摘要
[目的]通过探究植物根系分泌物中的低分子量有机酸对紫色土壤金属阳离子释放的具体影响机制,解析植物根系在矿物风化和土壤形成中的作用。[方法]采用有机酸浸提试验,研究不同低分子量有机酸下紫色土结构崩解特征及风化过程中离子的释放规律,定量分析释放速率与时间的相互关系,并探讨不同有机酸对化学蚀变指数(CIA)的影响。[结果]有机酸处理能显著提高紫色土风化产物的CIA值,增幅为7.25%~15.42%,在相同浓度下,柠檬酸较草酸更能加速风化过程;电镜(SEM)扫描结果显示有机酸促进紫色土的结构破坏,Matlab软件分析进一步表明有机酸浸提处理促进土壤矿物表面孔隙的发育,降低土壤颗粒的均匀程度;不同浓度的低分子量有机酸(LMWOAs)浸提处理时土壤金属阳离子释放速率不同,且随着浸提时间的持续,释放速率逐渐降低。金属离子的释放速率随有机酸浓度的增加而增加,且离子释放总量整体呈现Fe^(3+)>Mg^(2+)>Mn^(2+)>K^(+)>Ca^(2+)>Na^(+)的规律,通过多元非线性回归建立溶液酸度变化条件下的金属阳离子释放速率的定量分析模型发现,金属阳离子的释放速率与时间之间存在显著的指数函数关系。[结论]低分子量有机酸浸提促进紫色土金属阳离子释放和风化,且柠檬酸较草酸显著。
[Objective]The specific mechanism of influence of low molecular weight organic acids in root exudates on metal cation release in purple soil in Yuanmou dry and hot river valley of Yunnan Province was explored to fill the current research gap and provide scientific basis for understanding soil weathering and plant-soil interaction.[Methods]The organic acid leaching test was employed to investigate the structural disintegration characteristics of purple soil under various low molecular weight organic acids and the release kinetics of ions during weathering.The quantitative analysis of the relationship between release rate and time was conducted,and the influence of different organic acids on CIA(chemical index of alteration)was discussed.[Results]Application of organic acids leads to a substantial increase in CIA value for purple soil weathering products ranging from 7.25%to 15.42%.Citric acid,at equivalent concentrations,demonstrates greater efficacy in accelerating weathering compared to oxalic acid.Scanning electron microscopy(SEM)results reveal that organic acids induce structural damage in purple soil,while MATLAB software analysis indicates that leaching by organic acids promotes the development of surface pores in soil minerals and reduces particle uniformity.The release rates of metal cations from soil vary with concentrations of low molecular weight organic acids(LMWOAs),decreasing gradually over leaching time.The metal ion release rates increase with increasing organic acid concentrations,and the total ion release pattern follows Fe^(3+)>Mg^(2+)>Mn^(2+)>K^(+)>Ca^(2+)>Na^(+).A quantitative analysis model for the metal cation release rate under changing acidity conditions is established using multivariate nonlinear regression.There exists a significant exponential function relationship between the release rate of metal cations and time.[Conclusion]The leaching of low molecular weight organic acids promoted metal cation release and weathering of purple soil,and citric acid was more significant than oxalic acid.
作者
李华辉
李雪
李琬婷
王婷
李春培
王雪瑶
赵吉霞
LI Huahui;LI Xue;LI Wanting;WANG Ting;LI Chunpei;WANG Xueyao;ZHAO Jixia(College of Resources and Environment,Yunnan Agricultural University,Kunming 650201,China;Key Laboratory of Mountain Surface Processes and Ecological Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Ministry of Water Resources and Electric Power,Chengdu 610299,China)
出处
《水土保持学报》
CSCD
北大核心
2024年第5期343-352,共10页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目(42007002)
云南省基础研究计划项目(202101AT070220)
云南省教育厅科学研究基金项目(2024J0419)
云南农业大学科研启动基金项目(KY2018-26)。
