Fate of Pesticides in the Environment and its Bioremediation

The present paper is an overview of the presence and fate of pesticides as persistent organic pollutants in the environment as well as of the potential for their detoxification, also combined with chemical and physical treatment. It contains information gathered from a range of currently available sources. The fate of pesticides in the environment is analyzed considering the processes that determine their persistence and mobility, grouped into transport, transfer and transformation processes. Few pesticide characteristics such as persistence, mobility and biodegradability are emphasized. The fate of a pesticide and the potential for its persistence and mobility from the site of application are considered to be affected by the chemical and physical properties of the pesticide, site characteristics such as soil and groundwater individuality, climate and local weather conditions, biological population, and the handling practices of the pesticide user. Bioremediation, as one of the most environmentally‐sound and cost‐effective methods for the decontamination and detoxification of a pesticide‐contaminated environment is discussed especially considering the factors affecting the biodegradability of pesticides such as biological factors and the characteristics of the chemical compounds. In situ and ex situ bioremediation as possible types of bioremediation activities are weighted up. Also, the paper includes some considerations for developing strategies regarding the choice of bioremediation technology, as well as advantages and disadvantages of the bioremediation of environmental components polluted with pesticides.     

多孔介质中的微生物迁移行为与影响因素研究进展

微生物在地下水和土壤环境中的迁移与地下水资源保护、地下水污染修复及土壤污染防治等息息相关。自然界中多孔介质具有结构复杂性和空间异质性。这导致微生物在其中的迁移易受多重环境因素的影响。本文总结了几种典型多孔介质中微生物迁移模型、理论与研究方法,并对多孔介质中影响微生物迁移行为的3种因素——物理、化学和生物因素进行了梳理。其中物理因素的影响主要包括多孔介质的粒径、表面粗糙度、饱和度、环境温度、水体流速等相关;化学因素主要包含流体pH、离子种类与强度、可溶性有机物含量、多孔介质自身化学性质等;生物因素不但涉及微生物种类、细胞大小和细胞表面特性,还与胞外聚合物的分泌、鞭毛运动及趋化性等相关。本综述旨在总结近年来有关微生物在多孔介质中迁移的相关研究,深入理解微生物在多孔介质中的迁移行为,为其在地下水和土壤污染修复中的实际应用提供理论依据。     

土壤乙烯产生和氧化的研究进展

乙烯作为植物生长调节素及挥发性有机气体影响着植物生长和大气环境质量。有关土壤源乙烯产生和氧化特征,已发表的文献偏重实验室过程研究,很少涉及野外观测实验;陆地生态系统中土壤源乙烯行为有可能影响到植物生长及区域大气环境,大气环境变化(如水热状况和氮/酸沉降等)势必引起陆地土壤理化和生物学特性发生改变,进而影响土壤源乙烯产生和氧化过程。根据以前出版的文献,就土壤理化性质及外源碳氮施加、土壤微生物和重金属行为等对影响土壤乙烯产生和氧化作了详细综述,并简要阐述根际土壤乙烯产生和氧化以及不同土地利用方式对土壤乙烯产生和氧化的影响。指出应加强大气氮/酸沉降对典型林地土壤乙烯产生和氧化的影响机制以及不同土地利用方式下土壤乙烯产生和氧化的原位观测等方面的研究;同时也应关注不同成熟林型及森林演替不同阶段土壤理化和生物学特性跟乙烯产生和氧化的关联,明确土壤微生物(如细菌和真菌等)对此的相对贡献程度,利于丰富陆地土壤乙烯产生和氧化等有关科学认识,寻求适宜措施减少陆地土壤源乙烯产生潜势。     

川西亚高山林线过渡带及邻近植被土壤性质

研究了川西亚高山林线过渡带及邻近植被上缘流石滩草甸与下缘冷杉林残积母质土壤物理、化学和生物学特性.结果表明:从流石滩草甸→林线过渡带→冷杉林,土层逐渐增厚,表层土壤(0～30 cm)粉粒、粘粒、物理性粘粒含量、团聚度、结构系数和自然含水量逐渐增高,砂粒含量逐渐降低,阳离子交换量(CEC)、交换性盐基含量、盐基饱和度以及水解性酸含量逐渐增高,pH值逐渐降低,有机质及养分库全P、全K、有效N、有效P和速效K含量逐渐增高,土壤物理结构和化学性质逐步有所改善,但亚高山林线过渡带区域残积母质土壤成土过程缓慢.林线过渡带表层土壤细菌、真菌、放线菌及微生物总量,土壤脲酶、蔗糖酶、酸性磷酸酶、中性磷酸酶、多酚氧化酶及过氧化氢酶活性高于邻近植被上缘流石滩草甸与下缘冷杉林,体现了作为生态交错带,林线过渡带比邻近植被土壤具有相对较强的生物学活性.     

