4.7 Article

Speciation and bioavailability of mercury in sediments impacted by gold mining in Colombia

Journal

CHEMOSPHERE
Volume 119, Issue -, Pages 1289-1295

Publisher

PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2014.09.044

Keywords

Mercury; Methylmercury; Sediments; Fractionation; Bioavailability; Gold mining

Funding

  1. University of Cordoba
  2. Administrative Department of Science, Technology and Innovation, COLCIENCIAS, Bogota, Colombia [1112-569-35214]
  3. Monteria-Colombia

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Mercury (Hg) speciation and bioavailability were studied in surface sediments affected by artisanal and small-scale gold mining (ASGM) in the Mojana region of Colombia. The results demonstrated higher levels in sampling stations that receive water streams carrying Hg from mining areas. The T-Hg concentrations were slightly elevated with values between 196.2 and 1187.6 ng g(-1) dry weight (dw) (mean 524.2 +/- 256.8 ng g(-1) dw). The MeHg concentrations were significantly correlated with the T-Hg and organic matter (OM) and represent between 1.7% and 3.6% (mean: 2.6%) of the T-Hg. A five-step sequential extraction procedure shown that most of T-Hg in sediments occur primarily as organically bound Hg (Hg-o), which constitutes 48.4% of the T-Hg, followed by elemental Hg fraction (Hg-e) bound to amorphous compounds, such as Fe/Mn oxides with 26.5%, and the fraction bound to sulfur (Hg-s), which constitutes 18.7%. Exchangeable Hg (Hg-w; water-soluble Hg and stomach acid soluble mercury; Hg-h) represents between 1.7% and 4.7%. These fractions constitute a low percentage but exhibit a high level of risk when entering the water column, and they can bioaccumulate in organisms. The significant relationship between OM, T-Hg and MeHg suggests an important role in the control of the distribution, mobility and bioavailability of the Hg in the sediments. (C) 2014 Elsevier Ltd. All rights reserved.

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