Efecto de la recuperación natural asistida en la distribución de elementos traza en un suelo contaminado

Abstract

We used a widely accepted sequential extraction procedure to assess possible shifts in trace element pools (As, Cd, Cu, Pb and Zn) of a contaminated soil that was revegetated with agrostis (Agrostis stolonifera L.) and where amendments had been applied. The experiment lasted 30 months and was carried out in containers. Seven treatments were established: four organic, one inorganic and two controls (control without amendment but with agrostis and control without amendment and without agrostis). Addition of amendments produced some changes in trace element distribution, but only showed a small influence on trace element extractability associated with the first fractions (most labile pool). The rhizosphere did not affect trace element distribution at all, as results from both controls were very similar. Arsenic and Pb showed were mainly recovered in the residual fraction. In contrast, residual fraction accounted for 70% of total Cd, 50% of total Cu and 30-40% of total Zn. Cu association with the third fraction (where organically-bound Cu is expected) and Zn association with the first fraction (most labile) were higher than for the other elements. Natural attenuation processes or the intrinsic recalcitrant nature of the contamination are the main factors controlling the distribution of trace elements in our soil. Reclamation practices improved soil quality and did not reverse trace element stabilization in soil.