Chronic exposure of Lactuca sativa to a mine-contaminated soil from La Planta-Marayes (Argentina): I. Bioavailability of Zn, Cu and Pb.Congreso

CALABRÓ MARIA ROSA; ROQUEIRO GONZALO; TAPIA, RAÚL.; MONETTA PABLO; CRESPO DIANA; BARGIELA, MARTHA; YOUNG, BRIAN JONATHAN

Sao Pablo

Congreso; Congreso SETAC-L; 2017

The unplanned disposal of raw mine residues causes environmental pollution due to the release ofmetals, rocks and chemicals. The bioavailability of metals causes the adverse effects on organisms.The aim of this study was to determine the bioavailable concentrations of Zn, Cu and Pb in acontaminated soil with residues from an abandoned gold mine in La Planta-Marayes. Two sampleswere taken from the first 20 cm of soil in La Planta town: A contaminated soil with mine residues(Site 1), and one located to 2 Km which was used as reference (Site 2). A completely randomexperimental design consisted of 7 treatments: mixtures of soil from Site 1 and 2 (dw/dw) in therange of 0 to 100%.Three replicates per treatment were used. The hotplate aqua regia method wasused to extract the pseudo total fraction (PF). Mobilizable and soluble fractions (MF and SF) wereextracted using DTPA and deionized water, respectively. Metal concentrations were quantifiedusing an atomic absorption spectrophotometer. Also pH and electrical conductivity (EC) weremeasured in the PF and SF. Concentrations of metals in PF were compared with pre-anthropogenicconcentrations and soil quality guidelines to determine pollution. Also Geoaccumulation Index,Contamination Factor and the Contamination Degree were determined. Site 2 was characterized bya basic pH (8.80 ± 0.09) and low salinity (EC = 0.85 ± 0.04 mS cm -1 ), whereas Site 1 wascharacterized by an acid pH (2.57 ± 0.03) and high salinity (EC = 7.26 ± 1.50 mS cm -1 ). Resultsshowed the highest metal concentration in PF and lowest in the bioavailable fractions (MF and SF).High metal concentrations and low values of pH in PF were associated with an increase of mineresidues, while no differences in EC were observed. The percentage of metal extracted in MFshowed a concentration-dependent decrease of Zn and Pb, whereas an increase of Cu. Aconcentration-dependent increase was observed in SF of Zn and Pb (p<0.05). The comparison withsoil quality guidelines and pre-anthropogenic concentrations showed the usefulness of Site 2 as areference site. The results indicated that Site 1 is heavily contaminated at least with Zn (9975 ±696.87 µg g -1 ), Cu (457.17 ± 3.21 µg g -1 ) and Pb (1608.33 ± 50.52 µg g -1 ). A remediation proposalfor this site is suggested.