Evaluation of the suitability of three Mediterranean shrub species for phytostabilization of pyritic mine soils

Abstract

A greenhouse pot experiment was conducted to evaluate the potential use of Nerium oleander, Cistus albidus and Pistacia lentiscus for phytostabilization of acidic mine soils. The selected species were grown in mine tailing soil, unamended (TS) and amended with calcium carbonate and pig manure (ATS), and in a reference unpolluted substrate for control (CT); plant growth, root characterization, soil trace element contents, and their accumulation in plants were measured. Results indicated that seed emergence was independent of the substrate characteristics, but seedlings were seriously affected and died in TS, with survival of 5–40% in ATS. Only stem biomass of P. lentiscus and root volume of N. oleander were negatively affected when grown in TS, but without differences between ATS and CT. There were significant negative correlations between soil and plant trace element concentrations and plant biomass and root development, indicating the effect of trace elements on plant growth. The application of amendments reduced the soil exchangeable and extractable fraction concentrations of trace elements in ATS compared with TS, mainly for As, Cd and Pb. The tested species directly contributed to the immobilization of trace elements in the soil. As a general pattern, trace element concentrations in plants grown in the unamended tailing soil were similar to those reported for the amended soil, with levels below toxicity thresholds. Thus, these species fulfill the criteria to be used for phytostabilization purposes, aided by application of amendments to increase plant growth.