过硫酸钠对砂壤土中三氯乙烯的氧化研究

以过硫酸钠(Na2S2O8)为氧化剂,柠檬酸(CA)螯合Fe(Ⅱ)溶液作为活化剂,对砂壤土中的三氯乙烯(TCE)进行处理.采用正交试验获得优化操作条件为: Na2S2O8浓度5mmol/L,Fe(Ⅱ)浓度2.5mmol/L,CA浓度0.25mmol/L,反应时间30min.在此条件下,土壤中不同浓度的TCE去除率均在93%以上.对于污染程度高的土壤,采用连续氧化处理可达到较高的修复目标要求.土柱实验结果表明经过Na2S2O8溶液氧化7d后,TCE氧化率达到88.9%以上,且去除效果与处理方式有关,分次加入方式的效果最好.     

对苯醌活化过硫酸盐降解罗丹明B的动力学特征及其影响因素

考察了对苯醌(HQ)活化过硫酸盐(PS)过程中降解罗丹明B(RhB)的动力学特征及其影响因素.结果表明:HQ含量、pH值以及温度对活化PS降解RhB的动力学过程和特征均产生不同程度的影响.在pH=4.6时,HQ能有效活化PS,显著促进其对罗明丹B的降解效能;随着体系中HQ含量的上升,RhB的降解程度得到提升,反应速率常数k的值与体系中HQ含量之间呈线性相关.在HQ的活化作用下,PS降解RhB反应的活化能由41.99kJ/mol降低至13.90kJ/mol,RhB降解程度和反应速率均得到提升.当pH=4.6,HQ=0.1mmol/L以及PS=1.0mmol/L时,HQ活化PS的过程中罗丹明B降解率可高达90%以上,反应速率增加了106%.染料RhB在充当表征活化PS效果试剂的同时,也积极参与了HQ活化PS过程,使得“HQ-RhB-PS”耦合体系的氧化降解能力得到显著提升.     

高铁酸钾氧化去除水中三氯生的研究

采用高铁酸钾对水中三氯生（TCS）的去除进行了研究,探讨了TCS的降解机理,考察了高铁酸钾投加量、pH值、天然有机物（NOM）和双氧水等因素对TCS去除和中间产物2,4-二氯苯酚（2,4-DCP）生成的影响.结果表明：TCS通过醚键断裂降解生成2,4-DCP,TCS浓度为550μg/L,高铁酸钾浓度为15mg/L时,600s后TCS去除率可达96.48%.增加高铁酸钾投加量可以提高TCS的去除,TCS的去除率随pH值升高呈现出降低的趋势,酸性环境有利于TCS的去除,pH值为4时,TCS的去除达100%,腐殖酸和双氧水对TCS的去除有抑制作用.高铁酸钾可以有效降解TCS并降低溶液的急毒性,降低水质健康风险.     

过硫酸盐缓释材料释放性能的影响因素研究

运用不同配比制备多种过硫酸盐缓释材料,采用欧盟标准化组织制定的NEN 7375标准浸出方法测试其释放性能,利用相关性分析和克里格插值法探究材料组分配比对过硫酸盐缓释材料释放性能的影响规律.结果表明:作为制备过硫酸盐缓释材料基质材料的水、砂和水泥均有一定的适配范围,即水含量在5%~35%之间,砂含量在0~85%之间,水泥含量在5%~85%之间;缓释材料的扩散系数与砂含量呈现显著的正相关,与水泥含量呈现显著的负相关,而与水含量无显著相关性;基质材料对过硫酸盐缓释材料扩散系数的综合作用较为复杂,总体而言,当水泥含量高于砂含量时,水含量是影响缓释材料扩散系数的主要因素,当砂含量大于水泥含量时,砂含量则是影响缓释材料扩散系数的主要因素.此外,增加缓释材料中过硫酸盐的含量可以提高过硫酸盐的释放速率并延长缓释材料的使用寿命.     

水质总氮空白实验分析及改进措施

在总氮测定过程中,空白测试是必不可少的分析试验.但在实际操作中,发现空白值经常存在偏高的情况,加大了系统误差.如何降低分析空白实验值,保证分析样品的精密度和准确度,成为测定过程的关键之一.本文从试剂影响、器皿影响、操作过程影响及环境影响等方面全面分析,并以实验数据予以验证.在此基础上提出降低空白值的手段和措施,以指导实验室操作实践.     

高锰酸钾预氧化对剑水蚤DBPsFP的去除特征研究

以剑水蚤为试验对象,研究在不同条件下,高锰酸钾预氧化对剑水蚤代谢产物在氯化消毒过程中消毒副产物前体物的去除特征.研究表明:随高锰酸钾投加量的增加,水合氯醛(CH)、1,1,1-三氯丙酮(1,1,1-TCP)、三氯甲烷(TCM)总体呈上升趋势,二氯乙酸(DCAA)逐渐减少,而三氯硝基甲(TCNM)、1,1-二氯丙酮(1,1-DCP)、二氯乙腈(DCAN)和三氯乙酸(TCAA)先上升后下降,在本试验高锰酸钾投量范围内,高锰酸钾浓度为5mg/L时 CH、TCNM、DCAN、TCAN、DCAA、TCAA和1,1-DCP的去除效果最佳,去除率最高可达72.2%;延长预氧化时间,DCAN、DCAA、TCAA浓度逐渐降低,TCM、CH浓度逐渐升高,TCNM、TCAN、1,1,1-TCP浓度先升高后降低,而1,1-DCP浓度先迅速下降后逐渐升高,预氧化时间宜控制在20min;pH<7可有效抑制TCM的生成.pH=7时TCAA达到最小值,而1,1-DCP含量最高,pH>7有助于1,1-DCP的减少,CH、DCAA、DCAN、TCAN、TCNM和1,1,1-TCP随pH的增加而减少.在pH=9时生成量均最小, 最高去除率为80%;最佳温度为30℃,随着温度的升高,DCAA、TCAA和TCM浓度有所增加,1,1-DCP、DCAN和1,1,1-TCP生成量减少,在20℃时,CH的浓度最小,而TCAN的浓度最大.     

