Assessment of Heavy Metals Contamination in Sediments of Bra Kanon Lake (Daloa, Côte d’Ivoire) Using Pollution Indices

The objective of this study is to evaluate the level of metal contamination in the sediments of Lake Bra Kanon (Daloa, West-Central Côte d’Ivoire) by applying pollution indices. Sediment samples were collected and transported to the laboratory for analysis. A total of ten (10) heavy metals, namely Aluminum, Arsenic, Cadmium, Chromium, Copper, Iron, Manganese, Nickel, Lead and Zinc, were measured using an argon plasma ionizing source mass spectrometer (ICP-MS). The recorded values were compared to those of the upper continental crust. The results obtained showed that the sediments are contaminated by cadmium (4.69 – 6.92 mg/kg), copper (53.4– 65.2 mg/kg), and manganese. (751.8 – 985 mg/kg). Furthermore, the order of accumulation of the metal charge in the sediments is: D1 > D3 > D2. Environmental assessment of sediment pollution by heavy metals was carried out using contamination factor (CF), degree of contamination (DC), modified degree of contamination (mDC), index of metal pollution (MPI) and pollution load index (PLI). The results of CF (CFCd = 46.9 – 69.2; CFCu = 3.73 – 4.56; CFMn = 1.42 – 1.87), DC (54.73 – 77.63), mDC (5.473 – 7.763) and MPI (5.81 – 8.55) showed that the sediments were polluted. The pollution load index (PLI < 1) indicated that the lake sediments were weakly affected by anthropogenic sources. However, the results reveal signs of the lake's vulnerability. Hence the need to develop strategies for the protection of this aquatic ecosystem.