Phytoremediation of contaminated sites in urban environment : preliminary results of a study focussed on Lubumbashi.

A specific flora has developped in Central Africa on soils which are naturally rich in Cu and Co. Mining and ore treatment activities in the Katanga province (RDC) have generated contaminations which do endanger ecosystem viability and/or human health. A survey of edaphic conditions prevailing for plant growing in natural metalliferous outcrops, the « copper hills », in mining sites (quarries), and in contaminated areas around metal smelters, is conducted as a first stage of a phytoremediation-based research program. Soluble, available and total content in some metallic trace elements have been measured. The first results show a relatively high heterogeneity inside and between sites. But the main finding is related to the very different nature of contamination between the three types of sites. This point constitutes an additionnal difficulty that should be taken into account for the selection of metallophytic species from the copper hills or the quarries in order to vegetalize a site contaminated by atmospheric fall outs from metal smelters in Lubumbashi.