农田灌溉水中挥发酚的流动分析-分光光度分析法的建立

主要通过使用流动分析仪对农田灌溉水中的挥发酚进行测定,有效地提高了检测的精密度与准确度。相比传统分光光度计检测法,此法更方便和快捷,大大降低了样品的使用量,节省了人力物力,较好地满足了批量样品测定的要求,值得大力推广和应用。     

Penicillium chrysogenum: Phenol Degradation Abilities and Kinetic Model

Phenol is a typical contaminant of the environment generated by many industries. Several fungi had been reported to degrade phenol as the only source of carbon and energy, but many of them are not useful to apply in soil bioremediation process. In this work, we study the dynamics of phenol degradation by a Penicillium chrysogenum, isolated from soil. Degradation of phenol was studied at room temperature and resting mycelium conditions. High specific degradation rates were obtained. Inhibition was observed on the specific growth rate (30?mg?l¹) and the degradation rate (200?mg?l^?1). Experimental results were fitted to several models during exponential phase, with the Andrews-Haldane model given the best fit. Dynamic mass balance equations for biomass and phenol during the exponential and stationary growth phases were solved and compared very satisfactorily to experimental outcomes. P. chrysogenum degrades phenol completely during the exponential and stationary growth phases. The results obtained are relevant for its practical applications in soil decontamination processes. Model predictions were satisfactory. This is the first work which describes a kinetic model for phenol biodegradation using a filamentous fungus considering both, exponential and stationary phases, and the first one in which a Penicillium isolate is used.     

Organobentonite for Sorption and Degradation of Phenol in the Presence of Heavy Metals

An experimental study was performed to determine the feasibility of usingorganobentonite modified with quarternary ammonium cations (QACs) as a reactive medium in immobilization and biodegradation barriers for mixed contaminants in the subsurface soil. Various factors, including interactions between heavy metals, organic contaminants, and soil microorganisms, were investigated when they coexisted with untreated bentonite and organobentonite. Batch sorption tests for cadmium and lead were conducted to quantify sorption selectivity of these metals on untreated bentonite and organobentonite. Metal concentrations of 50 × 10^-6 M slightly reduced the growth of soil microbes and partially interfered with the biodegradation of phenol. Soil microorganisms tested with untreated bentonite grew after approximately 25 hr of lag period and degraded phenol completely within 350 hr. The results from this study demonstrate that organobentonite could be used as a reactive medium for immobilization and biodegradation of organic contaminants in the presence of heavy metals in the subsurface soil.     

From Media to Molecules: New Approaches to the Detection of Micro-organisms in Water

Present methods for the detection of micro-organisms in the environment are slow, inefficient and often unreliable. Alternative approaches which are reliable and rapid, enabling results to be obtained within one working day, are required. The development of molecular techniques, in particular in situ hybridisation offers the potential for rapid and specific assays. This paper describes the use of oligonucleotide probes targeted against the 16S and 18S ribosomal RNA molecules of Escherichia coli and Cryptosporidium parvum for rapid and specific detection. In situ hybridisations with biotinylated peptide nucleic acid (PNA) probes in combination with the tyramide signal amplification (TSA) system enabled the specific detection of Escherichia coli and Cryptosporidium parvum within 3 hours. The C. parvum assay provided a species-specific alternative to the currently available fluorescent antibody approach.     

Microalgal Dynamics in Batch Reactors for Municipal Wastewater Treatment Containing Dairy Sewage Water

This study investigates the microalgal community dynamics associated with changes in municipal wastewater quality and discharges from the dairy industry in central Veracruz, Mexico, using an experimental stabilization-reactors system. Thirty one species of microalgae were recorded and 15 physicochemical variables were measured daily over 25 days in pretreated water. The biomass of microalgal groups displayed significant negative correlations with biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspend solids (TSS). Conversely, a significant positive correlation was found with dissolved oxygen, pH and nitrates. Using the Canonical Correspondence Analysis we identified an initial anaerobic phase (Phase I), characterized by high BOD, TSS and COD, ammonium and faecal coliforms. This was followed by a transition phase (Phase II), an initial aerobic phase (Phase III), when water quality improved considerably, and finally an aerobic phase (IV) with a high percent reduction in these parameters and almost complete organic load removal. The most abundant species associated with these phases were Arthrospira jenneri (Cyanophyceae) and Coccomonas sp. (Chlorophyceae) in Phase I; Polytomella sp. (Chlorophyceae) in Phase II; Polytoma tetraolare, Chlamydomonas caeca (Chlorophyceae) and some Cyanophyceae including Geitlerinema, Synechocystis, Cyanobium and Glaucospira in Phase III; Carteria sp. (Chlorophyceae), Lepocynclis ovum and Euglena clavata (Euglenophcyeae) in Phase IV. Maximum richness, diversity, and biomass levels occurred during the aerobic phase. Similar to other wastewater treatment systems the high succession rates decreased with reactor stabilization. These findings provide statistical evidence on the suitability of certain microalgae species as indicators of wastewater stabilization reactor status and effluent quality.     

