Copper and Zinc Contents in Urban Agricultural Soils of Niger State, Nigeria

Abstract

Study of the Cu and Zn contents in urban agricultural soils is paramount in order to assess concerning the possible potential risks they may pose at high concentrations to life and environment through the food chain. Levels of Cu and Zn in soil samples collected from cultivated farmlands in the vicinity of abandoned industrial sites at two cities of Minna and Bida in Niger State, were determined using flame atomic absorption spectrophotometry technique. The concentrations were in the following ranges; 12-89mgCukg-1 and 2.8-41mgZnkg-1 for Minna and 2.4-6.5mgCukg-1 and 0.57-36mgZnkg-1 for Bida. The accumulation of Cu in Minna cultivated farmlands was apparent, with a mean Cu content of 24 + 22ppm, which was almost five times that of the control soils, but other mean values were similar to the soilbackground average contents. Soil properties were also analysed, andobtained results for the cultivated farmland soils of the two cities were of the following ranges: - pH (5.0-7.5), Organic carbon (0.36-2.5)%, sand (46.4- 94.2)%, silt (2.3-20.0)% and clay (1.8-33.6)%. Cu and Zn positively correlated among themselves, Cu correlated with clay content and Zn correlated with pH and organic carbon in all the soils. Keywords: heavy metals, accumulation, environment, cultivated farmlands, abandoned industrial sites.