Potential use of Erica andevalensis and Erica australis in phytoremediation of sulphide mine environments:: Sao Domingos, Portugal

The area around the Sao Domingos copper mine (Iberian Pyrite Belt) is subject of great environmental concern as acid mine water occurs several kilometres downstream of the mine. In addition thousands of tons of mine waste are present. Erica australis and Erica andevalensis, which are two spontaneous plant species of this area, have been studied with regard to their potential for phytostabilization. Soils and plants from Sao Domingos and from a reference site (Moreanes) were analysed for soil characteristics, chemical element content in soils (total and AB-DTPA bioavailable fraction) and in plants. Superficial and seepage water as well as waste material leachates were also analysed. Seepage water showed high redox potential (mean 481 mV), high conductivity (mean 4337 mu S cm(-1)) and low pH values (mean 2.6), being classified as mining water. Leachate solutions possessed mainly high levels of Fe, Al and SO42-. Soils in the mining area were highly contaminated in Pb, As and Sb. Locally also high values of Cu and Zn were encountered and the soil available fraction of the majority of the elements showed also quite high values. E. andevalensis grows in soils with pH between 3 and 4, whereas E. australis was only found in soils with pH above 3.5. Both species grow spontaneously in soils, highly contaminated with Pb, As and Sb. These plants, even in the non contaminated soils, are Al-tolerant and Mn-accumulators. In contaminated soils these species are also As-tolerant. Considering the tolerant behaviour in extreme environmental conditions, these Erica species may be of major importance for the recovery of the sulphide mining areas, with climate conditions compatible with its breeding and growing, by physical and chemical stabilization of contaminated soils and even waste materials. (c) 2007 Elsevier B.V. All rights reserved.