Assessment of Heavy Metal Sources in Soils from a Uranium-Phosphate Deposit Using Multivariate and Geostatistical Techniques

Abstract

The quantification of heavy metal contents in soils and their sources are essential for contamination monitoring and the assessment of the potential risks to the ecosystems. This study aims to investigate the source of heavy metals and other elements in soils from a uranium-phosphate deposit using integrated multivariate and geostatistics techniques. For this, 50 soil samples in Itataia deposit, Northeastern, Brazil, were collected at 0–0.2-m depth for the determination of U, Fe, Al, Mn, Ti, Zn, Cu, Ni, Mo, Co, Cr, Cd, Pb, As, Se, V, B, and Zr. The Pb, Se, Ni, Cr, As, and Mo mean contents were closer or exceeded The Brazilian Environmental Council (CONAMA) prevention values for soils. Uranium content was about 500 times higher than the mean levels reported for Brazilian soils. The cluster analysis indicates three geochemical groups based on different contamination levels. The first principal component was associated with lithological origin, the second principal component may be related to anthropogenic sources, and the third and fourth principal components indicated a joined source (natural and anthropogenic), indicating different sources of contamination. Mo was not related to other heavy metals, being found independent in the area. The accumulation of heavy metals in soils is associated not only with the parent material but also with the minerals of the soil. In the area of study, calcareous soils favored alkaline conditions that influenced the dynamics of heavy metals. The multivariate and geostatistical analyses were able to provide preliminary information regarding the metal contents in soil for environmental management.