Influence of soil pH on the fractionation of Cr, Cu and Zn in solid phasesfrom a landfill site

The spatial variability of soil pH for engineered Weathered Oxford Clay is described using 35 samples collected from the base of a new cell in an exis ting landfill. Soil pH variability influences the reactivity of Cr, Cu and Zn in the site. The reactivity of these metals as natural components was de termined using a sequential extraction method. The total concentration of C r, Cu and Zn and the mineralogical composition were also determined. The re sults showed that due to the presence of a layer rich in pyrite in the base , a natural acidification may occur which can produce a soil pH as low as 2 .7. The spatial variability of soil pH in this area has been described with an anisotropical variogram model and the estimation of its values at unsam pled locations was carried out using the ordinary kriging algorithm. From t he spatial modelling of the soil pH, it was found that the metals in the so il solid phases follow a similar distribution. (C) 2000 Elsevier Science Lt d. All rights reserved.