ZnO纳米粒子通过线粒体通路抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性的作用研究

氧化锌(ZnO)纳米粒子已被发现具有生物毒性,氧化应激被认为是最重要的因素之一。前期实验证实,ZnO纳米粒子能显著减少锰超氧化物歧化酶(Mn SOD)蛋白的表达,降低Mn SOD活性。本文通过检测乳酸脱氢酶(LDH)释放、线粒体活性氧(ROS)水平和膜电位(Δφm)、延迟整流钾电流变化和Na~+/K~+-ATP酶的表达及活性等变化,检测ZnO纳米粒子对小鼠光感受器细胞的细胞毒作用。结果表明,ZnO纳米粒子可显著增强小鼠光感受器细胞中LDH的释放、增加线粒体内ROS水平并下调Δφm、阻断延迟整流钾电流,同时降低Na~+/K~+-ATP酶的表达及活性,从而对小鼠视网膜光感受器细胞产生细胞毒作用,提示ZnO纳米粒子可通过线粒体通路引起氧化应激,从而抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性,产生细胞毒性,导致细胞死亡。本文的研究结果有助于理解ZnO纳米粒子引起细胞毒性的作用机理。     

区域土地利用方式变化对土壤性质影响研究——以土壤钾为例

选取经济发达区原锡山市作为研究区域,以1982年和2005年土壤速效钾作为研究对象,分析探讨不同时空状态下区域土地利用变化对土壤钾含量的影响,以期获得较长时空条件下土壤质量对土地利用变化的响应。20年来,通过统计分析和独立样本t检验表明,原锡山市土壤速效钾含量增加了36.9mg/kg。变异函数分析表明,土壤速效钾的变异函数理论模型呈指数型,块金方差与基台值的比值、自相关阀值发生较大变化。kriging插值分析结果表明,土壤速效钾空间分布较简单,但空间变异明显。     

Sodium Persulfate Oxidation for the Remediation of Chlorinated Solvents (USEPA Superfund Innovative Technology Evaluation Program)

This study has been conducted at the University of Connecticut (UCONN) in connection with the USEPA Superfund Innovative Technology Evaluation (SITE) program to evaluate a chemical oxidation technology (sodium persulfate) developed at UCONN. A protocol to assess the efficacy of oxidation technologies has been used. This protocol, which consists of obtaining data from a treatability study, tested two in-situ chemical oxidation technologies that can be used on soil and groundwater at a site in Vernon, Connecticut. Based on the treatability report results and additional field data collected at the site, the design for the field implementation of the chemical oxidation remediation was completed. The results indicate that both sodium persulfate and potassium permanganate were able to effectively degrade the target VOCs (i.e., PCE, TCE and cis-DCE) in groundwater and soil-groundwater matrices. In the sodium persulfate tests (120 hrs), the extent of destruction of target VOCs was 74% for PCE, 86% for TCE and 84% for cis-DCE by Na₂S₂O₈ alone and 68% for PCE, 76% for TCE, and 69% for cis-DCE by Fe(II)-catalyzed Na₂S₂O₈. The results demonstrate the sodium persulfate's ability to degrade PCE, TCE and cis-DCE. It is expected that given sufficient dose and treatment time, a higher destruction rate of the dissolved phase contamination can be achieved. The data also indicates that the catalytic effect of the iron chelate on persulfate chemistry was much less pronounced in the soil-groundwater matrix. This indicates an interaction between the iron chelate solution and the soil, which may have resulted in a lower availability of the chelated iron for catalysis. The study showed that the remediation of the VOCs-contaminated soil and groundwater by in-situ chemical oxidation using sodium persulfate is feasible at the Roosevelt Mills site. As a result, the USEPA SITE program will evaluate this technology at this site.     

The influence of season and leaf age on concentrations of radiocaesium (137Cs), stable caesium (133Cs) and potassium in Agrostis capillaris

The transfer of radioactive caesium from soils to plants has been well researched. In contrast there is limited knowledge on natural stable 133Cs and its potential role as a predictor for radiocaesium behaviour. In a pot experiment with Agrostis capillaris close correlations were found between plant 137Cs and plant 133Cs concentrations (R2 90-96%). Season and leaf age had significant effects with concentrations increasing 10-30-fold between June and December. Simultaneously the plant concentrations of K, the nutrient analogue of Cs, decreased to around one third. In the soil the exchangeable fractions of K and 137Cs declined. No clear relationships were found between 137+133Cs in the plant and exchangeable K in the soil. However, at the end of the experiment the K content of the above-ground biomass was higher than the exchangeable pool in the soil, suggesting that depletion of soil K could be a key factor in the observed increase of plant 137+133Cs over time.