Assessment of Some Physicochemical Parameters of Soil And Heavy Metals In Vegetables Cultivated On Irrigated SitesAlong The Bank of Mpape River In FCT, Abuja, Nigeria
The purpose of the study was to assess some physicochemical parameters of soil and the heavy metal concentrations in soil and vegetables along the bank of Mpape River in FCT, Abuja. The study was carried out in dry season between 2016 and 2017. Soil and vegetables samples were collected simultaneously from three irrigated farm sites. Heavy metal levels were quantified using Atomic Absorption Spectrophotometer (AAS) Other parameters were determined using standard methods. The levels of physicochemical characteristics in soil and the heavy metals in soil and vegetables varied significantly according to sites without adhering to any significant trend. Soil pH (5.62+ 0.72) was slightly acidic, soil temperature (27.37+ 0.60 0 C) and OM content (3.31+ 0.37 )were significantly higher and within WHO/FAO 1 permissible limits.Levels of Cr and Cd were below detectable limits while Mn (7.61+ 0.76) and Cu (0.65+ 0.016) in soil were below EU 2 permissible limits. The levels of Cr (0.17+ 0.08),Mn (7.22+ 0.59) Cd (0.02+ 0.01) and Cu (0.80+ 0.26) in Lagos Spinach were significantly higher than the levels of Cr (0.29+ 0.16) Mn (3.92+ 0.53) Cd (0.01+ 0.03) and Cu (0.67+ 0.28) in African Egg plant which were below FAO/WHO 1 and EU 2 permissible limits. Transfer factors (TF) values for Mn and Cu surpass 0.5 showing that the vegetables were largely contaminated by Mn and Cu while Cr and Cd were below 0.5 in the two vegetables. Daily intakes value (DIM) calculated for Cr, Cd and Cu in vegetables were generally below the WHO/EU 2, 3 and SEPA 5 maximum limits except for Mn that was higher than the limits indicating that people who consumed these vegetables may accumulate more of the Mn. Health Risk Index in both vegetables from all the farms was less than 1, indicating that no significant potential health risk associated with the consumption of these vegetables. All the metals were significantly different <0.05) The correlation analysis showed that the metals in these farms have varying correlations. All the metals in all the farms were strong and positively correlated which is an indication that they have common source of pollution.