In response to the low removal capacity and poor tolerance of fungi to diesel-contaminated soil, a novel immobilization system using biochar to enhance composite fungi was proposed. Rice husk biochar (RHB) and sodium alginate (SA) were used as immobilization matrices for composite fungi, and the adsorption system (CFI-RHB) and the encapsulation system (CFI-RHB/SA) were obtained. CFI-RHB/SA exhibited the highest diesel removal efficiency (64.10%) in high diesel-contaminated soil over a 60-day remediation period compared to the free composite fungi (42.70%) and CFI-RHB (49.13%). SEM demonstrated that the composite fungi were confirmed to be well attached to the matrix in both CFI-RHB and CFI-RHB/SA. FTIR analysis revealed the appearance of new vibration peaks in diesel-contaminated soil remediated by immobilized microorganisms, demonstrating changes in the molecular structure of diesel before and after degradation. Furthermore, CFI-RHB/SA maintains a stable removal efficiency (>60%) in higher concentrations of diesel-contaminated soil. High-throughput sequencing results indicated that Fusarium and Penicillium played a key role in the removal of diesel contaminants. Meanwhile, both dominant genera were negatively correlated with diesel concentration. The addition of exogenous fungi stimulated the enrichment of functional fungi. The insights gained from experiment and theory help to provide a new understanding of immobilization techniques of composite fungi and the evolution of fungal community structure.

采用《固体废物浸出质量浓度浸出方法 硫酸硝酸法》(HJT 299-2007)对稳定化后污染土壤中铅浸出质量浓度进行测定,并结合土壤样品的扫描电镜分析和铅在土壤中的形态变化,分析了污染土壤中铅稳定化的作用机理.实验结果表明:三种不同药剂均能降低铅的浸出质量浓度(磷酸二氢钙复配氧化铝>磷酸二氢钙>氧化铝);当磷酸二氢钙添加质量比为 2%,氧化铝添加质量比为 3%时,稳定化后污染土壤中铅浸出质量浓度能满足地下水 Ⅲ 类标准;磷酸二氢钙与氧化铝施加入土壤后,能有效降低污染土壤中铅弱酸可提取态含量,增加铅残渣态含量,同时也增强了土壤的致密性,从而降低铅的浸出质量浓度.说明磷酸二氢钙协同氧化铝处置铅污染土壤有较好的工程应用价值.

为了探讨环境友好型有机酸对铅(Pb)污染土壤的淋洗修复效果和淋洗机制,采用震荡淋洗的方法,考察了淋洗剂在不同参数(浓度、液固比、时间、pH值)条件下对土壤中Pb淋洗效果的影响,并在最优条件下将柠檬酸和苹果酸复配淋洗.结果表明:柠檬酸、苹果酸和酒石酸单一淋洗时对Pb的去除率分别为76.87％、69.73％和61.39％.柠檬酸与苹果酸复配比为3:2对Pb的淋洗率高达87.31％,且复配淋洗后土壤中Pb的浸出毒性降低至3.71 mg/L,低于危险废物鉴别标准值.机理分析结果表明:复配淋洗能有效降低土壤中Pb的弱酸可提取态、可还原态和可氧化态的含量,使残渣态含量增加,降低了后续的环境风险;复配淋洗去除Pb的可能机理包括酸溶解、离子交换和表面络合.柠檬酸与苹果酸复配是一种高效且环境友好型的淋洗剂,本研究成果可为Pb污染土壤的修复治理提供了参考.

