海藻酸钠微胶囊负载纳米铁吸附水中的As(Ⅴ)

利用本实验所制备的海藻酸钠微胶囊负载纳米零价铁材料(M-NZVI)对水中不同浓度的As(V)进行了吸附去除研究,并比较了不同材料的吸附等温曲线。实验结果表明,2 g/L M-NZVI在pH=6.5±0.1,常温常压条件下对5 mg/L的As(V)的吸附去除率为90.35%,吸附速率较快,在30 min即可达到吸附平衡。通过M-NZVI、Ca-ALG和NZVI的热力学对比实验可知,M-NZVI表现出优越的吸附性能。溶液吸附剂添加量、初始pH值、离子浓度等因素对M-NZVI吸附水中砷离子的效率有一定影响:在其他条件不变的情况下,As(V)的去除率随着添加量的增加而逐渐增大;M-NZVI对As(V)的最佳吸附效果在pH=6~7范围之间;溶液中高浓度Na Cl能对M-NZVI的吸附性产生较强的干扰。同时,对于As(V)≤5mg/L的溶液,M-NZVI可以不做任何处理多次利用3~4次。这些结果显示,M-NZVI是一种用于原位修复重金属污染水体的潜在理想材料。     

复合分子筛去除水中氟化物的研究

通过使用复合分子筛对模拟含氟水进行静态吸附实验,研究了复合分子筛对水中氟化物的吸附性能,并分析了吸附过程中温度、pH值和停留时间等因素对分子筛除氟效率的影响。结果表明,用80 g粒径0.9 mm的分子筛处理150 mL浓度为5 mg/L的模拟含氟水,分子筛的除氟效率达到90%以上,而同样条件下天然沸石和改性涂铁沸石的去除率分别为23.35%和80.69%。分子筛的除氟效率随着温度呈现先上升后下降的趋势,50℃时去除效率达到最高,为92.7%;在弱酸性条件下的去除率比碱性条件要高,在pH=4时去除率最大,为91.8%;停留时间初始阶段与去除率保持正相关,在45 min后反应达到平衡。分子筛的吸附速率符合二级动力学方程dqe/dt=k(qe-qt)2,吸附等温线符合Langmuir方程。     

模拟酸雨对氧化锰吸附砷(Ⅲ)的解吸行为研究

以合成的氧化锰为吸附剂研究了酸雨pH值、酸雨离子强度、解吸时间和解吸次数等因素对模拟酸雨解吸砷(Ⅲ)的影响。实验结果表明:氧化锰对砷(Ⅲ)吸附容量较大,等温平衡吸附量为:48.38 mg/g。模拟酸雨的pH值与离子强度对砷(Ⅲ)的解吸影响不大;解吸反应在90 min后基本达到平衡,平衡解吸量为2.69×10-2mg/g;随解吸次数的增加解吸量变化不大。氧化锰对砷(Ⅲ)的吸附主要是专性的配位吸附,吸附砷(Ⅲ)后难以被模拟酸雨解吸。     

用于磷吸附的载铁(β-FeOOH)沸石制备及特性简

以天然沸石为载体,采用FeCl₃水解法制备用于磷吸附的载铁沸石（β-FeOOH-Z）,优化β-FeOOH-Z的制备条件,包括FeCl₃溶液浓度、负载pH值、负载时间、负载温度和烘干温度,并利用X射线衍射（XRD）和傅里叶变换红外光谱（FTIR）对β-FeOOH-Z及其磷吸附特性进行分析。结果表明,β-FeOOH-Z的优化制备条件为：FeCl₃溶液浓度1 mol/L、负载pH值6、负载时间24 h、负载温度25℃和烘干温度60℃。优化制备条件下,100~120目沸石的载铁量为100.2 mg/g,铁的负载率为18%,其磷吸附量为7.68 mg/g,比天然沸石提高79.6%。XRD分析结果表明,β-FeOOH-Z中的杂质元素较天然沸石减少,并有效负载β-FeOOH;制备条件对β-FeOOH-Z的成分有较大影响,FeCl₃溶液浓度较低、负载温度和烘干温度过高均使β-FeOOH-Z中含有α-Fe₂O₃,并导致其磷吸附效率降低。FTIR分析结果表明,β-FeOOH-Z的表面羟基在其吸附磷过程中起重要作用,羟基与磷酸根离子的配位交换是β-FeOOH-Z吸附磷的主要作用机制。     

一步还原焙烧法制备炭载零价铁及其对水中Cr(Ⅵ)的去除

以活性炭为还原剂和载体,通过一步还原焙烧法制备出炭载零价铁(AC-ZVI)材料。电镜扫描和X射线衍射分析结果表明,零价铁以平均粒径为2μm的颗粒均匀分布在活性炭表面和孔道中。采用间歇实验考察了炭载零价铁去除水中Cr(Ⅵ)的效果,结果显示炭载零价铁对水中的Cr(Ⅵ)具有很好的去除效果,在初始pH值为5、Cr(Ⅵ)浓度为50 mg·L~(-1)、AC-ZVI投加量(铁用量)为0.6 g·L~(-1)和反应温度为25℃的条件下,反应5 h后Cr(Ⅵ)的去除率达到86.8%;降低溶液pH、增加炭载零价铁投加量和提高反应温度均有利于Cr(Ⅵ)的去除,反应过程符合准一级动力学,表观反应速率常数k为0.655 h~(-1)(30℃),反应活化能为67.6 k J·mol~(-1)。研究结果表明,通过一步还原焙烧法制得的炭载零价铁可作为一种高效吸附还原材料用于Cr(Ⅵ)污染水体的治理。     

4A沸石对复合污染水体中Pb2+、Cu2+和Cd2+的去除

采用静态吸附法以4A沸石为吸附剂研究其对复合污染水体中Pb2+、Cu2+和Cd2+的竞争吸附特性,并探讨了影响吸附的环境因素。实验表明,在室温条件下,溶液pH5～6,4A沸石15 mg对10 mL复合污染溶液(Pb2+、Cu2+和Cd2+浓度分别为100 mg/L)吸附20 min时,对溶液中3种重金属的吸附去除率均可达99.8%以上。反应过程中4A沸石对3种重金属的吸附速率大小为Pb2+>Cu2+>Cd2+。复合污染水体中4A沸石对Pb2+、Cu2+和Cd2+的吸附符合Langmuir和Fre-undlich等温吸附方程,相关系数分别为0.9981、0.9901、0.9916和0.9638、0.9194、0.9689。经计算,4A沸石对Pb2+、Cu2+和Cd2+的饱和吸附量分别为129.9 mg/g、107.5 mg/g和99.0 mg/g。4A沸石吸附重金属离子达到吸附平衡的时间较短,对溶液pH值的适应性较好。吸附后的4A沸石可以再生利用,对铅离子洗脱重复利用性较铜离子和镉离子强。     

5种铁氧化物去除As(V)性能的比较研究

为了从铁氧化物中筛选得到潜在经济有效的除砷材料,对5种铁氧化物去除As(V)的性能进行了比较研究。吸附实验结果表明,其吸附容量依次为施氏矿物四方纤铁矿水铁矿赤铁矿针铁矿,其吸附过程均符合准二级动力学,约24 h时吸附达到平衡。其中,pH=5时,施氏矿物的吸附容量达到83 mg/g。分别投加500 mg/L和300 mg/L的施氏矿物,可将含砷1.484 mg/L和0.850 mg/L、高TOC含量和高pH特征的模拟配水砷浓度降至0.01 mg/L以下。鉴于施氏矿物良好的吸附除砷性能,进一步通过SEM、FTIR和电位滴定对其表面特性进行了深入研究,结果显示,本研究中制备的施氏矿物存在结构性或表面吸附的SO42-,其(质子)表面位密度约为4.32个/nm2,表面质子化常数pK1为4.60,pK2为-8.98。     

用于磷吸附的载铁（β-FeOOH）沸石制备及特性

以天然沸石为载体,采用FeCl3水解法制备用于磷吸附的载铁沸石（β-FeOOH-Z）,优化β-FeOOH-Z的制备条件,包括FeCl,溶液浓度、负载pH值、负载时间、负载温度和烘干温度,并利用x射线衍射（XRD）和傅里叶变换红外光谱（FTIR）对β-FeOOH-Z及其磷吸附特性进行分析。结果表明,β-FeOOH-Z的优化制备条件为：FeCl3溶液浓度1mol／L、负载pH值6、负载时间24h、负载温度25℃和烘干温度60℃。优化制备条件下,100-120目沸石的载铁量为100．2mg／g,铁的负载率为18％,其磷吸附量为7．68mg／g,比天然沸石提高79．6％。XRD分析结果表明,β-FeOOH-Z中的杂质元素较天然沸石减少,并有效负载β-FeOOH;制备条件对β-FeOOH-Z的成分有较大影响,FeCl,溶液浓度较低、负载温度和烘干温度过高均使β-FeOOH-Z中含有α-Fe2O3,并导致其磷吸附效率降低。FTIR分析结果表明,β-FeOOH-Z的表面羟基在其吸附磷过程中起重要作用,羟基与磷酸根离子的配位交换是β-FeOOH-Z吸附磷的主要作用机制。     

膨润土负载硫化纳米零价铁去除对硝基苯酚的研究

以具有较大比表面积和良好吸附性能的膨润土作为载体,制备了膨润土负载硫化纳米零价铁,并利用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及比表面积等手段表征膨润土负载硫化纳米零价铁的特性。研究了膨润土负载硫化纳米零价铁的硫铁比(摩尔比)、投加量、初始pH对对硝基苯酚(PNP)去除的影响,并对PNP降解机理进行了初步探究。结果表明,膨润土负载硫化纳米零价铁比表面积为33.06m~2/g,大于膨润土的比表面积(26.72m~2/g),负载的纳米零价铁颗粒分散均匀。当硫铁比为0.011 2、投加量为0.5g/L、初始pH为5.0时,10min基本能把1L1.5mmol/L的PNP完全降解,具有最大的去除速率和去除率。PNP的最主要降解产物为对氨基苯酚。     

天然有机物对零价铁去除水体中砷的影响研究

在研究零价铁对水体中砷去除动力学的基础上,着重探讨了天然有机物腐殖酸对零价铁除砷的影响.并对零价铁的腐蚀产物进行了分析.结果表明,水体中的砷可以通过在零价铁腐蚀产物上的吸附得到快速去除.腐殖酸显著降低了砷的去除率,这归因于腐殖酸与零价铁腐蚀产生的铁离子形成络合物,阻止了Fe(OH)3(或Fe(OH)2)沉淀的产生.腐殖酸浓度越高.砷的去除率越低.1.00 mg腐殖酸最多可以络合约0.75 mg铁离子.当铁离子与腐殖酸的络合达到饱和后,零价铁进一步腐蚀产生的铁离子可形成Fe(OH)3(或Fe(OH)2)沉淀,这些沉淀物可吸附水体中的腐殖酸和砷,从而加速砷的去除.冷冻干燥后的零价铁腐蚀产物的结构以无定型为主,含有少量的结晶化合物,包括γ-Fe2O3、γ-FeO(OH)和Fe3O4等.腐殖酸的存在可进一步增加腐蚀产物中的无定型成分.光电能谱(XPS)分析结果显示,吸附在腐蚀产物上的砷为5价,没有发现5价砷被还原成3价砷.在应用零价铁修复砷污染水体时,应考虑腐殖酸的影响.     

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.     

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 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.