ASSESSMENT OF HEAVY METALS LEVELS IN SOIL AND VEGETABLES IN THE VICINITY OF UNLINED WASTE DUMPSITE IN NNEWI, ANAMBRA STATE NIGERIA

Abstract

Unlined waste dumpsites are known to generate pollutants in the environment where they are located. This study investigates the pollutant load of unlined dumpsite by assessing the heavy metals levels of soil and vegetables in and around the waste dumpsite. 16 samples (study samples and control) for each soil and vegetable samples (Telfairia occidentalis, Talinum triangulare and Amaranthus hydridus) were collected respectively during wet season. The levels of 10 heavy metals were analysed using Atomic Absorption Spectrophotometric method. The highest and lowest heavy metals concentrations in the study sample site for vegetables ranged from 11.5 mg/kg – 0.01 mg/kg, while 7.79 mg/kg - 0.00 mg/kg was analysed for control site. The soil heavy metals values ranged from 13.1 mg/kg – 0.28 mg/kg for study samples, while 7.45 mg/kg – 0.02 mg/kg for control site. The study samples heavy metal results for vegetables and soil were higher than the control samples, which was attributed to high mobility of metal ions as a result of its closeness to the dumpsite through leaching. The total transfer factors ranged from 3.89 – 3.01 for study samples and 3.46 – 2.75 for control samples. The study samples were higher than the control site due to high levels of soil contaminations. The vegetables samples showed high levels of heavy metals, which were above WHO/FAO limits. The risk index range of 16.015 – 14.551 for study samples, and 6.821 – 5.761 for control samples from the extrapolated vegetable results, revealed that the vegetables collected from both sites were above the critical value of 1. The vegetables are unfit for human consumption and can cause non-cancer health risks to the populace who consume them. A proper refuse disposal system in and around the residential areas should be adopted. Routine monitoring of heavy metals in such plants to prevent excessive accumulation of the metals in the food chain is also advocated.