合理利用城市水资源的几种途径

在水资源日益匮乏的今天,如何最大限度地利用已有的水资源,更好地为人们的生产、生活服务,已成为倍受社会关注的焦点问题。目前,我国面临的水资源短缺状况和水资源的有限性都要求我们另辟蹊径来解决用水问题。本文从节约用水、回收可处理利用的工业废水、减少城市污水排放等方面阐述了在建设节水型社会的大环境下,合理利用城市水资源的几种途径。     

Identification of Cytotoxicity Intermediate Products and Degradation Pathways for Microcystins Using Low-Frequency Ultrasonic Irradiation

In this study, two microcystins (MCs) were examined. MC-LR and MC-RR were degraded with low frequencies (20, 40, 60, 100, and 200?kHz) of ultrasonic waves. The optimal ultrasonic frequency for treating MCs was 200?kHz. Kinetic reaction results indicated that the degradation reactions of MC-LR and MC-RR from low-frequency ultrasound obeyed the pseudo-first-order kinetic model. The structural characterizations of the intermediate products were identified via liquid chromatography-mass spectrometry, which elucidated the mechanism of the degradation pathways. The main degradation pathways in the LC-MS analysis were Adda and Mdha. The cytotoxic effects on human oral epidermoid carcinoma (KB) cells were evaluated through cell viability assay using 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. The inhibitory effect of ??5???g/mL MC-LR on KB cells was significantly enhanced in a dose-dependent manner. Compared with the control, the viability of the KB cells cultured with 15 and 5???g/mL MC-LR was increased by 23?% and 29?%, respectively, after the application of MC-LR and the optimization of the frequencies' ultrasonic irradiated treatment for 48?h. A similar trend was observed in the degradation of ultrasonic irradiated MC-RR. Compared with the control, the viability of the KB cells cultured with 15 and 5???g/mL MC-RR increased by 12?% and 22?%, respectively (P?<?0.05). Results showed that low-frequency ultrasonic irradiation effectively reduced the cytotoxicity of the intermediate products of MCs. Therefore, low-frequency ultrasound is a feasible method for the detoxification of drinking water.     

Sonochemical Degradation of Chlorinated Phenolic Compounds in Water: Effects of Physicochemical Properties of the Compounds on Degradation

This study examined a comparative degradation of various chlorinated phenolic compounds including phenol, 4-chlorophenol (4-CP), 2,6-dichlorophenol (2,6-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP) using 28, 580, and 1,000 kHz ultrasonic reactors. The concentration of hydrogen peroxide was also determined in order to investigate the efficacy of different sonochemical reactors for hydroxyl radical production. Clearly, it was observed that the 580 kHz sonochemical reactor had maximum efficacy for hydroxyl radical production. The degradation of all the compounds followed the order; 580 kHz (91?C93%) > 1,000 kHz (84?C86%) > 28 kHz (17?C34%) with an initial concentration of 2.5 mg L^?1 at a reaction time of 40 min with ultrasonic power of 200 ± 3 W and aqueous temperature of 20 ± 1°C in each experiment. Overall, the degradation of those phenolic compounds followed the order, PCP > 2,3,4,6-TeCP > 2,4,6-TCP > 2,6-DCP > 4-CP > phenol at various frequencies in the presence/absence of a radical scavenger (tert-butyl alcohol). It was revealed that the correlations between the compound degradation rates and the physicochemical parameters, R ² = 0.99 for octanol?Cwater partition coefficient, R ² = 0.95 for water solubility, R ² = 0.94 for vapor pressure, and R ² = 0.88 for Henry??s law constant, excluding PCP, were very good in the entire range of each parameter.     

