混合螯合剂的不同施加方式对重金属污染土壤套种修复效果的影响

[目的]开发具有应用前景的植物与化学联合修复重金属污染土壤的技术.[方法]通过盆栽试验,研究混合螯合剂(MC)的不同施用方式对东南景天Sedum alfredii和玉米Zea mays套种系统的影响,探讨MC作为植物提取的强化剂和重金属的淋洗剂对土壤的修复效果.[结果]东南景天和玉米套种情况下,MC可以提高植物对重金属提取的效率,也可以淋洗出土壤中的部分重金属,其中MC分2次淋洗时淋出的重金属量显著大于单次淋洗.经过套种和MC淋洗后,土壤全量Cd、Zn和Pb含量降低幅度分别为30.7％ ～ 33.0％、11.9％ ～ 14.7％和13.3％～16.4％.东南景天和玉米套种的共有根际土壤微生物数量与单种植物的不同,施加MC后显著提高了套种共有根际的细菌和放线菌数量,然而,高剂量MC淋洗时共有根际的微生物数量又会下降.[结论]套种和MC淋洗联合技术对土壤重金属的去除量大于植物提取的;Pb的去除主要靠淋洗,Zn/Cd可以用植物提取去除,套种+淋洗可以加快对Zn/Cd/Pb复合污染土壤的修复.     

Varietal tolerance to Zinc deficiency in wheat and barley grown in chelatorbuffered nutrient solution and its effect on uptake of Cu,Fe, and Mn

Tolerance to zinc (Zn) deficiency was examined for three wheat (Triticum aestivum L.) and three barley (Hordeum vulgare L.) varieties grown in chelator‐buffered nutrient solution. Four indices were chosen to characterize tolerance to Zn deficiency: (1) relative shoot weight at low compared to high Zn supply (“Zn efficiency index”), (2) relative shoot to root ratio at low compared to high Zn supply, (3) total shoot uptake of Zn under deficient conditions, and (4) shoot dry weight under deficient conditions. Barley and wheat exhibited different tolerance to Zn deficiency, with barley being consistently more tolerant than wheat as assessed by all four indices. The tolerance to Zn deficiency in the barley varieties was in the order Thule=Tyra>Kinnan, and that of wheat in the order Bastian=Avle>Vinjett. The less tolerant varieties of both species accumulated more P in the shoots than the more tolerant varieties. For all varieties, the concentrations of Mn, Fe, Cu, and P in shoot tissue were negatively correlated with Zn supply. This antagonism was more pronounced for Mn and P than for Cu and Fe. Accumulation of Cu in barley roots was extremely high under Zn‐deficient conditions, an effect not so clearly indicated in wheat.     

碾压麻茎及添加螯合剂对亚麻酶法脱胶的影响

在酶法亚麻脱胶的基础上,研究碾压亚麻原茎和添加螯合剂对脱胶的影响。结果表明,碾压麻茎和添加螯合剂(EDTA和草酸)均能够促进酶法脱胶。将碾压的麻茎和添加螯合剂联合使用,进行亚麻酶法脱胶,螯合剂EDTA的添加量为5mM/L,脱胶过程中果胶酶活力的损失降低,脱胶周期为7h,较只使用酶液脱胶的时间缩短了70.8%,且酶液可稀释1倍使用,节约了脱胶成本。     

DTC类重金属捕集剂对猪场废水中Cu、Zn的去除试验研究

通过黄原酸化反应将二硫代氨基甲酸(DTC)基团引入至壳聚糖, 制备DTC类重金属捕集剂, 用以去除猪场废水Cu、Zn。结果表明, DTC类重金属捕集剂对Cu、Zn的捕集性能受废水初始pH值和捕集剂投加量的影响, pH值有一个适宜范围, 即pH 3.0~5.0;随着捕集剂投加量的增加, 去除效果逐渐增加, 但增加速率逐渐减缓。捕集剂性能受进水Cu、Zn浓度以及废水温度的干扰不很明显。在废水pH值5.0, 捕集剂投加量2.0 g·L^-1(废水), 初始Cu、Zn浓度25~200 mg·L^-1时, 捕集剂对Cu、Zn的去除率可达到99%以上, 且处理后Cu、Zn浓度低于污水综合排放标准(GB 8978—1996)一级标准限值规定。DTC类重金属捕集剂对Cu、Zn的等温吸附特征可用Langmuir方程进行拟合, 其吸附平衡时间约为20 min左右。     

可降解螯合剂对草坪植物高羊茅发育及生理的影响

以盆栽高羊茅为试验材料,研究了土壤中添加不同浓度(3、6、9、12和15 mmol·kg~(-1))生物可降解螯合剂谷氨酸二乙酸四钠(Glutamic acid N,N-diacetic acid tetra sodium salt,GLDA)和亚氨基二琥珀酸四钠盐(Iminodisuccinic acid sodium salt,IDS)处理对种子萌发和幼苗发育及生理的影响。结果表明,GLDA和IDS处理对高羊茅种子萌发有一定的抑制作用,并且高浓度的抑制作用更强。对高羊茅地上生物量的影响表现为低浓度促进,高浓度抑制,6 mmol·kg~(-1)处理生物量达到最大;而所有螯合剂处理均显著抑制了根系的生长。与对照相比,低浓度的螯合剂(3、6和9 mmol·kg~(-1))对叶绿素和类胡萝卜素含量没有显著影响,但高浓度处理显著降低了其含量。螯合剂对SOD和CAT活性的影响呈现先增加后降低的趋势,而POD活性和MDA含量则随螯合剂浓度的增加而升高,表明添加螯合剂对高羊茅构成了逆境胁迫。鉴于此,在两种螯合剂应用于土壤重金属修复时,以低浓度(6 mmol·kg~(-1))施加为宜,并且可以考虑在植物收获前几天施加或分次加入。     

