污泥施入黄土后重金属Cu、Zn、Cd的淋滤迁移

污泥土地利用是目前国内外污泥处置的主要方式和鼓励方向,在中国西北黄土地区更有前景和意义.污泥富含有机质和营养元素可弥补黄土的贫瘠缺陷,改善黄土肥力、增加植物产量.污泥施入黄土后,灌溉水对污泥重金属的淋滤迁移和污染风险是值得研究的课题之一.研究旨在了解重金属Cu、Zn、Cd在黄土层中的淋滤迁移特征,为黄土地区污泥的土地利用及重金属污染控制提供实验依据.实验选择污泥中含量或毒性大的Cu、Zn、Cd 3种重金属作为研究对象,通过室内模拟土柱对表层堆肥污泥中2种源强的重金属进行1年灌溉用水量的淋滤对比实验,测定淋滤前后土柱中和渗出液的Cu、Zn、Cd总量、有机质及pH值,以期分析重金属在黄土中的淋滤、迁移特征.结果表明,淋滤作用可使堆肥污泥Cu、Zn、Cd发生少量迁移并富集于土柱中、上部,大部分或绝大部分重金属仍滞留于耕作层(0～20 cm);淋滤使堆肥污泥Cd与Cu向下迁移约30 cm,Zn向下迁移约20 cm;渗出液呈弱碱性,其中Cu、Zn、Cd 3种重金属的浓度较入渗水均有增多,但随渗出液从黄土柱中溶出的重金属量极少.实验表明,耕作层重金属源强对Cu、Zn、Cd在土柱剖面中的淋滤、迁移和滞留作用以及溶出量均有不同程度的影响,堆肥污泥土地利用可以明显改善黄土肥力,灌溉对耕作层污泥有机质的淋滤损失量较小.并得出,堆肥污泥在黄土地区的土地利用是可行的.     

堆肥污泥重金属在黄土中的淋滤特征

堆肥污泥中所含重金属是污泥堆肥土地利用最大的障碍,实验选用北方贫瘠的黄土作为供试样品,通过室内土柱淋滤实验,对堆肥污泥重金属在黄土中的淋滤特征进行了研究。结果显示,在0～40 cm的浅层淋滤层,各种重金属在黄土中的纵向迁移能力为:Pb>Zn>Ni>Cu,而在50～55 cm的深层淋滤层,Cd在黄土中的迁移能力相对其他4种重金属是比较强的;各种重金属在50～60 cm深层淋滤层中会出现二次富集,出现明显富集层。研究揭示了堆肥污泥重金属在黄土中的迁移特征,为有效控制和消除堆肥污泥土地利用中重金属的污染研究提供了理论依据。     

垃圾渗滤液中溶解性有机物对土壤中重金属迁移的影响

垃圾渗滤液主要组分中含有重金属和大量的溶解性有机物(DOM).实验选用北方最具代表性的褐土为供试样品,通过室内土柱淋滤实验研究了垃圾渗滤液溶解性有机物对重金属Cu、Cd、Pb和Zn在土壤中的迁移行为的影响.结果显示,DOM对土壤中Cd、Zn的垂直迁移起着促进作用,而对Cu、Pb迁移起着一定的抑制作用;不同浓度的垃圾淋洗...     

柱淋滤模式下脱硫石膏中重金属组分的迁移特性

采用柱淋滤模式研究了来自武汉和浙江电厂的2个脱硫石膏样品FA1和FA2中Cr、As、Ni、Pb和Hg 5种重金属组分的迁移过程,了解这一过程为脱硫石膏污染防治工作具有指导意义。首先采用改进的Tessier法分级提取脱硫石膏晶体中重金属组分,完成了不同重金属组分赋存形态研究,结果表明重金属组分以氧化物结合态为主,其中FA1中重金属可淋滤态大小为PbAsCrNi,而FA2中重金属可淋滤态为AsPbNiCr。柱淋滤实验中选择p H值分别为4.0及4.5的醋酸-醋酸钠缓冲溶液为淋滤液,淋滤周期为17 d,得到不同重金属淋出率L随时间的淋出特征。结果表明:在本研究体系中各重金属组分淋出率均随淋滤时间有显著增加;淋滤液酸性增强可促进重金属组分的淋滤溶出;重金属组分赋存形态对重金属淋出迁移过程具有重要影响。脱硫石膏FA1中Cr、As、Ni、Pb、Hg以及脱硫石膏FA2中的Pb、Hg的最高淋出量超过《地表水环境质量标准》,在脱硫石膏资源化应用过程中可能对环境造成危害。     

柴油污染包气带的气相抽提影响因素

气相抽提(SVE)是一种经济、高效的土壤原位修复技术。为了研究介质、介质含水率和通风方式对SVE去除效率的影响,并探讨实验运行过程中包气带不同深度柴油浓度的变化规律,实验利用了有机玻璃柱模拟包气带环境,开展柴油污染的SVE实验。结果表明,对于不同介质,SVE去除粗砂中柴油的效率高于中砂;不同含水率,含水率为1%的粗砂中柴油的去除率大于含水率为12%的粗砂;不同的通风方式,连续通风的效率大于间歇通风。此外,不同深度介质均出现柴油浓度先升高后降低的趋势。     

