Chemical Diversity and Defence Metabolism: How Plants Cope with Pathogens and Ozone Pollution

Chemical defences represent a main trait of the plant innate immune system. Besides regulating the relationship between plants and their ecosystems, phytochemicals are involved both in resistance against pathogens and in tolerance towards abiotic stresses, such as atmospheric pollution. Plant defence metabolites arise from the main secondary metabolic routes, the phenylpropanoid, the isoprenoid and the alkaloid pathways. In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates. Chronic exposure to tropospheric ozone (O₃) stimulates the carbon fluxes from the primary to the secondary metabolic pathways to a great extent, inducing a shift of the available resources in favour of the synthesis of secondary products. In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids. Exposure to ozone can also modify the pattern of biogenic volatile organic compounds (BVOC), emitted from plant in response to herbivore feeding, thus altering the tritrophic interaction among plant, phytophagy and their natural enemies. Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype.     

Evolutionary Ecology of Multitrophic Interactions between Plants,Insect Herbivores and Entomopathogens

Plants play an important role in the interactions between insect herbivores and their pathogens. Since the seminal review by Cory and Hoover (2006) on plant-mediated effects on insect–pathogen interactions, considerable progress has been made in understanding the complexity of these tritrophic interactions. Increasing interest in the areas of nutritional and ecological immunology over the last decade have revealed that plant primary and secondary metabolites can influence the outcomes of insect–pathogen interactions by altering insect immune functioning and physical barriers to pathogen entry. Some insects use plant secondary chemicals and nutrients to prevent infections (prophylactic medication) and medicate to limit the severity of infections (therapeutic medication). Recent findings suggest that there may be selectable plant traits that enhance entomopathogen efficacy, suggesting that entomopathogens could potentially impose selection pressure on plant traits that improve both pathogen and plant fitness. Moreover, plants in nature are inhabited by diverse communities of microbes, in addition to entomopathogens, some of which can trigger immune responses in insect herbivores. Plants are also shared by numerous other herbivorous arthropods with different modes of feeding that can trigger different defensive responses in plants. Some insect symbionts and gut microbes can degrade ingested defensive phytochemicals and be orally secreted onto wounded plant tissue during herbivory to alter plant defenses. Since non-entomopathogenic microbes and other arthropods are likely to influence the outcomes of plant–insect–entomopathogen interactions, I discuss a need to consider these multitrophic interactions within the greater web of species interactions.     

Interactions Between Ozone,Halogens and Organic Compounds

During drinking-water treatment, ozone used as a preoxidant and chlorine required for final disinfection, lead to competing chemical reactions, in the case of raw water containing both organic compounds and inorganic salts (such as bromides and ammonia).

The study of the interactions between those reactants has been made according to the following main topics :

As for THM formation, experiments conducted on simple organic compounds or on natural fulvic acids show important decreases in THM or TCAA formation after ozonation. It may be noticed, however, that the ozonation of surface waters may induce the formation of haloform precursors, usually with a low level of reactivity.

In water supplies containing bromide ions, oxidation of the latter through hypobromous acid may take place during the ozonation stage. Failing preozonation treatment, hypobromous acid is generated very rapidly during chlorination, thus inducing the formation of chloro- brominated organic compounds.

During the ozonation of fulvic acid solutions, the presence of small amounts of bicarbonate was found to improve precursor removal significantly.

It can be concluded that the partial analogy of the action of ozone or chlorine on aromatic structures, whether simple or complex (such as humic and fulvic acids), seems to indicate that the consequence of preozonation is the destruction, at least in part, of the most reactive sites for THM production, thus leading to a decrease of the volatile organochlorinated compounds formed during the post-chlorination. However, some ozonation products of natural waters are THM precursors, though of low reactivity. Then, in the presence of bromide ions, the formation of volatile organobrominated compounds may be observed during ozonation.     

