Effect of Diammonium Phosphate On the Solubility of Heavy Metals in Heavy Metals in Contaminated Soils Under Flooded.

Soils contaminated by heavy metals can result in serious negative consequences, such as the loss of ecosystems and of agricultural productivity, tainted water resources, human beings health problems etc. In-situ chemical immobilization is a remediation technique that decreases the heavy-metal damage to environment by decreasing heavy metals solubility and bioavailability. The objective of this study was to evaluate the effect of diammonium phosphate on the solubility of heavy-metal in polluted flooded soils. The results showed that the concentrations of the Cr and Cu in soil solution significantly increased by the addition of diammonium phosphate, which was ascribed to the increasing soluble organic matter induced by soil pH during flooding incubation periods. Contrast to the results of Cr and Cu, the concentrations of Cd, Ni, and Zn decreased in soil solution as a result of re-adsorption on newly releasing exchangeable sites or co-precipitation with phosphate. The results suggested that flooding and the addition of diammonium phosphate in the contaminated soils on one hand decreased the solubility of Cd, Ni, and Zn, but on the other hand increased the solubility of Cr and Cu.