Air-Pollutant-Philic Plants for Air Remediation

In this communication, we review our work over two decades on air-pollutant-philic plants that can grow with air pollutants as the sole nutrient source. We believe that such plants are instrumental in mitigating air pollution. Our target air pollutant has been atmospheric nitrogen dioxide (NO2), and our work on this subject has consisted of three parts: Variation in plants’ abilities to mitigate air pollutants among naturally occurring plants, genetic improvement of plants’ abilities to mitigate air pollutants, and the plant vitalization effect of NO2. So far, an estimation of the half-life of nitrogen derived from NO2 uptake in plants belonging to the 217 taxa studied to date has shown no plants to be naturally occurring air-pollutant-philic. However, we found that an enormous difference exists in plants’ ability to uptake and assimilate atmospheric NO2. Future studies on the causes of this process may provide an important clue to aid the genetic production of plants that are effectively air-pollutant-philic. Both genetic engineering of the genes involved in the primary nitrate metabolism and genetic modification by ion-beam irradiation failed to make plants air-pollutant-philic, but mutants obtained in these studies will prove useful in revealing those genes critical in doing so. During our study on air-pollutant-philic plants, we unexpectedly discovered that prolonged exposure of plants to a sufficient level of NO2 activates the uptake and metabolism of nutrients that fuel plant growth and development. We named this phenomenon “the plant vitalization effect of NO2” (PVEON). Investigations into the mechanisms and genes involved in PVEON will provide an important clue to making plants air-pollutant-philic in the future.

Remediation of Arsenic Toxicity in the Soil-Plant System by Using Zinc Fertilizers

Availability of soil arsenic (As) and plant As at various levels of zinc (Zn) and As applications were examined. A pot-culture experiment with a leafy vegetable, Kalmi (Ipomoea aquatica), on an Inceptisols, was conducted where As was applied with irrigation water at the rates of 0 mg/L (As control), 0.5 mg/L, 1 mg/L and 2 mg/L and Zn was added to the soil as ZnCl2 solution at the rate of 0 mg/L (Zn control), 1 mg/L, 2 mg/L and 3 mg/L during pot preparation. The experiment was conducted in triplicates for 45 days till the plants were grown to maturity. At the end of the experiment the remedial effect of Zn on As toxicity was examined and as such, yield parameters, As and Zn accumulation in Kalmi plants, residual concentrations of As and Zn in soils and plants were measured. It appeared from the present study that there exists an antagonistic relationship between Zn and As i.e., Zn in soils was found to reduce As availability in soils as well as its accumulation in plants, particularly at an elevated application rate of 3 mg/L Zn. The findings could be used as a strategy to mitigate arsenic toxicity in As contaminated soils.

Optimization of reed-specific degrading bacteria by response surfaces for remediation of crude oil-polluted soil in Xinjiang,China

This paper discussed the optimization of conditions for remediation of crude oil-polluted soil based on pot experiment by applying reed-specific degrading bacteria, and using response surfaces methodology. We took the initial crude oil concentration, the amount of inoculation, the ratio of nitrogen and phosphorus, and the use of surfactant （Tween-80） as independent variables （factors）, and the degrading ratio of crude oil as the dependent variable （response） after a 90-day experiment. The experiment explored the impacts of each independent variable and their interactions on the bioremediation of crude oil-polluted soil using the Box-Behnken design. Working with a simulated forecasting model the study obtained optimization va reed＋specific degrading bacteria, a nitrogen to phosphorus ues for the treatment parameters of 200 g/kg of the ratio of about 6.0. and 0.2% surfactant. Under experimental conditions, for crude oil concentrations of 10, 30 and 50 g/kg, the optimal effects of the treatments achieved 71.87%, 66.61% and 54.52% degradation of the crude oil, respectively. The results can provide a basis for the technical development of plant-microorganism combined bioremediation of crude oil-polluted soil.