臭氧在食品加工用水处理工程上的应用

本文叙述了臭氧的一些特性 ,并以烟台某食品加工公司食品加工用水处理工程为例 ,介绍了臭氧的产生及应用情况 ,提供了处理前后水中各项指标的对照     

Impact of Botanical Pesticides Derived from Melia azedarach and Azadirachta indica Plants on the Emission of Volatiles that Attract Parasitoids of the Diamondback Moth to Cabbage Plants

Herbivorous and carnivorous arthropods use chemical information from plants during foraging. Aqueous leaf extracts from the syringa tree Melia azedarach and commercial formulations from the neem tree Azadirachta indica, Neemix 4.5^®, were investigated for their impact on the flight response of two parasitoids, Cotesia plutellae and Diadromus collaris. Cotesia plutellae was attracted only to Plutella xylostella-infested cabbage plants in a wind tunnel after an oviposition experience. Female C. plutellae did not distinguish between P. xylostella-infested cabbage plants treated with neem and control P. xylostella-infested plants. However, females preferred infested cabbage plants that had been treated with syringa extract to control infested plants. Syringa extract on filter paper did not attract C. plutellae. This suggests that an interaction between the plant and the syringa extract enhances parasitoid attraction. Diadromus collaris was not attracted to cabbage plants in a wind tunnel and did not distinguish between caterpillar-damaged and undamaged cabbage plants. Headspace analysis revealed 49 compounds in both control cabbage plants and cabbage plants that had been treated with the syringa extract. Among these are alcohols, aldehydes, ketones, esters, terpenoids, sulfides, and an isothiocyanate. Cabbage plants that had been treated with the syringa extract emitted larger quantities of volatiles, and these increased quantities were not derived from the syringa extract. Therefore, the syringa extract seemed to induce the emission of cabbage volatiles. To our knowledge, this is the first example of a plant extract inducing the emission of plant volatiles in another plant. This interesting phenomenon likely explains the preference of C. plutellae parasitoids for cabbage plants that have been treated with syringa extracts.     

多杀霉素在甘蓝环境中的残留分析方法

[目的]采用高效液相色谱法建立多杀霉素在甘蓝及环境系统中的残留分析方法。[方法]样品用甲醇提取(调pH值10),二氯甲烷萃取,层析柱净化后采用HPLC-UVD测定。[结果]多杀霉素的最小检出量为2×10-10 g,甘蓝植株和土壤中多杀霉素的添加回收率为82.14%-105.3%,变异系数为3.030%-7.519%,最低检测质量分数均为0.05 mg/kg。[结论]均符合农药残留分析方法的技术要求。     

江门市臭氧污染特征及变化趋势分析

通过对江门市臭氧监测数据分析,了解臭氧的变化特征和臭氧已成为影响空气质量达标率的最主要因子,对能合理、科学地制定相关防治臭氧污染措施有重要意义。     

上海城区近地面臭氧污染研究

利用上海城区空气自动监测站2014年1月1日至2018年12月31日的连续观测数据,分析了臭氧污染物的变化特征、影响因素。结果表明:臭氧已成为影响上海城区空气质量的主要污染物,夏季臭氧日均浓度高于其余季节,臭氧日内浓度变化呈单峰型,与前体污染物氮氧化物呈负相关性。臭氧的生成与气象条件密切相关,温度越高,臭氧浓度越高。相对湿度在50%～60%时臭氧浓度出现峰值,通过后向轨迹分析,上海南面大气输送对监测点臭氧污染贡献最大。     

大气臭氧污染防治措施探讨

近年来,随着社会的不断发展和经济的不断进步,人们对于自然的认识也不断加深,也正是因为这样,对环境的影响也越来越大,自然环境状态也日益恶化。在这越来越凸显的环境问题中,人们发现了大气臭氧的污染问题。大气臭氧层是地球气候环境稳定的重要前提和保障,也是我们生存的重要基础。可是,随着人类对自然的不断探索和资源的不断开采,大气臭氧也逐渐被污染和破坏。为了缓解我们大气臭氧的不断污染和破坏,维持我们赖以生存的地球环境的稳定,人类对大气臭氧污染的防治措施进行了探索。简要介绍了大气臭氧污染防治措施。     

珠江三角洲臭氧污染特征与趋势初步分析

根据国家城市环境空气质量监测网2013~2015年、粤港澳珠三角区域空气质量监测网2006~2015年监测结果,结合珠三角地区开展的大气环境科研工作,经初步分析,得到珠江三角洲区域臭氧污染特征、演变趋势。     

The Interactions of Aquaporins and Mineral Nutrients in Higher Plants

Aquaporins, major intrinsic proteins (MIPs) present in the plasma and intracellular membranes, facilitate the transport of small neutral molecules across cell membranes in higher plants. Recently, progress has been made in understanding the mechanisms of aquaporin subcellular localization, transport selectivity, and gating properties. Although the role of aquaporins in maintaining the plant water status has been addressed, the interactions between plant aquaporins and mineral nutrients remain largely unknown. This review highlights the roles of various aquaporin orthologues in mineral nutrient uptake and transport, as well as the regulatory effects of mineral nutrients on aquaporin expression and activity, and an integrated link between aquaporins and mineral nutrient metabolism was identified.     

