共代谢基质对苯酚降解菌XTT-3降酚作用的影响

采用驯化的方法从活性污泥中分离到一株苯酚降解菌XTT-3,经16SrDNA鉴定为Sphingobiumsp.。对该菌株进行碳饥饿处理,发现其降解苯酚的能力受到抑制。以只含苯酚的M9培养基为参照,添加0.2g/L酵母膏作为共代谢基质,对XTT-3菌株降解苯酚有较明显的促进作用,36h后苯酚降解率为68%。在含0.2g/L酵母膏的M9培养基中,同时添加20mg/L邻苯二酚,XTT-3降解苯酚作用显著增加,24h后苯酚降解率达75%,苯酚降解速度达0.261mg/min。     

金属离子对菌株JY01生长和苯酚降解性能的影响研究

金属可能通过生理和生态两方面对微生物的苯酚降解过程产生重要影响.为了提高芽孢杆菌Bacillus sp.JY01(以下称菌株JY01)的苯酚降解效率,探讨了6种金属离子(Ba2+、Cu2+、Co2+、Fe3、Zn2+、pb2+)对其生长和苯酚降解性能的影响.结果表明,在质量分数为0.001％～0.050％时,Cu2+、Zn2+、Co2、Fe3+、Ba2+、pb2+对菌株JY01的生长和苯酚降解均有抑制作用,并且抑制作用总体随金属离子浓度的升高而增强,当6种金属的质量分数分别达到0.005％时,菌株JY01对苯酚的降解能力为Ba2+ ＜Cu2+ ＜Co2+ ＜Fe3+ ＜Zn2+ ＜pb2+；金属离子通过影响菌株JY01的生长状况来影响其苯酚降解性能；很多金属离子对菌株JY01生长有明显抑制作用,因此在实际生物处理含苯酚废水时,要考虑废水中金属离子对降解菌生长状况的影响.     

两相分配式生物反应器处理高盐废水中的苯酚

采用新型两相分配式生物反应器(TPPB)和前期研究得到的高效苯酚降解菌对高盐废水中苯酚的降解进行研究,研究中确定煤油为反应系统的最佳有机溶剂,并考察了废水苯酚含量、废水盐度以及搅拌器搅拌速度对苯酚降解的影响。结果表明,反应系统能正常降解苯酚含量为1 000～2 500 mg/L的高盐苯酚废水;反应系统在含盐量为100 g NaCl/L、搅拌速度为50 r/min的运行工况条件下,降解时间缩短为52 h,总酚去除率为20.58 mg/(L.h)。     

高浓度苯酚降解菌Candida tropicalis Z-04的鉴定及其对苯酚降解条件的优化

从降解苯酚的好氧颗粒污泥中筛选出一株苯酚降解菌,该菌株最高可耐受2.0 g/L的苯酚.依据形态特征和内源转录间隔区(ITS)的核酸序列分析,将该菌株鉴定为热带假丝酵母菌(Candida tropicalis),并命名为Candida tropicalis Z-04.采用中心复合设计(CCD)法对Candida trop...     

Shewanella sp.XB缺氧反硝化降解苯酚

苯酚的生物降解一直受到关注。以苯酚为惟一电子供体,研究了Shewanella sp.XB对苯酚的缺氧降解特性。研究结果表明,在反硝化条件下,当C/N为13.3时,苯酚可以完全降解,NO-2-N积累量很少。另外,当加入氧化还原介体,如核黄素3μmol/L、AQDS 0.01 mmol/L、AQS 0.05 mmol/L和LQ 0.01 mmol/L时,苯酚降解速率分别为不加介体时的1.45、1.77、1.67和1.63倍。当以氯化铵代替硝酸盐时,苯酚也能进行厌氧发酵降解。另外,菌株XB反硝化降解苯酚可能是厌氧和好氧降解的混合过程。     

