title: Speciation and bioavailability of mercury in sediments impacted by gold mining in Colombia.
abstract: 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.
authors.affiliation: University of Córdoba, Faculty of Basic Sciences, Department of Chemistry, Water, Applied and Environmental Chemistry Group, Laboratory of Toxicology and Environmental Management, Montería, Colombia.
authors.forename: José
authors.initials: J
authors.lastname: Pinedo-Hernández
authors.affiliation: University of Córdoba, Faculty of Basic Sciences, Department of Chemistry, Water, Applied and Environmental Chemistry Group, Laboratory of Toxicology and Environmental Management, Montería, Colombia. Electronic address: jlmarrugon@hotmail.com.
authors.forename: José
authors.initials: J
authors.lastname: Marrugo-Negrete
authors.affiliation: Environmental Chemistry Department, Institute of Environmental Assessment and Water Research, IDÆA-CSIC, E-08034 Barcelona, Spain. Electronic address: sergi.diez@idaea.csic.es.
authors.forename: Sergi
authors.initials: S
authors.lastname: Díez
mesh_terms: D001682:Biological Availability; D005591:Chemical Fractionation; D003105:Colombia; D005744:Gastric Acid / Q000737:chemistry; D019015:Geologic Sediments / Q000032:analysis*; D006046:Gold; D008628:Mercury / Q000032:analysis* / Q000737:chemistry; D008767:Methylmercury Compounds / Q000032:analysis* / Q000737:chemistry; D008906:Mining; D045483:Rivers; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D006046:Gold; D008628:Mercury
keywords: Bioavailability; Fractionation; Gold mining; Mercury; Methylmercury; Sediments