ASSESSMENT OF HEAVY METAL CONTAMINATION OF SOME DESIGNATED SCRAP-YARDS IN BENIN CITY, EDO STATE, NIGERIA

Abstract

This study was conducted to investigate the heavy metal (HM) contamination of some designated scrapyards located in Benin City, Edo State. The designated scrapyards are in Upper Iwehen and Idahosa streets Benin City. Navy Street and Lagos Street were chosen as Control sites. Soil samples were obtained at a depth of 30cm for laboratory analysis. Heavy metals were analysed using atomic absorption spectrometry (Polarized Zeeman Atomic Absorption Spectrophotometer ZA3000 Series). The value of Iron in the soil samples from Upper Iwehen scrapyard and Idahosa Street range from 1566 – 2902 mg/kg and 385-1267.50 mg/kg respectively. Upper Iwehen scrapyard was observed to have higher concentration of iron compared to Idahosa Street. Generally, it was observed that control soil samples for Upper Iwehen (Lagos Street) and Idahosa Street (Navy Street) had lower concentration of 216.50 mg/kg and 126mg/kg respectively. Concentration of manganese (Mn), zinc (Zn), copper (Cu) and chromium (Cr) for soil samples from Upper Iwehen ranged from 43.50 – 80.60mg/kg, 62.65- 116.10 mg/kg, 29.30 - 41.5 mg/kg and 28.90 - 40.7mg/kg respectively while those observed for Idahosa Street ranges from 15.7 - 35.20mg/kg, 26.95-50.7 mg/kg, 13.95-19.15 mg/kg and 13.10-20.70 mg/kg respectively. Percentage composition of clay, silt and sand in samples from Upper Iwehen ranged from 7.30-8.95%, 3.20-4.05%, 87.25-89.45% respectively while that of Idahosa Street ranged from 5.00-8.05%, 2.00-3.00%, 89.05-93.05% respectively. This study revealed the presence of various heavy metals in the soil samples due to uncontrolled activities of scrapyards at the various sites and showed that the samples were contaminated above permissible levels.