钙对李氏禾富集和耐受铬的调控作用

通过水培实验,研究钙对铬胁迫下李氏禾幼苗生理生化、草酸分泌及铬吸收量的影响,考察钙对李氏禾体内草酸合成的调控,进而促进李氏禾的铬耐性富集能力的作用。结果显示,不同浓度Cr³⁺胁迫下缺钙处理,李氏禾生长受抑制及质膜过氧化作用加剧,体内总草酸含量为对照处理的113%~169%,且主要表现为水溶性草酸含量显著高于对照,水溶性草酸含量为对照处理的135%~197%;高钙处理,李氏禾细胞膜透性、丙二醛（MDA）含量低于对照,李氏禾叶部总草酸含量为对照处理的125%~155%,且主要表现为不溶性草酸含量显著高于对照,其含量为对照处理的181%~270%。低浓度（0.2、0.4 mmol/L）铬胁迫下,高钙处理总铬含量分别为对照处理的175%和215%,高浓度（0.8、1.0 mmol/L）铬胁迫下,总铬含量与对照处理无显著差异（P>0.05）。可见,添加Ca²⁺能在一定Cr³⁺浓度胁迫下,有效缓解铬对李氏禾的毒害,且能通过提高植物体内不溶性草酸含量达到促进植物富集和耐受铬的能力。     

EDTA reduces lead accumulation in Symphytum officinale L. (comfrey) roots

The addition of EDTA in phytoextraction studies has been reported to increase heavy metal accumulation in above-ground parts or to have no negative impact on the overall (root/shoot) accumulation levels in terrestrial plants. At a purely quantitative level, this study assessed the phytoextraction potential of a previously untested high-biomass terrestrial plant, Symphytum officinale L. (comfrey), in the presence of Pb and EDTA. In this hydroponic-based study, we report a small increase in shoot accumulation of Pb with EDTA but, conversely, the presence of EDTA in the nutrient medium markedly reduced the overall quantity of Pb in the plant root by at least 80%. The loss does not appear to be explained by EDTA acting alone, increased transport of Pb to the shoots, or anionic charge repulsion of the [PbEDTA]^2? complex. The elusive action and negative effect of EDTA on Pb accumulation in S. officinale provides additional reasons towards a growing trend away from the use of EDTA as a chelating agent in phytoextraction.     

Accumulation of lead and cadmium by four tropical forage weeds found in the premises of an automobile battery manufacturing company in Nigeria

The potentials of tropical weeds namely, Nephrolepis biserrata, Panicum maximum, Eleusine indica, and Chromolaena odorata to accumulate lead (Pb) and cadmium (Cd) from soil within the premises of an automobile battery manufacturing company in Ota, south-western Nigeria, were explored. The weed samples were collected in both wet and dry seasons. Standard analytical methods were employed to collect, digest, and analyze the weeds. Lead levels in the weeds for both seasons ranged from 1990–4870, 1090–1730, 4800–7890, and 400–1210 µg g^?1 dry weight (DW) for Nephrolepis biserata, Panicum maximum, Eleusine indica, and Chromolaena odorata, respectively, while the cadmium level in the weeds for both seasons ranged from 3.92–6.78 µg g^?1 DW for N. biserata, 1.99–6.85 µg g^?1 DW for P. maximum, 2.90–7.40 µg g^?1 DW for E. indica, and 2.90–5.09 µg g^?1 DW for C. odorata. There was no significant difference in the accumulation of both Pb and Cd for the two seasons. All the weeds showed Pb levels higher than the phytotoxic range. On the contrary, 99% of the weeds showed Cd concentration within the phytotoxic range. The weeds demonstrate good phytoremediation potentials of contaminated soil.     

化学性大气污染的植物修复技术

大气污染的植物修复技术是一种安全可靠的环境污染治理技术,也是目前大气污染研究的热点课题.介绍了植物对化学性大气污染物的吸附、吸收、同化、降解、转化等修复机理,并指出了其研究方向.     

Partial characterization of the exopolysaccharide from Oscillatoria trichoides Szafer and the role of released polysaccharide in sequestration of Cr6+

The structural investigation and the chromium adsorptive potential of an exopolysaccharide (EPS) released during the growth of an indigenous cyanobacterium, Oscillatoria trichoides Szafer, were investigated in a laboratory‐scale study. The results showed that, of the total EPS produced, 410.53 milligrams/gram (mg g^?1) were released polysaccharides (RPS) and 11.36 mg g^?1 were capsular polysaccharides (CPS). The sorption of hexavalent chromium (Cr⁶⁺) by the RPS achieved a maximum amount of metal removal (q_max) value of 76.92 mg g^?1 of polysaccharide dry weight. The highest coefficient of determination (0.9742) for the Langmuir adsorption model indicates best fitness of the model in explaining the sorption as a unilayer process. Equilibrium studies indicated that 30 to 40 milligrams per liter initial chromium concentration and a pH of 2 were optimal for biosorption of chromium by the RPS. Scanning electron microscopy with energy‐dispersive X‐ray spectroscopy analysis of Cr⁶⁺‐treated RPS showed the presence of 3.76% bound chromium. Compositional analysis of the EPS showed the presence of carbohydrates, proteins, pyruvic acid, and hexosamines. High‐performance liquid chromatography analysis demonstrated the presence of hexoses, as neutral sugars and glucuronic acid as an acidic sugar. The presence of carboxylic groups was also detected by infrared spectroscopy. The presence of these chemical constituents may serve as binding sites for the metal ions; therefore, the RPS of this species appears to be a promising biosorbent for Cr⁶⁺.     

