Goix S., Maurice Laurence, Laffont L., Rinaldo R., Lagane Christelle, Chmeleff J., Menges J., Heimburger L. E., Maury-Brachet R., Sonke J. E. (2019). Quantifying the impacts of artisanal gold mining on a tropical river system using mercury isotopes. Chemosphere, 219, p. 684-694. ISSN 0045-6535.
Titre du document
Quantifying the impacts of artisanal gold mining on a tropical river system using mercury isotopes
Année de publication
2019
Auteurs
Goix S., Maurice Laurence, Laffont L., Rinaldo R., Lagane Christelle, Chmeleff J., Menges J., Heimburger L. E., Maury-Brachet R., Sonke J. E.
Source
Chemosphere, 2019,
219, p. 684-694 ISSN 0045-6535
In some locations, artisanal and small-scale gold-mining (ASGM) represents a significant source of anthropogenic Hg to freshwater environments. The Hg released from ASGM can contaminate aquatic fauna and pose health risks to downstream populations. Total Hg (THg) concentrations, speciation, and isotopic compositions were analyzed in water, suspended particulate matter, soil, and bottom sediment samples from pristine areas and in places of active and legacy gold mining along the Oyapock River (French Guiana) and its tributaries. Mass-independent fractionation (MIF) of even Hg isotopes in top soils (Delta Hg-200 = -0.06 +/- 0.02 parts per thousand, n = 10) implied the uptake of gaseous Hg(0) by plants, rather than wet deposition, as the primary Hg source. Odd isotope MIF was lower in deep soils (Delta Hg-199 = -0.75 +/- 0.03 parts per thousand, n = 7) than in top soils (Delta Hg-199 = -0.55 +/- 0.15 parts per thousand, n = 3). This variation could be attributed to differences between the isotopic signatures of modern and pre-industrial atmospheric Hg. Combining a Hg-isotope binary mixing model with a multiple linear regression based on physicochemical parameters measured in the sediment samples, we determined that active mined creek sediments are contaminated by ASGM activities, with up to 78% of THg being anthropogenic. Of this anthropogenic Hg, more than half (66-74%) originates from liquid Hg(0) that is released during ASGM. The remaining anthropogenic Hg comes from the ASGM-driven erosion of Hg-rich soils into the river. The isotope signatures of anthropogenic Hg in bottom sediments were no longer traceable in formerly mined rivers and creeks.
Plan de classement
Pollution [038]
;
Hydrologie [062]
;
Géologie et formations superficielles [064]
Description Géographique
GUYANE FRANCAISE
Localisation
Fonds IRD [F B010075107]
Identifiant IRD
fdi:010075107
