John Libbey Eurotext

Environnement, Risques & Santé


Chemical characterization of the impact of toxic waste dumped in Abidjan (Côte d’Ivoire): Searching for pertinent indicators of contamination to monitor residual pollution after waste cleanup Volume 13, issue 1, Janvier-Février 2014


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1 Université Félix Houphouët Boigny
Laboratoire des sciences et techniques de l’eau (LSTE)
22 BP 582
Abidjan, Côte d’Ivoire
2 Centre suisse de recherches scientifiques en Côte d’Ivoire (CSRS)
01 BP 1303
Côte d’Ivoire
3 Association africaine de l’eau (AAE) (African Water Association [AfWA])
05 BP 1910
Côte d’Ivoire
* Tirés à part

In August 2006, the Probo Koala, a ship chartered by the Trafigura company, dumped 528 m3 of toxic waste at 16 sites in Abidjan, causing 12 deaths and the poisoning of more than 100,000 people. The aim of this study is to characterize the chemical composition of the waste in order to assess the magnitude of the disaster and to determine relevant indicators of contamination for monitoring residual contamination after waste removal. Thus, 59 samples of contaminated soil and 31 samples of liquid waste (scraped off bodies of water) were taken a few hours before decontamination operations began. Measurements of pH indicated the waste was basic (pH [7.9 to 10.5]). Chemical analysis by X-ray fluorescence determined the levels of the following carcinogenic, neurotoxic, and reprotoxic (CNR) metal trace elements: Pb [21-26 ppm], Cd [3 ppm], Hg [2 ppm], Cr [76 -139 ppm], Co [58-81 ppm], and As [2-3 ppm] for soil and Pb [3.33 ppm], Cd [4.67 ppm], Hg [2 ppm], Cr [<1 ppm], Co [4 ppm], and As [<1 ppm] for liquid waste. These values do not reach the limit values for soil with pH> 7 ([European Commission-AFNOR NF U 44-041]): Pb [100 ppm], Cd [1.5-2 ppm], Hg [1 ppm], Cr [100-150 ppm], and Co [30 ppm]. On the other hand, they exceed the Ciapol standards for liquid waste: Pb [0.5 ppm], Hg [0.2 ppm], and Cr [0.1 ppm]. Levels for sulphur and chlorine, measured by the same technique, were higher than any of the other parameters measured (S [332-1,451 ppm] and Cl [717-4,025 ppm]). Moreover, the organic content, assayed by gas chromatography coupled with mass spectrometry, indicated the presence of CNR polycyclic aromatic hydrocarbons (PAHs), albeit at low levels (<11 ppm) . The analysis of these results allowed us to identify two indicators of residual petroleum pollution to be monitored during the cleanup: sulfur and chlorine, because of their high concentrations, their reactivity, and their persistence.