ASSESSMENT OF STATUS OF THE SOIL PHYSICOCHEMICAL PROPERTIES AND HEAVY METALS IN UKPOM-ABAK WATERSHED IN ABAK LOCAL GOVERNMENTAL AREA, AKWA IBOM STATE NIGERIA
Abstract
The study was conducted at the Ukpom-Abak watershed in Abak Local Government Area of Akwa Ibom State, Nigeria using Randomized Complete Block Design (RCBD) to evaluate the physicochemical properties and heavy metal status of the area which shows a differentiation between the watershed soil and the upland soil. The sand, silt and clay fractions at 0-15cm and 15-30cm soil depth were 90.10, 5.10 and 4.04% and 88.60, 6.67 and 4.73% respectively showing a significant different (p0.05) between the two locations. The soil textural classes for the two locations were sand and loamy sand respectively due to the nature of their parent material. The difference between the mean pH contents of the watershed and upland soils were considered not to be significantly different (p0.05) without any trace of salinity at both 0-15 and 15-30cm soil layers. The organic matter contents of 0-15 and 15-30cm soil layers were 1.37 and 1.34% for the watershed soil. At the upland soil, it was 3.78 and 3.06% for 0-15 and 15-30cm soil depths respectively and were considered to be very statistically significant (p0.0) between the iron (Fe) values of the watershed and upland which were above the critical value of 4.5mgkg-1 for agricultural soil. There was a significant difference (p0.05) between the watershed and upland soils and both were above the critical value of 0.2mgkg-1 at 5.04mgkg-1 and 5.12mgkg-1 for the upland soil, and 4.38mgkg-1 and 5.06mgkg-1 respectively for 0-15 and 15-30cm. The zinc (Zn) content of the watershed and upland soils was not statistically significant (p>0.05) and were higher than the critical value of 0.5mgkg-1 at 3.8mgkg-1, and 4.20mgkg-1 and upland soil of 4.70 and 4.78mgkg-1 for 0-15 and 15-30cm respectively. Leaching and sand mining account for the increase in concentration of heavy metals with increasing depth. Suspension of anthropogenic activities especially sand mining and agricultural practices are recommended as a panacea to regain soil fertility and ecosystem services.
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