POTENTIAL RISK ASSESSMENT OF HEAVY METALS IN AGRICULTURAL CROPS CULTIVATED AROUND ABANDONED MINE AREAS IN BARKIN LADI, PLATEAU STATE, NIGERIA

Abstract

Irrigation food crops are intensively cultivated on/or around the abandoned tin mine areas in Plateau State, Nigeria. Vegetables cultivated on contaminated soil are a potential risk to human health, particularly, through consumption. The physico-chemical properties of the soil and sediment revealed that the soil/sediment were acidic, non- saline and of low fertility. Most of the heavy metals’ concentrations in the agricultural mine soils were above the DPR maximum allowable limits with order of abundance of metals in the soils as Fe>>Mn>Cr>Cu>Zn>Ni>Pb. The ingestion health index (HI) in children and that of dermal route in both children and adults were greater than 1 indicating a potential adverse effect. Contamination index, degree of contamination and pollution load indices indicated slight contamination to excessive pollution, ultra-high degree of contamination and very highly polluted soils and sediments respectively. The geo accumulation index showed pollution was from uncontaminated to moderately contaminated in Zn (0< Igeo< 1) to extremely contaminated in Fe (5< Igeo). There was no enrichment of metals (0 ˂ EF ˂ 1) in the studied matrices but low ecological pollution; (Eri<40) to considerable (80≤Er<160) with substantial contributions from Cu and Cr. The risk index was moderate (150≤R<300) for all the locations in the study. The health risk assessment of heavy metals in the vegetables showed that the HQ and HI values of heavy metals in tomatoes from B/Ladi were higher than that of other vegetables. All the metals HQ values were lower than 1 except As HQ was higher than 1. The study also revealed that all of the CR values exceeded the threshold level (CR>10−4) suggested by US EPA for water and Cr, Cd and As in most of the studied tomato in the two sample areas. Cultivation of tomato should not be on or around abandoned mine. Key Words: Risk Assessment, Agricultural crops, Abandoned mine, Barkin Ladi