水体中酮硝基麝香的臭氧氧化降解研究

采用臭氧氧化水体中的酮硝基麝香,考察pH、H2O2等因素对降解程度的影响,结果表明提高初始pH能加快酮硝基麝香的氧化降解,当pH为12时,反应时间1 h,酮硝基麝香几乎完全去除,浓度为2 mol/L和5 mol/L的H2O2存在有利于O3分解生成·OH自由基,使得酮硝基麝香的氧化降解速率加快,当H2O2浓度超过5 mol/L,H2O2会成为·OH的清除剂,降低·OH利用率;无论O3单独作用和O3/H2O2协同作用,酮硝基麝香降解符合准一级动力学规律;酮硝基麝香氧化降解产物包括甲酸、二乙酸和硝酸根等,其中硝基从苯环上脱落降低了硝基麝香对环境的风险.     

光/电Fenton牺牲阳极法降解有机污染物

采用Fe片为阳极和石墨为阴极,在可见光(λ450 nm)照射并外加电压条件下,以有机染料橙Ⅱ(orangeⅡ)及有机无色小分子2,4-二氯苯酚(2,4-dichlorophenol,DCP)为目标化合物,探讨了光/电Fenton牺牲阳极法降解有机污染物的最佳反应条件,结果表明,在电压=3 V,pH=3.0,H2O2浓度为5×10-5mol/L时,orangeⅡ的降解效果最好,反应10 h矿化率可达到78%,210 min内2,4-DCP降解率为91.4%。通过对光/电Fenton体系原位循环伏安参数测定及过氧化物酶催化反应吸光光度法和苯甲酸荧光分析法检测光/电Fenton降解orange II过程中H2O2和羟基自由基(.OH)的变化,表明orangeⅡ降解过程涉及.OH历程。     

光催化降解水体异味物质2-MIB的机理

以水体异味物质2-甲基异莰醇(2-methylisoborneol,2-MIB)为研究对象,在紫外光(λ<380 nm)照射下,探讨TiO2(P25)对2-MIB的光催化降解特性及光化学作用机理。结果表明,UV/TiO2光催化体系可以有效去除水体异味物质2-MIB,紫外光照射60 min,对2-MIB的降解率达95%。同时研究了光催化降解体系介质pH,共存腐殖酸(HA)和过硫酸钾(K2S2O8)对UV/TiO2光催化体系降解2-MIB的影响,发现低浓度HA([HA]≤0.5 mg/L)可以提高2-MIB降解速率,当HA浓度高于0.5 mg/L,2-MIB降解反应受到抑制;同时当加入电子受体K2S2O8后,降解体系中活性物种羟基自由基(.OH)明显增加,提高了TiO2对2-MIB的降解能力。利用苯甲酸荧光光度法和POD-DPD显色法跟踪测定降解过程中羟基自由基(·OH)和过氧化氢(H2O2)的变化,表明光催化反应涉及·OH机理。     

UV及UV/US降解对二氯苯水溶液的研究

使用紫外光(UV)和超声波(US)降解水溶液中的对二氯苯(p-DCB)。考察了p-DCB初始浓度,初始pH、腐殖酸和H2O2的存在对p-DCB光解的影响。结果表明,较低的初始浓度或弱酸性pH有利于p-DCB降解。溶液中存在20 mg/L的腐殖酸可使p-DCB的反应速率常数提高32.6%。加入氧化剂H2O2可以显著提高p-DCB的降解率,在[p-DCB]0=0.1 mmol/L,[H2O2]0=0.1 mmol/L,pH0=5.8,反应180 min条件下,p-DCB的降解率为95.5%。超声波对p-DCB的降解速率(14.6×10-3/min)大约是紫外光(4.3×10-3/min)的3.4倍,紫外光-超声波耦合时的降解速率(20.6×10-3/min)大于两者单独降解速率的加合。在各种实验条件下,p-DCB的降解均遵循表观一级动力学。     

溴酸钾对二茂铁(Fc)非均相Fenton效能的影响

研究了KBrO3对二茂铁(Fc)非均相Fenton效能的影响,深入考察了KBrO3对体系中Fc溶解、H2O2分解和羟基自由基(·OH)生成的影响。结果表明,KBrO3的加入对不同反应阶段Fc/Fenton体系的效能均有明显的促进作用,初始阶段主要是由于KBrO3对·OH产生的促进作用所致,后期主要是由于KBrO3促进了体系中Fc的溶解,使得体系中溶解态的Fc催化的均相Fenton反应的比例增加,体系中H2O2的分解加快,·OH的表观生成率增加,进而促进了反应的进行。无KBrO3添加,pH=4,MB初始浓度为10 mg/L,Fc的量为1.6×10-3mol/L,[H2O2]/[MB]=3.14时,45 min时,MB的剩余率为9.1%,105 min时为0。当KBrO3的用量为3×10-4mol/L时,反应45 min后MB的去除率即可达到100%。随着KBrO3浓度的增加,其对Fc/Fenton效能的促进作用增强。     