Immobilized EDDHA and DFOB as Iron Carriers to Cucumber Plants

Abstract

Iron chelators are the most effective Fe fertilizers known to date. However, due to their negative charge they are easily leached out of the root zone. Besides the risk of groundwater contamination with organic compounds and metals, repeated applications of expensive Fe chelates are often required. With the aim to reduce leaching, desferrioxamine B (DFOB) and ethylenediaminedihydroxyphenylacetic acid (EDDHA) were immobilized on Sepharose and tested as Fe sources to plants. Two cultivars of cucumber (Dlila and Kfir) grown in hydroponic cultures at pH 7.3, efficiently utilized Fe from immobilized FeDFOB, and immobilized FeEDDHA. In general, plant response to the immobilized fertilizers became comparable to that of soluble chelates within a period of 17 to 26 days. The kinetics of alleviating Fe induced chlorosis in plants treated with the immobilized chelates was slower than that obtained with soluble chelates. Moreover, the Fe³⁺ reduction rates obtained for immobilized FeDFOB were slower than those measured for soluble FeDFOB. Our observations suggest that immobilized FeDFOB can serve as a slow release Fe fertilizer. The slow kinetics of reduction and uptake from the immobilized as compared to the soluble chelates can be attributed to the lower accessibility to the plant's roots.     

一种磁性固体螯合材料对农田土壤Cd的移除修复效果研究

通过室内模拟试验,开展了投加一种磁性固体螯合材料(Magnetic solid chelator,MSC)并进行磁选回收对农田土壤Cd的移除修复效果、MSC回收率及磁选物质螯合捕集Cd能力的研究。结果表明,投加0.4%~1.2%的MSC材料并进行磁选回收对总Cd和有效态Cd的去除率分别为15.91%~17.69%和33.33%~50.26%,而MSC的回收率在74.01%~94.33%之间,有随投加量增加而增加并逐渐趋于稳定的趋势;磁选物质(主要为MSC材料)螯合吸附的Cd含量在19.31~25.72 mg·kg~(-1)之间,在0.4%处理中最高,显著高于0.8%、1%和1.2%处理,有随MSC材料回收量的增加而降低的趋势。0.8%和1.2%投加量时磁选物质螯合捕集的Cd能较好地解释土壤被去除的那部分Cd。处理后水样中的Cd含量低于我国地表水环境质量标准(GB 3838—2002)中的Ⅰ类标准(0.001 mg·L~(-1)),不会成为新的污染源。因此,MSC材料对农田土壤Cd具有一定的移除修复效果,为农田土壤重金属修复提供了一种新方法。     

间作条件下螯合剂对龙葵和大叶井口边草吸收重金属的影响

用室内土培试验方法,在采自田间的Pb、Cd和As复合污染土壤中单作或间作龙葵和大叶井口边草条件下,筛选出修复Pb-Cd-As复合污染土壤较好的种植方式为间作。进一步在间作方式下,研究了外源添加不同浓度EDDS（乙二胺二琥珀酸）、NTA（氨三乙酸）和EDTA（乙二胺四乙酸）对植物吸收Pb、Cd和As的影响。结果表明,间作显著促进了龙葵地上部对Cd的吸收量和大叶井口边草地上部对As的吸收量,间作龙葵地上部吸收Cd和大叶井口边草地上部吸收As含量分别是单作龙葵和大叶井口边草的1.3倍和1.4倍,说明间作龙葵和大叶井口边草比单作更有利于修复Pb-Cd-As复合污染土壤。间作条件下,大叶井口边草对螯合剂的耐性比龙葵更强。3、6、12mmol.kg-1EDTA能极显著增加土壤中Pb、Cd有效态含量,从而促进龙葵地上部对Pb吸收和大叶井口边草地上部对Pb、Cd吸收。EDTA比NTA具有更强的提高土壤Pb、Cd有效态的能力,但对土壤As有效态促进作用与EDTA相比,NTA效果极显著,1.5、3mmol.kg-1NTA处理极显著提高土壤As有效态含量及促进龙葵和大叶井口边草地上部对As吸收。     

一种利用铁离子螯合剂恢复丁香假单胞菌菌落荧光的方法

丁香假单胞菌产生的荧光色素是一种具有毒性功能的致病性因子,也是细菌鉴定和分类的重要依据。测定了基本培养基不同组分的浓度对丁香假单胞菌荧光色素产生能力的影响,并比较了几种金属离子螯合剂对恢复丁香假单胞菌荧光物质合成能力以及细菌生长能力的影响,旨在找到恢复丁香假单胞菌在常规培养基上合成荧光色素的方法。结果如下:①丁香假单胞菌荧光色素的合成能力主要受培养基中铁离子浓度的影响,而与眎蛋白胨,以及K2HPO4、MgSO4的浓度均无关;② 0.05 g/L的螯合剂8-羟基喹啉可使丧失荧光物质合成能力的丁香假单胞菌恢复产生荧光,恢复的荧光物质合成可以被铁盐（FeCl3）逆转;但同时8-羟基喹啉对细菌生长也有一定的抑制作用;③其他金属离子螯合剂,如柠檬酸(C6H8O7·H2O)、酒石酸钠(Na2C4H4O6)、磷酸三钠(Na3PO4)和乙二胺四乙酸二钠(EDTA-Na2),均不能恢复丁香假单胞菌产荧光色素。该结果表明在KB培养基中添加螯合剂8-羟基喹啉（0.05 g/L）可以使丁香假单胞菌恢复荧光物质的合成能力。