超声波/纳米铁协同降解氯代苯酚的试验

通过间歇试验对超声波/纳米铁协同降解氯代苯酚(CPs)废水进行了研究,结果表明,超声波/纳米铁协同对CPs的降解率明显高于单纯超声波和单纯纳米铁的降解率;协同体系、单纯超声波和单纯纳米铁降解CPs均符合准一级反应动力学,协同体系的降解速率较单纯超声波提高了5.1~5.6倍,较单纯纳米铁提高了17.7~21倍,并且比它们的几何迭加值高4倍以上;氯代苯酚降解的准一级速率常数和降解率满足以下规律:PCP>2,4,5-TCP>2,4-DCP>3-CP;探讨了混合废水的降解:在混合废水体系中,结构易裂解的优先降解,然后为浓度高的优先降解。     

纳米铁协同超声降解氯苯的研究

报道了纳米铁协同超声波降解一氯代苯 (CB)的研究。探讨了有效声强、pH、CB初始浓度对降解效果的影响。比较了纳米铁协同超声波和单纯超声波对CB的降解效果和降解速率 ,反应 2 0min时 ,纳米铁协同超声波的降解率达到95 % ,而单纯超声波的降解率仅为 1 0 8%。上述两者都符合准一级反应动力学 ,超声波降解CB的准一级速率动力学常数k=6× 1 0 -3 min-1 ,而协同作用降解CB的准一级动力学常数k =1 6 3× 1 0 -1 min-1 ,提高了 2 7倍。     

超声波和零价铁联用对氯代苯酚脱氯降解作用的研究

采用超声波和零价铁联用对氯代有机物3氯苯酚(CP)、2,4-二氯苯酚(DCP)和2,4,6-三氯苯酚(TCP)模拟废水进行了脱氯处理研究。以单因素法, 考察了铁粉初始投加量、溶液的初始浓度、超声波功率和溶液的pH值等因素对氯代酚降解的影响，并探讨了降解反应动力学。结果表明，超声波和零价铁联用对氯酚具有显著的降解效果，当水样初始浓度为25 mg/L，溶液pH呈弱酸性，超声波功率为200 W时，氯代酚的脱氯效率达到最大值。降解反应符合准一级反应，CP、DCP和TCP的反应速率常数分别0.0613 h^-1、0.374 h^-1和0.197 h^-1。     

Fe^o／厌氧微生物体系降解2，4，6-三氯酚特性研究

通过摇床间歇实验，研究了厌氧微生物与零价铁（Fe^o）联合体系降解2，4，6-三氯酚（TCP）的特性，结果表明，在pH7．5，35℃，150r／min，Fe^o10g／L条件下，TCP初始浓度为30mg／L时，TCP降解的拟一级反应速率常数为0．0207h～，添加少量碳源可达到0．0390h^-1，其降解速率是前者的1．88倍；添加碳源的体系在220h内连续多次投加TCP降解率都达到80％以上，而不加碳源的体系在第2次投加TCP后降解率就只有30％左右；添加不同碳源，降解速率不同；添加2-溴乙烷磺酸钠（BESA）以及SO4^2-、NO3^-和S^2-对TCP降解有不同的抑制作用。     

超声波/零价铁降解对氯苯胺性能及机理研究

在超声波/零价铁体系中考察了溶液初始pH值、浓度对对氯苯胺降解的影响.在pH值为3～11范围内最佳条件为pH=9;初始浓度为0.1、0.2和0.4 mmol/L时的降解率(180 min)分别为83.2%、63.5%和36.1%.对氯苯胺在单纯铁粉、单纯超声波和超声波/零价铁3种体系中降解符合拟一级反应动力学规律,速率常数分别为6.83×10-4、3.95×10-3和1.01×10-2 min-1,增强因子为218%,表明铁粉与超声波对对氯苯胺降解有明显的协同效应.在体系中加入自由基捕捉剂正丁醇能抑制对氯苯胺的降解,证实对氯苯胺降解主要是依靠羟基自由基的氧化作用.     

