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
Keywords: Biomagnification, heavy metals, soils, economic crops

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 chemical
characteristics. 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.. The
correlation 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.
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