Format: ORAL

Charles Mulenga1*, Darius Phiri2, Daigard Ricardo Ortega-Rodriguez3,4, Martina Meincken5

1. Department of Biomaterials Science and Technology, Copperbelt University, P.O. Box 21692, Kitwe, Zambia 2. Department of Plant and Environmental Sciences, Copperbelt University, P.O. Box 21692, Kitwe, Zambia. 3. Universidade de São Paulo, Escola Superior de Agricultura Luiz de Queiroz, Departamento de Ciências Florestais, Av. Pádua Dias 11, 13418-900 Piracicaba, São Paulo, Brazil 4. DendrOlavide-Dept. Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Crta. Utrera km. 1, 41013 Sevilla, Spain 5. Department of Forest and Wood Science, Stellenbosch University, Bag X1 Matieland 7602, Stellenbosch, South Africa

There is an international debate on the potential of exotic or native species in phytoextracting potentially toxic elements (PTEs) from contaminated soil to contain the impact of mining activities on forest ecosystems. Exotic and indigenous trees have been evaluated as greenbelts to trap dust and thereby limit the dispersion PTEs. This study compares the potential of native (Brachystegia longifolia) and exotic (Eucalyptus camaldulensis and E. grandis) tree species growing around a copper mine in Zambia to accumulate PTEs and evaluate their ability to biomonitor metal pollution. Tree bark and leaves were collected from trees growing at the same site downwind from a copper-leaching plant. Topsoil was collected one metre from each sampled tree trunk. Portable X-ray fluorescence was used to analyse the elemental composition and concentration of heavy metals in biomass and soil samples. Pollution indices were used to establish the status and degree of soil contamination, while the bioaccumulation factor (BF) determined the ability of studied species to accumulate PTEs. PTEs (Cd, Fe, Cu, Pb, Ni, Mn, and Zn) were detected across biomass and soil samples, with a significant variation between species and plant parts. The pollution indices established that the soil at the study site is highly contaminated with Cu. The concentration of the studied heavy metals varied across species following the order E. grandis B. longifolia E. camaldulensis in both tree bark and leaves. The BF indicated that Zn, Mn, and Cd accumulates in all the studied species. Furthermore, a higher concentration of Cu was detected in B. longifolia bark, suggesting that this tree species has potential for biomonitoring Cu pollution attributed industrial activities. This study presents new insights in managing polluted environments through biomonitoring and bioaccumulation of PTEs, because these findings can guide policy on species selection when establishing greenbelts.