催化铁内电解法处理硝基苯废水的机理与动力学研究

对催化铁内电解法处理硝基苯废水降解动力学特性进行了研究。结果表明，降解过程符合准一级动力学规律。进水浓度、pH值和反应温度强烈影响硝基苯的降解速率。在实验pH值范围内，反应速率常数依次为：强酸性〉弱碱性〉弱酸性〉中性；循环伏安扫描图显示了硝基苯可以在铜电极上直接得电子还原，该反应在强酸和弱碱性条件下效果较好。反应速率常数随进水浓度的增大而减小。提高反应温度可改善处理效果，在30-45℃范围内，提高温度对处理效果的改善并不显著；当温度升高到45℃以上时，升温可以显著改善处理效果。     

pH值对“Fe^0．厌氧微生物”体系去除2，4，6-三氯酚过程的影响

考察了pH值对“Fe^0一厌氧微生物”体系降解2，4，6，一三氯酚（2，4，6．TCP）效果的影响，结果表明：pH值是影响“Fe^0-厌氧微生物”体系降解2，4，6-TCP效果的重要参数，初始pH值直接影响微生物活性和铁腐蚀，进而影响过程pH值变化，反过来又影响铁腐蚀和微生物活性，pH7．0～9．0的中性偏碱范围较适于厌氧微生物生长。Fe^0与微生物对目标污染物的降解具有协同促进作用，其协同促进机制表现在3方面：Fe^0与微生物对体系过程pH值具有互补调节作用，可将体系的pH值调节值适于微生物生长的中性范围；Fe^0腐蚀产生的Fe2＋和H2可为微生物代谢提供电子对和营养物质，从而促进生物还原脱氯的进行；Fe^0的腐蚀过程直接对氯代有机物还原脱氯，而微生物又可促进Fe^0腐蚀。     

MnO2催化Fenton试剂降解苯酚废水

实验对MnO2催化Fenton试剂氧化高浓度苯酚废水的动力学特性和去除效果进行了研究。结果表明,MnO2可以提高Fenton试剂体系对苯酚的降解率以及COD的去除率;Fenton试剂以及MnO2催化Fenton试剂氧化苯酚废水体系中苯酚的降解都符合拟一级动力学模型。在MnO2催化Fenton试剂氧化体系中,苯酚的降解速率常数有明显提高,反应活化能也有所降低,说明MnO2的加入可以使反应容易进行。废水降解前后紫外可见吸收光谱和红外谱图表明,Fenton试剂法将苯酚可能降解为羧酸、烯烃等有机物中间体。     

高频超声辐照降解水中4—氯酚的研究

本文着重探讨了高频超声波（1．7MHz）降解4－氯酚的反应过程和反应机理，研究了高频超声波降解4－氯酚的效果，并讨论了4－氯酚初始浓度等因素对降解效果的影响。高频超声波降解4－氯酚为一级反应，超声波空化效应在降解过程中起主导作用。     

超声波降解水溶液中对二氯苯

采用超声波降解含对二氯苯(p-DCB)的溶液,研究了p-DCB降解的动力学和影响因素.结果表明:(1)超声波降解水溶液中的p-DCB,随着p-DCB初始浓度的增加降解率减小;p-DCB的超声波降解反应符合表观一级动力学规律.(2)增大超声波频率和功率以及双频率联合使用可以增大p-DCB的降解率和一级反应速率常数.(3)弱酸性或中性环境更有利于p-DCB的降解进行.(4)反应时的搅拌和自由基清除剂的投加都降低了p-DCB的降解率,这是因为超声波降解时空化气泡内的热裂解和自由基作用的削弱.(5)在单一体系中,p-DCB比对氯苯胺(p-ClA)更易降解.在混合体系中,p-ClA的加入没有显著降低p-DCB的去除效果,因为亲水的p-ClA不易挥发,难以进入空化气泡竞争能量和自由基,其存在对空化气泡内混合气体的比热容比影响较小;而p-DCB的存在却明显降低了p-ClA的降解效果,因为疏水的p-DCB易挥发进入空化气泡竞争能量和自由基,并降低混合气体的比热容比.     

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.     

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 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.     

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.