ASSESSMENT OF SPATIAL DISTRIBUTION OF HEAVY METALS IN ROADSIDE SOILS AND SOME VEGETALES ALONG NNAMDI AZIKIWE EXPRESS WAY, KADUNA.

Abstract

The research aimed to assess the spatial distribution of heavy metals in some vegetables and roadside soils along the Nnamdi Azikiwe Expressway in Kaduna. The soil samples were collected at random from nine locations down to a depth of 20 cm in replicates. In the same area where the soil samples were collected, the vegetable samples were likewise chosen at random. The Nariya farm provided the control samples. The samples were allowed to air dry, mixed, and sieved. Nine soils and twenty-seven vegetables were used to prepare the samples. The samples were then digested using the wet technique. Using a pH meter and the conventional Walkley-Black method, the following physiochemical parameters were measured: pH, electrical conductivity, organic carbon, and soil organic matter. Atomic Absorption Spectroscopy was used to assess the concentrations of Pb, Cd, Zn, Cu, and Ni in soil and vegetable samples that were gathered from the roadside at Kawo, Panteka, Kurmin Mashi, Badikko, Tudun Wada, Kabala West, Kudenda, Nassarawa, and Trikania. The findings showed that the soil's pH was generally basic (7.8) and somewhat acidic (6.9). At Kawo and Nassarawa, the EC value was 0.278 ds/cm and the OC value was 12.0g/kg. Zn had the greatest mean concentration in mg/kg of Pb, Cd, Zn, Cu, and Ni, measuring 166.40. The same was true for vegetables, with Zn values of 278.28, 230.90, and 274.90 for spinach, lettuce, and cabbage, respectively. The contamination factor indicates that Ni is marginally enhanced in vegetables at Badikko and Tudun Wada and below the detection limit in all soil samples. For every metal, the translocation factor was less than 1, however at Kawo, Panteka, Badikko, Tudun Wada, and Nassarawa. With the exception of one location that exhibits heavy pollution with PLI >1, the area was not significantly polluted. Nonetheless, the assessment's findings show that there was an increased concentration of Zn and Pb at all nine locations, which was consistent with findings from other researchers. As a result, the toxicants were below the NESREA-established permissible limit. However, because of the metals present from various operations that took place at the site, the concentration of these metals does not follow a regular pattern; instead, fluctuation was seen in the sample. To reduce the spread of harmful contaminants into the environment, government organizations should, however, provide for legislation, awareness, education, waste management, a modern transportation system, and regular analysis.