The Effect of EDTA on the Extractability of Zinc(Zn),Cadminum(Cd),and Nickel(Ni) in Vertisol and alluvial Soils

摘要

Ethylenediaminetetraacetic acid (EDTA) is persistent in the environment.The presence of EDTA in soil may alter the mobility and transport of Zn,Cd,and Ni in soils because of the formation of water soluble chelates,thus increasing the potential for metal pollution of natural waters.Mobility of metals is related to their extractability.to investigate metal extractability affected by EDTA,Zn,Cd,and Ni were added to vertisol and alluvial soils at rates of 50,2,and 5mg/kg,respectivley.both natural and metal amended soils were treated with Na_2EDTA at rates of 0,0.2,and 0.5 mg/kg.After five months of incubation,soil samples were extracted with 0.1 N HCl,0.005M DTPA+0.01M CaCl_2+0.1M TEA(0.005 M diethylenetriaminepentaacetic acid+0.01 M calcium chloride+0.1 M triethanolamine),and 1M Mg(NO_3)_2,the latter of which extracts the exchangeable form of metals (Zn,Cd,and Ni).According to experimental results,Zn,Cd,and Ni in all extractions increased with increasing rates of EDTA in the natural and metla amened soils.