LEVELS OF SOME ALKALINE AND HEAVY METALS IN SOILS OF SELECTED FADAMA AREAS AROUND THE SOKOTO METROPOLIS, NIGERIA

Abstract

This study. aimed at providing baseline information on the levels of some heavy metals in selected fadama soils around the Sokoto metropolis. Three .., pollution-prone fadruna farmlands; "Kalambaina" site,' .•Illela ••... garagei'(More~ sire and University site were chosen for the study. Seven heavy metals, Cu, Zn, Mn, Pb, Cr, Ni and Fe, plus four alkaline metals, Na, K. Ca and Mg were determined in soils from each site. A comparison of the values for heavy metals obtained in the soils and the guide values for soil pollution concentration showed that the amount-of Cu have exceeded the guide limits of 40 p.g Cu/g dry soil at all the three study sites. Excess value of Cr, beyond the safe limits of ?O u g Cr/g dry soil, was found at Kalambaina site. Further, comparison of the results with the FEPA and WHO permissible limits for the heavy metals in industrial effluents applicable for land showed that the levels of these heavy metals present in the soils were overwhelmingly high. This suggests that the presumed wastes at the sites could be very toxic and hazardous to both plants and animals. On the other hand, high levels of Ca and other alkaline metals and the neutral-toalkaline pH observed in the study sites may affect the mobility of the heavy metals and further concentrate them in the soi Is. Because of the possibi lity of uptake and accumulation steps must be taken to reduce the net quantity of the heavy metals present.