Technetium in biology and medicine

Although twenty-eigth radionuclides of technetium have been prepared, only technetium-99m, technetium-99 and technetium-95m have so far become important.Technetium-99, available in large amounts, is used in the study of the physical and chemical properties of the element, and offers the possibility of many industrial applications where its radioactivity does not create serious problems. With the increase in the use of nuclear power, however, more and more technetium-99 is being produced which is entering into the environment. This has resulted in increased interest in the biogeochemical behaviour of this radionuclide during recent years.The ideal physical properties, half-life of 6 hours and monochromatic gamma emission of 140 kev, and the versatile chemistry of technetium-99m have recently made it the radiotracer of choice for the external noninvasive imaging of almost all internal organs of the body. In the preparation of technetium- 99m radiopharmaceuticals and in the interpretation of their biological behaviour, the chemistry of technetium-99 has so far served as a guide. Similarly assumptions have been made that technetium-95m and technetium-99 have identical biogeochemical behaviour. We have shown that even the radioisomers, technetium-99m and technetium-99, have different chemical properties. These results suggest that in the study of the biological and environmental behaviour of technetium, a rigorous knowledge of the chemistry of each radionuclide is needed.     

Assessment of Physical and Chemical Attributes of Sub-Tropical Soil to Predict Long Term Effluent Treatment Potential

On-site wastewater treatment systems aim to assimilate domestic effluent into the environment. Unfortunately failure of such systems is common and inadequate effluent treatment can have serious environmental implications. A research project was undertaken to determine the role of physical and chemical soil properties in the treatment performance of subsurface effluent disposal areas. Monitoring changes in these properties permits improved prediction of the treatment potential of a soil. The changes within soil properties of the disposal area due to effluent application were found to be directly related to the subsurface drainage characteristics, including permeability, clay content and clay type. The major controlling soil physical and chemical attributes were found to be moderate drainage, significant soil cation exchange capacity and dominance of exchangeable Ca or exchangeable Mg over exchangeable Na, low exchangeable Na, clay type and a minimum depth of 0.4 m of potential unsaturated soil before encountering a restrictive horizon. The study confirmed that both the physical properties and chemistry of the soil can be valuable predictive tools for evaluating the long term operation of sewage effluent disposal systems.     

颗粒有机质的来源、测定及其影响因素

土壤活性有机质及其组分作为土壤质量的重要指标在土壤化学、物理和生物性质方面起着重要作用。颗粒有机质能够有效地反映有机质的特性,与微生物生长、营养供给及C、N的生物学调节密切相关。作为活性有机质的一个量度指标,颗粒有机质越来越受到人们的重视。本文综述了土壤颗粒有机质的来源及其在土壤有机质转化过程中的作用,对其测定方法作了系统的描述,阐明了土壤理化性质、农业措施(施肥与耕作)及土地利用类型对土壤颗粒有机质在土壤形成及维持其稳定性方面的影响。     

微藻源生物刺激剂的制备及在设施农业中的应用

化肥和农药的过量使用导致的农业面源污染已经成为我国环境污染的重要组成部分,对农业绿色高效安全生产及设施农业带来了巨大挑战。寻找新型的传统化肥替代品、提高化肥使用效率及保护生态环境是亟待解决的重大问题。生物刺激剂是具有调控植物生长作用的成分和(或)微生物的统称,用于农业生产,可改善土壤理化性质与群落微生物,能促进作物的代谢与生长,增强对营养物质的吸收和利用,提升作物抗逆能力及提高作物产量与产品品质。微藻体内具有结构新颖、功能独特的天然活性物质,是制备新型生物刺激剂的理想来源。微藻用于环境治理的同时,可获得足量的微藻生物质来制备生物刺激剂,从而达到治理环境、降低成本及提质增效的目的。就微藻源生物刺激剂的定义及功能、微藻全细胞和天然活性物质生物刺激剂的制备、应用效果及对植物和土壤的作用原理进行综述,以期为微藻源强效生物刺激剂的规模化制备及农业生产应用奠定理论基础和提供生产实践指导。     

