剑麻对重金属铅的吸收特性与累积规律初探

以热带地区一种生物量极大的经济作物剑麻(AgaveSisalanaPerrineexEngelm)作为研究对象,采用网室砂培,对Pb在该植物体内的吸收特性、累积分布及迁移规律进行了初步的探索。试验表明,Pb处理浓度低于1300mg·kg-1时对剑麻生长影响较小,但Pb加入浓度达到15900mg·kg-1时,显著抑制了剑麻的生长,其生物量仅为对照的6.7%。剑麻对Pb有很强的吸收性,并分布在其植株的各个部位,其中根系的吸收性最强,是地上部的3.0～13.6倍。Pb处理浓度为12700mg·kg-1时,剑麻地上部和根系的吸收量最大,分别为2220.3和22544.8mg·kg-1,是对照的65.6和221.3倍,且地上部迁移量高达55.87mg·株-1,说明剑麻对修复Pb污染土壤有一定的潜力,因而为今后探明植物积累Pb的机理和Pb污染土壤的植物修复提供了一种新的种质资源。     

Zn超富集植物长柔毛委陵菜对Cd的耐性与富集特征

通过野外调查和营养液培养,证明Zn超富集植物长柔毛委陵菜(Potentilla griffithii var.velutina)无论在自然条件下还是营养液培养条件下,都对Cd具有很强的耐性和富集能力,是一种潜在的重金属Cd超富集植物。自然条件下生长于铅锌矿区的长柔毛委陵菜,其根系土壤Cd总量为101～1331mg·kg-1,平均320mg·kg-1;植物Cd含量叶片为39～765mg·kg-1,平均178mg·kg-1,叶柄为64～1422mg·kg-1,平均280mg·kg-1;Cd转运系数为0.64～1.18,平均值0.84;生物富集系数为0.22～1.68,平均0.80。营养液培养条件下,长柔毛委陵菜在Cd浓度≤20mg·L-1的介质中能够正常生长;植物叶片、叶柄及根部Cd含量随介质中Cd浓度的增大而增大,叶和柄中Cd含量在60mg·L-1的Cd处理时都达到最大,分别为1604和6145mg·kg-1;不同组织的Cd含量顺序为根>柄>叶;体内累积的Cd有60%以上储存在地上部。营养液培养的Cd转运系数小于自然状况。     

3种水生植物对水溶液中乐果的降解作用研究

通过在人工配制的含有机磷农药乐果的营养液中培养水生植物,研究了水葱、香蒲和石菖蒲对水溶液中有机磷农药乐果的去除效果,并探讨了水葱对乐果降解的动力学过程。结果表明,在抑菌条件下,3种植物都能够显著促进乐果的降解,去除能力为:水葱>香蒲>石菖蒲。水葱10d内对5mg·L-1乐果的去除率为59.8%,香蒲和石菖蒲组对乐果的去除率分别为42.5%和36.9%。在不抑菌条件下,水葱对乐果的去除符合一级动力学方程,去除速率常数为0.099d-1,水溶液中未检测到乐果降解的中间产物。     

刈割次数对紫花苜蓿镉吸收影响及生理响应

采用盆栽试验研究了4种镉(Cd)浓度(0,10,25,50 mg/kg)下,刈割次数(1次,2次,3次)对紫花苜蓿生长和Cd累积量的影响及其生理响应。结果发现,多次刈割提高了紫花苜蓿地上部分的生长速率,促进了地上部分生物量的累积,3次刈割下地上部平均生长速率可达61.6 mg/(株·d),但3次刈割显著抑制了根系的生长(P<0.05)。生长季内2次和3次刈割可以促进根系Cd吸收,增加地上部分Cd累积量,进而提高紫花苜蓿Cd富集量,单株最大镉积累量出现在25 mg/kg Cd浓度的2次刈割处理中,达到75.98 μg/株。同时,2次或3次刈割会降低紫花苜蓿相对电导率、MDA含量,增加脯氨酸含量,改善紫花苜蓿在Cd胁迫下的生理状况。综合分析表明,当土壤Cd浓度不高于25 mg/kg时,紫花苜蓿生长季内2次刈割可以提高Cd污染土壤修复效率。     

Effect of Ethylenediaminetetraacetic Acid on Growth and Phytoremediative Ability of Two Wheat Varieties

Chelating agents are commonly used to enhance the phytoremediative ability of plants. The type of chelating agent applied and the selection of plant species are important factors to consider for successful phytoremediation. This study investigates the effects of four different rates (0, 2, 4, 8 mmol kg^?1) of ethylenediaminetetraacetic acid (EDTA) on lead (Pb) dissolution, plant growth, and the ability of two spring wheat varieties (Auqab-2000 and Inqalab-91) to accumulate Pb from contaminated soils in a pot study. The results indicated that the addition of EDTA to the soil significantly increased the aqueous solubility of Pb and that wheat variety Inqalab-91 was more tolerant to Pb than Auqab-2000. Application of EDTA at 8 mmol kg^?1 resulted in biomass yield, photosynthetic rate, and transpiration rate significantly lower in Auqab-2000 than in Inqalab-91. Although EDTA enhanced the uptake of Pb by both wheat varieties, Auqab-2000 accumulated significantly more Pb in the shoots than Inqalab-91. The results of the present study suggest that under the conditions used in this experiment, EDTA at the highest dose was the best amendment for enhanced phytoextraction of Pb using wheat. High concentrations of Pb were found in leachates collected from the bottom of columns treated with EDTA. Application of EDTA in the column leaching experiment increased the concentration of Pb in leachate with increasing EDTA dosage (0–8 mmol kg^?1). These results suggest that EDTA addition for enhancing soil cleanup must be designed properly to minimize the uncontrolled release of metals from soils into groundwater.     