微囊藻毒素-RR的提取和臭氧氧化降解

在对采自云南滇池水华蓝藻细胞中的微囊藻毒素-RR(microcystin-RR,MC-RR)提取并发现其含量达到0.19mg/g(干重)的基础上,重点研究了臭氧氧化降解所提取的MC-RR。结果表明,当反应体系中臭氧浓度为5.7 mg/L时,初始浓度1.9 mg/L的MC-RR在15 min内被完全降解。利用HPLC/ESI/MS对提取的MC-RR及其氧化降解产物质荷比测定发现,降解前MC-RR的质谱图中出现特征离子m/z=1 038.7、m/z=519.8以及m/z=135.0。而降解后的产物质谱图中只有Adda基团中带苯环结构化合物(C9H10O)的特征离子峰m/z=135.0存在,其他2个离子峰完全消失。由此推断反应体系中MC-RR(m/z=1 038.2)在大量臭氧及其.OH自由基全面攻击下,分子结构中Adda基团以及单环结构中的不饱和双键直接被氧化而发生断链,最终形成小分子的有机物。     

附载型复合光催化剂TiO2·SiO2/beads降解有机磷农药

研究以四异丙醇钛 [Ti( iso- O C3 H7) 4]、硅酸乙酯为原料 ,以空心玻璃微球为载体 ,用溶胶—凝胶法制备可漂浮附载型复合光催化剂 Ti O2 · Si O2 / beads的过程 ,利用附载型复合光催化剂降解有机磷农药。结果表明 ,复合型光催化剂 Ti O2 · Si O2 摩尔比存在最佳值 ,n ( Ti O2 ) / m ( Si O2 ) =30 / 70时 ,光催化剂活性最高 ,其活性是同样降解条件下、同样含量 Degussa P- 2 5Ti O2 的 2倍左右。该光催化剂比表面大 ,吸附性强。并用 XRD和 SEM对附载型复合光催化剂进行表征     

零价铁与双氧水异相Fenton降解活性艳橙X-GN

采用Fe0与H2O2构成异相Fenton体系降解偶氮染料活性艳橙X-GN,考察了初始pH、H2O2和Fe0投加量、温度等对反应过程的影响。实验结果表明,在初始pH值为3.0、Fe0投加量为0.8 g/L、H2O2投加量为5 mmol/L和反应温度30℃的条件下,反应60 min后活性艳橙降解率达到96.2%。Fe0与H2O2投加量都存在一个最佳范围,当Fe0与H2O2浓度大于0.8 g/L和5 mmol/L时,羟基自由基会通过其他方式消耗,致使活性艳橙降解率下降。酸性条件和提高温度均有利于反应的进行。反应符合准一级动力学,表观反应速率常数k为0.064 min-1(30℃),反应活化能为80.62 kJ/mol。UV-Vis光谱扫描表明,反应过程中活性艳橙的发色基团及苯环结构均被破坏。     

Fenton体系降解水中偶氮染料的研究

研究了Fenton体系对于水溶液中偶氮染料橙G(orange G,OG)的降解,反应30 min后,在[Fe2+]0=0.1mmol/L、[H2O2]0=10 mmol/L、pH=3.0的条件下,初始浓度为20 mg/L的OG的去除率达到99%以上。与H2O2相比,OG的降解速率随着Fe2+不同投加量的变化更为敏感。Fe2+和H2O2初始浓度较高时,反应过程中的Fe2+的浓度维持在一个较低的水平,OG的降解速率较快。腐殖酸对OG在Fenton体系中的降解影响表现出明显的阻碍作用,并且随着腐殖酸浓度的增加,抑制作用越来越大。     

可见光下 H2La2Ti3O10/TiO2光催化降解有机染料的研究

通过固相反应、离子交换、粒子插入等一系列反应合成一种层状纳米光催化复合材料H2La2Ti3O10/TiO2.可见光照射下,对选定的染料模型--甲基橙溶液(20 mg/L)、汽巴克隆黄(100mg/L)、依利尼尔红(100 mg/L)溶液做光降解实验.结果表明,在可见光照射下,H2La2Ti3O10/TiO2均能对溶液中甲基橙、汽巴克隆黄、依利尼尔红有效降解,光照30min后,其对溶液中甲基橙、汽巴克隆黄、依利尼尔红的降解率分别可达60.4%、60.7%和72.0%,而标准TiO2(P-25)仅为6.2%、10.6%和12.3%.     

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.     

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.     

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.