Chemical characterization of dissolved organic matter in moist acidic tussock tundra soil using ultra-high resolution 15T FT-ICR mass spectrometry

Global warming is considered one of the most serious environmental issues, substantially mediating abrupt climate changes, and has stronger impacts in the Arctic ecosystems than in any other regions. In particular, thawing permafrost in the Arctic region with warming can be strongly contributing the emission of greenhouse gases (CO₂ and CH₄) that are produced from microbial decomposition of preserved soil organic matter (SOM) or are trapped in frozen permafrost soils, consequently accelerating global warming and abrupt climate changes. Therefore, understanding chemical and physical properties of permafrost SOM is important for interpreting the chemical and biological decomposability of SOM. In this study, we investigated dissolved organic matter (DOM) along the soil depth profile in moist acidic tussock tundra to better understand elemental compositions and distributions of the arctic SOM to evaluate their potential decomposability under climate change. To achieve ultra-high resolution mass profiles, the soil extracts were analyzed using a 15 Tesla Fourier transform ion cyclotron resonance mass spectrometer in positive and negative ion modes via electrospray ionization. The results of this analysis revealed that the deeper organic soil (2Oe1 horizon) exhibits less CHON class and more aromatic class compounds compared to the surface organic soils, thus implying that the 2Oe1 horizon has undergone a more decomposition process and consequently possessed the recalcitrant materials. The compositional features of DOM in the Arctic tundra soils are important for understanding the changes in biogeochemical cycles caused from permafrost changes associated with global warming and climate change.     

土壤质量与土壤质量指标及其评价

土壤作为一种重要的自然资源可以为人类生产食物和纤维,并维持地球生态系统.土壤也是植物生长的媒介、水、热和化合物的源、水分的过滤器和废物分解的生物介质.土壤与水、气和植物互作并抑制环境的波动.土壤可以调节很多控制水气质量和促进植物生长的生态过程.土壤质量概念的引入使我们更全面地理解土壤,也有助于合理地使用和分配劳力、能源、财政和其它投入.土壤质量也提供了一个通用的概念使得专业人员、生产者和公众明白土壤的重要性.此外,它也是一个评价管理措施和土地利用变化对土壤影响的评价工具.土壤质量由土壤的物理、化学和生物性质组成,MDS已被科学家们提出用于土壤质量评价.国际上比较常用的评价方法主要有多变量指标克立格法、土壤质量动力学方法、土壤质量综合评分法和土壤相对质量法.人类对土地不和谐地利用和管理可以导致全球生物地球化学循环发生改变和加快土壤性质变化的速度,当前世界各地土壤退化相当严重,已日益威胁到人类赖以生存的土地资源.在探讨相关概念的基础上综述了近年来土地利用变化对土壤理化质量和生物质量的影响进展,以引起国内外学者对土地利用变化对土壤质量影响研究的重视,从而为探讨土地利用对土壤质量影响的机理和规律以及退化土地的恢复和区域土地资源管理以及土地的持续利提供理论依据.土壤质量未来的研究应该集中在土壤质量指标与评价方法;土壤质量变化的发生条件、过程、影响因素及其作用机理与时空规律性;尺度问题的研究;土壤质量保持与提高的途径及其关键技术研究.     

Effect of physical, chemical and environmental characteristics on arbuscular mycorrhizal fungi in Brachiaria decumbens (Stapf) pastures

Aim:  To evaluate the effects of soil physical and chemical factors (pH, conductivity, humidity, available phosphorus and organic matter) and environmental factors (temperature, relative air humidity, altitude and atmospheric pressure) on arbuscular mycorrhizal fungi (AMF)– Brachiaria decumbens grass relationship. Furthermore to establish patterns of microbiological responses that allow to differentiate the study sites in two relief types.
Methods and Results:  Mycorrhizal characteristics (spore density, external hyphae and root colonizations by hyphae, vesicles and arbuscules), physical and chemical factors in soil and environmental factors were measured.
Conclusions:  The effect of physical, chemical and environmental factors on microbiological variables was related to the type of relief 'valley and hilly terrain'; the AMF behaviour was affected only over narrower ranges of evaluated variables. Similarly, the colonization of B. decumbens roots by AMF hyphae, vesicles and the mycorrhizal spore density follow different patterns according to the relief type.
Significance and Impact of the Study:  The type of relief is one of the factors to be taken into consideration to evaluate the AMF inoculum and root colonization of these pastures, because of the influence of slope – as physical property of soil – on AMF.     