根迹土壤根诱导的化学变化对植物吸收重金属的影响

It is increasingly recognized that metal bioavailability is a better indicator of the potential for phytoremediation than the total metal concentration in soils; therefore, an understanding of the inffuence of phytoremediation plants on metal dynamics at the soil-root interface is increasingly vital for the successful implementation of this remediation technique. In this study, we investigated the heavy metal and soil solution chemical changes at field moisture, after growth of either Indian mustard (Brassica juncea) or sunffower (Helianthus annuus L.), in long-term contaminated soils and the subsequent metal uptake by the selected plants. In addition, the fractions of free metal ions in soil solution were determined using the Donnan membrane technique. After plant growth soil solution pH increased by 0.2-1.4 units and dissolved organic carbon (DOC) increased by 1-99 mg L^-1 in all soils examined. Soluble Cd and Zn decreased after Indian mustard growth in all soils examined, and this was attributed to increases in soil solution pH (by 0.9 units) after plant growth. Concentrations of soluble Cu and Pb decreased in acidic soils but increased in alkaline soils. This discrepancy was likely due to a competitive effect between plant-induced pH and DOC changes on the magnitude of metal solubility. The fractions of free Cd and Zn ranged from 7.2% to 32% and 6.4% to 73%, respectively, and they generally decreased as pH and DOC increased after plant growth. Metal uptake by plants was dependant on the soil solution metal concentration, which was governed by changes in pH and DOC induced by plant exudates, rather than on the total metal concentrations. Although plant uptake also varied with metal and soil types, overall soluble metal concentrations in the rhizosphere were mainly inffuenced by root-induced changes in pH and DOC which subsequently affected the metal uptake by plants.     

土壤重金属污染背景下的任豆修复试验

为寻找适合矿业尾矿坝人工生态恢复的植物,以广西南丹长坡矿堆存 50 a之久的尾矿坝为背景,通过盆栽模拟,运用室内土培和水培两种试验方法,研究了不同矿土比例（尾矿样与泥土比例分别为5∶0、4∶1、3∶2、2∶3、1∶4、0∶5）以及不同浓度（0、2.5、5、10、25、50、100、150、200、250 mg·L^-1）Pb^2＋、Cu^2＋、Zn^2＋在任豆苗体内的吸收、积累和分布的动态变化规律。结果表明,任豆对Pb、Cu、Zn都具有一定的吸收能力,任豆幼苗可以在一定的重金属胁迫环境下存活,任豆对重金属Pb的耐性最大,在高浓度下依然可以存活。任豆对不同类型的重金属的吸收及转运能力存在较大差异,从任豆对Pb、Cu、Zn的转运能力来看,任豆并非这3种重金属的超累积植物。试验表明,任豆在矿业尾矿坝的人工生态恢复（植物修复）中有一定的应用价值,但能否大规模采用任豆作为尾矿坝的生态修复物种,尚需进一步研究验证。     

超积累植物修复铜污染土壤的研究现状

铜是植物必需的营养元素,但是过量的铜会严重影响动植物的生长,随着现代工农业的发展,铜已经成为了我国重金属污染土壤中主要的污染元素之一。在污染土壤的修复措施中,植物修复是一种绿色技术,具有传统土壤治理方法所无法比拟的优点,也是现今国际环境修复的热点和前沿领域。近年来,我国铜污染土壤的植物修复研究发展很快,发现了海州香薷、鸭跖草、蓖麻等铜超积累植物,同时有机酸、耐铜微生物也能加强超积累植物的修复作用。综述了植物修复的一般原理,介绍了现今研究较多的超积累植物对铜的富集效果,超积累植物对铜的耐性及解毒机理以及其他因素的强化作用。     

3个陆地棉种质(系)重金属镉的积累、转运和富集特性分析

以2个转基因陆地棉种质系(ZD-90和SGK3)和陆地棉标准系TM-1为材料,于2009-2010年进行盆栽试验,对镉胁迫下棉花植株不同器官镉的累积、转运和富集特性进行了研究。结果表明,3个棉花种质(系)不同器官镉的累积量随镉胁迫浓度的增加而增加,其中纤维中镉累积量最低,叶柄中镉累积量最高;营养器官镉累积量远高于种子和纤维。各器官累积镉能力的顺序为:纤维<种仁<棉子壳<根<叶片<茎秆<铃壳<叶柄。3个棉花种质(系)各器官的镉转运能力和富集系数与镉累积能力顺序一致,但品种间有显著差异,SGK3和ZD-90的镉累积能力和镉富集系数高于TM-1。棉花具有较强的吸收、转运和聚集重金属镉的能力,体内存在较好的镉运输机制,具备作为超富集植物的基本特征,可以作为超富集植物来治理土壤镉污染。     

重金属污染土壤植物修复技术研究进展

随着城市化和工业化的加速,土壤的重金属污染问题日趋严重。植物修复技术作为一种环境友好型治理措施,越来越受到人们关注。植物修复是利用某些植物对土壤重金属的超量吸收、挥发以及固定等特殊功能,并与根际微生物协同作用,原位修复污染土壤的方法,费用低、效果显著,是极具发展潜力的"绿色产业"。