INFLUENCE OF IRON-CHELATES ON TRACE ELEMENT UPTAKE FROM TWO CALCAREOUS SOILS AND THE ACTIVITY OF OXYGEN-SCAVENGING ENZYMES IN LETTUCE

A pot experiment was carried out to determine the ability of lettuce (Lactuca sativa cv. ‘Waldmann's dark green’) to acquire iron (Fe) from Fe-ethylenediaminedisuccinic acid [EDDS, both as an isomeric mixture, EDDS(mix), and (S,S)-EDDS], Fe-ethylenediaminetetraacetic acid (EDTA) and Fe-ethylenediimonobis(2-hydroxyphenyl)acetic acid (EDDHA) in two calcareous soils and consequent effect on the activity of reactive oxygen species scavenging enzymes. Probably due to the rapid biodegradation of [S,S]-EDDS, EDDS(mix) provided Fe to lettuce more efficiently. Iron-EDDS(mix) and Fe-EDDHA were equally efficient in increasing Fe concentration in lettuce. The activity of superoxide dismutase (SOD) was not affected by Fe deficiency and the activity of copper (Cu) and zinc (Zn) containing SOD (Cu/ZnSOD) was dependent on lettuce Zn concentration. Ascorbate peroxidase and guaiacol peroxidase activities were increased by Fe-EDDHA, probably due to the steady supply of Fe. Physiologically active Fe pool for lettuce was equally provided by Fe-EDDS(mix) and Fe-EDTA.     

EDDS对Cd、Pb污染下荻生长、重金属积累及修复土壤能力的影响

为初步探明荻与EDDS联合修复重金属污染土壤的可行性,采用盆栽试验,以轻微Cd、Pb污染土壤为培养基质,研究不同添加量[0(对照)、1、3、5 mmol/kg]的乙二胺二琥珀酸(EDDS)对荻生长,Cd、Pb积累及污染土壤修复能力的影响。结果表明:在Cd、Pb污染下,添加EDDS处理荻的光合色素含量、株高和干质量与对照相比总体上均无显著差异,总体上光合色素以5 mmol/kg EDDS处理较好,株高和干质量以3 mmol/kg EDDS处理较好。在Cd污染下,随着EDDS添加量增加,荻地上部、根部Cd含量和富集系数均呈现出先增加后降低的趋势,且均在1 mmol/kg EDDS处理时达到峰值,分别较对照显著提高72.8%、15.4%和73.6%、15.4%,3 mmol/kg EDDS处理次之;Cd转运系数持续增加,且添加EDDS处理均显著高于对照;植株的Cd总积累量呈先增加后减小的趋势,在3 mmol/kg处理时达峰值,较对照显著提高44.2%;添加EDDS处理的Cd转运量系数均高于对照,以5 mmol/kg处理最高;荻对Cd污染土壤的修复效率以3 mmol/kg EDDS处理最高,较对照显著提高44.2%。在Pb污染下,地上部Pb含量和富集系数以5 mmol/kg EDDS处理较大,但与对照无显著差异;根部Pb含量和富集系数在5 mmol/kg EDDS处理时最大,分别较对照显著提高37.5%和35.3%;随着EDDS添加量增加,地上部、根部及总的Pb积累量均表现出先降低后增加的变化趋势,以5 mmol/kg EDDS处理最高,分别较对照提高9.4%、56.7%、46.6%,但差异不显著;荻对Pb污染土壤的修复效率也随着EDDS添加量增加表现出先降低后增加的变化趋势,在5 mmol/kg EDDS处理时最大,较对照提高45.2%,差异不显著。综合分析,在Cd污染下,以3 mmol/kg EDDS处理荻对Cd的富集、积累及土壤修复效果最好;在Pb污染下,以5 mmol/kg EDDS处理荻对Pb积累及土壤修复效果较好,但是效果不是很明显,故EDDS与荻联用修复轻微Cd污染土壤的潜力较大。     

螯合剂EDDS和EDTA诱导海州香薷积累土壤重金属的比较研究

用土培试验的方法,比较研究了可生物降解螯合剂EDDS和难生物降解螯合剂EDTA对耐Cu植物海州香薷地上部积累土壤Cu、Pb、Zn和Cd的影响。结果表明,施加5mmol·kg-1EDTA和EDDS可增加海州香薷地上部的Cu、Pb、Zn和Cd的含量和积累量。其中,EDDS比EDTA具有更强的溶解土壤Cu、Zn和增加植物吸收积累Cu、Zn的能力。但对土壤Pb、Cd的溶解及Pb、Cd在植物地上部积累的促进作用,EDTA大于EDDS。