柴油污染地下水修复生物反应墙中功能微生物数量及群落多样性

利用功能微生物、泥炭和含水层介质构建生物反应墙原位修复柴油污染地下水,系统经调试稳定后运行80 d,目标污染物去除率为83.60%～99.85%.运行期结束.采用荧光素一最大或然数和Biolog方法研究了生物墙内不同位置处功能微生物的数量及群落多样性.结果表明:墙体内各处均能保持较高的功能微生物数量,且微生物群落的物种数、丰富度、均一性、碳源利用性以及代谢特征均相似;但随着生物墙深度的增加,功能微生物比例有所下降,微生物群落略显丰富,但均一性略差,碳源利用倾向略微不同.生物反应墙原位修复地下水时,功能微生物能够长期保持较高的数量、较好的降解性能和稳定的群落多样性;但随着墙体深度的增加,营养结构发生了改变,导致微生物群落结构略显不同.     

化学氧化联合微生物修复石油烃污染土壤

在石油开采、运输以及炼化的过程中,发生的“跑、冒、滴、漏”事件造成土壤污染引起广泛关注,其中石油烃具有高毒性和持久性,对人体健康和生态环境造成严重危害。文章综述了石油烃污染土壤物理、化学、生物修复技术及化学修复联合生物修复技术的国内外研究进展,重点探讨化学氧化联合微生物修复技术的应用前景,并对未来的研究发展方向提出了展望,以期为石油烃污染土壤化学联合微生物修复技术的应用与研究提供理论依据。     

石油污染场地浅层地下水MNA原位修复潜能及微生物降解效益评估

监测式自然衰减(MNA)能够高效低耗地原位修复石油污染地下水的场地,微生物对污染物的降解对MNA过程起到了重要作用.在分析东北石油污染场地地下水中总石油烃(TPH)、电子受体的质量浓度分布和变化规律基础上,划分了微生物功能区.采用溶质通量计算法.对MNA原位修复的潜能及其微生物降解效果进行了评估.结果显示,场地微生物降解正在发生.利用的电子受体不同,划分为Mn、Fe和SO(2/4-)还原区.污染通量模型计算显示:上游地区微生物降解强度不断增强,下游地区微生物降解强度不断降低.监测期内石油烃总量降低了394 kg,微生物降解为自然衰减过程中的主要作用,其贡献率为64%～93%,每个通量断面内微生物降解率为0.18～0.73 kg/d.由此可以证明,MNA可以有效地修复地下水中的石油污染.     

矿区污染地下水的生物修复

矿产资源的开发、加工和使用，产生各种污染物质，造成地下水污染，给矿区生态环境和人类带来不利影响。本文在分析矿区地下水污染源的基础上，介绍了修复地下水环境新技术—生物修复的原理和技术。     

电动联合可渗透反应墙强化修复重金属污染土壤研究进展

已有大量研究证明电动（EK）-可渗透反应墙（PRB）联合技术能用于重金属污染土壤的修复,但其修复效率低且能耗高,还可能导致聚焦效应等问题,因此深入EK-PRB在强化修复方面的研究是十分必要的。简述了EK-PRB技术的原理,介绍了EK-PRB技术的主要影响因素,归纳了EK-PRB强化修复方法的优缺点和修复效果,介绍了EK-PRB技术的研究进展,并对该技术强化修复重金属进行了展望,指出深入探究的方向,以便为EK-PRB修复多种重金属污染土壤的实际应用打下基础。     

固定化微生物对石油污染土壤修复条件优化研究

探讨固定化微生物降解石油污染土壤最佳理化条件,为修复石油污染土壤提供理论依据。从几种农业废弃物中选出固定化微生物的最优载体,并以吉林前郭油田原油为降解对象,考察固定化微生物投入量、原油初始浓度、表面活性剂投加量、孔隙率、含水率、pH及营养成分含量对原油降解率的影响。秸秆为固定化微生物最佳载体。取1 500g土样进行单因素试验,投入60g原油,最优化的降解条件是添加固定化微生物50g/L,最佳环境因素是:孔隙率45%、含水率20%、pH=8,营养成分C/N=9。固定化微生物降解能力远超过游离菌降解石油污染土壤的能力,调节到最佳的土壤环境,投入一定量的固定化微生物,能够大幅提高石油污染土壤降解率。     

室内模拟BPRB修复阿特拉津污染地下水

设计了新型生物可渗透反应墙(BPRB)用于处理被污染的地下水。以阿特拉津为污染物,装填固定有阿特拉津降解菌(Pseudomonas W4)的磷酸化聚乙烯醇(PPVA)生物活性材料介质,前半部分以草炭土-PPVA/砂子为填料,以长期稳定地释放C、P;后半部分以珍珠岩-PPVA/砂子为填料,消耗草炭土-PPVA释放的C、P。选择V(PPVA生物活性材料)∶V(砂子)=1∶1的比例安装BPRB。在BPRB内设置曝气井,供氧方式为连续空气曝气,整个BPRB内DO质量浓度大于3 mg/L。BPRB模拟槽共运行140 d,累计进水1 213.6 L,共去除阿特拉津(19.35±1.00)g,出水中始终未检出阿特拉津。试验结果表明,在不额外添加碳源、磷源的条件下,BPRB能够长期稳定修复阿特拉津污染地下水。     

我国工业场地地下水原位修复技术浅析

随着我国经济的快速发展,工业场地地下水污染问题日益严重,地下水原位修复技术已成为环境保护的重要课题。鉴于地下水原位修复技术较异位修复技术具有针对性强、扰动性小并且修复效果彻底的突出优势,本文综述了我国工业场地地下水原位修复技术的进展,分析了现有技术原理及相关技术应用研究,并对未来发展趋势进行了展望,为工业场地原位修复提供了更加全面的技术参考。     

某有机污染场地土壤修复方案设计

文章对华北区域某石油烃污染场地的项目基本情况及修复方案设计进行了介绍。根据前期场地调查和风险评估工作明确了场地的污染范围、方量,确定了修复目标值。经过方案比选,本场地最适合的修复技术为原地异位化学氧化修复技术。根据场调数据及修复要求,将石油烃污染土壤进行分级开展小试试验。通过小试试验知,不同污染层级的土壤分别添加4%、6%、9%比例的氧化剂(过硫酸盐)能达到本项目的修复目标要求,最终制定了场地的修复方案。     

In situ detection of diamine oxidase activity using enhanced chemiluminescence

This study examines the early effects of 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone on cytosolic free calcium concentration ([Ca2+]i in primary cultures of fetal rat hypothalamic neurons. Microspectrofluorimetry of fluorescent Ca2+(-)sensitive indicator Fura-2 was used to quantify these changes. Allopregnanolone (1 pM to 100 nM) increased [Ca2+]i within 2-3 sec, in a dose dependent manner, with an EC50 of 10 +/- 4 nM. The stimulatory effect of allopregnanolone was attributable principally to a Ca2+ influx, as shown by the strong inhibition of external Ca2+ removal or by the calcium channel blocker nifedipine. The effect was stereospecific because the allopregnanolone isomer 3 beta-hydroxy-5 alpha-pregnan-20-one had no effect on [Ca2+]i. Among two other steroids examined, progesterone had no effect on [Ca2+]i, but 17 beta-estradiol evoked a rise in [Ca2+]i, although to a lesser extent than allopregnanolone. The allopregnanolone-induced [Ca2+]i rise was inhibited by picrotoxin and bicuculline but was unaffected by tetrodotoxin or by pretreatment of neurons with pertussis toxin. These results are consistent with a membrane site of action for allopregnanolone associated with GABAA receptors, leading to rapid changes in [Ca2+]i in fetal rat hypothalamic neurons.     

Technologies for in situ cleanup of contaminated sites

Groundwater contamination by non-aqueous phase liquids (NAPLs) and denser than water non-aqueous phase liquids (DNAPLs) poses one of the greatest remedial challenges in the field of environmental engineering. Due to low water solubilities and aqueous diffusivities, conventional pump-and-treat technologies have a poor record of success in remediation of DNAPL contaminated aquifers. Better success has been found with the removal of volatile LNAPLs due to higher gaseous diffusivities, propensity for aerobic biodegradation, and ease of pumping and handling large quantities of gas. An evaluation of in situ cleanup technologies on the basis of their applicability to in situ treatment of NAPL contaminated aquifers is presented. Emphasis is placed on treatment of the separate phase occurring in the saturated zone. Soil washing, air sparging, biodegradation, electro-osmosis, enhanced steam extraction, stabilization/solidification, treatment walls, radio frequency heating, and containment systems and barriers are among the in situ technologies reviewed. In the context of the governing contaminant fate and transport processes, the relative merits of each technology are assessed on the basis of its theoretical background, field implementability, level of demonstration and performance, waste, technical and site applicability/limitations, commercial availability, and cost and residuals management.     