UV Light-Assisted Degradation of Methyl Orange,Methylene Blue,Phenol, Salicylic Acid,and Rhodamine B: Photolysis Versus Photocatalyis

Methyl orange (MO), methylene blue (MB), phenol (F), salicylic acid (SA), and rhodamine B (ROD) were used as substrates during the photodegradation experiments in the absence and in the presence of nanostructured Ag/titania-silica. The catalyst was characterized by scanning electron microscopy (SEM), scanning transmission electron microscope high-angle annular dark field (STEM-HAADF), stereological analysis, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy (XPS) measurements. The results were fitted on pseudo-first and pseudo-second kinetic order models. The film diffusion was also determined. The photolysis degrades MO and F to a greater extent than the photocatalysis. The degradation of SA occurred at the same rate either by photolysis or by photocatalysis. MB was best removed by photocatalysis. With regard to the photocatalysis, the highest rates of film diffusion were obtained for MB, F, and ROD, meaning that these molecules crossed the film to arrive at the catalyst surface more rapidly than the others. For MO and MB, the results followed the pseudo-first-order kinetic model while for SA, F, and ROD, the pseudo-second-order kinetic model was more appropriate.     

Photocatalytic Degradation of Herbicide Quinmerac in Various Types of Natural Water

The efficiency of the photocatalytic degradation of the herbicide quinmerac in aqueous TiO₂ suspensions was examined as a function of the type of light source, TiO₂ loading, pH, temperature, electron acceptors, and hydroxyl radical (^?OH) scavenger. The optimum loading of catalyst was found to be 0.25?mg?mL^?1 under UV light at pH?7.2, with the apparent activation energy of the reaction being 13.7?kJ?mol^?1. In the first stage of the reaction, the photocatalytic degradation of quinmerac (50???M) followed approximately a pseudo-first order kinetics. The most efficient electron acceptor appeared to be H₂O₂ along with molecular oxygen. By studying the effect of ethanol as an ^?OH scavenger, it was shown that the heterogeneous catalysis takes place mainly via ^?OH. The results also showed that the disappearance of quinmerac led to the formation of a number of organic intermediates and ionic byproducts, whereas its complete mineralization occurred in about 120?min. The reaction intermediates (7-chloro-3-methylquinoline-5,8-dione, three isomeric phenols hydroxy-7-chloro-3-methylquinoline-8-carboxylic acids, and 7-chloro-3-(hydroxymethyl)quinoline-8-carboxylic acid) were identified and the kinetics of their appearance/disappearance was followed by LC?CESI?CMS/MS. Tentative photodegradation pathways were proposed and discussed. The study also encompassed the effect of quality of natural water on the rate of removal of quinmerac.     

The Effect of Polyethylene Glycol (PEG) Modification on Fe Dispersal and the Catalytic Degradation of Phenol Wastewater

Modification of a catalyst with polyethylene glycol (PEG) created a dramatic increase in the catalytic activity for the degradation of phenol wastewater. The Fe/PEG-modified γ-Al₂O₃ catalyst was prepared by an impregnation method. The as-prepared catalyst was characterized by X-ray photoelectron spectroscopy, wide- and small-angle X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and N₂ adsorption-desorption experiments, and the results showed that the Fe species were highly dispersed on the surface of the PEG-modified support. At the same time, the PEG modification resulted in an increase in the Brunauer-Emmett-Teller surface area and pore volume. The catalytic activity test showed that the Fe/PEG-modified γ-Al₂O₃ catalyst exhibited a superior performance for the degradation of phenol wastewater in this study, and the phenol and COD removal values reached 94.1 and 88.9%, respectively, within 60 min. The results clearly show that PEG modification is a promising methodology for the preparation of a catalyst with good dispersal of the active component on the support.     