电动力学技术修复苯酚污染土壤的研究

用电动力学技术对苯酚污染砂土的修复进行了实验研究.探讨了苯酚污染砂土电动力学修复的可行性及在不同电场强度下苯酚的迁移特征和机制.研究了采用添加阴离子表面活性剂十二烷基苯磺酸钠(LAS)和控制液(柠檬酸和NaOH)等对迁移效果的影响,以及苯酚在砂土中的迁移和分布规律.实验结果表明,在电场作用下苯酚在砂土中发生富集.在电场强度为2.0V/cm时的苯酚富集效果明显,比在电场强度为0.5 V/cm时苯酚多增加30%,且向阳极的迁移距离增大了12 cm;在阴极添加不同浓度的LAS,苯酚在砂土中的富集效果不同,LAS浓度越大向阳极迁移得越快富集效果越明显,当LAS为0.046 0 mol/L时苯酚最高增加了143%;向阳极添加NaOH,苯酚在阳极区增加了136%,比向阴极添加柠檬酸的效果明显.     

土壤柴油污染修复的抽气提取去除实验研究

为得到土壤气相抽提(SVE)去除柴油的优化条件,进行了一维土柱抽气提取去除柴油污染物的实验研究,研究不同初始含水率、不同抽气量对污染土壤中柴油去除率的影响及不同深度残留柴油的变化规律。结果表明：在本实验模拟的范围内,抽气量越大,SVE处理效果越好;初始含水率越低,处理效果越好;此外,不同深度去除率变化的规律基本上是随深度的增大而减小。实验结果可为土壤轻油污染实际治理提供实验数据基础。     

表面活性剂淋滤对土壤中邻苯二甲酸酯纵向迁移的影响

以无表面活性剂的去离子水为对照、设置1倍(1 CMC)和2倍临界胶束浓度(2 CMC)浓度,研究了单一和混合表面活性剂,包括十六烷基三甲基溴化铵(CTAB)、十二烷基苯磺酸钠(SDBS)和曲拉通X-100(TX-100)对人工污染土壤中邻苯二甲酸酯(PAEs)纵向迁移的影响,土柱中上层为PAEs污染土(3 cm),下层为清洁土(20 cm)。CTAB和SDBS在2 CMC时、TX-100为1 CMC时可增强污染土中PAEs的纵向迁移,其中DMP和DEP有无表面活性剂均可发生迁移,在相同表面活性剂条件下,延长老化时间对污染土中PAEs的迁移产生一定的影响。CTAB和SDBS在2 CMC时,清洁土中PAEs总含量较低,但TX-100在1 CMC时较低。清洁土中PAEs总含量均随土层深度的增加而降低。当老化时间较短时,土壤有机质对PAEs在清洁土柱的迁移影响较小,老化时间的延长对清洁土中的PAEs迁移影响较大。3种表面活性剂均可有效促进清洁土中DMP和DEP的迁移,CTAB和SDBS在2 CMC、TX-100在1 CMC时可促进DNBP和BBP的迁移,但3种表面活性剂对清洁土中DNOP迁移的影响较小。与单一表面活性剂相比,混合表面活性剂有助于污染土中PAEs的迁移,且随着浓度的升高,清洁土中PAEs的含量呈现降低的趋势。就整个土柱而言,单一表面活性剂CTAB和SDBS在较高浓度时、TX-100较低的浓度时对PAEs的淋滤效果更好;在较短老化时间下,土壤有机质含量的高低对淋滤率没有显著影响;老化时间延长有效降低了淋滤率;而混合表面活性剂的淋滤率有明显提高,更有助于PAEs的迁移。     

油污土壤中柴油去除的影响因素

以柴油为污染物,通过一维砂柱实验模拟油污土壤中柴油去除过程,从油水界面张力(IFT)角度分析溶液pH、淋滤速度和表面活性物质对除油效果的影响。结果表明,延长油水接触时间、升高或降低蒸馏水pH值均使油水界面张力下降,低淋滤速度下单位孔隙体积水中石油浓度较大,而水溶液pH的变化对除油效果影响不明显。十二烷基硫酸钠(SDS)和乙醇使油水界面张力显著下降,因此表面活性物质的除油效率明显高于蒸馏水,乙醇溶液的除油效率随着体积浓度的增加而升高。从石油释放动力学方程计算的柴油累积释放量看,50%乙醇除油效率最高,8 mmol/L SDS溶液次之,在淋洗初期柴油去除效果最为明显,而在中期和后期除油率增加幅度逐渐减小。     

鼠李糖脂对不同菌株降解柴油污染物的影响

通过一系列实验分析了鼠李糖脂对柴油污染物生物降解的影响。单菌株柴油降解实验结果表明,在添加生物表面活性剂鼠李糖脂后,各菌株细胞表面疏水性均发生不同程度的增加,并且对柴油的降解率均有所提高。在混合菌的柴油污染物降解实验中,发现当向土壤中添加了200 mg/L鼠李糖脂时,对柴油的降解才有较大的提高;而当添加100 mg/L的鼠李糖脂到水体中时,对柴油的降解就有较大的提高,而当鼠李糖脂浓度提高为200 mg/L时,柴油的降解率却没有进一步明显的提高。这说明鼠李糖脂对柴油降解的影响程度不仅与环境介质有关,还与添加的鼠李糖脂浓度有关。进一步分析表明,添加适当浓度的鼠李糖脂不仅可以提高对柴油的降解率,而且可加速其降解速度,缩短生物修复所需时间。     

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.     

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.     

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.     

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.     

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.     

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.     

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.