Metallic Trace Elements (MTE) in soils and plant organs of some crop in periurban of Abidjan (Ivory Coast)

Abstract

The quality of the plant production in periurban agriculture is subjected to question given the potential contamination of soils that can affect the crops. The levels of contamination of soils and vegetables by Metallic trace elements (MTE) as copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in the district of Abidjan, have been evaluated. Multi-sites survey of cropping areas of sweet potato and Hibiscus was conducted in three municipalities in Abidjan (Port-Bouët, Yopougon and Bingerville) in relation to the intensity of industrial and commercial activities. The site of Bingerville has been used as the reference site referring to the low activities. Soil samples (in 0-20 cm and 20 - 40 cm), combined with that of plants (leaf, stem, and root), and water were collected, transported in laboratory for analysis. The total amounts of MTE in soil, as well as the different fractions extracted were determined in addition to the respective concentration in plants (Hibiscus and Sweet potato). Toxic level of Pb (< 8 mgkg-1) was observed in the plant organs collected at Port-Bouët site indifferently to crops while lowest content of Pb (35.5 mgkg-1) was accounting for the soil of Yopougon (39.8 mgkg-1). A neutral pH of the soil has been considered more favorable to the contamination of plants in Pb on the polluted sites somewhat differing for extractable fractions. The acidity and small width of leaf as observed for Hibiscus, were identified as the control factors of crop contamination in periurban agroecosystems prone to Pb pollution. To strengthen the consistency of the knowledge, studies of the interaction between Pb and Zn as well as the translocation of Pb in the plants to tubers are suggested in the tropical ecosystems