活性炭负载Fe~(3+)催化H_2O_2氧化邻苯二甲酸二甲酯

将Fe3+负载在活性炭上制得载铁催化剂Fe/AC,并研究了该催化剂对邻苯二甲酸二甲酯(DMP)的催化降解性能。通过正交实验和单因素实验,探讨了催化剂投加量、H2O2投加量、溶液pH值和反应温度对水中DMP降解率的影响,同时对DMP矿化度进行了分析。实验结果表明,制得的载铁催化剂具有较高的催化活性;降解效果的影响顺序是反应温度催化剂投加量H2O2投加量溶液pH值;在反应温度为80℃、催化剂投加量为4 g/L、H2O2投加量为20 mL/L和溶液pH值为3的条件下反应120 min后,质量浓度为10 mg/L的DMP降解率最高可达97.73%;在优化的实验条件下反应150 min,DMP矿化度可达62.73%;催化剂反复使用5次仍具有较好的催化活性,DMP降解率仍可达到77%以上;反应过程中溶液Fe3+浓度的变化维持在1.07 mg/L左右,且可推测催化降解DMP主要是由非均相和均相催化氧化反应共同作用的。     

活性炭负载Fe^3＋催化H2O2氧化邻苯二甲酸二甲酯

将Fe3＋负载在活性炭上制得载铁催化剂Fe/AC,并研究了该催化剂对邻苯二甲酸二甲酯（DMP）的催化降解性能。通过正交实验和单因素实验,探讨了催化剂投加量、H2O2投加量、溶液pH值和反应温度对水中DMP降解率的影响,同时对DMP矿化度进行了分析。实验结果表明,制得的载铁催化剂具有较高的催化活性;降解效果的影响顺序是反应温度〉催化剂投加量〉H2O2投加量〉溶液pH值;在反应温度为80℃、催化剂投加量为4 g/L、H2O2投加量为20 mL/L和溶液pH值为3的条件下反应120 min后,质量浓度为10 mg/L的DMP降解率最高可达97.73%;在优化的实验条件下反应150 min,DMP矿化度可达62.73%;催化剂反复使用5次仍具有较好的催化活性,DMP降解率仍可达到77%以上;反应过程中溶液Fe3＋浓度的变化维持在1.07 mg/L左右,且可推测催化降解DMP主要是由非均相和均相催化氧化反应共同作用的。     

一株耐盐柴油降解菌的分离鉴定及其降解性能

从某油田附近受石油污染土壤中分离出一株以柴油为惟一碳源的耐盐菌株LS1。通过对菌株的生理生化特性、菌体的形态观察及16S rDNA基因序列分析鉴定菌株LS1为假单胞菌属(pseudomonas)。该菌株可耐受的最高盐度(NaCl)和柴油浓度分别为6%~8%和12 000 mg/L。菌株生长的适宜pH和温度条件分别为6.0~8.0和28~36℃。在盐度为6%、pH为7.0、温度为32℃、菌种投加量为10%的条件下,初始浓度为3 000 mg/L的柴油经6 d降解后,去除率可达78.3%,加入适量外加碳源葡萄糖和蔗糖,可使降解率分别提高至92%和90%左右。菌株LS1的耐盐机理可能是通过在细胞内积累甜菜碱以调节菌株细胞内外渗透压平衡。投加甜菜碱可提高耐盐菌LS1在高盐环境下对柴油的降解效率。     

纳米铁酸铜催化剂活化过一硫酸盐降解苯胺废水

使用溶胶凝胶法制备纳米铁酸铜催化剂,并用于活化过一硫酸盐催化降解苯胺废水。探究了纳米铁酸铜投加量、过一硫酸盐投加量和pH对苯胺降解率的影响。结果表明,在纳米铁酸铜投加量为2.0g/L、过一硫酸盐投加量为0.2g/L、pH=7.0的条件下,纳米铁酸铜活化过一硫酸盐催化降解苯胺废水的效果最好,反应60min,100mL质量浓度为10mg/L的苯胺降解率可达99%。纳米铁酸铜在反应过程中的总铁溶出量仅为0.87mg/L,总铜溶出量仅为0.03mg/L。苯胺的降解途径:一是苯胺中的氨基被自由基攻击,生成亚硝基苯,继续氧化生成硝基苯,然后开环矿化为CO_2和H_2O;二是氨基对位苯环上的氢原子被羟基取代生成对羟基苯胺,对羟基苯胺被自由基攻击生成亚氨基苯醌,进一步反应生成对苯醌,然后开环矿化为CO_2和H_2O。     

间接阳极氧化处理活性黑5模拟染料废水的研究

采用Ti/IrO2电极间接阳极氧化处理活性黑5模拟废水,主要研究pH值、电压、电解时间及NaCl投加量对其降解效果的影响.结果表明,在pH值为3,电压20 V,电解时间60 min,NaCl投加量2.5 g/L的条件下,该染料的降解率及脱色率均达到100%,苯环结构的降解可达45%,COD去除率可达60%.并对该染料的...     