Abstract Soil washing is a rapid and efficient remediation technique for soil contaminated by heavy metals. In this study, Pb was removed from contaminated soil with citric acid (CA) and malic acid (MA). The effects of washing concentration, liquid-solid(L/S) ratio, washing time, and pH value on the removal rate and metal stability in lead-contaminated soil were investigated. Results showed that the mixed chelating agent's (MC) removal rates of the heavy metal lead from the soil by citric acid (0.3m) and malic acid (0.3m) at a certain volume ratio of 4:1 (CA: MA = 4:1) was up to 88.65%. After washing, the leaching concentration of lead in soil decreased by 63.39%, which was lower than the identification standard value of hazardous waste. The speciation analysis study indicated that the acid-soluble and reducible fractions in the soil with excellent bioavailability after MC washing were reduced by 83.23% and 71.99%, respectively. Which reduces the environmental risk greatly. Besides, heavy metal lead was also found to become more stable after the soil was washed by MC. This method is shown to help reduce the bioavailability and leachability of lead and has proven to environmentally friendly way to remediate lead-contaminated soil.

Hexavalent chromium pollution is one of the most serious types of site pollution. In this study, a microorganism was screened to remove most hexavalent chromium from soil by leaching in 24 h. After ITS sequencing, the microorganism was identified as belonging to the genus Fusarium solani. The optimization experiment of leaching conditions determined that the removal rate reached the maximum 80% when the rotation speed was 200 rpm, the liquid-soil ratio was 15:1, the temperature was 35 degrees C, and the pH was 7. The study has also shown that tea saponin can effectively strengthen the leaching of Fusarium solani to remove hexavalent chromium from the soil. Compared with tea saponin, the strengthening effect of glucose and rhamnolipid was relatively small. The removal rate of hexavalent chromium reached 85% when the added amount of tea saponin was 0.02 g/mL. The leaching solution destroyed part of the iron-manganese nodule structure of the soil, and its hydroxyl, carboxyl, and other groups complexed metal ions into the solution to achieve the purpose of removing hexavalent chromium. However, since the main crystal of the soil was -SiO2, there was no obvious change in the XRD of the soil. Toxicity test showed that after leaching, the content of hexavalent chromium leached was 0.28 mg/L (< 1.5 mg/L), which meet the entry standard of the landfill site.

This study investigated the effect of Ca(H2PO4)(2) on pH, leaching toxicity and speciations of soil before and after leaching on it. Different amounts of Ca(H2PO4)(2) were added to Pb-contaminated soil and stabilized for 30 days. The changes of pH and leaching toxicity of Pb-contaminated soil were tracked during that period. The content of Pb in soil before and after leaching was also determined after 30 days of stabilization. Results showed that the pH of the Pb-contaminated soil didn't change much with the addition of-Ca(H2PO4)(2). When the amount of Ca(H2PO4)(2) reached to 3 wt%, the leaching toxicity met the standard limiting level of groundwater class III of China. The change of leaching toxicity was found to be mainly affected by the water-soluble fraction and mild acid-soluble fraction of lead. The speciation experiments revealed that the changes on reducible, oxidizable, and residual fractions are significant, while there are only minor changes on the water-soluble and mild acid-soluble fractions. X-ray diffractometry (XRD) analysis showed that Pb-9(PO4)(6) and Pb2P2O7 substances were generated in the stabilized soil. The stabilization mechanism of Ca(H2PO4)(2) was mainly attributed to the formation of insoluble Pb phosphate precipitates through interactions between the heavy metal Pb and the Ca(H2PO4)(2.) In such a way the active species of Pb in the soil can be successfully stabilized. Novelty statement At present, the leaching toxicity is currently used for the evaluation of stabilization effect of heavy metal contaminated soil. The speciation distribution of stabilized contaminated soil before and after leaching has rarely been studied, and the research on stabilizing contaminated soil after leaching is less. Therefore, this paper mainly studies the stabilization effect through the speciation changes of contaminated soil before and after leaching, providing a new idea and method for the evaluation of the stabilization effect of contaminated soil remediation. Ca(H2PO4)2 has no significance in pH of contaminated soil: 5.055.5. The content of the water-soluble fraction and the mild acid-soluble fraction of Pb were availably reduced by Ca(H2PO4)2. The content of the water-soluble fraction and the mild acid-soluble fraction of Pb has no marked change before and after leaching. The stabilization mechanism of Ca(H2PO4)2 is through interaction between the Pb in the soil and phosphate to form insoluble substances of lead phosphate. Ca(H2PO4)2 has a good effect on the stabilization of lead-contaminated soil.

