Cd和盐联合胁迫下紫茉莉的生长反应及Cd积累特性研究

[目的]研究Cd和NaCl联合胁迫下紫茉莉的生长反应及Cd积累特性。[方法]采用溶液培养的方法,植物收获后,测量生物干重以及各部位Cd含量。[结果]紫茉莉对Cd和盐联合胁迫表现出了强的耐性,在适宜Cd及盐处理浓度下,投加NaCl促进了紫茉莉对Cd的积累。[结论]紫茉莉具有修复Cd和盐复合污染土壤的潜力。     

Long-term phytomanagement of metal-contaminated land with field crops: Integrated remediation and biofortification

Several studies on the phytomanagement of mixed-metal-contaminated land were carried out over a period of 10 years in an agricultural soil at Carpiano (Milan, Italy) and in pyrite waste at Torviscosa (Udine, Italy), in order to investigate the practicability of using various field crops for this purpose. Here we demonstrate that seed germination and initial growth are never critical steps under high levels of Cd or Cr, whereas poor plant productivity limits metal removal rates from contaminated waste. Phytoextraction alone was rarely an efficient remediation technology and, if the process was not chemically assisted, only Zn and Mn were accumulated above-ground in considerable amounts. A maximum of 8 kg ha⁻¹ of metals with rapeseed and only 0.33 kg ha⁻¹ with fodder radish were removed from soil. Cultivation of metal-contaminated land did provide some limited opportunity for natural biofortification of crops with Zn and Cu, with no apparent risk of toxic metals in the seeds of only a few crops. Improvements in tissue metal rates achieved with auxins, humic acids or chelators were largely detrimental to biomass yield. We conclude that the efficient use of crop species in phytoremediation requires the achievement of high productivity by appropriate agricultural management involving tillage, fertilisation and perhaps also capping or dilution with clean soil. The considerable metal stock in roots suggests exploring the effectiveness of long-term stabilisation, particularly in non-tillage systems.     

Enhanced dissipation of chrysene in planted soil: the impact of a rhizobial inoculum

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. Mixed grass-legume systems, together with microbial inoculants, were used to remediate a polycyclic aromatic hydrocarbon (chrysene) spiked agricultural soil. Inoculants were symbiotic rhizobia, which may play an important role in rhizoremediation by increasing plant and root growth. An inoculum of an isolate of Rhizobium leguminosarum bv. trifolii, selected for PAH tolerance, was produced using a peat carrier. The inoculum and white clover (Trifolium repens L.), were planted into soils with ryegrass (Lolium perenne L.). The soils spiked with chrysene (500 mg kg⁻¹) then aged for 4 weeks. Shoot- and root-biomass of plants, and the amount of root nodulation, were determined. Rhizobial populations, soil pH and soil nitrogen were also monitored throughout the trial. In addition, the ability of the inoculated rhizobial strain to utilise chrysene as a sole carbon source was assessed. Direct uptake and/or degradation of chrysene by the clover and ryegrass did not occur to a significant degree. Enhanced losses of chrysene were seen in planted, non-sterile soils that contained a rhizobial inoculum. No direct degradation of chrysene by R. leguminosarum bv. trifolii was observed and no enhanced losses of PAHs were detected in sterile soils after inoculation with rhizobia. Results suggest that the enhanced dissipation of chrysene, observed in the non-sterile planted inoculated pots, was not a result of degradation of chrysene by R. leguminosarum bv. trifolii. The symbiotic association with R. leguminosarum bv. trifolii improved plant vigour and growth in inoculated planted treatments. This may have stimulated the rhizospheric microflora to degrade chrysene.     

Biotransformation of pentachlorophenol by Chinese chive and a recombinant derivative of its rhizosphere-competent microorganism, Pseudomonas gladioli M-2196

The use of plants or microorganisms to detoxify contaminated soil or groundwater is a potentially cost-effective alternative to traditional remediation technologies. This study investigated the effects of a rhizosphere microbe on the biotransformation of pentachlorophenol (PCP). Chinese chive (Allium tuberosum Rottler) and its rhizosphere-competent bacterium, Pseudomonas gladioli M-2196, were used as a plant-bacterium pair. The genes encoding PCP-degrading enzymes from Sphingobium chlorophenolicum ATCC39723 were introduced into the chromosome of P. gladioli M-2196. The resultant transformants were able to degrade PCP almost completely in liquid medium within 4 d in culture. PCP degradation experiments showed that the amount of PCP in soil (3.3 μg g⁻¹) planted with the P. gladioli transformant (T-9) and Chinese chive decreased by 40% as compared with untreated soil (control) by day 28. Strain T-9, which was used in the PCP degradation experiments, retained the ability to colonize the Chinese chive rhizosphere after 28 d. Tetrachlorocatechol (TCC) was detected as a metabolite of PCP in Chinese chive extract. The amount of PCP in soil treated only with Chinese chive decreased by 30% as compared with the control, but the total amount of PCP plus TCC detected in the plant was less than 10% of the amount of PCP removed from soil. This might be due to the enhancement of a soil microflora population capable of degrading PCP by root exudates from Chinese chive. Therefore, Chinese chive itself, in addition to the rhizosphere-competent bacterium, seemed to play an important role in reducing the PCP level in the soil.     

