Effect of organic amendments on trace element availability in contaminated soil by three extraction methods (0.01 M CaCl2, soil pore water and diffusive gradient in thin films)

Presentación Oral PPS‐HM3 en la Session 1: Heavy metals en el International Congress of Phytoremediation of Polluted Soils. July 29- 30, 2014. Vigo, Spain

We studied the effeet of two organic amendments (biosolid compost and alperujo compost) and two plant species (Medicago sativa and Poa annua) on trace element (TE) bioavailability on two contaminated soils (one with neutral pH and other with acid pH) comparing three methods (0.01 M CaCl2-extractable in soil, concentration in soil pore water SPW and extraction by diffusive gradient in thin films DGT). The experiment was carried out in 72 pots (3L of volume each) that were filled with the two soils. Two treatments with amendments for each soil and species and a control without soil amendments for each species were established. In neutral soils no significant differences between treatments were found for TE availability. The behaviour of Cu, Mn y Zn extracted by CaCI2 was similar to that obtained in SPW and DGT, although characterized by higher concentrations. For Cd, the highest mean values were observed in soil in which M. sativa was growing for the three extraction methods. In the acid soil was found the greatest effect due to organic amendment addition, in which an increase in soil pH and the establishment of vegetation into the pots were observed. The presence of the amendments and the rhizosphere reduced the content of Cd and Zn, reaching the lowest values in the DGT extraction method, especially in soil with alperujo compost in presence of M. sativa. The contents of Cu and Mn follow a different tendency, characterized by an increase in amendment treatments, especially with CaCb extraction.

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