Heavy Metal Concentrations of Citrus Species (Citrus reticulata and Citrus sinensis) Cultivated on Road Sides in Uyo Metropolis in Akwa Ibom State, Nigeria

摘要

A field study was undertaken to establish heavy metals’ (Cd, Cu, Mn, Pb and Zn) concentrations in soil and Citrus species samples from two locations in Uyo metropolis in Akwa Ibom State, Nigeria; L1 (Ebuk’s farm, Atan Offot village), L2 (Ukpabio’s farm, Ikot Akpan Abia village, Ibesikpo L. G. A.) using atomic absorption spectrophotometer. The results showed that the heavy metals (Cd, Cu, Pb, Mn and Zn) present in the soils were within World Health Organization (WHO) permissible limits. Similarly, the heavy metals concentrations of fruits were within WHO permissible limits. The highest concentration of Mn (7.818±0.624mg/kg) was in L2, Pb (0.676±0.164 mg/kg) and Zn (2.196±0.436mg/kg) were in L1. The levels of Cd, Cu, Mn, Pb and Zn in soil L1 were 0.212±0.036, 1.896±0.128, 0.676±0.164, 5.556±1.316 and 2.196±0.436mg/kg, L2 were 0.157±0.014, 1.157±0.285, 0.568±0.088, 7.818±0.624 and 1.403±0.311 respectively. In Citrus plants, the highest concentration of Pb was fromCitrus sinensis (1.75±0.04 mg/kg) and Zn was from Citrus reticulata (6.27±0.10 mg/kg). The linear regression (graphs) result showed Cu and Mn of Citrus reticulata; Cd and Cu of Citrus sinensis which indicated that these plants have the ability to bioaccumulate these metals. The concentrations of metals in soil and Citrus plant were in decreasing order: Mn> Zn>Pb>Cd>Cu. The concentration of the heavy metals in the Citrus fruit and soil samples in this study could serve as a baseline data for the assessment of agricultural and vehicular exhaust pollutants in soils and Citrus fruit obtained in Akwa Ibom State of Nigeria. There should be regular monitoring of toxic heavy metal levels in soil, sewage and foods, to prevent their excessive build-up in the food chain.