Pedogeochemistry background Diagnosis of soil developed on volcanosedimentary materials at Blafo-Guéto (Toumodi) in South-central Côte d'Ivoire

This study is made in order to establish a database, which can be used as reference value for the current contents in Heavy metals, such as arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in the manganese and gold-bearing region of Blafo-Guéto at the Center-South part of Côte d'Ivoire. So, the soil Diagnosis based on the pedogeochemistry background, throuth two lines, the one on the hill Blafo, the other one on the hill Guéto, allowed to know that except the manganese (Mn) and the copper (Cu), the studied heavy metals, does not exceed the naturally indicated limit values and are thus polluted. These measured values are included between 0.2 to 1.9 mg.kg-1 for Cd, 12 to 56 mg.kg-1 for Cr, 25 to 299 mg.kg-1 for Cu, 6000 to 50000 mg.kg-1 for Mn, 13 to 38 mg.kg-1 for Ni, 13 to 49 mg.kg-1 for Pb and 25 to 110 mg.kg-1 for Zn. For As and Hg, the measured values are lower than 0.25 mg.kg-1 and, Only Mn and Cu indicated a geochemical anomaly, because exceeding the natural contents in soil. The ranking, in the decreasing order, from the geochemical anomaly to the lowest contents measured in the Blafo-Guéto soils, indicates that: Mn>Cu>Zn>Cr>Pb>Ni>Cd>As, Hg.