植物修复技术在城市园林中的应用

植物修复作为一种有潜力、正在发展的清除环境污染的绿色技术,在城市环境土壤改良、水质改善以及空气污染物的清除等方面发挥着越来越大的作用,在园林绿化等实际工作中有着广阔的应用前景。     

Effect of Root Zone Temperature on Accumulation of Molybdenum and Nitrogen Metabolism in Potato Plants

Abstract

Changes in root temperature caused by the application of plastic covers were studied in relation to the uptake and content of molybdenum (Mo) in the different organs of potato (Solanum tuberosum L. var. Spunta) plants (roots, tubers, stems, and leaves) and in relation to nitrogen (N) metabolism. For the semi‐forcing technique of mulching, four different covers were used: T ₁ (transparent polyethylene), T ₂ (white polyethylene), T ₃ (coextruded black and white polyethylene), and T ₄ (black polythylene). The control treatment had no mulch. The results revealed a positive and significant effect of plastic covers on root temperatures: T ₀ = 16°C, T ₁ = 20°C, T ₂ = 24°C, T ₃ = 27°C, T ₄ = 30°C. These thermal differences significantly influenced the Mo concentration, particularly in the T ₂ and T ₃ treatments in the leaves, roots, and tubers. The same temperatures significantly altered N metabolism in both the aerial and underground parts of the plants, and a strong interrelationship was found between Mo and nitrate reductase (NR) activity. The mulching of this crop proved to be a promising technique in phytoremediation.     

Culture-based and culture-independent assessment of the impact of mixed and single plant treatments on rhizosphere microbial communities in hydrocarbon contaminated flare-pit soil

Phytoremediation is a novel treatment option for weathered, hydrocarbon contaminated, flare-pit soil in prairie ecosystems. The remediation potential of six different naturalized prairie plants was assessed by examining their impact on the degradation potential of indigenous bacterial communities. Culture-based and culture-independent microbiological methods were used to determine if mixed plant treatments stimulate different microbial communities and catabolic genotypes in comparison to individual plant species that comprise the mix. DGGE analysis of PCR-amplified 16S rRNA genes revealed that alfalfa (Medicago sativa) had a dominant effect on the structure of rhizosphere microbial communities in mixed plant treatments, stimulating relative increases in specific Bacteroidetes and Proteobacteria populations. Alfalfa and mixes containing alfalfa, while supporting 100 times more culturable PAH degraders than other treatments, exhibited only 10% TPH reduction, less than all planted treatments except perennial rye grass (Lolium perenne). Total petroleum hydrocarbon (TPH) reduction was greatest in single-species grass treatments, with creeping red fescue (Festuca rubra) reducing the TPH concentration by 50% after 4.5 months. Overall TPH reduction throughout the study was positively correlated (p<0.001) to culturable n-hexadecane degraders.     

Lead Phytostabilization and Cationic Micronutrient Uptake by Maize as Influenced by Pb Levels and Application of Low Molecular Weight Organic Acids

ABSTRACT

Phytoremediation is a promising technique to clean up toxic heavy metals including lead (Pb). A greenhouse trial was conducted to evaluate the effectiveness of citric, succinic, malonic and oxalic acids on micronutrient uptake and phytoremediation of Pb contaminated soil by maize under different Pb levels. Mean root and shoot dry weights of maize decreased with increasing Pb levels. At the lowest Pb level, application of citric and oxalic acids caused increase effects on root and shoot dry weight, respectively, as compared to the absence of organic acid. As Pb levels increased, micronutrient uptake in maize shoot decreased. Among the studied organic acids, only the application of oxalic acid increased uptake of all micronutrients in maize shoot as compared to control at the lowest Pb level. Mean root and shoot Pb concentration and uptake and also uptake index noticeably increased at the highest Pb level. All tested acids increased Pb concentration and uptake in maize root. At the highest Pb level, organic acids, except for citric acid, significantly increased shoot Pb uptake and uptake index as compared to the absence of organic acid. Translocation factors less than 1, demonstrated that most of Pb taken up by maize accumulated in root as compared to shoot. According to results reported herein, application of malonic, succinic and oxalic acids is a good strategy to enhance phytostabilization potential of Pb by maize in pb-polluted soils.     

土壤中有机污染物的植物修复研究进展

植物修复是土壤有机污染物修复的有效途径之一，主要包括植物吸收、根际土壤酶促进降解和微生物对其的一系列降解。本文简述了植物修复的含义，系统综述了植物修复有机污染物的机理，并阐述了利用植物对农药、氯代化合物、多环芳烃和其它有机污染物进行修复的研究成果与应用，展望了今后进一步研究的重点。     

污染土壤植物修复技术研究进展

综述了国内外污染土壤植物修复技术研究进展 ,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对土壤中有机污染物降解等特殊功能 ,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 ,环境友好 ,是极具发展潜力的“绿色产业”。