Assessment of Soil and Earthworm (As Bio-Indicator) of Heavy Metals around the Cattle Market, Isheri, Along Lagos-Ibadan Express Road.

Abstract

Heavy metal released by traffic activities on the road sides are important  sources of soil pollution in developed and developing countries for decades. Earthworms have been used as bio indicator of soil pollution (heavy metals) by many researchers over the years.  Vehicular emission is a major source of heavy metal in this site. This research work aimed at examining the level of heavy metals concentration in the soil and in the earthworm at the Isheri Cattle Market along Ibadan-Lagos Express road in Lagos State, Nigeria.

The soil samples were collected at the surface and subsurface levels from different sections of the  market (upstream, downstream and around the market) Earthworms were also collected at the three different sections of the market. The concentration of heavy metals at the site is higher than that of the control site collected from Botanical garden, University of Ibadan. The heavy metals were digested using aqua regia (Conc. HNO₃ and Conc. HCl in 1:3 ratios) and analyzed by atomic absorption spectrophotometer (AAS).

This result showed that the concentration of heavy metals in all the sites ranged from 0.14 – 15.4mg/kg for Cr  , 0.012 – 1.072mg/kg for  Cd  while that of Ni, Cu,  Zn  and Pb are (0.025 – 4.69, 0.33-9.35;  2.42-41.0 and 0.19-15.82 mg/kg). The concentration of heavy metals in earthworm in the three major sections of the market ranged from 18.0 – 909mg/kg for Cr, 0.0014 – 0.056mg/kg for Cd, 0.32 – 1.39 mg/kg for Pb, 1.76 – 66.0mg/kg for Ni, Cu is 9.12 – 489mg/kg and Zn is 3.18 – 12.9mg/kg.  The earthworm present in the market is a good bio-indicator of heavy metals. This implies that vehicular emission and various burning activities are sources of environmental pollution which possesses a serious risk to human health and animals. There is need for a continuous research in this site  to monitor the increase in the concentration of heavy metals because of their toxic and carcinogenic effect in the environment.

Key words Earthworm, Heavy metals, Bio- indicator