%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Guédron, Stéphane
%A Arnouroux, D.
%A Tessier, E.
%A Grirnaldi, C.
%A Barre, J.
%A Berail, S.
%A Perrot, V.
%A Grimaldi, Michel
%T Mercury isotopic fractionation during pedogenesis in a tropical forest soil catena (French Guiana) : deciphering the impact of historical gold mining
%D 2018
%L fdi:010074390
%G ENG
%J Environmental Science and Technology
%@ 0013-936X
%K GUYANE FRANCAISE ; AMAZONIE ; ZONE TROPICALE
%M ISI:000447816100014
%N 20
%P 11573-11582
%R 10.1021/acs.est.8b02186
%U https://www.documentation.ird.fr/hor/fdi:010074390
%> https://www.documentation.ird.fr/intranet/publi/2018/11/010074390.pdf
%V 52
%W Horizon (IRD)
%X We used natural mercury (Hg) stable isotopes to investigate the Hg cycle in a rainforest soil catena (French Guiana) partially gold-mined during the early 1950s. Litterfall showed homogeneous Delta Hg-199 values [-0.18 +/- 0.05 parts per thousand, i.e., a modern gaseous elemental Hg (GEM) isotopic signature]. After litter decomposition, Hg bound to organic matter (OM) is mixed with Hg from pristine (-0.55 +/- 0.22 parts per thousand) or gold-mined (-0.09 +/- 0.16 parts per thousand) mineral materials. Negative Delta Hg-199 values in deep pristine mineral horizons (-0.60 +/- 0.16700) suggest the transfer of Hg bound to dissolved OM depleted in odd isotopes due to mass-independent fractionation during Hg abiotic reduction. Perennial palm tree leaves collected above gold-mined and pristine soil recorded contrasting Delta Hg-199 signatures likely resulting from GEM re-emission processes from soils and leaf surfaces. Upslope, soil delta Hg-202 signatures showed a negative shift (epsilon similar to -1 parts per thousand) with depth attributed to mass-dependent fractionation during Hg sorption and complexation onto iron oxides and dissolved OM. Downslope, higher delta Hg-202 values in soils resulted from hydromorphy [lower humification, greater Hg(II) reduction, etc.]. The unique Hg isotopic signatures of Amazonian soils probably result in multistep fractionation processes during pedogenesis (millions of years) and in a potentially different Hg isotopic signature of preanthropogenic background GEM.
%$ 068 ; 038 ; 082