Essential-Oil-Mediated Interactions Between Oregano Plants and Helicidae Grazers

Aromatic plants dominate in Mediterranean-type ecosystems. They often produce remarkable quantities of essential oils containing high amounts of phenolic isoprenoids, such as thymol and carvacrol. The purpose of this work was to examine the interactions between commonly occurring aromatic plants in the Mediterranean environment and their snail grazers. The aromatic plants used were two Origanum vulgare subspecies, subsp. hirtum and subsp. vulgare. They differ in the content and the qualitative composition of their essential oil; subsp. hirtum contains a much larger amount and is rich in phenolic compounds. Their effect on the foraging behavior of three snail species, native in Greece, was studied; the snail species were Helix lucorum, H. aspersa, and Eobania vermiculata. The snails' responses to different food sources, raw or processed, with or without essential oils, were evaluated during the different stages of the foraging cycle. During the encounter stage, snails were more repelled than attracted when close to phenol-rich foods. During the acceptance stage, all snail species tended to reject food types that contained high concentrations of subsp. hirtum essential oil. At the feeding stage, subsp. hirtum essential oil caused reduction of daily consumption rates. Overall, the essential oil of O. vulgare subsp. vulgare did not produce any marked change in the snails' behavior. In contrast, that of O. vulgare subsp. hirtum had a repellent effect, particularly when present in naturally occurring high concentrations. Among the snail species, H. lucorum, which does not share the same biotope with O. vulgare subsp. hirtum, was the least tolerant to its essential oil.     

热动力设备排放污染及控制

我国幅员辽阔人口众多,对资源的需求量极大,在对资源的具体利用的过程中造成了一系列的污染。加之我国在进入21世纪以来社会的经济水平不断提升,越来越多的热动力设备加入到人们的生产生活中,因热动力设备的使用所造成的排放污染也随之日益严重。我们在享受其带来的便利的同时,更应加大对其所造成的污染的治理与控制,并不断地提升热动力设备的科学性与低污染性。主要就因热动力设备所导致的排放污染进行讨论,旨在找出一种行之有效的控制方案。     

Impact of Ozone Treatment on Selected Microbiological Parameters

A pilot plant study was conducted to evaluate the effects of ozonation on the quality of Colorado River water delivered to the Phoenix (Arizona) Union Hills Water Treatment Plant through the Central Arizona Project canal. Raw and finished water were monitored for basic chemical water quality parameters and for microorganisms including total coliforms, heterotrophic plate count, enteric viruses, Giardia and Crvptosporidium cysts. Ozone, applied through diffusion contactors in dosages optimized to provide the required CT (concentration x contact time) value, was used as a primary disinfectant in two of the four 10 gpm (37.8 L/min) treatment trains.     

Gas-Phase Ozone Oxidation of Hydrogen Sulfide for Odor Treatment in Water Reclamation Plants

Gas-phase O₃ oxidation is effective to treat H₂S emitted from wastewater treatment processes. The reaction is fast for full-scale applications. In most cases, 67–96% of total H₂S removed in 40-s reaction time was achieved within the first 8 s of reaction time. The initial [O₃]/[H₂S] ratio of 8 was sufficient to reduce H₂S from up to 8 ppmv to less than 0.5 ppmv in 40-s reaction time. The reaction stoichiometry ratio of [O₃]/[H₂S] ranged from 2.0 to 3.7, depending on the initial [O₃]/[H₂S] ratio. The moisture content, dimethyl sulfide, and dimethyl disulfide in the odorous air influence H₂S removal.     

Application and Misapplication of Ozone for the Control of Odors at Sewage Treatment Plants and Pumping Stations

Ozone has been applied to control odors in ventilating air at sewage treatment plants for about fifty years. Papers describing many presumably successful such applications can be found in the literature. Very little has been written about failures in these and other ozone-odor applications. This paper examines some failures. It reviews the rather dismal experience of The Ocean County Utilities Authority with ozone for odor control at three sewage treatment plants and 34 pumping stations. It provides information on the total costs for such systems. And finally it examines the parameters necessary to control odors with ozone, speculates on the actual mechanisms involved and presents some recommendations on how best to apply ozone to odor problems.