Investigating the application of Kiwi shell and incubation time on mobility of selected heavy metals in soil contaminated with clay texture soil

ABSTRACT: The soil contaminations with heavy metals such as lead, Cadmium, Copper, Zinc, are regarded as one of the environmental issues. Heavy metal in soil are distribution among several fractions which include water-soluble fraction, exchangeable fraction, organic associated fraction, carbonate associated fraction, bound and accluded in oxides and residual fraction. The effect of applying Kiwi shell and incubation time on the mobility of heavy metals in soils contaminated with Clay texture was studied in this study. The soil was contaminated at the rate of 600 ppm lead, Zinc and Copper and also 10 ppm cadmium, and we provided two specimens of polluted soil, one with five percent absorbent of kiwi shell and one as without kiwi shell as control. The samples were incubated for 3 hours, 1, 3, 7, 14, 21 and 28 days at 28 0C and constant moisture content, both soils were fractionated by sequential extraction procedure. The metal concentrations for Pb, Zn, Cu and Cd were analyzed by atomic absorption. The results of soil fractions were shown that there is a change in the distribution and mobility of added heavy metal to the soil and kiwi shell was effective in the immobilization of Cd, Pb, Zn and Cu in soil. Also results show in order of the highest percent for the heavy metal in organic matter fraction of the soil with kiwi shell: Cu > Pb > Cd > Zn. Generally, there is significant difference in heavy metal consistency in the five fractions of the two soil samples.