A comparative study of the influence of heavy metals on soil and crops growing within quarry environment at Akamkpa, Cross River State, Nigeria

Fe Ekpo,Ec Nzegblue,Me Asuquo

doi:10.4314/gjass.v11i1.1

Abstract

A comparative study of the influence of heavy metals on soils and crops grown within quarry environment at Akamkpa, Cross River State was conducted in 2009 year. The study area was delineated into3 zones P1, P11, P111 based on the intensity of exposure to tailings, wind speed, wind direction and distance from the quarry. The selected sample distances were (0km, 1km and 3km as control). Soil sample with the depth of (0-15cm), cassava leaves and, fluted pumpkin leaves were collected separately from each of the sampling area and analyzed for chemicalcharacteristics. The concentration of heavy metals Pb, Cr, Ni, Cd, Mn, Fe and Cu in the leaves samples of fluted pumpkin and cassava in sample position (P1) were (25.26± 0.58, 15.54± 0.75, 14.28± 1.23, 18.05±0.20, 42.25±0.10, 87.22±0.40 and 28.14±0.71)mg/kg for fluted pumpkin and (23.41±0.50, 11.25±0.11, 10.78±0.23, 12.25±0.60, 38.25±0.05, 75.28±0.40 and 26.51±0.15)mg/kg for cassava leaves respectively. The values of these heavy metals Pb, Cr, Ni, Cd, Mn, Fe and Cu of soils in zone (P1) were (12.26±0.86, 5.75±0.50, 3.25±1.84, 8.25±1.24,14.29±0.25,125.0.85±0.05 and 5.67±0,98)mg/kg respectively.  The values of heavy metals in plant species were significant (P<0.05) higher than values of the soils in sample position. Similar trend was recorded in zones P11 and P111. The high concentrations of trace metals recorded in the leaves of the plant species may be due to bioaccumulation and biomagnifications of those metals in plant. The decrease in concentration of these metals in the soil may be as a result of losses due to leaching, harvest of agricultural products, volatilization and soil pH.. Thecorrelation between heavy metals in the soil and the relationship with the soil factors showed that some metals correlate significantly and positively with other metals while some do not. It is concluded that quarry activities in Old Netim in Akamkpa Local Government Area of Cross River State has a significant impact on the level of heavy metals on crops around the area. This is a matter of great concern in view of the environmental and health implication, since man and livestock depend on these plant species for food.

Highlights

Quarrying is a major land used activity in Akamkpa Local Government Area of Cross River State, Nigeria
Some heavy metals are essential in plants nutrition, plants growing in an environment of heavy metals pose serious risk to human health when such plant based food stuffs are consumed (Vousta et al, 1996)
The highest concentrations of all the heavy metals analyzed from the samples were recorded in the sampling position (0Km) which is the immediate vicinity of the quarry

Summary

Introduction

Quarrying is a major land used activity in Akamkpa Local Government Area of Cross River State, Nigeria. Due to the availability of mineral deposits in commercial quantity in the area, the mining activity provides large tones of chippings of various sizes as well as accompanying toxic waste affect both environment and human. The social and environmental disturbances as a result of mining and mineral processing activities include destruction of wildlife and biodiversity, loss of fertile soil, pollution of drinking water and air, degradation of farm land, impairment of human health, forced pollution migration, destruction or reduction of agricultural and related activities and damage to aquatic ecosystems (Adepoju, 2002). Inputs of heavy metals into the soils have gradually increased over the past decades as a consequence of agricultural practices (e.g. the use of fertilizers and pesticides), disposal of sewage sludge, and mining operations (Adriano, 1999; Berrow, 1986). Unlike energy which tend ton deplete and becomes more dispersed at each step in the trophic level, heavy metals become more concentrated with each trophic level in the food chain “bioaccumulation and biomagnifications” (Egunjobi and Nkwoko, 2002)

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Conclusion