Public perceptions of a radioactively contaminated site: concerns, remediation preferences, and desired involvement

A public attitudes survey was conducted in neighborhoods adjacent to a radioactively contaminated site whose remediation is now under the auspices of the U.S. Department of Energy's Formerly Utilized Sites Remedial Action Program (FUSRAP). The survey's purpose was to ascertain levels of actual and desired public involvement in the remediation process; to identify health, environmental, economic, and future land-use concerns associated with the site; and to solicit remediation strategy preferences. Surface water and groundwater contamination, desire for public involvement, and potential health risks were found to be the most highly ranked site concerns. Preferred remediation strategies included treatment of contaminated soil and excavation with off-site disposal. Among on-site remediation strategies, only institutional controls that leave the site undisturbed and do not require additional excavation of materials were viewed favorably. Cost of remediation appeared to influence remediation strategy preference; however, no strategy was viewed as a panacea. Respondents were also concerned with protecting future generations, better assessment of risks to health and the environment, and avoiding generation of additional contaminated materials.     

Method development for trace analysis of heteroaromatic compounds in contaminated groundwater

An analytical method providing high sensitivity (limit of quantitation of 50 ng/l) with acceptable reproducibility (mean R.S.D. 19%) has been developed for determining heteroaromatic compounds in creosote-contaminated groundwater. The best technique (highest recovery and reproducibility) found between liquid-liquid extraction using either dichloromethane, diethyl ether or pentane and solid-phase extraction with reversed-phase bonded columns, was the classical liquid extraction with dichloromethane from weak basic solutions and GC-MS (selective ion monitoring) analysis of concentrated extracts.     

Evaluation of a remediation program using senior citizens as psychoeducational agents

A remediation program for learning and psychosocially disabled pupils utilizing senior citizens as paraprofessional aides was evaluated. The senior citizens were effective in developing tutorial relationships conducive for the students' academic and psychosocial development, as indicated by pre- and posttesting. The disabled pupils improved their academic skills, as measured by standardized achievement and intelligence tests and by school grades. Statistical comparison with a control group further demonstrated the significance of the gains. The pupils' psychosocial adjustment also showed significant improvement on various personality assessment measures and behavior ratings by teachers and parents. Finally, self-reports by the senior citizen aides suggest that they also profited by their involvement in STEP.     

Production of high-quality ferrosilicon using petroleum coke

Practical results are presented for the use of low-ash petroleum coke in ferroalloy production, rather than the traditional coke nuts. The smelting of ferrosilicon using petroleum coke is shown to be an efficient method.     

Use of copper shavings to remove mercury from contaminated groundwater or wastewater by amalgamation

The efficacy of copper shavings (Cu(0)) for the removal of Hg2+ from aqueous solution by amalgamation is demonstrated. Two kinds of copper shavings were investigated: (a) chemically processed shavings (Fluka) and (b) recycled shavings from scrap metal. Batch sorption experiments yielded very high retardation coefficients of 28 850-82 830 for the concentration range studied (1-10 000 microg/L Hg2+ dissolved in distilled water or in a 0.01 M CaCl2 matrix solution). Sorption data were well-described bythe Freundlich isotherm equation. Kinetic batch sorption experiments showed that 96-98% of Hg2+ was removed within 2 h. Column experiments were performed with a mercury solution containing 1000 microg/L Hg in a 0.01 M CaCl2 matrix with a flow rate of 0.5 m/d. No mercury breakthrough (c/c(0) = 0.5) could be detected after more than 2300 percolated pore volumes, and the high retardation coefficients determined in the batch studies could be confirmed. Copper was released from the shavings due to the amalgamation process and to copper corrosion by oxygen, resulting in concentrations of mobilized copper of 0.2-0.6 mg/L. Due to their high efficiency in removing Hg2+ from aqueous solution, the use of copper shavings for the removal of mercury from contaminated water is suggested, employing a sequential system of mercury amalgamation followed by the removal of mobilized copper by an ion exchanger such as zeolites. Possible applications could be in environmental technologies such as wastewater treatment or permeable reactive barriers for in situ groundwater remediation.