Cadmium concentration in diferent particles sizes of Lake Valencia Basin soil

The objective of this study is to determine the concentration of cadmium in hydrosoluble fractions, associated with carbonates and totals in different sizes in a soil particles from the Valencia Lake (Venezuela) basin. Lacustrine soil from the Guacara zone with important concentrations of cadmium was used, sifted through a 2 mm screen. The soil was physically fractionated according to particle size, through 1mm, 0,5mm and 0,25 mm stainless steel sieves in a sequential order. For the chemical analysis, the soil was screened with each sieve. For the cadmium total extraction, the methodology used was the 3050 (Carter, 1993) of the United States Environmental Protection Agency, (USEPA), while for the hydrosoluble and carbonate associated cadmium, Martinez's (2005) proposed methodology was employed.. The cadmium concentration for each extract was determined by atomic absorption. The obtained concentrations were subject to statistical analysis. The results point out that the 2 mm sieved soil is 42% made up by &le0,25 mm particle size. The total cadmium soil concentration resulted over the agricultural soils limits (0,7 mgCd/kg-soil) and lacustre lacustrine sediment norms (0.1-1,5 mgCd/kg-soil). For the small particles, the highest hydrosoluble fractions (6%) and carbonate associated (24%) were obtained. In conclusion, there are no significant differences between the soil particle sizes and the total cadmium concentration.