Assessment of Soil Pollution by Heavy Metals in the Market Gardening Areas of Korsimoro

The aim of this study was to assess heavy metal soil pollution in market garden areas in the commune of Korsimoro. The analysis focused mainly on zinc (Zn), nickel (Ni), chromium (Cr), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), arsenic (As) and mercury (Hg). Composite samples of soil labels s1 to s21 were taken from the market garden site around the dam at a depth of 0-20 cm. A total of 21 soil samples were taken. The soil samples were analysed using inductively coupled plasma mass spectrometry (ICP/MS) at the Bureau of Mines and Geology of Burkina Faso laboratory (BUMIGEB).

The enrichment factor (EF), contamination factor (CF), géoaccumulation index (Igeo) and pollution load index (PLI) were determined from the metal concentrations obtained.

The average concentrations of heavy metals vary as follows:

Cd > Co > Cr > Zn > Ni > Cu > Hg > Pb > As.

The average concentrations of cadmium (587.039mg/kg±20.546), mercury (29.048mg/kg±20,647), nickel (60.037 mg/kg±14,615) and cobalt (575.956mg/kg±66,693) exceed the WHO limit values for agricultural soils.

The calculated CF values show very high contamination of Co, Cd and Hg, considerable contamination of Cu, Cr, Zn, Ni and As, and no contamination of Pb.

The EF values show very severe enrichment for cobalt (Co), followed by overall extremely severe enrichment for cadmium (Cd) and mercury (Hg).

The calculated Igeo indicates extreme cadmium, mercury and cobalt contamination.

The calculated PLI values are all greater than one. These results show that all the soils are polluted.

The index determination approach makes it possible to predict the extent of soil pollution by the heavy metals considered in our study.