2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 11: Recycling & Environmental
| Editors: | Kongoli F, Havlik T, Pagnanelli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 410 pages |
| ISBN: | 978-1-987820-34-8 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Bioaccessibility Study Of As, Cd and Pb in Impacted Soils with Mining Waste: An Evaluation of the Mexican Standard Method
Margarita Gutierrez-Ruiz1; Thalia Garcia Rodriguez2; Agueda Ceniceros1; Francisco Romero1;1UNAM, Mexico, Mexico; 2CHEMISTRY SCHOOL, UNAM, Mexico, Mexico;
Type of Paper: Regular
Id Paper: 384
Topic: 10
Abstract:
The bio-accessible fractions of As, Cd and Pb were measured to calculate the soil cleanup levels in a terrain where metallurgical plants and an As2O3 plant had been operating for almost a century. The Mexican environmental regulation method (NOM-147) that only includes the gastric phase was tested comparing it with the PBET method that includes gastric and intestinal phases (Ruby et al., 1996). General parameters and total concentrations of As, Cd, Pb, Cu, Ni, Ag, Tl and V were measured. The soluble fraction of the As, Cd and Pb was determined and the speciation of As was done.
The As concentrations were high in all the area studied. Nevertheless, As(V) was the predominate species in solid wastes with high content of Al, Fe and toxic elements, mainly As, Pb and Cd. These wastes presented relatively low solubility of these elements. As(lll) more toxic than As(V), was detected mainly in soil samples taken around the As2O3 plant. The Bioaccessible percentages determined following the NOM-147 method, varied significantly: As between 10 to 69 %, Cd from 24 to 99 % and Pb from 3 to 99.
The bioaccessible concentrations of Cd and Pb were lower with the PBET method than with the NOM-147 method, probably due to the increase of pH during the intestine phase. In some samples, arsenic concentrations were higher in the intestine phase (PBET method) than in gastric phase (measured by both methods).
Lead bioaccessible percentages measured with the NOM-147 method were higher than those obtained with the PBET method, probably overestimating the potential of lead absorption.
When the NOM-147 data is used to calculate soil cleanup levels, applying the NOM-147 formula, incorrect results are obtained. An alternative approach is proposed in this work in order to avoid the weakness of this regulation, helping the mining industry involved in several important projects of soil remediation. Also, we recommended changes in the extraction equipment required by the regulation, in order to get better reproducibility.