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。     

降酚菌株的固定化细胞处理含酚废水的性能研究

用海藻酸钠作为载体将一株降酚菌株进行固定化包埋。利用正交实验确定了该菌株固定化细胞制备的最优条件。研究表明,该降酚菌株的固定化细胞对苯酚的降解能力和耐受能力均大于游离细胞。降酚菌株固定化细胞降解苯酚的最适温度范围是30~35℃,最适pH值范围为6~8。该菌株的固定化细胞对废水中的COD也具有良好的降解效果。     

降酚菌株的固定化细胞处理含酚废水的性能研究

用海藻酸钠作为载体将一株降酚菌株进行固定化包埋.利用正交实验确定了该菌株固定化细胞制备的最优条件.研究表明,该降酚菌株的固定化细胞对苯酚的降解能力和耐受能力均大于游离细胞.降酚菌株固定化细胞降解苯酚的最适温度范围是30～35℃,最适pH值范围为6～8.该菌株的固定化细胞对废水中的COD也具有良好的降解效果.     

好氧反硝化苯酚降解菌的分离鉴定及动力学

从驯化菌群中分离筛选出一株好氧反硝化苯酚降解细菌,经生理生化反应及16S rDNA测序,鉴定为Diaphorobacter属细菌。在好氧条件下,该菌株以苯酚为唯一碳源和能源,利用NO-3-N作为反硝化电子受体,其生长与反硝化特性研究表明:在接种量5%(体积分数),30℃,180 r/min振荡培养条件下,菌株降酚能力可达1 400 mg/L,同时,能有效去除初始浓度为165 mg/L的硝酸盐氮,60 h其去除率为91.5%,高含量苯酚对菌体生长有一定的抑制作用。应用Haldane方程对其生长过程进行动力学模拟,拟合曲线与实验测定值相关性良好,各参数分别为μmax(最大比增长率)0.324 h-1,Ks(半饱和常数)9.36 mg/L,Ki(抑制常数)146.72 mg/L,通过理论分析及实验验证得,该菌株苯酚降解动力学与其生长动力学表现出相似的趋势。     

一株苯胺降解菌的分离鉴定及其降解特性

为研究苯胺污染的生物控制,通过驯化培养,从南京化工厂污水处理厂的活性污泥中分离出一株高效苯胺降解菌——菌株AN4.生理生化试验鉴定菌株AN4为金黄杆菌属(Chryseobacterium sp.).菌株AN4利用苯胺生长和降解苯胺的最适温度为30 ℃、pH为7.0,它可在苯胺质量浓度低于3 000 mg/L的无机盐固体培养基上生长.菌株AN4除可降解苯胺外,还可以苯酚、苯甲酸、硝基苯、甲苯、萘、氯苯、二甲苯作为唯一碳源生长,蛋白胨可加速其对苯胺的代谢.代谢机制研究证实,菌株AN4在邻苯二酚1,2-双加氧酶作用下经邻位裂解途径降解苯胺.     

萘降解菌的分离鉴定、生长特性和降解途径探究

从天津大港油田附近污染土壤中分离出1株萘降解菌株DGN9,经形态学和16S rDNA测序鉴定,该菌株属于无色杆菌(Achromobacter sp.)。其最适生长温度为30℃,最适pH为7,最适萘初始质量浓度为1 000mg/L,在NaCl质量分数为1%、2%的条件下生长良好,具有一定的耐盐性。其对萘的可能降解途径为水杨酸降解途径。同时,该菌株对蒽、菲、芘、联苯、对苯二甲酸、邻苯二酚、苯酚、苯甲酸钠、水杨酸、邻苯二甲酸等底物也有降解作用,具有底物生长广谱性。     

一株苯酚降解菌的筛选及降解动力学特性

利用富集驯化的培养方法,从首钢焦化厂废水处理系统中的二沉池出水中,分离筛选出一株能够高效降解苯酚的菌株B3对其16S rDNA序列进行分析,并选择Monod方程和Andrews方程分别研究该菌在不同苯酚浓度条件下的降酚动力学模式。结果表明,B3为蜡状芽孢杆菌(Bacillus cereus);苯酚浓度较低时,苯酚对菌株的生长基本不产生抑制作用,用Monod模型对B3降酚动力学过程进行拟合,其动力学参数V max=0.03 h-1,K s=25.53 mg/L;苯酚浓度较高时,按照Andrews模型对B3降酚动力学过程进行非线性最小二乘曲线拟合,其动力学参数V max=0.08 h-1,K s=147.52 mg/L,K i=384.96 mg/L。根据动力学方程,推论菌株B3降解对于浓度238.30 mg/L的苯酚具有最佳降解效果。     

