摘要
植物多酚可通过络合作用改变元素的存在形态。采用双因素完全随机试验设计,通过浸提试验研究表没食子儿茶素没食子酸脂(EGCG)溶液浓度、酸碱度、浓度与酸碱度互作对黄壤可溶态、游离态、无定形态和络合态铝(Al)、铁(Fe)和锰(Mn)的影响。结果表明:EGCG溶液浓度对黄壤可溶态和络合态Al、Fe、Mn及无定形态Al、Fe均产生极显著影响,EGCG溶液酸碱度对黄壤可溶态及无定形态Al、Fe、Mn均产生显著或极显著影响,EGCG溶液浓度与酸碱度对黄壤可溶态Al、Fe、Mn,无定形态和络合态Al也有极显著或显著的互作效应。相关分析结果显示,土壤中3种元素的无定形态氧化物含量与对应的可溶态氧化物含量呈显著或极显著负相关,表明EGCG溶液主要通过改变氧化物形态,特别是无定形态氧化物含量,影响元素活化,进而改变其可溶态含量;Al和Mn的活化会使土壤滤液pH降低,在pH降低幅度较大时,可能导致土壤酸化。本试验一方面为研究酸性茶园土壤酸化的来源提供了方向,另一方面也可为植物Al/Mn毒害的防治提供参考,但在利用植物多酚类物质防治土壤Al/Mn毒害的同时要处理好土壤酸化与治理毒害的关系。
[Objective] Plant polyphenols may alter forms of the elements existing in soil through complexation. The study is oriented to explore effects of epigallocatechin gallate （EGCG） relative to concentration and pH and the interactions between its concentration and pH on soluble, free, amorphous and complex forms of A1, Fe and Mnin Yellow soil. [Method] A two-factor experiment laid out at random was carried out by extraction of the tested soils, of which each had 3 replicates. Firstly, soil was collected from the 30 - 50 cm soil layer （ surface ） in a Yellow soil field as a sample for test, air-dried and ground to pass through a 10-mesh nylon sieve.Then a total of 48 portions, 10 g each, were weighed out of the prepared soil sample and placed into 250 ml polyethylene bottles, respectively. Into the bottles, prepared EGCG solution was added, 100 mL each. Then the bottles were placed into a constant temperature oscillater for 24 h oscillation under room temperature （ 25 ℃ ） . At the end of the oscillation, the suspensions were filtered for extracts, which were then analyzed for soluble A1, Fe and Mn （ Als, Fes and Mns ） . The second step was to have the remainders from filtration dried up in an oven at 60℃ for 48 h and reground with an agate mortar to pass through a 60-mesh nylon sieve for determination of oxidized forms of Al, Fe and Mn. Free Al, Fe and Mn （Ald, Fed and Mnd） , amorphous Al, FeandMn （Alo, Feo and Mno） , complexA1, FeandMn （Alp, Fep and Mnp ） were extracted by the dithionite-citrate-bicarbonate （ DCB ） method, acid ammonium oxalate （ AAO ） at pH=3 in the dark and Na-pyrophosphate （ Na4P2O7 ） at pH=10, respectively. Contents of all the above-mentioned fractions of Al, Fe and Mn were determined with ICP-AES. [Result] Concentration of the EGCG solution was found to have a very significant effect on the content of Als, Fes, Mns, Alp, Fep, Mnp, Alo or Feo in Yellow soil; and pH of the solution had a significant or extremely significant effect on the content of AI,, Fes, Mns, Alo, Feo or Mno in Yellow soil, while the interaction between the two did on the content of Als, Fes, Mns, Alo, Alp or Mnd in Yellow soil. The addition of EGCG affected the elements both in content and in form, but their relative contents did not change much. In terms of content, the soluble forms displayed an order of Al 〉 Fe 〉 Mn, the free forms, did an order of Fe 〉 Al 〉 Mn, and the amorphous and the complex forms both followed an order of A1 〉 Fe 〉 Mn. However, concentration of EGCG was not a factor affecting the content of Ala, Fed and Mnd, and neither was pH of EGCG affecting the content of Fed, Mnd, Alp, Fep and Mnp, while the interaction between the two did not have much effect on the content of Ala, Mna, Feo, Mno, Fep and Mnd in Yellow soil. Correlations analyses show that Aio, Feo and Mno was closely related to Als Fes and Mns, respectively, which suggests that EGCG solution affects mobilization of the elements by changing their oxide forms, especially the amorphous ones and hence contents of the soluble ones . The more Alo in the soil, the more A1, in soil solution, and all the same with Fe and Mn. On the other hand, pH of the EGCG solution was significantly and negatively related to Als and Mns, which suggests that reactivation of Al and Mn may lower pH of the extractant, posing a potential risk. [Conclusion] The study has further verified that the effect of EGCG solution on Al, Fe and Mn mobilization varies with its concentration and pH of the solution and interaction between the two. All the findings in this study may help orient the study on causes of soil acidification in tea gardens and serve as reference for prevention of plant Al/Mn toxication. It is, therefore, worthwhile to note when plant polyphenols are used to prevent Al/Mn toxicity, adequate attention should be given to control of soil acidification.
出处
《土壤学报》
CAS
CSCD
北大核心
2017年第4期905-916,共12页
Acta Pedologica Sinica
基金
国家自然科学基金项目(41371230)资助~~