Soil organic matter dynamics: a biological perspective derived from the use of compound-specific isotopes studies

Current attempts to explain the persistence of carbon in soils focuses on explanations such as the recalcitrant plant residues and the physical isolation of substrates from decomposers. A pool of organic matter that can persist for centuries to millennia is hypothesized because of the evidence provided by the persistence of pre-disturbance C in fallow or vegetation change experiments, and the radiocarbon age of soil carbon. However, new information, which became available through advances in the ability to measure the isotope signatures of specific compounds, favors a new picture of organic matter dynamics. Instead of persistence of plant-derived residues like lignin in the soil, the majority of mineral soil is in molecules derived from microbial synthesis. Carbon recycled multiple times through the microbial community can be old, decoupling the radiocarbon age of C atoms from the chemical or biological lability of the molecules they comprise. In consequence is soil microbiology, a major control on soil carbon dynamics, which highlights the potential vulnerability of soil organic matter to changing environmental conditions. Moreover, it emphasizes the need to devise new management options to restore, increase, and secure this valuable resource.     

Identifying and Predicting Biological Risks Associated With Manufactured Nanoparticles in Aquatic Ecosystems

Nanotechnology has great potential for revolutionizing the treatment of disease, optimizing manufacturing processes and consumer products, and remediating polluted environments. Increased use and disposal of products containing nanoparticles will inevitably result in their accumulation in aquatic ecosystems via direct input and runoff from contaminated soils. Aquatic organisms are particularly susceptible to pollutants due to their large, fragile respiratory epithelium. This potential toxicity can be exacerbated by common stressors, such as changes in water temperature, salinity, pH, and oxygen levels, and must be considered in environmental risk assessments. The unique properties of manufactured nanoparticles present serious problems for risk assessment strategies, and there is a concern in the regulatory community that standard toxicological methods may be inadequate to address these compounds. Our capacity to detect and quantify nanoparticles is extremely limited, especially in complex biological, soil, or water samples. The distinctive chemistry and physical structure of each nanomaterial will determine its bioavailability, and these parameters can be altered over time or with changes in water chemistry. The use of advanced analytical techniques, such as functional genomics, proteomics, and metabolomics, can provide a global assessment of the biological response to a novel chemical and will be important in determining the potential toxicity of nanoparticles. Industry should adopt a proactive approach to identifying potential risks to aquatic ecosystems so that the benefits of nanotechnology can be fully realized.     

石墨烯的环境行为及其对环境中污染物迁移归趋的影响

石墨烯是当前研究最热的碳纳米材料,具有独特的理化特性,在各领域具有广阔的应用前景.随着其生产和使用量的不断增大,石墨烯不可避免地会进入到环境中,从而给生态环境和人类健康带来风险.深入理解石墨烯在环境中的行为和归趋,探讨石墨烯对污染物环境行为的影响,对于科学客观评价石墨烯的环境风险具有十分重要的意义.本文对石墨烯的环境行为及其对污染物迁移归趋的影响进行了综述,主要介绍了石墨烯在水环境中的胶体特性和稳定性,以及在多孔介质中的迁移,重点探讨了石墨烯与重金属和有机物之间的相互作用,并从吸附机理、石墨烯与土壤组分之间的相互作用、石墨烯对污染物在环境中迁移及生物有效性的影响、石墨烯的定量方法等方面对该研究领域的前景和重点进行了展望,以期为该领域的深入研究提供借鉴并拓展新的思路.     

华南典型尾叶桉纯林经营对土壤理化性质、微生物和线虫群落的影响

桉树是我国华南地区的重要速生营林树种,具备极高的经济价值,然而我国桉树人工林的发展还存在巨大争议,桉树营林的生态环境效应还有待进一步考究。针对我国华南地区典型尾叶桉(Eucalyptus urophylla)纯林经营的潜在生态问题,选取广东鹤山森林生态系统国家野外研究站的10树种混交林(10 species mixed forest plantation, 10S)、30树种混交林(30 species mixed forest plantation, 30S)和桉树纯林(Eucalyptus monoculture, E)三种林型,另外设置桉树砍伐(Eucalyptus cutting, EC)和桉树砍伐清除林下灌草(Eucalyptus cutting and understory removal, ECUr)这两种常见经营措施的处理,通过比较不同林型和管理措施下土壤理化性质和生物指标的差异,解析了桉树营林对土壤理化特性、土壤微生物以及线虫群落的影响。本结果表明：三种林型间的土壤理化特性没有显著差异,但桉树纯林的土壤真菌生物量、真菌细菌比、食细菌线虫多度显著高于10和30树种混交林...     

Soil structure formation and management effects on gas emission

The aim of this paper is to clarify the effect of soil management and thus also of soil aggregation on physical and chemical properties of structured soils both on a bulk soil scale, for single aggregates, as well as for homogenized material. Aggregate formation and aggregate strength depend on swelling and shrinkage processes and on biological activity and kinds of organic exudates as well as on the intensity, number and time of swelling and drying events. Thus, soil management like conventional or conservation tillage alter not only the mechanical strength but also the pore continuity and the hydraulic, gas and heat fluxes, and also alter the accessibility of exchange places for nutrients and for carbon storage (global change aspects). The possibility to predict physical properties on these various scales depends on the rigidity of the pore system. In general this rigidity depends on the above-mentioned physical and chemical processes both with respect to intensity and frequency, which again are linked to the soil management systems.     

植物寄生对生态系统结构和功能的影响

寄生植物是生态系统中的特殊类群之一。植物寄生可以驱动生态系统中生物与非生物因子的变化,在生态系统结构与功能中起关键作用。寄生植物可以通过对寄主营养的集聚、改变凋落物的质量与数量、改变根的周转与分泌物格局、改变土壤水势,从而影响土壤理化特性。寄生植物会改变寄主的行为,改变寄主与非寄主植物之间的相互作用,从而影响植物群落的结构、多样性和动态,进而影响植被演替和植被生产力等。寄生植物与寄主均可被消费者取食,可直接或间接地影响生态系统的食草动物,包括草食昆虫等。寄生植物与寄主的其它寄生物存在竞争关系,可以直接或间接地影响寄主的其它寄生植物或病原真菌。寄生植物可以明显地改变土壤地球化学循环,将固有的不可动的成分转变为可利用的营养成分,改变土壤生物群落的结构与功能,从而显著影响地下生物群落。这些表明,植物寄生对生态系统的结构和功能有重要影响。针对特殊的被入侵的植物群落,该地寄生植物可以通过影响入侵植物寄主的生长、繁殖、生物量分配格局,改变土壤的理化特性,促进非寄主的非优势本地植物的生长,从而改变被入侵植物群落结构与多样性,达到生物防治及生态恢复的目的。     

The role of root exudates and allelochemicals in the rhizosphere

Plant roots serve a multitude of functions in the plant including anchorage, provision of nutrients and water, and production of exudates with growth regulatory properties. The root–soil interface, or rhizosphere, is the site of greatest activity within the soil matrix. Within this matrix, roots affect soil structure, aeration and biological activity as they are the major source of organic inputs into the rhizosphere, and are also responsible for depletion of large supplies of inorganic compounds. Roots are very complicated morphologically and physiologically, and their metabolites are often released in large quantities into the soil rhizosphere from living root hairs or fibrous root systems. Root exudates containing root-specific metabolites have critical ecological impacts on soil macro and microbiota as well as on the whole plant itself. Through the exudation of a wide variety of compounds, roots impact the soil microbial community in their immediate vicinity, influence resistance to pests, support beneficial symbioses, alter the chemical and physical properties of the soil, and inhibit the growth of competing plant species. In this review, we outline recent research on root exudation and the role of allelochemicals in the rhizosphere by studying the case of three plants that have been shown to produce allelopathic root exudates: black walnut, wheat and sorghum     

Synthetic ferrichrome analogues with growth promotion activity for Arthrobacter flavescens

Two families of trihydroxamic acid analogues of ferrichrome were chemically synthesized and tested for biological activity with Arthrobacter flavescens. Compounds using a tertiary amine as anchor showed little activity. Several compounds using tetrahedral carbon as anchor showed activity approaching or equalling that of the natural siderophore, ferrichrome. The biological activity is discussed in relation to physical and chemical properties of the analogues.