一株对硝基苯酚降解菌的筛选鉴定及其降解特性

从受甲基对硫磷污染的土壤中分离筛选得到一株能够以对硝基苯酚(PNP)作为唯一碳源、氮源生长的菌株,命名为TM.经16S rDNA序列分析初步鉴定该菌株为节杆菌(Arthrobacter).考察了该菌株在PNP浓度、盐度(NaCl)、pH、外加碳源(葡萄糖)、外加氮源等因素下对PNP降解特性的影响.结果表明:该菌株对PNP的最大耐受质量浓度为300 mg/L,并在降解的过程中生成NO2-该菌株的耐盐能力可达0.30％(质量分数),其最佳pH为8.在此pH下,200 mg/L的PNP在16h时即可被完全降解,添加0.30％(质量分数)的葡萄糖可使生物量和降解速率达到最大,牛肉膏作为外加氮源最有利于该菌株对PNP的降解.     

嗜联苯红球菌B403对酚类污染物的降解特性及动力学分析

为提高降酚菌株的降酚能力,实验测定了嗜联苯红球菌B403对6种酚的最小抑菌浓度,考察了该菌在不同碳源条件下的生长与降酚特性及其关联,进而研究其降解动力学规律。结果表明,菌株B403对苯酚、间甲酚、邻苯二酚、对硝基苯酚、2,4-二氯苯酚和2,4,6-三氯苯酚的最小抑菌浓度分别为1 190、630、700、140、70、48 mg·L~(-1),菌株B403对苯酚、间甲酚、邻苯二酚表现出较强的耐受性。分别以这3种酚为唯一碳源,该菌株能有效降解苯酚和间甲酚,无机盐培养基中处理30h后,苯酚、间甲酚、邻苯二酚的降解率分别为97.85%、100%、56.54%;当有其他有机碳源存在时,菌株B403的生物量大幅度提高,3种酚的降解效率也显著提高,处理15 h后LB-无机盐混合培养基中苯酚、间甲酚、邻苯二酚的降解率分别为98.92%、99.93%、94.35%。菌株B403的降酚动力学过程符合Haldane模型,菌株B403降解苯酚的动力学参数为q_m=0.503 h~(-1),K_s=270.9 mg·L~(-1),K_I=69 mg·L~(-1);降解间甲酚时,q_m=0.672 h~(-1),K_s=171.9 mg·L~(-1),K_I=23.74 mg·L~(-1);降解邻苯二酚时,q_m=1.749 h~(-1),K_s=541.9 mg·L~(-1),K_I=42.61 mg·L~(-1)。根据动力学方程,推论降解苯酚、间甲酚、邻苯二酚的最佳浓度分别为136.4、87.4、116.1 mg·L~(-1)。综合上述结果,其他有机碳源的存在可以显著提高该菌株降酚能力和降解效率,在工业含酚废水治理及有机质丰富的酚类污染土壤修复领域具有一定的应用潜力。     

高铁酸盐氧化降解水中苯酚的动力学及机理研究

以自制高铁酸钾(K₂FeO₄)为原料，探讨了影响高铁酸盐氧化降解苯酚的主要因素，并研究了苯酚降解的动力学特征和反应机理。结果表明，高铁酸盐加入量、pH值、持续搅拌、反应温度、反应时间都影响苯酚去除效果。其中高铁酸盐加入量是影响苯酚去除效果的关键因素，高铁酸盐氧化降解苯酚的最佳pH值范围为9～10，持续搅拌和提高反应温度只影响苯酚降解速率而不影响苯酚降解率。苯酚的降解过程遵循一级反应动力学模型。苯酚被高铁酸盐氧化生成CO₂、H₂O以及一部分难矿化的有机物。     

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.     

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.     

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.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.     

Biochemical interaction of six op delayed neurotoxicants with several neurotargets

Abstract

Five organophosphorous insecticides: Leptophos, EPN, Cyano‐fenphos, trichloronate and salithion proved to cause irreversible ataxia not only to chicken but also to mice and sheep. TOCP was included as a reference. Cyanofenphos blocked the catecholamine B‐receptor binding activity with ³H‐norepinephrine at a level similar to that of the specific inhibitor propranolol in the mouse heart preparation. In the lamb heart preparation, the B‐receptor was more sensitive to Leptophos, salithion and TOCP than to propranolol. The six compounds and their oxons were screened for their in‐vitro inhibition to monamine oxidase (MAO), acetyl cholinesterase (AChE) and neurotoxic esterase (NTE) in the brain of either mouse, lamb or chicken. It is believed that their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia.