Mapping heavy metal (Cu, Zn, and Pb) pollution and ecological risk assessment, in the surroundings of Gabes cement plant—Tunisia

Abstract

The pollution and contamination assessment of three heavy metals (Cu, Pb, and Zn) in the topsoil, and common plants (Olea europaea, Prunus persica vulgaris, Ficus carica, Medicago sativa, Zygophyllum album, and Helianthemum kahiricum) were carried out at different distances from a cement plant. This evaluation was based on four evaluation methods: Bioconcentration factor, Contamination factor, Geoaccumulation Index and Potential ecological risk factor. The chlorophylls a and b contents were also analyzed. The highest levels of Cu, Zn, and Pb in the topsoil were found close to the cement factory (cluster D), and the lowest values were observed in a distant oasis (cluster H). The lowest chlorophylls values were observed in perennial plants (O. europaea and F. carica) near the cement plant. Zygophyllum album and H. kahiricum showed capability to remove Cu an Zn in contaminated locations, depending on the soil type. The spatialization of the results was essential to the understanding of the potential contribution of different sources of Cu, Zn, and Pb in the topsoil and to distinguishing different behaviors of the same plant species. Concerning H. kahiricum, further research should be undertaken since it has a high livestock acceptability index and is used in traditional medicine.

Novelty statement The impact of three heavy metals (Cu, Zn, and Pb) on the topsoil and six species of plants common in Tunisia (arid climate) will be assessed, and the potential contribution of different sources to the contamination. Few studies have addressed the impact of cement dust in the topsoil and common plant species in arid rangelands, and, as far as we know, none of them have considered the spatialization of the data and results, considering the prevailing wind, plant species location, soil type, and use. Moreover, the ability of steppic vegetation to remove these three heavy metals (phytoextraction) was evaluated using the bioconcentration factor (BCF), soil pollution indices, and ecological risk. Chlorophylls a and b contents were also evaluated to establish the effect of the cement plant on the health of plants located nearby.

Keywords:

• Arid climate
• cement dust
• chlorophylls
• contamination indices
• heavy metals
• steppic vegetation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded and aid by the following entities The Tunisian Ministry of High Education and Scientific Research, which provided a PhD scholarship for the student Zrouga Ben Atia Khaoula, Department of Horticultural Sciences and Landscape in the Higher Agronomic Institute of Chott Mariem Sousse-Tunisia, Department of Civil Engineering, Architecture and Georesources of Instituto Superior Técnico, University of Lisbon, Portugal, and Mr Tlili Abderrazak Researcher in the Institute of Arid Region f and Mrs Ben Amor Afaf PhD student in the Faculty of Sciences of Gabes of Tunisia.