以荷叶花粉为碳源,通过研究三种活化方式制备多孔活性炭;因活化剂消耗量低和活化气氛成本低廉,最终确定KOH-CO2活化方式制备的多孔活性炭环境最为友好.氮气吸脱附测试表明HC-4样品比表面积大、孔容最高,SEM表征了其碳球形貌、高倍数下呈颗粒状.当电流密度为0.5 A g-1时,四种碳材料的比电容大小顺序为HC-4>HC-3>HC-2>HC-1.研究表明KOH-CO2活化荷叶花粉基前驱体制备的多孔活性炭的成本较为低廉,且电化学电容性能最高.

采用化学还原技术,添加硫代硫酸钠、硫酸亚铁、连二亚硫酸钠、硫化钠处理某化工厂遗留地的铬污染土壤,考察了4种还原剂处理铬污染土壤的效果.结果 表明:在养护时间为30 d时,4种还原剂对土壤Cr(Ⅵ)的稳定效率均高于90％,其中采用硫代硫酸钠和硫酸亚铁的稳定效率分别为99.1％和96.8％;硫酸亚铁、硫代硫酸钠、连二亚硫酸钠和硫化钠对土壤Cr(Ⅵ)的还原效率分别为74.2％、64.1％、52.7％、49.2％;连二亚硫酸钠和硫化钠处理后土壤中铬有效态无明显变化,硫酸亚铁和硫代硫酸钠处理后土壤中铬有效态有所下降,占比(质量分数)从原土的27.4％降至14.0％、21.4％,残渣态从原土的23.4％分别增加至39.8％和39.7％,稳定性增强.在相同投加量下,硫酸亚铁是处理铬污染土壤效果最佳的还原剂.

基于Voxler平台对污染地块中的石油烃空间分布进行了三维建模,通过对石油烃的形体渲染和切片,直观反映了该污染地块受石油烃污染的状况,同时以等值面输出的形式确定了石油烃污染土壤的方量,完成了该地块的污染土壤定量工作.研究结果表明:Voxler平台可运用于地块污染状况调查工作,能够直观模拟污染物污染状况,通过切片和等值面输出可高效、准确地匡算污染物方量,是一种科学有效的方式,在环境污染监测与治理方面有较好的应用前景.

Nickel-contaminated soil was treated by adding different amounts of calcium oxide in this study. The leaching concentration, pH, and bioavailability of the soil samples were investigated on the 3rd, 6th, 9th, 12th, and 15th days. The chemical speciation changes of the contaminated soil treated with calcium oxide were analyzed, and the soil phases were analyzed by X-ray diffraction (XRD). Results showed that the application of calcium oxide increased the pH of the soil, resulting in passivation of nickel ions in soil by forming a poorly soluble precipitate. It was identified that addition of 5% of calcium oxide showed the best result, with the leaching concentration on the third day reaching 0.35 mg/L, which is 99.21% lower than the untreated soil's leaching concentration of 44.24 mg/L. On the 15th day, the bioavailability of nickel decreased from the untreated soil's 93.82 to 36.73%. It was also observed that the pH of the soil increased at the beginning and decreased afterwards. The pH value was 7.94 on the 15th day. In addition, the water-soluble fraction of Ni decreased from 7.39 without treatment to 0.19%; the reducible fraction of Ni decreased from 35.14 to 25.79%, and the oxidizable fraction of Ni increased from 10.37 to 29.10%, respectively, on the 15th day after the treatment with calcium oxide. XRD analysis of soil samples showed the amorphous nickel hydroxide may be formed in the precipitation process.

