Extracción selectiva de Pb, Ni y Cd en un suelo no contaminado en relación con la heterogeneidad del mismo

Resumo

The topsoil of on arable field was characterized as homogeneous far majar element contents by Xray fluorescence. Total concentrations of potentially toxic metals, as extractable by aqua regia digestion, showed no heavy metal accumulation. The spatial behavior of EDTA extractable Pb, Ni and Cd in this field and its dependency on soil properties (pH organic carbon content, CEC and the texture) was investigated by sampling the topsoil according to a nested grid. Extractable Pb, Ni and Cd were characterized geostatistically are found to be spatial/y dependent. Semivariograms were described reasonably well by a structure involving a small nugget component plus a spatial component that becomes independent at distances of 50 m. Block-kriged contour maps allowed to identify microrregions with significantly increased extractability. Apparently organic matter content, CEC, silt content and pH are the most important soil parameters that regulate Pb, Ni and Cd extractability in this soil. The number of soil composite cores required to assess a mean value with a specified confidence in analytical results was calculated.