Assessment of Heavy Metal Pollution of Surface Soils from Scrapyards in Benin City, Nigeria

Abstract

Scrap metals found in scrapyards accounts for a large proportion of municipal solid waste in Nigeria. They are a menace to the environment and pose potential health risk to nearby residents. T his study assessed the physicochemical quality and heavy meta l contamination of surface soils from selected scrapyards in Benin City, Nigeria. Surface soils were collected from 12 randomly selected scrapyards between February and April 2018. Physicochemical analyses were carried out using standard analytical methods , while heavy metal ( Fe, Cd, Zn, Cr, and Pb ) concentrations were determined using atomic absorption spectrophotometry. The physicochemical indicators showed values which ranged from 6.17 ± 1.17 to 7.81 ± 0.88, 335.00 ± 60.62 to 2467.33 ± 1708.95μS/cm and 2 .18 ± 0.39 to 44.27 ± 17.72 mg/kg for pH, electrical conductivity (EC) and nitrate ( NO - 3 ) respectively. The texture of the scrapyard soils was predominantly sand. The concentrations of the heavy metals in the scrapyard sites were significantly ( p < 0.05 ) higher than the control site. A strong positive correlation existed among the studied metals. The concentrations of heavy metals were above the WHO/FAO critical level of 100 mg/kg except for Cr and Cd. Contamination indexes of the scrapyard soils showed th at the soils samples from all the locations were highly contaminated with heavy metals. There is urgent need for evacuation of the scrap metal wastes from the scrapyards and enactment of appropriate legislations which prohibits the use of land in residenti al areas as scrapyards in the city to prevent likely health hazard