Ethnobotanical Study of Some Useful Plants Used as Folk Remedies in Anatolia （Turkey）

Turkey contains about 11,000 plant taxa. The study area covers East Mediterranean Region of South Anatolia. It is detected that plant diversity in this area corresponds to 51% of Turkey＇s native flora. In this study, we investigated native plants in point of ethnobotanic usage of some endemic and endangered plants used as folk remedies in Anatolia. Especially collected causes of these plants are executed. A questionnaire form is designed as a tool for gathering information from many villages of different districts within the area. Endemic taxon rate in the study area is 25% and non-endemic taxon rate is 5%. 45% of the plants in the area have ethnobotanical importance. 21% of them are utilized as medicinal, 14% as foods, 10% as agricultural products, 6% as industrial inputs and 3% as ornamental plants. 6% of the endangered plants with ethnobotanical importance are endemic and 2% of them are non-endemic. Due to ethnobotanical usage, endemic plants are endangered. 12 of 13 critically endangered taxa are utilised as medicinal, 5 as foods, 1 as agricultural and industrial input. In research area, some other taxa are also mistakenly collected because of morphological, physiological or aromatical resemblance to those collected plants. This fact creates even more negative impact especially on endemic and endangered taxa population.

Use of Trichoderma spp. in remediation of polluted soils and waters

Trichoderma spp. probably have a role in remediation of polluted soils and waters. Highly rhizosphere competent strains persist on roots for an extended period of time (at least months) and continuously interact with the plants. They can increase general plant and root growth and increase uptake of a variety of materials. This makes the Trichoderma-plant interaction highly attractive for use in phytoextraction technologies. Moreover, Trichoderma spp. are resistant to a wide range of toxic compounds and can degrade some of these. One highly attractive target for remediation are soils that are polluted with cyanide and metallocyanides. Shrub willows (genus Salix) have been shown to take up and degrade these compounds by unknown mechanisms. Thus, they remove these compounds from soil but there are no cyanide residues in the plants. Similarly, Trichoderma spp. degrade free cyanide via production of extracellular enzymes and take up and then degrade metallocyanides such as Prussian blue. The willow-Trichoderma system therefore provides a plant-microbe system for degradation of these toxic compounds. The fungi also can be used directly in remediation strategies; for example, they degrade polyphenols such as those found in large quantities in waste water from production of olive oil. Thus, the abilities of the fungi to interact and enhance plant growth, their ability to grow in the presence of toxicants and their enzymatic abilities to degrade polluting substances provide a number of opportunities for either plant-microbe or pure fungal systems to remove pollutants from lands and waters.

Problems, challenges and future of plant disease management: from an ecological point of view

Plant disease management faces ever-growing challenges due to： （i） increasing demands for total, safe and diverse foods to support the booming global population and its improving living standards; （ii） reducing production potential in agriculture due to competition for land in fertile areas and exhaustion of marginal arable lands; （iii） deteriorating ecology of agro-ecosystems and depletion of natural resources; and （iv） increased risk of disease epidemics resulting from agricultural intensification and monocultures. Future plant disease management should aim to strengthen food security for a stable society while simultaneously safeguarding the health of associated ecosystems and reducing dependency on natural resources. To achieve these multiple functionalities, sustainable plant disease management should place emphases on rational adaptation of resistance, avoidance, elimination and remediation strategies individually and collectively, guided by traits of specific host-pathogen associations using evolutionary ecology principles to create environmental （biotic and abiotic） conditions favorable for host growth and development while adverse to pathogen reproduction and evolution.

Plant growth and their root development after inoculation of arbuscular mycorrhizal fungi in coal mine subsided areas

