Synchronous-scan fluorescence spectra of Chlorella vulgaris solution

The characterization of the Chlorella vulgaris solution was carried out using synchronous-scan spectroscopy. The range of concentration of algae and Fe(III) in aqueous solutions were 5 × 10⁸–8 × 10⁹ cells l⁻¹ and 10–60 μM, respectively. Effective characterization method used was synchronous-scan fluorescence spectroscopy. The wavelength difference (Δλ) of 90 nm was maintained between excitation and emission wavelengths; 90 nm was found to be the best Δλ for effective characterization of Chlorella vulgaris solution with or without quencher species (e.g., Fe(III), humic acid (HA)) for the first time. The peak was observed at about EX 236.6 nm/EM 326.6 nm for synchronous-scan fluorescence spectra. The fluorescence quenching of algae in system of algae–Fe(III)–HA was studied using synchronous-scan spectroscopy for the first time. Fe(III) was clearly the effective quencher. The relationship between I₀/I (quenching efficiency) and c (concentration of Fe(III) added) was a linear correlation for the algae solution with Fe(III). Also, Aldrich humic acid was found to be an effective quencher. pH effect on synchronous-scan fluorescence intensity of algal solution with Fe(III) and/or HA was evident.     

纳米金属氧化物对土壤酶活性的影响研究进展

纳米金属氧化物的大量生产和广泛应用使其不可避免地进入环境中,土壤是其释放到环境中主要的汇。纳米颗粒由于尺寸效应,具有许多独特的物理化学性质,其进入环境后潜在的生态和健康风险问题日益受到研究者的关注。土壤酶是土壤生物化学过程的主要参与者,也是生态系统物质循环和能量流动过程中最活跃的生物活性物质。土壤酶活性的变化能反映土壤中生化反应的情况,可作为评价土壤中纳米材料污染状况的生物学指标。本文较系统地回顾和总结了纳米金属氧化物对土壤酶活性的影响及可能的影响途径,探讨了纳米金属氧化物作用于土壤酶的主要影响途径,并展望了未来研究主要发展方向。     

Hydrochemistry of urban groundwater, Seoul, Korea: the impact of subway tunnels on groundwater quality

Hydrogeologic and hydrochemical data for subway tunnel seepage waters in Seoul (Republic of Korea) were examined to understand the effect of underground tunnels on the degradation of urban groundwater. A very large quantity of groundwater (up to 63 million m³ year^− 1) is discharged into subway tunnels with a total length of 287 km, resulting in a significant drop of the local groundwater table and the abandonment of groundwater wells. For the tunnel seepage water samples (n = 72) collected from 43 subway stations, at least one parameter among pathogenic microbes (total coliform, heterotrophic bacteria), dissolved Mn and Fe, NH₄⁺, NO₃⁻, turbidity, and color exceeded the Korean Drinking Water Standards. Locally, tunnel seepage water was enriched in dissolved Mn (avg. 0.70 mg L^− 1, max. 5.58 mg L^− 1), in addition to dissolved Fe, NH₄⁺, and pathogenic microbes, likely due to significant inflow of sewage water from broken or leaking sewer pipes.Geochemical modeling of redox reactions was conducted to simulate the characteristic hydrochemistry of subway tunnel seepage. The results show that variations in the reducing conditions occur in urban groundwater, dependent upon the amount of organic matter-rich municipal sewage contaminating the aquifer. The organic matter facilitates the reduction and dissolution of Mn- and Fe-bearing solids in aquifers and/or tunnel construction materials, resulting in the successive increase of dissolved Mn and Fe. The present study clearly demonstrates that locally significant deterioration of urban groundwater is caused by a series of interlinked hydrogeologic and hydrochemical changes induced by underground tunnels.     

纳米零价铁改性膜强化厌氧生物处理氯酚废水

针对厌氧生物技术处理氯酚废水驯化周期长和纳米零价铁易团聚的问题,采用压滤法制备纳米零价铁改性聚偏氟乙烯膜(nZVI@PVDF),并将其与厌氧生物体系耦合处理氯酚废水,通过序批实验探究nZVI@PVDF对耦合体系脱氯、水解酸化、产甲烷阶段的影响.结果表明,48h内,包含3种不同nZVI负载量(0.075,0.15,0.3...     

