室内空气总挥发性有机物净化实验装置设计及应用

为了探究进气流量和相对湿度对活性炭吸附法和光催化转化法动态净化室内空气中总挥发性有机物(TVOC)的影响,设计了一套包含活性炭吸附器和光催化反应器的多功能空气动态净化实验装置,并利用该装置进行了室内空气净化实验。通过设置不同进气条件(进气流量和相对湿度)对室内空气进行净化实验,采用气相色谱仪对样品TVOC浓度进行检测,并与未经净化处理的空气样品进行对比,计算TVOC去除率。结果表明:该实验装置能够实现连续进气且能对进气流量和相对湿度进行精准调节;随着进气流量增大,活性炭和光催化对TVOC去除率减小;随着进气相对湿度增大,活性炭对TVOC去除率减小,光催化对TVOC的去除率呈现先增大后减小的趋势。以上实验结果为气候舱空气净化系统、家用空气净化器及室内新风过滤系统等动态空气净化系统的设计提供了参考。     

利用UVC去除低浓度丁烷的实验研究

探讨了不同实验参数对丁烷在UVC下去除效果的影响,获得了丁烷的去除率与丁烷的初始浓度、气体流量、相对湿度、氧气含量等参数之间的关系。数据表明：在实验条件范围内,丁烷的去除率随其初始浓度和气体流量增大而减小;丁烷的去除率随相对湿度的增加呈现先快速升高后缓慢降低的关系,最佳相对湿度值在40%～60%之间;丁烷的去除率随氧气...     

污水厂生物除臭设施运行及影响因素的研究

在污水处理过程中会有大量的恶臭气体产生,主要含硫化氢和氨等发臭物质.这些臭味物质逸散到空气中,对污水处理厂及其周边的空气环境造成危害.针对清河污水处理厂原有生物除臭设施除臭效率难以提高的问题,对气体收集系统和生物除臭滤池内的喷淋管路进行了改造,并更换了新型生物填料.本研究对改造前后的除臭效果进行了考察,结果显示,硫化氢的平均去除率从改造前的36.5%提高到62.9%,最大去除率可以达到96.2%;氨的去除率从28.2%提高到接近100%.臭味气体的处理效果随除臭滤池的温度、气体的相对湿度的升高而提高.为此,对臭味气体的负荷、流量、温度以及湿度等因素进行了研究,在温度＞20℃、相对湿度＞80%的条件下,生物除臭滤池能够有比较理想的处理效果.     

电弧放电产生NOx及其对亚硫酸铵的氧化

将脱硫塔产生的高浓度亚硫酸铵氧化为硫酸铵是氨法脱硫研究的一个难点.利用二氧化氮(NO2)的氧化性,可以有效氧化高浓度的亚硫酸铵.空气中电弧放电可以产生氮氧化物(NOx),本研究采用高频交流电源,不锈钢针-针电极,研究了放电间距、气体流量、湿度和O2含量等参数对产物NOx的浓度和NO2/NOx比值的影响,并对产物气体做了红外分析和光谱分析.实验结果表明,放电间距增大有利于NOx浓度和NO2/NOx的提高,气体流量和湿度的增大使NOx浓度和NO2/NOx降低,O2含量为50％和60％时NO2浓度和NO2/NOx分别达到最大值.产物NOx对亚硫酸铵的氧化速率最高可达0.0264 mol/(L·min).     

催化氧化还原吸收法脱除工业含湿废气中NOx

基于精细化工、制药行业排出 NOx 废气氧化度低、氧气含量高的特点,提出以改性活性炭(MAC)为催化剂的催化氧化-还原吸收脱除 NOx 的方法.考察了相对湿度、氧化温度、氧化时间对 NO 催化氧化以及还原液种类对 NOx 吸收的影响.结果表明,随着相对湿度的增加 NO 转化率急剧下降,但随着氧化时间的延长有所提高;干气条件下,随着温度升高,NO 转化率下降;湿气条件下,NO 氧化反应最佳反应温度范围为 50～70℃,实验条件下的 NO 最高转化率可达 51%;还原液种类中以尿素-碱液对 NOx 和 NO 的吸收效果最好,亚硫酸铵-碱液对 NOx 的吸收效果最好.通过催化氧化-还原吸收的多级组合可实现 NOx 的有效脱除与达标排放.     

