METAL TRACE ELEMENTS IN SOILS OF THE AREA M'POURIE - MAURITANIA

The development of the right side of the Senegal River can lead to the degradation of the soils around the neighboring countries. That's the reasons why this study was conducted on the soils of the plain of M'Pourie. A sampling of the soil was done by zig zag method, and carried out on three depths (20, 40 and 60 cm) in the South East area of the plain of M'Pourie. This sample has hydromorphic soils (type pseudo-gley), red brownish color with a granular structure. The study done on this sample is about some physico-chemical parameters (pH, organic matter and texture), major elements and metal traces elements (MTE). The results show that these soils have a silty clay texture and a low average of organic content (1.14%). PH has an acid tendency and this acidity increases with depth (6.74 6.15 and 5.7 respectively for 20, 40 and 60 cm). The major elements have an abundance of aluminum and iron with low concentration of carbonates. The highest MTE are Cr V and Ni while the lowest are Cd, Pb and As. The vertical dynamics of the majority of elements shows a low variability, yet the Cd, Pb and As are more concentrated near the surface (20 cm) the principal component analysis (PCA) shows that most of the MTE is controlled by the aluminum, iron, phosphorus, and calcium, which induces a lithogenic origin. Whereas Cd, Pb and As show a correlation with the organic material assuming, at least in part, a anthropogenic origin (fertilizers). The comparison of the values of ETM soils plain M'Pourie with environmental quality standards TEC and PEC shows contamination by Cd and Ni accompanied by Cr pollution.