岩溶塌陷诱发水土资源退化模式研究——以鲁中南岩溶塌陷区为例

在岩溶塌陷区,资源环境受到岩溶塌陷地质灾害的严重影响和危害,生态环境也发生恶化现象,尤其以水资源和土地资源的退化最为突出。以鲁中南典型岩溶塌陷区为例,阐述了岩溶塌陷诱发的3种水土资源退化模式:水土流失、水土污染和土壤退化,并分析了该区水土资源退化的现状,研究了水土资源退化的机理和特征。     

新时期水土保持设计指导思想和原则探讨

面对中国即将加入世界贸易组织 ,水土保持要及时调整指导思想和思路 ,在市场中求生存和发展。综合治理中必须考虑生态用水问题 ,以保证其效益发挥。国家实行以粮食换林草的政策后 ,水土保持基本农田的建设要因地制宜做调整。实行集约高效小流域治理和面上封育结合是加快水土流失治理、改善生态环境的有效途径     

Copper Oxide Nanoparticle-Coated Quartz Sand as a Catalyst for Degradation of an Organic Dye in Water

Copper oxide nanoparticles were immobilized on quartz sand and their catalytic activity for the degradation of an organic dye was investigated. The use of nanoparticles as catalysts for non photo-induced oxidation of water contaminants is relatively new. The CuO catalyst has shown promising results when suspended in free form in batch systems. Because heterogeneous catalysis is often the preferred mode of operation for application of catalytic technology, we studied the effect of immobilization of the nanoparticles on quartz sand in a flow-through system and its implication for the catalytic process. The coated sand was packed in a column and its catalytic activity for the degradation of an organic dye was investigated in a series of flow-through experiments with hydrogen peroxide as the oxidant. Control experiments with uncoated sand were also performed for comparison. The coated sand demonstrated high catalytic ability, achieving complete oxidation of the dye. During the reaction, CO₂ was produced, leading to a decrease in the water saturation in the column and reduced contact surface between the nano-CuO catalysts and the dye solution. The degradation was improved by enabling a longer residence time of the dye in the column, yielding up to 85% degradation of the dye. These results suggest that CuO nanoparticle-coated sand is an efficient catalyst for complete degradation of the organic dye.     

Phenol antioxidant quantity and quality in foods: fruits.

The free and bound phenols have been measured in 20 fruits commonly consumed in the American diet. Phenols were measured colorimetrically using the Folin-Ciocalteu reagent with catechin as the standard after correction for ascorbic acid contribution. On a fresh weight basis, cranberry had the highest total phenols, and was distantly followed by red grape. Free and total phenol quality in the fruits was analyzed by using the inhibition of lower density lipoprotein oxidation promoted by cupric ion. Ascorbate had only a minor contribution to the antioxidants in fruits with the exception of melon, nectarine, orange, white grape, and strawberry. The fruit extracts' antioxidant quality was better than the vitamin antioxidants and most pure phenols, suggesting synergism among the antioxidants in the mixture. Using our assay, fruits had significantly better quantity and quality of phenol antioxidants than vegetables. Fruits, specifically apples and cranberries, have phenol antioxidants that can enrich lower density lipoproteins and protect them from oxidation. The average per capita consumption of fruit phenols in the U.S. is estimated to be 255 mg/day of catechin equivalents.     

Water Quality Degradation of Coastal Waterways in the Wet Tropics, Australia

The Wet Tropics region of north Queensland has outstanding environmental values, contains the highest biological diversity in Australia, and borders the Great Barrier Reef. Comparable to other tropical areas worldwide, increasing urban and agricultural development in the Wet Tropics has caused concerns with respect to ecosystem degradation due to poor water quality in freshwater reaches and marine environments. Key issues currently identified in the Wet Tropics include erosion and subsequent stream turbidity and sedimentation, nutrients from erosion and fertiliser use and pesticide residue contamination. Issues such as reduced dissolved oxygen, acid sulfate soil runoff, and biological factors such as weed infestation, reduced and degraded riparian vegetation condition, and flow modification have also been identified. These issues mainly arise from agricultural activities with lesser effects from urban development. Management of pollution to improve in-stream water quality requires a long-term monitoring program to characterize water quality conditions over different flows and seasons. This type of monitoring program is underway; however, the focus is on the Great Barrier Reef and does not fully consider freshwater ecosystem health. Another major issue is the lack of a fully developed conceptual framework that links changed land use to water quality and subsequently to aquatic ecosystem health. In this paper, we establish the current level of water quality knowledge in the Wet Tropics while outlining a conceptual framework connecting changing land management practices and their effects to water quality and to ecosystem health.     

实现水土保持产业化的途径——以四川省宁南县为例

水土保持产业是指一项基础性产业，水土保持产业化是水土保持事业在市场经济条件下的必然选择。以四川省宁南县实现水土保持产业化发展的途径为例，探讨了在市场经济条件下如何实现水土保持产业化，并提出了笔者对我国水土保持产业化发展的几点看法。