STATUS OF SELECTED HEAVY METALS IN SOILS OF FLOODED AREA AT IKPOBA-OHKA LOCAL GOVERNMENT AREA, EDO STATE, NIGERIA.

ABSTRACT

This study examined the status of some selected heavy metals in flooded soils  in Ikpoba Okha  Local Government Area, Edo State. Soil samples were collected using the soil auger at different soil depth (0-15, 15-30, 30-45cm) from Sapele road, St Saviour and Upper sakponba area in Ikpoba Okha Local Government Area Edo State. Laboratory analysis was carried out on the soil samples using different standard methods. The soil was analyzed for Particle size distribution, chemical properties and some selected heavy metals (cadmium, chromium and lead ).

The results shows that the predominant textural class was Sand, with varying proportions of clay, and silt. Soil pH values ranged from 6.36 to 7.18  with mean value (6.744) for Sapele site,  6.70-7.18 with a mean (6.99) for St saviour and 5.91-5.2 with a mean (5.49) in Upper Sakponba respectively, indicating  slightly acid across all locations.  Organic carbon content was highest in  topsoil, while total nitrogen values from Sapele and Upper Sakponba sites was significantly different from each other across soil depths, From St Saviour sites soil depths from 0-15cm (0.92g/kg) was significantly different from soil depths of 15-30cm (0.53g/kg) and 30-45cm (0.36g/kg) respectively. Available phosphorus content decreased as soil depths increases across all locations. It was observed that the heavy metals were more at the top soil than the at the sub soil this could be as a result of flooding and anthropogenic activities. From the correlation tables it was observed that pH values positively correlated with all the Particle size distribution, Chemical properties in exception of clay, hydrogen and electrical conductivity. pH values positively correlated with all the selected heavy metals in Sapele and St Saviour sites but only correlated with  Lead in Upper Sakponba sites. This study shows that the pH value is suitable for crop production and the selected heavy metals were below threshhold limits at the top soil due to short duration of  flooding.