V2I10P35

Physico Chemical Characterization and Pollution Risk Assessment

Okoro M. U.^1*, Alisa C.O.¹, Opara A. I.¹,  Nkwuada A.U.¹,  Uyanwa M. N.¹,  Onuoha O. I.¹,  Nwaokorobia G. C.¹,  Uzoukwu C. S.¹

Abstract

This study evaluates the physico- chemical properties of soils in the vicinity of the Nekede open waste dumpsite, southeastern Nigeria, to determine their quality status and potential environmental risks. After the removal of the overlying waste, soil samples were collected from seven different location points within the dumpsite with two points serving as controls.100m away from each other and Soil samples were collected at a depth of three different depths (surface,15cm, 30cm) on an open waste landfill using a Dutch soil auger. The physicochemical parameters of the soil were determined using standard laboratory methods, while, EDXRF was used for heavy metal determination. The soils were observed to have a PH value of averaging 5.7 to 8.3 indicating slightly acidic to moderately alkaline, Nitrate levels up to 101.60 ppm and nitrate–nitrogen up to 22.80 ppm exceed WHO safety limits (50 mg/L nitrate; 10 mg/L nitrate–nitrogen), Elevated EC and salinity values surpass agricultural tolerance thresholds, potentially leading to soil structure degradation, reduced infiltration, and diminished crop yields. Nickel (Ni) levels ranged from 540 mg/kg at the surface to 437 mg/kg at 35 cm depth, remaining consistently above permissible limits. Lead was highest at the surface (211 mg/kg) and decreased slightly with depth, indicating partial retention in upper layers. Zinc was extremely elevated, with 1162 mg/kg at the surface, suggesting strong contamination from metallic and electronic waste. Iron, while naturally abundant, reached an exceptionally high 492,855 mg/kg at the surface, likely from corroded ferrous materials. The control site showed much lower values across all metals, confirming anthropogenic input as the primary contamination source. The soils under study are severely contaminated with Nickel, Copper, lead, and Zinc, which show values far above pollution thresholds. The geo accumulation factor reveals extreme levels of accumulation for these metals in this order copper >Zinc>Ni>Lead >Iron while enrichment factor suggests minimal to moderate enrichment. High value of PLI obtained shows the severe ecological risk posed by these contaminants, thereby confirming the presence of strong anthropogenic influences such as waste dumping, industrial discharges, and other pollution sources.

Keywords:

Leachate, Physicochemicals Tatus, Enrichment Factor, Soils, Dumpsite, Nekede