin lakes using stable isotopes of Hg as tracers. One of the lakes is a clear-water seepage lake situated in sandy terrain with minimal wetland influence. The other is a dark-water lake receiving channelized inputs from a relatively large terrestrial wetland. Methyl mercury (MeHg) accumulated in the anoxic hypolimnia of both lakes during summer stratification, reaching concentrations of 0.8 ng center dot L-1 in the clear-water lake and 5 ng center dot L-1 in the dark-water lake. The stable isotopic assays indicated that rate constants of Hg-(II) methylation (K-m) ranged from 0.01 to 0.04 center dot day(-1) in the clear-water lake and... (More)
Rates of Hg methylation and demethylation were measured in anoxic hypolimnetic waters of two pristine Wisconsin lakes using stable isotopes of Hg as tracers. One of the lakes is a clear-water seepage lake situated in sandy terrain with minimal wetland influence. The other is a dark-water lake receiving channelized inputs from a relatively large terrestrial wetland. Methyl mercury (MeHg) accumulated in the anoxic hypolimnia of both lakes during summer stratification, reaching concentrations of 0.8 ng center dot L-1 in the clear-water lake and 5 ng center dot L-1 in the dark-water lake. The stable isotopic assays indicated that rate constants of Hg-(II) methylation (K-m) ranged from 0.01 to 0.04 center dot day(-1) in the clear-water lake and from 0.01 to 0.09 center dot day(-1) in the dark-water lake, depending on the depth stratum. On average, K-m was threefold greater in the dark-water lake. Hypolimnetic demethylation rate constants (K-dm) averaged 0.03 center dot day(-1) in the clear-water lake and 0.05 center dot day(-1) in the dark-water lake. These methylation rates were sufficient to account for the observed accumulation of MeHg in hypolimnetic water during summer in both lakes. Despite substantial export of MeHg from the wetland to the dark-water lake, our study indicates that in-lake production and decomposition of MeHg dominated the MeHg cycle in both lakes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Canadian Journal of Fisheries and Aquatic Sciences
volume
62
issue
2
pages
400 - 411
publisher
National Research Council Canada
external identifiers
  • wos:000228083800015
  • scopus:21244456473
ISSN
1205-7533
DOI
10.1139/F04-205
language
English
LU publication?
yes
id
b1cc0efe-9f1e-495f-9b0b-979d6a2556ac (old id 146156)
alternative location
http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_abst_e?cjfas_f04-205_62_ns_nf_cjfas2-05
date added to LUP
2007-06-27 09:13:39
date last changed
2017-09-10 03:48:27
@article{b1cc0efe-9f1e-495f-9b0b-979d6a2556ac,
  abstract     = {Rates of Hg methylation and demethylation were measured in anoxic hypolimnetic waters of two pristine Wisconsin lakes using stable isotopes of Hg as tracers. One of the lakes is a clear-water seepage lake situated in sandy terrain with minimal wetland influence. The other is a dark-water lake receiving channelized inputs from a relatively large terrestrial wetland. Methyl mercury (MeHg) accumulated in the anoxic hypolimnia of both lakes during summer stratification, reaching concentrations of 0.8 ng center dot L-1 in the clear-water lake and 5 ng center dot L-1 in the dark-water lake. The stable isotopic assays indicated that rate constants of Hg-(II) methylation (K-m) ranged from 0.01 to 0.04 center dot day(-1) in the clear-water lake and from 0.01 to 0.09 center dot day(-1) in the dark-water lake, depending on the depth stratum. On average, K-m was threefold greater in the dark-water lake. Hypolimnetic demethylation rate constants (K-dm) averaged 0.03 center dot day(-1) in the clear-water lake and 0.05 center dot day(-1) in the dark-water lake. These methylation rates were sufficient to account for the observed accumulation of MeHg in hypolimnetic water during summer in both lakes. Despite substantial export of MeHg from the wetland to the dark-water lake, our study indicates that in-lake production and decomposition of MeHg dominated the MeHg cycle in both lakes.},
  author       = {Eckley, CS and Watras, CJ and Hintelmann, H and Morrison, K and Kent, AD and Regnell, Olof},
  issn         = {1205-7533},
  language     = {eng},
  number       = {2},
  pages        = {400--411},
  publisher    = {National Research Council Canada},
  series       = {Canadian Journal of Fisheries and Aquatic Sciences},
  title        = {Mercury methylation in the hypolimnetic waters of lakes with and without connection to wetlands in northern Wisconsin},
  url          = {http://dx.doi.org/10.1139/F04-205},
  volume       = {62},
  year         = {2005},
}