研究了用不同质量比的硫代硫酸钠对铬污染土壤的治理效果及治理过程中铬的形态变化,结果表明,硫代硫酸钠对铬污染土壤在短期内修复具有较好的效果,在投加比为3％的基础上,继续增加硫代硫酸钠的用量,虽然六价铬浸出浓度在降低,但幅度不明显.六价铬含量随养护时间的增加而逐渐减少,投加比例越高其效果越明显;在形态分析中,生物可利用的水溶态和弱酸提取态中的铬均在减少;在硫代硫酸钠修复过程中pH值无明显变化.因此,用硫代硫酸钠处置铬污染土壤能明显降低六价铬浸出浓度和六价铬含量,且满足修复目标要求.结合经济效益和治理效果,硫代硫酸钠投加比为3％处置含铬污染土壤效果最佳.

分别使用柠檬酸、β-环糊精螯合Fe 2+活化过硫酸钠体系修复模拟机油污染土壤,通过实验对比分析这两种螯合剂对机油的降解效果的影响.结果表明,β-环糊精相较于柠檬酸螯合效果更好,其最大去除率可达57.76％.利用红外光谱对其进行表征,得出其主要配位在羧基和羟基上.为了解决过硫酸钠导致土壤酸化的问题,利用过氧化钙代替部分过硫酸钠,结果表明,当其质量比为1:1,总投加量为1.5％(w)时,最大去除率达到63.43％,其反应符合一级动力学.

分析了Fe0、Fe2+和Fe3+活化过硫酸盐氧化石油烃的机理,介绍了土壤中石油烃污染物降解的影响因素以及总结了铁活化过硫酸盐修复石油烃污染土壤技术的不足.指出应以铁活化过硫酸盐原位修复作为土壤中高浓度有机污染物的前处置方法,再结合微生物或植物修复等技术,以减少对土壤理化性质的影响;另外,检测仪器的发展有利于土壤修复技术的应用.

建立了污染场地风险评估模型,计算场地污染物苯、镍和苯并(a)芘的风险贡献率和模型参数敏感性比例,分析了场地人群平均体重(BW)、暴露年限(ED)、暴露频率(EF)、土壤摄入量(IRs)、空气摄入量(IRa)和场地土壤含水率(Pws)、土壤颗粒密度(ρs)、土壤容重(ρb)、土壤有机质含量(fom)的敏感性.模型评估结果表明:场地风险评估的参数敏感性与污染因子所涉及的暴露途径有较大关系,其中Pws、ρs、ρb和fom主要影响呼吸吸入途径,IRs主要影响经口摄入途径,IRa对风险计算结果影响很小,而BW、ED和EF在模型中对各个暴露途径都有影响.在风险计算模型中,当污染物为苯时,ρs和 ρb极为敏感;当污染物为镍时,BW、ED和IRs表现为敏感;当污染物为苯并(a)芘时,BW、ED、IRs、EF、Pws、ρs、ρb和fom均有一定的敏感性,其中BW、ED和IRs表现最为敏感.

应用SBET法探究不同因素对铅污染土壤生物有效性的影响,实验结果表明:5组土样铅生物有效性为55.55％ ～109.16％,且土样中铅的含量与其生物有效性没有明显的相关性(P>0.05);反应条件对生物有效性的影响探究中表明,保留时间、反应温度、土液比及模拟胃液pH对土样生物有效性均有一定影响,且模拟胃液pH对土样生物有效性影响最大,在模拟胃液pH由1.5增长至4时,生物有效性降低近14倍;改良剂的施加对土样铅生物有效性存在一定影响,且磷酸二氢钠施加后的土样铅生物有效性稍低于石灰,模拟胃液pH依然对改良剂处置后的土样铅生物有效性存在较大的影响.