铁系混凝剂对大红染料废水处理效果研究

采用Fe(NO)3.39H2O和FeSO.47H2O混凝剂处理模拟大红染料废水,通过改变各药剂投加量及废水pH值,考察其对废水COD和色度的去除效果。实验结果表明:两种混凝剂在处理大红染料废水中都表现出了较好的脱色性能,而Fe(NO3)3.9H2O的去除性能较FeSO.47H2O更为优越。Fe(NO)3.39H2O对染料废水的脱色作用十分显著,所有的脱色率都在86%以上。当投加量为0.18 g时,脱色率达最大值93.3%;当投加量为0.24 g时,COD去除率为63.6%。FeSO.47H2O对废水色度的去除效果好于COD的去除。其最佳投加量为1.5 g,此时,脱色率达82.4%;当投加量为0.9 g时,COD去除率为51.8%。Fe(NO)3.39H2O在pH为5.0~9.0之间处理效果都较好,当pH=8时,其脱色率最高,为93.4%;FeSO.47H2O在pH为6.0~8.0之间最佳,当pH=8时,脱色率最高为83.2%。     

羟基铁柱撑膨润土处理含磷废水的研究

以羟基铁为柱化剂对天然膨润土进行柱撑改性制备了羟基铁柱撑膨润土,研究了其对废水中磷的吸附性能和影响因素。结果表明:羟基铁能够进入到膨润土的层间,使其层间距增大,表面积增加;羟基铁柱撑膨润土对废水中的磷有很好的去除效果,在常温下,当改性膨润土投加量为4 mg/L,溶液pH值为5,反应时间为60 min,处理质量浓度为20 mg/L的含磷废水时,磷的去除率达到93.9%。平衡吸附量与平衡质量浓度之间的关系更好地符合Langmuir等温吸附方程所描述的规律。     

干湿交替灌溉制度下纳米修复材料对杂交籼稻籽粒Cd累积及产量的影响

干湿交替灌溉具有节水高产特性,但在重金属Cd污染稻田,干湿交替灌溉常导致稻米Cd含量＞0.20 mg·kg-1,通过添加钝化剂可能对水分高效利用及优质稻米生产具有显著的调控效应.为此,本研究以吸收能力较强的籼型亚种为试材,在前期筛选出的高积累品种(深两优1813)和低积累品种(两优6206)基础上,于Cd轻度污染稻田设...     

Fe3+负载凹凸棒土(Fe/ATP)结构表征及其稳定化修复镉(Cd)机制研究

以凹凸棒土(凹土,ATP)为原料,采用浸渍法制备Fe3+负载凹土(Fe/ATP),表征了其结构与形貌,研究了凹土和Fe/ATP对土壤中镉(Cd)的吸附效果,以浸出浓度作为稳定化评价指标,通过吸附前后凹土和Fe/ATP形貌等特征的变化探讨了稳定化修复Cd机制.结果表明,加入质量比20%的凹土和Fe/ATP,Cd的浸出浓度分别降低了45%和91%,说明Fe/ATP对土壤中Cd有显著的稳定化作用.形貌表征分析表明,凹土主要通过结构中的水、—OH基团和晶格缺陷来稳定Cd,而Fe/ATP对土壤中Cd稳定化作用可能主要来自—OH基团以及Fe—O中桥氧的贡献.凹土与氧化铁均为土壤中天然矿物,廉价易得且环境友好,制备方法简单易实现,该复合材料用于Cd污染土壤的稳定化修复具有较好的应用前景.     

生物炭负载纳米零价铁去除废水中重金属的研究进展

纳米零价铁（nZVI）因比表面积大、反应活性高及独特的核壳结构,在去除水中重金属方面具有良好的应用前景。但nZVI自身存在易团聚、易氧化失活等缺点,使其工业推广和应用受到限制。将nZVI负载于生物炭（BC）制备生物炭负载型纳米零价铁（nZVI@BC）复合材料可在一定程度上克服nZVI的缺点,提高nZVI与重金属的反应活性。综述了nZVI@BC去除水中重金属的研究现状,着重介绍了不同BC材料用于nZVI@BC的制备、BC的改性及nZVI的修饰对nZVI@BC去除重金属性能的影响,阐述了nZVI@BC去除几种典型重金属的反应机理,并对nZVI@BC应用于水中重金属去除的发展前景进行了展望。

     

土壤中砷的污染控制技术研究

土壤砷污染修复是世界性的难题,日益受到人们的密切关注。本文阐述了土壤砷污染的现状、危害及其来源,探讨土壤砷污染的传统物理化学和生物修复技术的研究现状及特点的同时,重点阐述了纳米材料修复技术,尤其是纳米铁技术,并对土壤砷污染修复研究方向进行了展望。