Effect Of NPK Fertilizer On Changes Of Conformation Of Cd,Pb And Sorption-desorption Of Cd,Pb

The present study reports the effect of fertilizer and time on changs of conformation of Cd and Pb by Manul soils contaminated by heavy metals. The effect of NH4C1, (NH4)2S04, KCl and K2SO4 on kinetics data of sorption-desorption of Cd by soils were studied under the conditions of continuous liquid current. The main results were found out as follows:Firstly, soil pH was decreased by application of KCl, NH2Cl, K2SO4 , (NH4)2SO4 and Ca(H2PO4)2 in red soil. The effect of the five fertilizers on soil pH: KC1> NH4C1> K2SO4 >(NH4)2SO4>Ca(H2PO4)2. The relationship of the effect between NPK fertilizer on Cd and Pb and pH is close in red soil. The result of correlation analysis indicated that the concentration of water-soluble Cd and Pb was positively correlated with soil pH(r=-0.981**,-0.970**), but that of exchangeable Cd was negtively correlated with soil pH(r=0.837*). Effect of K+ is more that of NH4+.Secondly,as soon as Peddy soil and Yellow fluvoaquic soil are concerned, the concentration of water-soluble Cd and exchangeable Cd and Pb was increased by application of (NH4)2SO4 and NH4Cl. At the same time, the concentration of water-soluble Pb is decreased. Compared with red soil, the effect of N fertilizer was larger than K feitilizer, namely, NH4+>K+. But, the effect of anion was not significantly different.Thirdly, Ca(H2PO4)2 increased the concentration of Carbonate Cd and Pb in Peddy soil and Yellow fluvoaquic soil. KCl, NH4C1 , K2SO4 , (NH4)2SO4 and (NH4)2HPO4 all decreased the concentration of Carbonate Cd and the effect of them on Carbonate Pb was not significant.Fourthly,the concentration of exchangeable Cd was the most in red soil ,Yellow fluvoaquic soil and Peddy soil. The sequence of the concentration of exchangeable Cd was: red soil>yellow fluvoaquic soil>peddy soil and that of water-soluble Cd and Pb was: red soil>peddy soil > yellow fluvoaquic soil. The concentration of Carbonate Pb was the most in the three kinds of soils. NH4Cland KC1 significantly decreased the cotent of exchangeable Cd in red soil, and the concentration of exchangeable Cd was respectively decreased by 33.55% and 33.97%. Reversely, NH4Cl increased the extent of exchangeable Cd and Pb in Yellow fluvoaquic soil and Peddy soil. Ca(H2PO4)2 significantly decreased the concentration of exchangeable Cd and Pb in all kinds of soils, except exchangeable Pb in red soil.Fifthly, the concentration of Cd and Pb was gradually decreased with time going on.Sixthly, N K fertilizer shortened the time of the balance of sorption of Cd and decreased the balance concentration of Cd in red soil. The effect of NH4Cl and KCl was most significant. The concentration of Cd released during the initial 5 minute was, on average, about 85% of the total concentration of Cd.