Coal mining often cause serious land degradation, soil erosion, and desertification affecting growth of the local vegetation, especially the roots. Arbuscular mycorrhizal fungi （AMF） inoculation is considered a potential biotechnological tool for mined soil remediation because mycorrhizal fungi could improve plant growth environment, especially under adverse conditions due to their good symbiosis. A field experiment was conducted to study the ecological effects of AMF （Funneliformis mosseae, Rhizophagus intraradices） on the growth of Amygdalus pedunculata Pall. and their root development in the regenerated mining subsidence sandy land. The reclamation experiment included four treatments： inoculation of Funneliformis mosseae （F.m）, inoculation of Rhizophagus intraradices （R.i）, combined inoculation of F.m and R.i and non-inoculated treatment. Root mycorrhizal colonization, plant height, crown width, soil moisture, root morphology and certain soil properties were assessed. The results showed that AMF improved the shoot and root growth of Amygdalus pedunculata Pall., and significantly increased root colonization after 1 year of inoculation. Available phosphorus content, activities of phosphatase as well as electrical conductivity in soil rhizosphere of all the three inoculation treatments were higher than that of the non-inoculated treatment. AMF increased the quantity of bacteria and fungi in soil rhizosphere compared with the non-inoculated treatment. Our study indicates that revegetation with AMF inoculum could influence plant growth and root development as well as soil properties, suggesting that AMF inoculation can be effective method for further ecological restoration in coal mine subsided areas.

Studies on Heavy Metal Pollution in Soil-Plant System:A Review

Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry. The heavy metal pollution status in soil-plant system in China, the research progress on the bioavailability of heavy metals (affecting factors, extraction methods, free-ion activity model, adsorption model, multivariate regression model, Q-I relationship, and compound pollution), and soil remediation are reviewed in the paper. Future research and monitoring is also discussed.

Implications of crude oil pollution on natural regeneration of plant species in an oil-producing community in the Niger Delta Region of Nigeria

The study evaluated the impact of crude oil pollution on natu- ral regeneration of plant species in a major oil-producing community in the Niger Delta region of Nigeria. Three sites--unpolluted site （US）, polluted and untreated site （PUS）, and polluted and treated site （PTS）-- were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0-10 cm and 10--20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0-10 em US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0-10/10-20 cm of the PTS respectively. At 10-20 cm, non-woody species of theUS were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0-10/10-20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10-20 cm than 0-10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively af- fected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.

Ziziphus mucronata: an underutilized traditional medicinal plant in Africa

In Africa, rural people depend heavily, if not exclusively, on medicinal plants and indigenous healthcare knowledge to meet their medical needs. Over 80000 flowering plant species are used medicinally worldwide. Amongst them are the underutilized Ziziphus species in the Rhamnaceae family. In terms of abundance and economic value, Z. jujuba and Z. mauritiana are currently the most important, especially in China and India where they are cultivated and exploited for medicinal use and their edible fruits. We examined a related common species widely distributed in Africa, Z. mucronata, whose economic value has not, as yet, been explored. Local people in various African countries use its different parts to cure a large number of diseases, many of which are similar to those treated with Z. jujuba and Z. mauritiana. Several studies have shown that Z. mucronata has cyclopeptide alkaloids, i.e., mucronines F, G and H, with antibacterial properties. Conservation strategies to sustain and maximize the benefits of Z. mucronata to people are proposed.

Managing Public Health Risks Using Air Monitoring at a Former Manufactured Gas Plant Site

Monitoring emissions from a former Manufactured Gas Plant (MGP) site during remediation was used to manage risks associated with inhalation of Volatile Organic Compounds (VOCs) and contaminated particulates acting as an exposure conduit for Polycyclic Aromatic Hydrocarbons (PAHs) and heavy metals. This risk management case study presents a USEPA-approved air monitoring program implemented to manage public health risks during remediation at a former MGP site located in the southeast United States. Risk-based Acceptable Air Concentrations (AACs) were developed and a sampling regimen established to monitor potential emissions to maintain contaminant concentrations below the AACs. The exposure duration used was based on a twelve-month project duration and an exposure time of 24 hours per day;equations, toxicity values and sources were based on USEPA’s Regional Screening Levels. A total 535 twenty-four hour time weighted samples (269 VOC samples and 266 PAH samples) were collected over the project duration. Only minor levels of VOCs and PAHs were detected and no results were above the AACs. These timeweighted averages demonstrate that the real-time air monitoring and control measures implemented at the site effectively maintained concentrations below the AACs and were protective of public health.

