柠檬酸和葡萄糖存在下土壤锰溶解动力学研究

Kinetics of Mn dissolution in soils under presence of citric acid and glucose

研究探讨了土壤锰还原和溶解的动力学特征,为土壤锰的植物有效性提供科学依据。以无机酸和酸化还原剂(HCl、NH2OH.HCl-HNO3、NH2OH.HCl-HAc)处理为对照,用连续液流法研究柠檬酸和葡萄糖对土壤锰溶解的影响。结果表明,柠檬酸、葡萄糖可通过在土壤固相表面的吸附使其中的锰还原溶解,几种化合物对土壤锰的相对溶解能力强弱顺序为:0.04 mol.L-1NH2OH.HCl(25%HAc)>0.1 mol.L-1NH2OH.HCl-0.001 mol.L-1HNO3>1%柠檬酸>0.5%柠檬酸>0.1 mol.L-1HCl>1%葡萄糖>0.5%葡萄糖>0.01 mol.L-1HCl。用不同数学模型模拟化合物对土壤锰溶解动态过程,5种方程拟合的相关系数均达到极显著水平(P<0.01),并且以指数方程、Elovich方程和权函数方程拟合所得的标准差较小,抛物线扩散方程拟合的标准差最大。表明几种化合物对土壤锰氧化物的溶解速率受控于表面化学反应,而不是由扩散来控制。

The soil Mn dissolution dynamics was studied to reveal the bioavailability of soil Mn. By the technique of sequent liquid flow method, the dissolution characteristics of the citric acid and glucose to soil Mn were studied in comparison with the treatment of inorganic acid of HCl and acidified reductants of NH2OH· HCl- HNO3 and NH2OH· HC1 -HAc. And five models were used to reveal the process, such as first - order equation, power function equation, parabolic diffusion equation, Elovich equation and exponent function equation. Results showed that soil Mn were dissolved significantly by several compounds for all of 4 soils tested. The ability of Mn dissolution followed this order： 0.04 mol· L^- 1 NH2OH. HC1 （ 2.5 % HAc） 〉 0.1 mol· L ^- 1 NH2OH. HC1 - 0.001 mol·L^-1 HNO3〉 1% citric acid〉0.5% citric acid〉0.1 mol·L^-1 HCI〉 1% glucose〉 0.5% glucose 〉 0.01 mol·L^-1 HC1. The experimental data of Mn^2 ＋ dissolved with time was fitted by the selected models and all the models reached a significant level at P 〈 0.01, and SE of power function equation, Elovich equation and exponent function equation were little, namely, they were fitted better. But the SE of parabolic diffusion equation was the largest. It was suggested that the reaction process was controlled by surface reaction of Mn oxides, not by diffusion of Mn^2 ＋ .