@article{fdi:010048350,
  title = {{M}ercury speciation in a tropical soil association : consequence of gold mining on {H}g distribution in {F}rench {G}uiana},
  author = {{G}u{\'e}dron, {S}. and {G}rangeon, {S}. and {L}anson, {B}. and {G}rimaldi, {M}ichel},
  editor = {},
  language = {{ENG}},
  abstract = {{M}ercury ({H}g) speciation was compared in {F}rench {G}uiana pristine soils and in {H}g-contaminated soils impacted by former(similar to 1950's) gold mining activities which used {H}g for gold amalgamation. {F}our selective extractions were performed on soil samples to assess the fraction of {H}g present as {H}g({II}) and bond to organic matter (extracted by {NH}4{OH} and {KOH}), to amorphous iron oxides (ascorbate) and to soil components other than refractory minerals ({HC}l/{HNO}3). {I}n addition, pyrolysis was used to quantify the content of elemental {H}g in contaminated soils. {X}-ray diffraction ({XRD}) and {X}-ray fluorescence micro-mapping (mu {XRF}) were used in combination to selective extractions to assess the nature of targeted components, the possible overlaps between the different extraction procedures and the spatial correlation between {S}i, {K}, {F}e, {A}u and {H}g. {I}n soil profiles from pristine toposequences, {H}g concentrations (0.01-0.49 mu g.g(-1)) decreased with increasing depth in soil matrix. {H}g concentrations also decreased from ferralsols to acrisols and further to gleysols. {I}n pristine soil matrix, {H}g was mainly associated to the clay-size fraction (<2 mu m) which was mainly constituted of amorphous and crystalline {F}e oxides ({A}l-substituted goethite and hematite), gibbsite and fine organic matter ({OM}), whose relative abundances vary along the soil association. {T}otal {H}g concentration was positively correlated with sulfurs and organic carbon suggesting the association of {H}g with {OM} sulfur-bearing functional groups. {G}leysols were depleted in {H}g because of the prevailing reducing conditions that lead to the dissolution of iron oxides. {I}n the same soil profiles, {H}g concentrations in ferruginous nodules, which make up most of the soil coarse fraction (> 2 mm), were similar to those reported in the pristine soil matrix. {T}hese nodules mainly contained {A}l-substituted hematite and goethite and were especially abundant upslope in ferralsols and acrisols. {G}old-mined gleysols were strongly disorganized by former activities as neither the original structure nor the texture was preserved. {S}oil gramulometry was dominated by gravels, sands and silts. {H}g concentrations (0.09-9.22 mu g.g(-1)) largely exceeded those in pristine soils. mu {XRF} allowed the identification of {A}u-amalgamated {H}g and of elemental {H}g droplets. {P}yrolysis confirmed {H}g to be mainly present in its elemental form in contaminated soils. {S}elective extractions showed additional minor contributions of {H}g({II}) associated to {OM}, and to {A}l or {F}e oxides. {T}he combination of selective extractions with {XRD} and mu {XRF} data showed that extraction efficiency is strongly dependent on the soil type, and that this efficiency needs to be determined on a soil-by-soil basis for {H}g speciation studies. {KOH} extraction was especially delicate as crystalline and amorphous oxides were extracted together with organic matter.},
  keywords = {{M}ercury ; {T}ropical soils ; {F}rench {G}uiana ; {G}old mining ; {XRD} ; {S}elective ; extraction ; {S}peciation ; {GUYANE} {FANCAISE}},
  booktitle = {},
  journal = {{G}eoderma},
  volume = {153},
  numero = {3-4},
  pages = {331--346},
  ISSN = {0016-7061},
  year = {2009},
  DOI = {10.1016/j.geoderma.2009.08.017},
  URL = {https://www.documentation.ird.fr/hor/fdi:010048350},
}