V3I6P16

Ecological and Human Health Risk Assessment of Heavy Metal in Surface Soils in Makurdi Metropolis, Nigeria 

Nandeve Turhemba Paul^1*, Sesugh Ande¹, ⁠Rufus Sha’Ato¹

Abstract

Ecological and Human Health Risk Assessment of Heavy Metals Pollution in Surface Soils in Makurdi Metropolis was investigated. Soil samples were collected from five different locations namely: Rice Mills, Industrial layout Naka Road, BSU Teaching Hospital, Mechanic Village Apir, and Mechanic Village North Bank within Makurdi metropolis. The results of the physicochemical properties indicate that, pH ranged from 6.56 to 6.95 which is below WHO limits of 6.5–8.5. Other soil properties such as Electrical Conductivity (EC), cationic exchange capacity (CEC) showed the range of 43.5-68.2 and 7021-18771 respectively. Heavy metals Concentration in the samples were quantitatively determined using atomic absorption spectrometry (AAS).  The results showed that the concentrations (mg/kg) of heavy metals range from FE (0.167–3.16), Zn (0.038–0.248), Ni (0.116–0.92), Pb (0.795–45.7), Cu (0.236–0.506). The results were within WHO permissible limit excerpt that of Pb. Results of ecological risk indices showed that Igeo of all the selected metals in the study soils were unpolluted suggesting that soils in the sample areas have natural background levels for these metals excerpt Pb in Apir Mechanic Workshop (0.926) and North Bank (0.401) that indicate moderately polluted level. The contamination factor (C_f) of the elements in all the sampling sites was below 1 indicating low contamination of the studied soil excerpt Pb in Rice Mill, Teaching Hospital, Apir Mechanic Workshop and North Bank sites having showing moderate contamination. The enrichment factor values for the element range from moderate enrichment, moderately severe enrichment, extremely severe enrichment, severe enrichment for Zn, Ni, Pb and Cu respectively. The ecological risk indexes for all the elements in the study area were below 150 which mean the soils in the study sites were of low ecological risk. The results showed that chronic daily intake (CDI) of metals were in the following order Pb < Fe < Cu < Ni < Zn for both adults and children. The Hazard Quotient (HQ) and Hazard Index (HI) values remain below one for all three pathways (ingestion, dermal and inhalation), indicates that, there is no evident risk of chronic health effects to the age group. Hence, the population under study is considered to be safe from the heavy metals. The cancer risk due to Ni intake estimated in this study in all the entry routes range from 1.08×10^-7 to 4.39×10^-12 while that of Pb range from 1.78×10^-7 to 1.39×10^-12 across the age group respectively. These values fall below the range of predictable risk to cancer. Therefore, it is recommended that there should be continuous monitoring of heavy metals around the study areas to ascertain the health risk that may occur due to heavy metal accumulation

Keywords:

Heavy metals; Geoaccumulation; Contamination; Pollution; physicochemical; Health risk