Enrichment of trace elements in the clay size fraction of mining soils

• DOI: 10.1007/s11356-015-4236-x
• Publication Date: 2015-02-24T20:52:44Z
• Authors: Patrícia Gomes; Teresa Valente; M. Amália Sequeir...; J. A. Grande; M. L. de la Torre
• Keywords: Sulfides; Ferric Compounds; 01 natural sciences; Mining; Arsenic; Accumulation factor; Soil; Contamination; Mining soils; Soil Pollutants; Clay size fraction; Metalloids; 0105 earth and related environmental sciences; Trace elements; Minerals; Science & Technology; Portugal; Sulfates; 6. Clean water; Trace Elements; Waste Disposal Facilities; Metals; 13. Climate action; Clay; Aluminum Silicates; Environmental Pollution; Iron Compounds; Environmental Monitoring

Reactive waste dumps with sulfide minerals promote acid mine drainage (AMD), which results in water and soil contamination by metals and metalloids. In these systems, contamination is regulated by many factors, such as mineralogical composition of soil and the presence of sorption sites on specific mineral phases. So, the present study dedicates itself to understanding the distribution of trace elements in different size fractions (<2-mm and <2-μm fractions) of mining soils and to evaluate the relationship between chemical and mineralogical composition. Cerdeirinha and Penedono, located in Portugal, were the waste dumps under study. The results revealed that the two waste dumps have high degree of contamination by metals and arsenic and that these elements are concentrated in the clay size fraction. Hence, the higher degree of contamination by toxic elements, especially arsenic in Penedono as well as the role of clay minerals, jarosite, and goethite in retaining trace elements has management implications. Such information must be carefully thought in the rehabilitation projects to be planned for both waste dumps.