Accumulation and Movement of Four Potentially Toxic Elements in Soils Throughout Five Years, During and After Biosolid Application

Abstract

In this research, we have studied the accumulation of four PTEs (Cadmium, copper, lead and zinc) during and after biosolid application, in two soils with different clay content and their eventual movement with depth. The study was performed in the Province of Buenos Aires, Argentina, on a Typic Argiudoll and on a Typic Hapludoll. Treatments were: control and biosolid application, at doses of 14 Mg ha^-1year^-1 (dry matter). There were two types of sampling: (i) Topsoil samp ling, at 0-0.15 m depth, taken throughout five years and (ii) Depth soil sampling at regular intervals of 0.33 m from top soil to 3-4 m depth, taken two years after biosolid application. All samples were taken on April. PTEs, extracted hydrochloric, sulfuric and nitric acids (total) or extracted with DiethyleneTriaminePentaacetic acid-DTPA (available), were determined by ICP. Total concentrations of PTEs in topsoils of both soils did not increase significantly due to biosolid application. The exception was the significantly high Pb concentration in the Typic Hapludoll. DTPA extractable metals showed some concentration changes throughout the studied period. Total and available PTEs did not show mobility with the depth of both soils. The exception was total Cd in the Typic Argiudoll, which moved in depth. With only those two exceptions, there is neither PTEs accumulation in topsoils nor PTEs movements in soil depth. The first could be attributed to biosolid composition and dosage used in the region. The lack of movement in depth appears more related to the characteristics of the studied soils.