生物法修复盐渍化土壤研究进展

我国盐渍化土壤面积大,已严重制约了农业的发展和土壤的循环利用,修复盐渍化土壤有利于增加我国耕地面积、提高粮食产量。盐渍化土壤通常采用物理、化学和生物3种方法进行修复。相比于化学和物理修复法,生物修复法利用生物的生命代谢活动降低土壤的盐分,更经济、环保和高效,因此已在盐渍化土壤修复中得到广泛应用。文章总结了土地盐渍化危害及我国土地盐渍化现状,论述了植物、微生物和微生物-植物联合修复盐渍化土壤的机制和研究现状,并展望了生物法修复盐渍化土壤的应用前景。

城市高架桥下新自然生境重建模式及维持策略——以上海市为例

【目的】城市高架桥下低光照、高污染、强干旱的特殊生境,严重影响了植物健康生长。构建高架桥“植物筛选—生境营造—可持续运维”的立体绿化体系,重建城市高架桥下新自然生境,可以有效改善城市高架桥下生境与人居环境,提高城市生物多样性。【方法】基于生境相似性原理,运用适应性、观赏性、功能性3层过滤模式筛选适生植物;制定“建筑-设施-介质”一体化策略;提出实现高架桥下立体绿化自维持运营的创新模式。【结果】筛选出了27种适宜种植于高架桥下特殊生境的抗性强的适生植物,丰富了高架桥下特殊生境的植物多样性,使植物单次更换周期延长至5年以上;研发出集适生植物、轻型栽培介质、叠垒式种植容器、浇灌系统、雨水收集净化设施于一体的新型立体绿化模块,支撑植物长期保持良好的生长状态,同时实现了雨水资源化利用、污染源头控制和城市雨水消纳等多重目标;在景观形式上,将平面绿化拓展到立体绿化,复合利用大量已建成的城市灰色空间来增绿、填绿,预期可为上海市增加0.3 m^(2)的人均绿化面积;创新性地提出以“绿”促“商”、以“商”养“管”的运维模式,建立了上海虹梅高架桥下立体绿化新模式示范段。【结论】通过研发城市典型的低光照区域立体绿化技术,集成了新型立体绿化模块,将覆盖面广、连通性强的城市狭长污染线——城市高架桥下空间转型为生命景观线、生物多样性廊道,为城市可持续发展提供重要的生态、经济效益。

深色有隔内生真菌(DSE)功能和重金属耐性机制研究进展

重金属污染具有滞留时间久、难恢复和难治理等特点,重金属污染土壤修复备受关注。深色有隔内生真菌(Dark septate endophytes,DSE)可与多种植物建立良好的共生关系,其在促进植物生长、与植物联合共生增强植物对重金属的耐性机制及修复重金属污染土壤方面发挥着重要作用。为系统阐述DSE功能及其对重金属耐性机制,本文综述了DSE的结构特征及定植规律,其促进宿主植物生长的作用机制,重点分析了重金属胁迫下DSE的应答机制(吸附螯合、调控基因表达、抗氧化应激和“区室化”作用等),总结了DSE-植物共生体系在修复重金属污染土壤中的应用现状和前景,以期为DSE在重金属污染环境中的应用提供理论参考。

湿地植物对镉和抗生素单一及复合污染物的去除机制

本文对镉和抗生素残留的湿地植物体内体外2条去除途径、镉-抗生素复合污染的湿地植物去除研究进展进行综述。湿地植物根系是植物去除镉的主要部位——镉在湿地植物根际微环境的迁移转化受根际分泌物有机酸、土壤理化性质、微生物群落等影响,植物体内螯合素的螯合/络合作用对镉的植物体内去除起重要影响,而植物根表铁膜是重要的植物体外螯合物,是植物根际-微生物共同体发挥去除效应的场所。湿地植物-微生物协同效应能有效去除抗生素残留污染,但抗生素残留对根际微生物群落组成和结构影响显著,存在产生抗生素抗性细菌和抗性基因的风险。镉和抗生素复合污染因污染物母体种类、浓度不同而表现出不同的络合物行为特征,进而影响对湿地植物的毒性作用;也同时带有污染物母体的毒性特征,呈现复杂的毒性机制。相较于环境中的综合性污染现状,目前仅对少数种类重金属和抗生素复合污染的湿地植物去除进行研究。结合近年来国内外研究进展,我们提出湿地植物去除抗生素及其重金属抗生素复合污染物现有研究的不足及未来发展方向,以期为重金属和抗生素复合污染的湿地植物修复技术提供理论支撑。

