The use of a halophytic plant species and organic amendments for the remediation of a trace elements-contaminated soil under semi-arid conditions.

The halophytic shrub Atriplex halimus L. was used in a field phytoremediation experiment in a semi-arid area highly contaminated by trace elements (As, Cd, Cu, Mn, Pb and Zn) within the Sierra Minera of La Unión-Cartagena (SE Spain). The effects of compost and pig slurry on soil conditions and plant growth were determined. The amendments (particularly compost) only slightly affected trace element concentrations in soil pore water or their availability to the plants, increased soil nutrient and organic matter levels and favoured the development of a sustainable soil microbial biomass (effects that were enhanced by the presence of A. halimus) as well as, especially for slurry, increasing A. halimus biomass and ground cover. With regard to the minimisation of trace elements concentrations in the above-ground plant parts, the effectiveness of both amendments was greatest 12-16 months after their incorporation. The findings demonstrate the potential of A. halimus, particularly in combination with an organic amendment, for the challenging task of the phytostabilisation of contaminated soils in (semi-)arid areas and suggest the need for an ecotoxicological evaluation of the remediated soils. However, the ability of A. halimus to accumulate Zn and Cd in the shoot may limit its use to moderately-contaminated sites.