SPATIAL VARIABILITY OF SOIL PHYSICOCHEMICAL PROPERTIES AND HEAVY METAL CONCENTRATIONS IN OWERRI MUNICIPAL DUMPSITES

Abstract

Heavy metals pose a serious threat to our environment due to the fact that majority of annual vegetable crops consumed by man and animal are produced from the polluted sites without knowing the level of it taken up by plant which revolves into food chain. This study evaluated the variability of soil physicochemical properties and heavy metals concentration in Owerri municipal dumpsites in Imo State. Samples were collected in three replicates 0, 5 and 10m away from refuge dumpsites at 0 - 30cm depth using soil auger in Ihiagwa, Avu, Abazu and Obinze. Samples were analyzed for soil properties and heavy metals-concentrations using standard methods. The concentrations of the studied heavy metals (Pb and Cr) were compared with the permissible limits of other countries. pH results from the analyzed sampled soils from the four locations were high (6.89, 6.80, 6.59 and 6.40) in Ihiagwa, Abazu, Obinze and Avu respectively while organic carbon followed the trend Ihiagwa>Avu>Abazu>Obinze. Organic carbon and total Nitrogen concentrations followed the same trend in Ihiagwa, Avu, Abazu and Obinze. Pb concentrations in the studied sites were above the standard limit recommended (0.05mg/kg) by Federal Environmental Protection Agency but within limit (100mg/kg) stipulated by European Commission. Nevertheless, Pb concentration was within the tolerance limit set by European Union but should be cautiously minimized to prevent health hazard on man and the environment. The use of refuge dumpsite for cultivation of arable crops should be avoided and lands on cultivation should be given a distance from the refuse sites.