Evaluation of Cu and Zn Content in Soils and their Interaction with Some Physicochemical Soil Properties

The content of metals in soils depends on the combined effect of several factors, which include the properties of the metals themselves and their concentrations in the soil, environmental conditions and soil components. Topsoil samples from different plots of a rural area, which combines reforestation (forests soils) with agriculture (pasture and cultivation soils) and livestock in the Galicia region, NW Spain, were analyzed for total Cu and Zn, pH, organic matter content, and particle size distribution. The geological substrate of the study area is mainly biotitic schist. The aims of this study were to investigate the total Cu and Zn concentrations in the topsoil samples, and to examine the relationship of these metals with the mentioned physicochemical properties using a correlation analysis. Soils were characterized by conventional analytical methods. Total Cu and Zn contents were determined by atomic absorption spectrophotometry after wet digestion with a hot mixture of nitro-perchloric-hydrofluoric acids. The results showed that the soils have on average moderately acid pH, considerable organic fraction and clay loam texture. The total Cu and Zn concentrations were low (mean about 25 mg kg(-1) and 78 mg kg(-1) respectively), which reveals that these topsoils are not contaminated The statistical analysis showed positive correlations between the sum of the clay and silt contents, and the total Cu and Zn concentrations. There are no significant correlations between total Cu and Zn, and organic matter content.