天然沸石负载La2O3-ZnO-TiO2光催化降解活性艳红K-2BP

利用80目天然斜发沸石作载体制备La2O3(0.5%)-ZnO(20%)-TiO2/沸石复合光催化剂,以20 W紫外灯为光源,在自制的光催化反应器中降解活性艳红K-2BP,考察了光照时间、空气通入量、催化剂用量、溶液初始浓度、H2O2与Fe3+投加量等对活性艳红K-2BP光催化降解率的影响。结果表明,当溶液初始浓度为60 mg/L,催化剂投加量为12 g/L,通气量为1 200 mL/min,光照2.5 h,活性艳红K-2BP的降解率可达99.2%;H2O2和Fe3+投加量为4 mL/L和3 g/L时,光照1 h活性艳红K-2BP降解率分别为100%和97.2%。紫外 可见吸收光谱显示,LZTZ光催化剂可有效降解印染废水。     

机油高效降解菌群筛选及降解效果初探

从多处受石油污染的土壤中经过初步筛选、混合驯化得到以机油为唯一碳源进行生长代谢的混合菌群.利用此混合菌群进行的降解实验结果表明,该菌群对高浓度机油废水具有较强的降解能力,初始含机油约2.0 g/L的人工废水.接种量为0.1%(菌体湿重/培养液体积),经过7 d的降解,机油可降至403 mg/L,降解率达81.4%;对不同浓度机油废水的降解实验结果表明,在静态实验条件下,机油质量浓度在不高于1 000 mg/L(含1 075 mg/L),混合菌群在降解过程中能自行从降解产酸的不良环境中恢复,机油质量浓度在2 000 mg/L以上,初期产酸较多,pH下降幅度较大,在7 d的周期内,废水pH无法恢复,说明在降解后期仍有大量有机酸积累而未被彻底降解;与葡萄糖共基质的降解实验结果表明,经过7 d的降解.不超过150 mg/L,的葡萄糖与1 000 mg/L机油组成的共基质体系中,机油降解基本不受葡萄糖加入的影响,但可加强早期的降解速率.而葡萄糖高于150 mg/L时,则会对混合菌群的除油率产生抑制,抑制程度随着葡萄糖浓度的提高而加大.     

微波—Cu/Fe双金属催化剂—过氧化氢工艺催化降解甲基橙废水的研究

采用超声浸渍法制备了具有较高催化活性的Cu/Fe双金属催化剂。采用微波—Cu/Fe双金属催化剂—过氧化氢工艺处理甲基橙废水,并研究了相关影响因素。结果表明,Cu/Fe双金属催化剂的Cu和Fe具有协同催化效应,可大大提高甲基橙废水的降解率。在Cu/Fe双金属催化剂投加量10g/L、过氧化氢(质量分数为30%)投加体积1.0mL、微波功率500 W、辐照时间5min的最优化条件下,50mL质量浓度为100mg/L的甲基橙废水降解率可达98.94%。     

磁性载体固定化机油降解菌FZ5的研究

利用聚乙烯醇-海藻酸钠-磁性竹炭复合制备磁性悬浮小球,该小球的磁矫顽力为28.6 mT,具有较强的磁场,可用于磁场引导分离。利用磁性悬浮小球作为载体对机油降解菌FZ5进行固定化,研究了固定化时间、降解时间、固定化小球投加量、初始pH值和初始机油浓度对机油降油率的影响。结果表明,在固定化挂膜3 d,固定化小球投加量为8％,初始pH值为7,初始机油浓度为400 mg/L,降解培养3 d后对机油的降解率可达91.21％。     

电液压脉冲放电与铁屑内电解法联用处理TNT废水试验研究

TNT结构稳定,废水又具有生物毒性,难以生物降解,采用电液压脉冲放电与铁屑内电解法联用能有效处理TNT废水。研究了铁屑投加量、pH值和铁屑重复使用对TNT降解的影响。试验条件为：放电电压36 kV,废水体积7 L,TNT初始浓度90 mg/L,电极间距8 mm。结果表明,在投加铁屑700 g和pH值为6.5时,TNT降解率分别达到97.7%,铁屑重复使用6次不影响TNT降解效果;放电后静置一段时间,TNT仍然继续降解;在125 L的反应器中处理115 L废水,TNT初始浓度50 mg/L,TNT最大降解率达94.2％,TNT浓度降至2.9 mg/L。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Phytoextraction of lead-contaminated soil using vetivergrass (<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L.), cogongrass (<Emphasis Type="Italic">Imperata cylindrica</Emphasis> L.) and carabaograss (<Emphasis Type="Italic">Paspalum conjugatum</Emphasis> L.)

Background, Aims and Scope The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. Methods The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg⁻¹ (37.5 kg ha⁻¹) and 150 mg kg⁻¹ (75 kg ha⁻¹) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid out following a 3 × 2 factorial experiment in a completely randomized design. Results On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg ha⁻¹). Carabaograss had the lowest herbage mass production of 4.12 Mg ha⁻¹ and 5.72 Mg ha⁻¹ from soils added with 75 and 150 mg Pb kg⁻¹, respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg kg⁻¹). This was followed by cogongrass (2.34 ± 0.52 mg kg⁻¹) and carabaograss with a mean Pb level of 0.49 ± 0.56 mg kg⁻¹. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg kg⁻¹) to the soil. Discussion Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency of plants as phytoremediators could be correlated with the plants’ total biomass. This implies that the higher the biomass, the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most metal removal from the soil. Conclusions The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals; particularly Pb. Recommendations and Perspectives High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters, battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and public parks. ESS-Submission Editor: Dr. Willie Peijnenburg (wjgm.peijnenburg@rivm.nl)