木质素在土壤改良和修复中的研究及应用进展

具有酚羟基、醇羟基、羧基等极性基团的木质素,因具有较高的络合性,能够被用于提高植物对土壤中养分的利用效率,改良土壤团粒结构,提高土壤酶活;同时,木质素能够通过离子交换及络合作用,吸附去除土壤中的污染物,引发微生物对有机污染物的降解,从而起到修复污染土壤的作用。本文综述了木质素在土壤改良和修复方面的作用原理,介绍了木质素作为土壤改良剂、固沙剂和污染物吸附剂的应用效果。最后,对木质素在此领域的研究和应用进展进行了总结,并对其未来发展提出了相应的建议。

Gm-柠檬酸联合植物对矿山污染土壤的修复

以典型铀矿山周边放射性核素污染土壤为研究对象,采用盆栽试验,分析螯合剂与丛枝菌根真菌联合植物对强化修复放射性污染土壤的影响,揭示螯合剂和丛枝菌根真菌联合植物修复污染土壤的特征。结果表明:施加柠檬酸(CA)与摩西球囊霉菌(Glomus mosseae,Gm)对黑麦草-空心菜间作模式下的生长、铀富集存在不同程度的促进作用,以二者联合处理效果最明显;联合修复不仅增强了植物地下部分对放射性核素的固定,同时也降低了土壤中有机质的浓度,增强了放射性核素的附着能力;根际土样、植物灰样的扫描电镜分析和能谱图显示,接种Gm或施加CA对植物修复起到积极作用,以联合修复效果最好。

苹果响应水涝胁迫的研究现状与进展

涝害是中国频发的自然灾害之一,通过低氧胁迫、能量短缺和过氧化物毒害等方式抑制植物的生长发育,严重影响苹果(Malus domestica)的产量和品质,造成一定的经济损失。为提高苹果在水涝胁迫下的抗性,本文阐述了苹果对水涝胁迫的响应,分析了苹果在此过程中的适应机制,讨论了提高苹果耐涝渍性的遗传机制,总结了苹果水涝灾害的防御和补救措施,展望了关于苹果抵抗水涝危害的研究方向,以期为深入研究苹果抗水涝胁迫机制和培育抗水涝苹果提供理论指导。

植物-微生物联合修复石油烃污染土壤研究进展

石油烃污染引发了严重的土壤污染问题,在各种修复技术当中,植物-微生物联合修复技术以成本低、修复效果好、二次污染少等优点得到广泛重视。文章以植物-微生物联合修复技术为中心,阐述了内生菌-植物联合修复和植物-根际微生物联合修复两种典型的联合修复技术的原理以及最新的应用进展,并总结了当前植物-微生物联合修复技术研究的不足,以期为石油烃污染土壤的生物修复提供参考。

Interactions Between Arbuscular Mycorrhizae and Plants in Phytoremediation of Metal-Contaminated Soils: A Review

Metal contamination in the environment is a global concern due to its high toxicity to living organisms and its worldwide distribution. The principal goal of this review is to examine the current strategies and technologies for the remediation of metal- contaminated soils by metal-accumulating plants and assess the roles of arbnscular mycorrhizal （AM） fungi in remediation of soils under hyperaccumulator or non-accumulator plants. The use of plants to remove metals from the environment or reduce the toxicity, known as phytoremediation, is an environmentally sustainable and low cost remediation technology. The mechanisms of the use of hyperaccumulator plants for phytoremediation included solubilization of the metal in the soil matrix, the plant uptake of the metal, detoxification/chelation and sequestration, and volatilization. Recently, some ecologists have found that phytoremediation with the aids of mycorrhizae can enhance efficiency in the removal of toxic metals. AM fungi can facilitate the survival of their host plants growing on metal-contaminated land by enhancing their nutrient acquisition, protecting them from the metal toxicity, absorbing metals, and also enhancing phytostabilization and phytoextraction. Such information may be useful for developing phytoremediation program at metal-contaminated sites.