为评估流通领域典型持久性有机物存放库房及周边的场地环境风险,按相关标准要求监测了评估场地土壤和地下水的滴滴涕、六六六、汞、砷等因子.结果表明:场地土壤环境受到了比较明显的六六六及砷污染,场地土壤污染物主要分布在表层,而场地地下水未发现这些污染物.采用普通克里格插值法计算得出污染修复区域需要修复的污染土壤方量约为150 m3.通过本次评估发现,杀虫剂流通领域特别是存放库房所在场地受持久性有机物污染的可能性较高,需要特别关注.

随着近些年我国的城市化进程的加快,城市交通的发展也比较迅速,城市轨道交通工程量在增加,轨道交通工程施工过程中的机电安装是比较关键的,并影响着整体的轨道交通施工质量.基于此,文章先就城市轨道交通机电安装的特征体现以及施工质量影响因素加以分析,然后对城市轨道交通机电安装技术和施工质量控制详细探究.

The effects of sodium dihydrogen phosphate (MSP) on lead speciation and its leaching concentration in soil were studied by Tessier,BCR sequential extraction method and Solid waste-Extraction method for leaching toxicity-acetic acid buffer solution method (HJ/T300-2007).The results of both Tessier and BCR demonstrate that the lead in the experimental soil is changed from the active state to the steady state with the application of sodium dihydrogen phosphate,and the MF value measured by Tessier method is more conservative than that of BCR.It is shown from Linear regression analysis that the MF correlation coefficient measured by BCR method was 0.988,which is better than that by Tessier method as 0.895.It also can be seen that BCR and Tessier methods have a high recovery rate of lead in the polluted soil.Lastly,it is found that sodium dihydrogen phosphate can reduce the leaching concentration of lead in soil effectively with the reduction of 98.62％.

Trace water has a significant impact on the electrical performances of the insulating oil, such as the dielectric loss factor, resistivity. So there is an important significance to investigate the influence of insulating oil by trace water, and monitor its operating status with effective measures. First, it is necessary to prepare the insulating oil samples with different water content and treat them 8 hours with ultrasonic oscillator, and observe microscopic images about the water-oil mixtures in order to study their relative uniformity and stable time, in the way it can be concluded that the relative uniformity can be kept favorable during the 25 min stable time for free water and emulsification water in oil; Based on this conclusion, the dielectric loss factor, resistivity were tested and the electrical performances of insulating oil with different water content in oil can obtained by analyzing these data; Then, the absorbance value of the different water content in oil at the spectral wave number of 1 640, 3 400, 3 450, 3 615 cm(-1), with the mid-infrared spectral scanning and analyzing to the different water content in oil, Therefore, combined the water absorbance values by the mid-infrared spectral scanning and analyzing with the experimental data of dielectric loss factor value, resistivity value of oil samples. The results shows that the absorbance value of the different water content in oil has a significant difference at the spectral wave number of 1 640, 3 400, 3450, 3 615 cm(-1), their correlation coefficient are 0.964 1, 0.984 8, 0.984 5, 0.944 0 between the absorbance value and water content at the spectral wave number of 1 640, 3 400, 3 450, 3 615 cm(-1), it can be obtained that the absorbance value of sample of moisture in the corresponding characteristic wave number can better reflect the change trend of water content; there is the highly relative of water absorbance values at the spectral wave number of 3 400 and 3 450 cm(-1) with the trends of oil dielectric loss factor values, their correlation coefficient are 0.860 6, 0.863 6; and relative of water absorbance values at the spectral wave number of 1 640 and 3 615 cm(-1) with the trends of oil resistivity values, their correlation coefficient is -0.931 5 and -0.968 0, this result can be lay the foundation research for monitoring the trace water in oil.

An interleaved high step-up zero-voltage-switching boost converter is proposed in this study. The operating principle and voltage gain ratio of the proposed converter are presented. The variable inductor control method is used to regulate the output voltage and to achieve a high-voltage gain. The design procedure of the variable inductor with a double E core is also presented in detail. Finally, a 40 W prototype with a 12 V input and 100 V output is built to verify the consistency of the theory analysis. The highest efficiency measured is 84.5%.