FN Archimer Export Format
PT J
TI Mercury dynamics in lake sediments
BT 
AF FEYTE, Stephane
   GOBEIL, Charles
   TESSIER, Andre
   COSSA, Daniel
AS 1:1;2:1;3:1;4:2;
FF 1:;2:;3:;4:PDG-RBE-BE-LBCM;
C1 Univ Quebec, INRS ETE, Quebec City, PQ G1K 9A9, Canada.
   IFREMER, Ctr Mediterranee, F-83507 La Seyne Sur Mer, France.
C2 UNIV QUEBEC, CANADA
   IFREMER, FRANCE
SI TOULON
SE PDG-RBE-BE-LBCM
IN WOS Ifremer jusqu'en 2018
   copubli-int-hors-europe
IF 3.88
TC 37
UR https://archimer.ifremer.fr/doc/00070/18085/15628.pdf
LA English
DT Article
AB Triplicate porewater depth-profiles of pH and concentrations of total Hg (HgT), methylmercury (MeHg), Fe, Mn, sulfate, total sulfide, total zero-valent sulfur, organic C and major ions were determined at two sampling dates in a perennially oxygenated basin and a seasonally anoxic basin from Lake Tantaré, a Canadian Shield lake. The vertical distribution of HgT, MeHg, acid volatile sulfide, total S, Fe, Mn, Al and organic C were also determined in dated sediment cores from the same lake basins and from the deepest site of two other lakes, one also located in the Canadian Shield and the other in the Northeastern part of the Appalachian Mountains. Application of a one-dimensional transport-reaction equation to the dissolved HgT and MeHg profiles constrains the depth intervals (zones) where these species are produced or consumed in the sedimentary column and yields estimates of net reaction rates of HgT or MeHg in each of the zones as well as their fluxes at the sediment–water interface.  Dissolved HgT and MeHg diffused from the overlying water into the sediments, except for MeHg at one of the sampling dates in the perennially oxygenated basin. About 97% and 50% of the MeHg flux to the sediments is presently deposited with settling particles in the perennially oxygenated and seasonally anoxic basins, respectively. Removal of porewater HgT and MeHg occurred at all dates and sampling sites. Comparison of the consumption zones of porewater HgT and MeHg with the profiles of ancillary parameters, coupled with thermodynamic calculations, suggest that pure Hg mineral phases do not form in the sediments, that HgT and MeHg adsorption onto authigenic Fe oxyhydroxides occurs in minor proportions, and that the association of HgT and MeHg to Fe sulfide phases or sulfidized organic matter is possible. Assuming that the net consumption of MeHg in the porewaters was essentially due to demethylation, an apparent first-order rate constant for MeHg demethylation of 0.04–0.8 d−1 was estimated. Production of porewater MeHg occurred only in the perennially oxygenated basin, at sediment depths where SO4 was consumed. Assuming that the net production of porewater MeHg was essentially due to methylation, an apparent first-order rate constant for Hg methylation ranging between 0.006 d−1 and 0.1 d−1 was calculated. These field-derived Hg methylation and MeHg demethylation rate constant values are within the range of those derived from Hg-spiked experiments. We also show that the post-depositional redistribution of total Hg during the early stages of sediment diagenesis is minor and that the solid-phase HgT record can be used to reconstruct the evolution of the anthropogenic HgT deposition.
PY 2012
PD APR
SO Geochimica Et Cosmochimica Acta
SN 0016-7037
PU Pergamon-elsevier Science Ltd
VL 82
UT 000300974500008
BP 92
EP 112
DI 10.1016/j.gca.2011.02.007
ID 18085
ER

EF