淋洗液对沿海滩涂设施土壤重金属的洗脱效应

Eluting effects of different eluents on heavy metals in greenhouse soils from coastal mudflat area

为剖析不同淋洗液作用下土壤重金属的形态分布及淋洗效应,探究重金属活性钝化与总量消减调控技术,本文采用土柱模拟自然淋洗结合形态分析的方法,研究了不同浓度柠檬酸﹑EDTA和秸秆粉3种淋洗液对土壤Cd﹑Pb和Cr全量﹑形态分布及洗脱效果的影响.结果表明:盐碱环境下,柠檬酸和秸秆粉对土壤重金属的淋洗率不足1%,而EDTA对Pb和Cd的淋洗率分别达到24.62%和80.56%.形态分析结果表明:各处理对土壤Cd﹑Pb和Cr形态组成的影响程度表现为秸秆粉>EDTA>柠檬酸,EDTA和柠檬酸可增加酸溶态和可还原态含量进而促进重金属洗脱,但同时也提高了土壤有效态重金属含量并增加安全风险.秸秆粉对Cd和Pb的钝化效果最显著,促进其由其他形态向残渣态转化,但秸秆粉对Cr形态分布的影响较弱.

This study employed natural flow rinsing conducted in soil columns and morphological analyses to examine the characteristics of chemical fractions and the removal effect on soil heavy metals induced by different eluents,and to explore the regulation approaches of heavy metals passivation and total abatement.Effects of three different concentrations of the eluents(citric acid,EDTA and straw powder)on the total amount,morphology fractions and removal of Cd,Pb and Cr were investigated.The results showed that,under the saline and sodic soil condition,the leaching rate of soil Cd,Pb and Cr was below 1%using citric acid and straw powder,while the leaching rates of soil Pb and Cd leached by EDTA eluent were 24.62%and 80.56%,respectively.Results of morphological fractions analyses indicated that the influencing extent on chemical fractions of soil Cd,Pb and Cr was ranked as straw powder>EDTA>citric acid,and that EDTA and citric acid could facilitate heavy metal elution by increasing the quantity of acid-soluble and reducible fractions.Meanwhile,EDTA and citric acid also increased available heavy metal content and ecological risk.Straw powder had significant influence on the passivation of Cd and Pb,and facilitated the conversion from other forms to residual form.However,the impact of straw powder on the morphological fraction of soil Cr was not significant.