钝化土壤酸化过程机理及关键影响因子研究

施加钝化材料固定有毒重金属的方法在污染土壤修复领域有着广泛应用。但钝化土壤的酸化作用会使已固定的重金属重新活化,钝化剂应用在长效性方面存在局限。因此,研究钝化土壤酸化对土壤修复工作有重要应用参考价值。本研究选取西南地区3种代表性土壤,分别测定其酸化程度与交换性酸浓度,通过相关性分析判断土壤酸化的内在机理;同时应用SPSS软件,通过多元统计分析方法探究土壤理化性质对土壤酸化的影响,进一步采用主成分分析和线性回归方程建立定量函数表达以研究影响钝化土壤酸化的关键因子。结果表明：1）钝化土壤酸化的实质主要是致酸交换性离子H⁺和Al³⁺置换盐基离子Ca²⁺和Mg²⁺的过程。反应前期主要是Al³⁺积累,其与酸化程度相关性达0.567;2）影响土壤酸化关键的因子是Ca元素和土壤粒度,其中Ca的影响最大, 主成分分析结果显示其贡献率达到79%;在土壤粒度组成中,黏粒百分比对酸化影响最大;3）本研究尝试提出钝化材料的选择应遵循“补偿机制”,即在选择钝化成分时针对性地补充土壤较匮乏的因子,同时避免添加较丰足因子。本文的定量分析结果为今后深入研究钝化土壤酸化提供理论依据。

Study on Mechanism and Key Influencing Factors of Acidification on Passivating Soil

The application of passivation materials to immobilize toxic heavy metals has been widely used in the remediation of contaminated soil. However, the acidification of passivated soil can reactivate the fixed toxic heavy metals. The application of passivator is limited in the long-term effect. Therefore, it is of great practical significance to study the key factors affecting soil acidification. In this study, three representative soils in southwest China were selected, their acidification degree and exchangeable acid were measured respectively, and correlation analysis was carried out to determine the internal mechanism of soil acidification. Meanwhile, SPSS software was applied to explore the effect of soil physical and chemical properties on soil acidification through multivariate statistical analysis, principal component analysis and linear regression equation. The results showed that:1) The essence of soil acidification is mainly caused by the process of H⁺ and Al³⁺ acid ion exchange displacement base ion Ca²⁺ and Mg²⁺, Al³⁺ accumulation is mainly in the early stage of the reaction, its correlation with acidification is 0.567; 2) The key factors affecting soil acidification are Ca²⁺ element content and soil particle size. Ca²⁺ ion has the most influence, the principal component analysis showed that the contribution rate is 79%. While in the soil particle size composition, the percentage of clay particles has the greatest influence on acidification; 3) Passivation material selection should follow the "compensation mechanism", namely in the choice of passive components according to the physicochemical properties of soil factor, at the same time avoid adding factor which is sufficient. The quantitative analysis results provide a theoretical basis for further study on the acidification of passivated soil.