新型碱性肥料治酸改土降镉的效果和机理  

A Novel Alkaline Fertilizer and Its Function as well as Mechanism to Remediation Soil Acid and Cd Pollution

作　　者：曹巧滢 江家泉 王学江 范佳妍 詹曜玮 张立丹[1] 李峰 孙少龙 仇荣亮 樊小林[1] CAO Qiaoying;JIANG Jiaquan;WANG Xuejiang;FAN Jiayan;ZHAN Yaowei;ZHANG Lidan;LI Feng;SUN Shaolong;QIU Rongliang;FAN Xiaolin(College of Natural Resource and Environment Science,R&D Center of Environment Friendly Fertilizer Sci and Tech,SCAU,Guangzhou 510642,China;Wuzhou Feng Agricultural Science&Technology Co.,LTD.,Yantai,Shandong 264002,China;Guangdong Laboratory of Lingnan Mordern Agriculture,Guangzhou 510642,China)

机构地区：[1]华南农业大学资源环境学院,广东高校环境友好型肥料工程技术研究中心,广州510642 [2]烟台五洲丰农业科技有限公司,烟台264002 [3]岭南现代农业科学与技术广东省实验室,广州510642

出　　处：《土壤学报》2023年第1期175-188,共14页Acta Pedologica Sinica

基　　金：国家重点研发计划项目(2018YFD0201100);广东省省级重大科研项目(2016KZDXM029);国家现代农业产业技术体系建设专项(CARS-31-06)资助。

摘　　要：通过大田试验和模拟实验,研究碱性肥料治酸改土的效果、土壤pH对Cd吸附解吸热力学性能的影响,为碱性肥料治理土壤酸化和降低土壤Cd污染提供理论依据。结果表明:碱性肥料能明显提高大田土壤pH、显著降低土壤有效镉含量,明显遏制土壤酸化和土壤镉污染。施用碱性肥料是提高土壤pH和降低土壤有效镉含量的有效措施。当土壤Cd含量小于等于60 mg·L^(–1)时,pH从5增加到9时几乎不影响Cd的吸附强度(在15.77 mg·kg^(-1)/(mg·L^(–1))~16.67 mg·kg^(-1)/(mg·L^(–1))之间);而当Cd含量大于60 mg·L^(–1),Cd的吸附强度随pH的升高而明显增大,但吸附率随浓度的增大而减少。土壤Cd含量相等时,pH越高土壤Cd的吸附量及吸附率越大。土壤Cd的等温吸附曲线适于用Freundlich方程拟合和定量描述。土壤吸附Cd是自发反应过程,表现为Cd的吸附自由能(ΔG°)为负。同一pH下,ΔG°随着土壤Cd含量的增大而增大;ΔG°随着土壤溶液pH的升高而减小。碱性条件下Cd吸附自由能小于酸性条件下的ΔG°,即碱性条件下的Cd吸附反应更加剧烈。可见,提高土壤pH有利于增加土壤吸附Cd的能力。当土壤镉含量相对较低时,镉吸附为专性吸附;而当镉含量增加或当镉污染程度大时,在高pH下土壤可变电荷及其非专性吸附对Cd吸附起到积极作用。在农业生产实践中,建议采取施用碱性肥料的措施遏制土壤酸化,提高土壤pH,增加Cd的吸附量,降低土壤Cd的生物有效性,达到以肥治酸降镉的目的。【Objective】This study aimed to provide a theoretical basis for reducing soil Cd pollution through the application of alkaline fertilizer.【Method】Field and constant temperature incubation experiments were carried out to study the effect of alkaline fertilizer on soil acidification,Cd pollution,and the effect of soil pH on the thermodynamic properties of soil Cd adsorption and desorption.【Result】Application of alkaline fertilizer significantly(P<0.05)increased the soil pH and reduced the content of available Cd.This shows that soil treatment with alkaline fertilizer is an effective and reliable measure to reduce soil available or extractable Cd.When the ambient Cd concentration was≤60 mg·L^(-1),pH values from 5.0 to 9.0 had almost no effect on the adsorption strength of Cd(between 15.77 mg·kg^(^(-1))/mg·L^(-1)and 16.67 mg·kg^(^(-1))/mg·L^(-1))while Cd concentrations>60 mg·L^(-1)showed increased adsorption strength as the pH was increased.Nevertheless,the adsorption rate decreased with the increase in the initial concentration of Cd.Under the same Cd concentration conditions,the higher the pH value,the higher the adsorption capacity and adsorption rate of Cd.The Freundlich,Langmuir,and Temkin equations fitted the Cd isothermal adsorption data well.Of all three equations,the Freundlich equation had the best fit and was the most suitable to quantitatively describe the characteristics of Cd adsorption.The adsorption of Cd was a spontaneous process and characterized by a negative adsorption free energy(ΔG°).Importantly,DGo increased with an increase in Cd concentration at constant pH whereasDGo decreased with an increase in soil pH.Under alkaline conditions,DG was lower than under acidic conditions.However,Cd adsorption was more intense under alkaline conditions than in acidic conditions.This shows that increasing the soil pH with alkaline fertilizer was beneficial in improving the Cd adsorption capacity of the soil.At relatively low Cd concentration,Cd adsorption occurred through the specific adso

关 键 词：碱性肥料 有效镉 镉吸附 等温吸附 吸附自由能 

分 类 号：S143.1[农业科学—肥料学]