钴铜铁三元类水滑石材料催化过硫酸氢钾复合盐降解苯酚

采用共沉淀法制备过渡金属钴、铜、铁组成的钴铜铁三元类水滑石材料(CoCuFe-LDH),用于催化过硫酸氢钾复合盐(PMS)降解水中苯酚,并考察了初始pH、CoCuFe-LDH催化剂投加量、PMS用量对苯酚降解效率的影响。实验结果表明:CoCuFeLDH对PMS的催化活性较高;在pH为中性,催化剂为0.20g/L,PMS为2.5mmol/L,苯酚为50mg/L的条件下处理60min,苯酚的去除率可达96%;当催化剂投加量分别为0.05、0.10、0.15g/L,反应40min时,苯酚的去除率分别为76%、82%和91%。自由基猝灭实验表明,CoCuFe-LDH/PMS催化体系中存在硫酸根自由基和羟基自由基,但硫酸根自由基为主要活性自由基。     

盐单胞菌H17降解苯酚的响应面法优化及动力学

为获得盐单胞菌(Halomonas sp.)H17降解苯酚的最优条件,在单因素试验的基础上,通过Box-Behnken设计试验与响应面法,考察温度、pH、葡萄糖浓度对H17降解苯酚的影响,并通过动力学模型探究该菌株的生长和苯酚降解特性。结果表明,H17降解苯酚的最优条件为30℃、pH=8.0、葡萄糖质量浓度0.8g/L,在此条件下,苯酚降解率预测值为74.39%,实际值为73.92%,表明该模型可靠。该菌株降解苯酚动力学模型符合Haldane模型,其最大比降解速率、饱和常数和抑制常数分别为0.35h~(-1)、165.91mg/L和460.13mg/L。响应面法优化得到的生物降解条件准确,可为高盐含酚废水处理提供依据。     

序批式反应器生物强化处理苯酚废水的研究

将4株高效苯酚分解菌湿菌体分3批投加于序批式反应器(SBR),对活性污泥进行生物强化试验,分析活性污泥状态与性能变化,测定生物强化后对苯酚的降解能力.结果表明,随着生物强化过程的进行,沉降性能改善,污泥颗粒化趋势明显;生物强化后,活性污泥对苯酚降解能力、降解速率及对苯酚的耐受性明显提高:苯酚质量浓度为730～960mg/L时,苯酚完全降解时间可由正常的6h缩短至2h;6h内可完全降解苯酚的质量浓度由原来的880mg/L提高到2080mg/L,处理能力提高了1.36倍;当进水苯酚质量浓度增加到2400mg/L时,6h内污泥对苯酚的降解率仍达到60.1%.     

固体超强酸SO42-/TiO2-SnO2／Ce4+ 光催化降解含酚废水

采用共沉淀-浸渍法制备了固体超强酸SO24-/TiO2-SnO2/Ce4+,并用XRD、SEM等方法对其结构进行了表征。以苯酚的光催化降解为反应模型,确定了最佳的工艺条件和催化剂再生方法。结果表明:在pH值为6,苯酚初始浓度为50mg/L,催化剂投加量4 g/L,光照距离12 cm,光照时间为150 min,降解率达67.73%,添加助催化剂H2O2后,反应60 min,苯酚降解率达到86.33%,催化剂的最佳再生方法是先用1 mol/L的硫酸浸渍24 h后,在450℃下焙烧6 h。     

固体超强酸SO24-/TiO2-SnO2/Ce4+光催化降解含酚废水

采用共沉淀-浸渍法制备了固体超强酸SO42-/TiO2-SnO2/Ce4+,并用XRD、SEM等方法对其结构进行了表征.以苯酚的光催化降解为反应模型,确定了最佳的工艺条件和催化剂再生方法.结果表明:在pH值为6,苯酚初始浓度为50mg/L,催化剂投加量4 g/L,光照距离12 cm,光照时间为150 min,降解率达67.73％,添加助催化剂H2O2后,反应60 min,苯酚降解率达到86.33％,催化剂的最佳再生方法是先用1 mol/L的硫酸浸渍24 h后,在450℃下焙烧6h.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.