利用UVC去除低浓度苯的实验研究

探讨了不同实验参数对苯的UVC去除效果的影响,获得了苯的去除率与苯的初始浓度、气体流量、相对湿度和氧气含量等参数之间的关系。数据表明,在实验条件范围内,苯的去除率的倒数与苯初始浓度、气体流量之间为线性关系;苯的去除率随相对湿度的增加呈现先升高后缓慢降低的关系,最佳相对湿度值在30%～50%之间;苯的去除率随氧气量的增加而缓慢增加;波长为185+254 nm的UV与254 nm的UV相比净化效果更为理想。还分析了苯降解产生的中间产物,探讨了苯的降解机理。     

相对湿度对ZSM-5分子筛低温等离子体再生特性的影响

低温等离子体再生法是一种低温、快速和高效的吸附材料再生新方法。运用管式单介质阻挡放电反应器产生的低温等离子体对吸附了苯的ZSM-5分子筛进行再生处理,分析了湿度对低温等离子体放电状态的影响,研究了湿度对材料吸附性能及低温等离子体再生效果的影响,考察了特定湿度条件下低温等离子体再生吸附材料的可重复性。实验结果表明,当相对湿度小于60%时,吸附材料的脱附效率和再生效率随湿度增加而升高;当相对湿度由60%升高至80%时,吸附材料的脱附效率和再生效率开始下降;但通过对比不同湿度条件再生后吸附材料的饱和吸附容量可以发现,湿度越低,再生后吸附材料的饱和吸附容量越大;在相对湿度30%的条件下,重复再生效率稳定,且重复再生后吸附材料仍有较好的吸附效果。     

利用无泵水幕废气净化器治理高浓度NOx的工程实践

介绍了无泵水幕废气净化器的工作原理和运行特点,采用该设备处理某金刚石公司的酸洗车间高浓度的NOx气体,其净化效率达90%以上,净化后的NOx气体可直接达标排放.无泵水幕废气净化器解决了传统的水喷淋塔普遍存在的喷嘴堵塞、单级净化效率低、运行费用高等问题,在高浓度酸性气体治理方面具有很好的推广应用前景.     

大尺寸大孔径TiO_2/SiO_2光催化剂的制备及甲醛去除研究

以大孔径SiO2为载体,通过钛酸丁酯溶液的浸渍、原位水解以及高温煅烧制备出大尺寸、大孔径的TiO2/SiO2光催化剂。利用自制空气净化装置对室内甲醛的清除进行研究,分别考察了TiO2的百分含量、紫外光光强、温度、湿度和空气流量等不同条件下TiO2/SiO2光催化剂对除去甲醛效率的影响。结果表明,反应温度从10～50℃依次升高,去除率逐渐下降。在相对湿度为50%,TiO2负载率为55.6%,流量为8 m3/h时,甲醛的最佳除去率达96.5%;经过7周时间的考察,发现TiO2/SiO2光催化剂的催化活性没有明显的下降。     

隧道空气净化器的应用研究

本文以某一长大公路隧道为例,阐述了隧道空气净化器应用于公路隧道中的实施方法,论证了其技术上的可行性,分析了应用隧道空气净化器的社会经济效益和环境效益。结果表明,隧道空气净化器应用于公路隧道中的空气净化,是解决公路长大隧道空气污染问题的一种经济和有效方法     

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.     

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.     

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.     

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.     

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.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.     

Sorption and predicted mobility of herbicides in Baltic soils

This study was undertaken to determine sorption coefficients of eight herbicides (alachlor, amitrole, atrazine, simazine, dicamba, imazamox, imazethapyr, and pendimethalin) to seven agricultural soils from sites throughout Lithuania. The measured sorption coefficients were used to predict the susceptibility of these herbicides to leach to groundwater. Soil-water partitioning coefficients were measured in batch equilibrium studies using radiolabeled herbicides. In most soils, sorption followed the general trend pendimethalin > alachlor > atrazine～ amitrole～ simazine > imazethapyr > imazamox > dicamba, consistent with the trends in hydrophobicity (log K_ow) except in the case of amitrole. For several herbicides, sorption coefficients and calculated retardation factors were lowest (predicted to be most susceptible to leaching) in a soil of intermediate organic carbon content and sand content. Calculated herbicide retardation factors were high for soils with high organic carbon contents. Estimated leaching times under saturated conditions, assuming no herbicide degradation and no preferential water flow, were more strongly affected by soil textural effects on predicted water flow than by herbicide sorption effects. All herbicides were predicted to be slowest to leach in soils with high clay and low sand contents, and fastest to leach in soils with high sand content and low organic matter content. Herbicide management is important to the continued increase in agricultural production and profitability in the Baltic region, and these results will be useful in identifying critical areas requiring improved management practices to reduce water contamination by pesticides.     

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.