Spatial Distributions of Cadmium and Lead in Roadside Soils Along Owerri-Umuahia Highway

The research was conducted in 2019 to evaluate the spatial distribution of heavy metals (cd and pb) in roadside soil along Owerri-Umuahia highway Imo State Nigeria. Three locations were sampled-Owerri, Mbaise and Obowo. These locations are the major highways connecting Owerri-Umuahia. Soil samples were collected at a predetermined distance of 0-15 feet (ft), 15-30 ft, 30-45ft, and 45-60ft away (row) from the edge of the road. All were sample at a depth of 30 centimeter (cm) depth using soil auger. The locations were either cultivated with cassava or maize and in some cases vegetables. Reference (control) samples were also sampled from fallow (non-highway soil) lands but at a distance of 100meters (m) away from highway. Fifty four (54) samples were randomly collected, and bucked samples were replicated for treatment sources. Samples were air dried and sieved with 2mm sieve, crushed and stored in the polythene bag for laboratory activities. Analyses were done routinely. The physicochemical result (table 1) showed that the soils are mostly sandy and the pH were slightly acidic with mean value of (5.97) when compared with control (5.89). There were significant differences between locations and control with regard to macro nutrient levels. These ranges from (phosphorus (p) 14.43 to 16.06 mg/kg, Nitrogen 0.11 to 0.73 % and potassium 0.18 to 0.23 cmol.kg-1). These were significantly different when compared with control (NPK 0.54. 23.74 and 1.15) as the locations levels were lower than non-highway soils. The organic Matter (OM) where lower in highway location. The mean value were 2-12% while the control. The mean value was 2-12%, and control was 3.41%. The result followed same trend with Base Saturation and Basic Cation levels. Base Saturation (BS) were significantly different between locations and also when compared with control. The BS mean value was 77.91% while control was 84.60%. Cadmium levels at various distances, and between one location and another did not change significantly. Cadmium at distances 0-15ft, 15-30ft, 30-45ft and 45-60 ft, the mean values were 2.21, 1.87, 1.77, 2.03 and for control 2.19, 2.19, 2.02, 2.19 mg/kg respectively (table 2). For lead, at the sample distance away from road edge- 0-15ft, 15-30ft, 30-45ft and 45-60ft, the mean values were 11.7, 13.2, 12.5 , 12.0 and for control 13.22, 14.42, 13.03 and 14.14 (table 3). These slightly differences in the locations from control were not significant at p