多氯联苯复合污染农田土壤的植物协同修复效应

采用田间微域试验,初步研究了紫花苜蓿与海州香薷、伴矿景天在不同栽培模式下对多氯联苯(PCBs)复合污染农田土壤的协同修复作用.结果表明,紫花苜蓿与海州香薷、伴矿景天混作对PCBs复合污染土壤的修复效果明显高于紫花苜蓿单作,其中紫花苜蓿-海州香薷混作、紫花苜蓿-海州香薷-伴矿景天混作种植120d后,土壤中PCBs含量比紫花苜蓿单作时分别降低43.0%和47.8%,强化效果显著.与紫花苜蓿单作相比,紫花苜蓿与海州香薷、伴矿景天混作可有效提高植株总生物量,增强植物对土壤中PCBs的吸收富集能力.土壤PCBs同系物分析结果表明,种植植物可有效降低土壤中低氯代PCBs含量,植物混作栽培模式可以促进高氯代PCBs组分向低氯代PCBs组分的转变.可见,紫花苜蓿与海州香薷、伴矿景天混作对多氯联苯复合污染农田土壤具有较好的协同修复作用.     

重金属污染土壤中提高植物提取修复功效的探讨

随着对重金属超积累植物研究的加深 ,用植物提取修复技术来改良重金属污染的土壤已逐步进入实用阶段。本文所探讨的提高此技术功效的方法基于两个方面 :提高土壤溶液中重金属的浓度 ,促进植物对重金属的吸收 ;根据已了解的超积累的生理机制可能采取的一些措施     

外源螯合剂CA和NTA对苎麻修复铅镉复合污染土壤的影响

采用盆栽实验,研究了在两组铅镉复合污染（Cd（10 mg·kg-1）/Pb（100 mg·kg-1）和Cd（50 mg·kg-1）/Pb（500 mg·kg-1））条件下,不同浓度的柠檬酸（CA）和氮三乙酸（NTA）（0,1,5,10 mmol·kg-1）对苎麻生物量、地上部分丙二醛（MDA）含量和抗氧化酶活性、苎麻各部分对Pb和Cd的积累的影响。结果表明,CA和NTA的应用均能促进苎麻的生长和提高Pb和Cd在苎麻体内积累。CA在促进苎麻生长、增强了苎麻对Cd的吸收和转移方面效果显著,但是,CA对Pb的提取和转移促进效果不显著。NTA促进苎麻对Pb的吸收和转移,并且同样有助于Cd的植物修复。苎麻体内CAT,SOD,POD活性和MDA含量变化表明CA和NTA缓解了Cd和Pb对苎麻的氧化胁迫。因此,外源螯合剂CA和NTA的应用有利于铅镉复合污染土壤的植物修复。     

重金属污染土壤植物修复及进展

土壤污染是当今面临的一个重要环境问题。常规的土壤污染物理化学治理技术 ,如客土换土法、冲洗法、热处理、固化、玻璃化、动电修复法等 ,由于其技术要求高或经济成本高昂 ,对土壤结构的扰动破坏较严重 ,因而 ,大规模推广应用存在较大问题。重金属超累积植物的不断发现 ,使人们认识到有可能利用植物于土壤污染的治理修复。自 2 0世纪 90年代起 ,植物修复成为环境污染治理研究领域的一个前沿性课题。研究表明 ,通过植物的吸收、挥发、根滤、稳定等作用 ,可以净化土壤或水体中金属污染物 ,达到净化环境的目的。近 10年来 ,在超累积植物的找寻培育、植物根际微生物共存体系研究、植物对重金属的耐忍性、超量吸收及其解毒机制以及植物修复的工艺技术方面已有不少研究 ,并取得长足的进展 ,现代分子生物学的发展以及基因工程技术的应用有可能使植物修复技术取得根本性的突破。     

外源钙对镉胁迫下苎麻生长及生理代谢的影响

以苎麻为实验材料,采取营养液栽培方式,研究了不同浓度的钙(0、1、5和10 mmol·L-1)在5 mg·L-1 氯化镉胁迫下,对苎麻幼苗生长及植物体内重金属的积累、光合作用、抗氧化作用等的影响。研究结果显示,中浓度钙处理(5 mmol·L-1)能明显缓解镉胁迫对苎麻的毒害作用。与单独镉处理相比,外源5 mmol·L-1钙处理苎麻地上部分和根部的生物量分别为单独镉胁迫下的1.21倍和1.32倍,叶绿素含量增加了19.77%,丙二醛和过氧化氢含量分别下降了19.09%和29.02%,抗氧化酶的活性也发生了相应变化;低浓度钙处理(1 mmol·L-1)显著提高了苎麻茎叶中镉的含量,分别为单独镉胁迫下的2.54倍和3.59倍。由此表明,外源钙和镉的交互作用与外源钙的浓度密切相关。