Research on soil multi-media environmental pollution around a Pb-Zn mining and smelting plant in the karst area of Guangxi Zhuang Autonomous Region,Southwest China

The method of principal component analysis was applied to systematical research on the soil multi-media environment, including soil, surface water, ground water, waterbody sediment and agricultural crops, as well as pollution-inducing wastewater, mullock (or waste ore) and slag in the periphery of a large-sized Pb-Zn mining and smelting plant in a karst area of Guangxi Zhuang Autonomous Region. The results revealed that soils in the area studied have been heavily polluted by Cd, Zn, Pb and Hg, and the levels of these metals in the samples of agricultural crop greatly exceed the standards. The above-mentioned pollutants exist in all soil-multi-media environments. The mullock, slag, wastewater, surface water, ground water, soil, and agricultural crops constitute a composite ecological chain. Therefore, the improper disposal of mullock and slag, and the use of polluted wastewater for agricultural irrigation are the main causes of soil pollution. Heavy metals in the soil have three transition progresses: point (improved soil with slag, ground water inflow plot), linear (river transition) and non-point transition (regional pollution by slag) patterns, and the tailing yard is the most important locus for heavy metals to release into the environment.

考虑多孔介质渗透率变化的宾汉流体渗透注浆扩散模型

渗透注浆是一种广泛应用于岩土多孔介质加固的方法,但已有基于浆液流变方程和平衡方程的研究,侧重分析浆液本身性质如黏度时变性、滤过效应、自身重力等对渗透注浆扩散范围的影响,尚未考虑浆液在孔隙内的流动阻力对多孔介质渗透率的影响,导致现有理论解析结果与试验测试结果相差较大。因此,基于黏性流体的运动方程、连续方程和平衡方程,引入浆液在孔隙内的流动阻力对多孔介质渗透率的影响,推导获得多孔介质渗透率随介质孔隙特性、注浆施工参数和注浆扩散半径的函数解析表达式,据此建立考虑多孔介质渗透率变化的浆液扩散控制方程。与已有理论结果对比表明,考虑浆液流动阻力影响的理论结果更接近试验结果,可以验证该理论方法的有效性。参数分析结果表明:考虑浆液在孔隙内的流动阻力时,岩土多孔介质渗透率随注浆时间的增加呈现先迅速降低后缓慢上升趋势,随注浆压力的增大呈现逐渐下降趋势;对于工程中常见的符合宾汉流体性质的水泥浆液材料,当注浆时间小于5 min时,多孔介质渗透率变化是影响浆液扩散的主控因素,超过7 min后,浆液黏度时变性成为主控因素。研究成果能为岩土多孔介质渗透注浆工程实际中注浆参数选取和质量控制起到良好的理论指导意义。

较长时段尺度下4种配方介质土生物滞留系统的运行机制与效能

为探究较长时间尺度下配方介质土生物滞留系统的运行机制和效能,设计并构建了4种用不同配方介质土装填的生物滞留系统。研究结果表明:在22个月的运行时间内,4种系统对总氮(TN)和硝酸盐氮(NO^(-)_(3)-N)有较好的去除效果,当土砂比为7∶3、填料层深度为400 mm、添加比例为7.5%营养土时,氨氮、TN、NO^(-)_(3)-N、化学需氧量(CODCr)、总磷(TP)去除效果最好且稳定,平均去除率分别为88.83%、88.89%、93.16%、93.10%、94.69%;不同介质土对胞外聚合物(EPS)的含量和电子传递活性(ETSA)有影响,EPS增加可以加快电子传递速率,从而提高反硝化脱氮效率。相关性分析表明,生物滞留系统的下渗速率和TN、NO-3-N的去除呈显著负相关(p<0.05),而蛋白质(PN)和NO-3-N则与TN去除率呈显著正相关(p<0.05)。研究结果为提高生物滞留系统长期稳定运行效果和科学建造提供了技术参考。

基于多介质土壤渗滤技术的养殖污水处理系统研究

海水养殖常见污染物主要包括总磷、悬浮物、总氮等,主要来源是养殖过程中的粪便、水生植物昆虫尸体、残存饵料和底泥等。沿海地区的海水养殖业中在排污换水时多采用将养殖尾水直接排入大海,使得有毒有害藻类、细菌病毒大量繁殖且难以控制,超出近岸海洋的环境承载力和自净能力导致海洋生态环境的破坏。该文主要根据海水养殖业污水特点和排放特征,结合工程技术性和经济性要求,基于多介质土壤渗滤技术,运用理论分析、系统设计、现场试验等研究方法,对养殖污水处理方案优化设计,以满足养殖污水的闭环处理和循环使用,提出海水养殖污水治理的建议,实现养殖污水的近零排放。

地下水位对核电结构地震反应的影响分析

核电结构大多沿海或沿江、河而建,在地下水位以下,土体孔隙中的流体对土层的地震响应有较大影响,进而影响核电结构的响应。本文采用饱和多孔介质模型,考虑土-结相互作用效应,分析地下水位对核电结构地震反应的影响。通过传递矩阵方法,得到干土-饱和土水平成层场地的自由场,并结合透射人工边界,实现土-结相互作用分析的波动输入;采用土-结相互作用的分区并行计算方法,实现饱和土和结构相互作用分析。其中,含地下水位的场地土体采用广义饱和多孔介质模型描述,通过自编FORTRAN程序用集中质量显式有限元结合透射人工边界进行模拟,结构通过ANSYS中的隐式有限元进行分析。以某一核电结构为例,分析了0,−10,−20,−30,−40 m不同地下水位的五种场地上,土-基础-核电结构体系的动力响应。结果表明,地下水位对基础和结构的位移影响不大,对加速度的影响较大。

Numerical modeling of solute transport in deformable unsaturated layered soil

The effect of soil stratification was studied through numerical investigation based on the coupled model of solute transport in deformable unsaturated soil. The theoretical model implied two-way coupled excess pore pressure and soil deformation based on Biot's consolidation theory as well as a one-way coupled volatile pollutant concentration field developed from the advection-diffusion theory. Embedded in the model, the degree of saturation, fluid compressibility, self-weight of the soil matrix, porosity variance, longitudinal dispersion, and linear sorption were computed. Based on simulation results of a proposed three-layer landfill model using the finite element method, the multi-layer effects are discussed with regard to the hydraulic conductivity, shear modulus, degree of saturation, molecular diffusion coefficient, and thickness of each layer. Generally speaking, contaminants spread faster in a stratified field with a soft and highly permeable top layer; soil parameters of the top layer are more critical than the lower layers but controlling soil thicknesses will alter the results. This numerical investigation showed noticeable impacts of stratified soil properties on solute migration results, demonstrating the importance of correctly modeling layered soil instead of simply assuming the averaged properties across the soil profile.

Numerical Study of Heat Transfer and Contaminant Transport in an Unsaturated Porous Soil

Penetration of chemicals in the soil ground through irrigation water or rainfall induces important risks for the environment. These risks are badly known and may lead to direct contamination of the environment (atmosphere or ground water) or harmful effects on organisms living at ground level, indirectly affecting men. It is thus necessary to estimate these potential chemical risks on the environment. For that reason, the gradual change of these products (fertilizers, solutions, pollutants, ...) in the ground has been the subject of a lot of recent research works, based in particular on the study of non-saturated porous media in a theoretical, numerical or experimental way. Most of these works are incomplete and, in order to simplify the problem, they don’t take into accounts some process, which may be of prime importance under particular natural conditions. Complexity of such studies results from their multidisciplinary nature. In this communication, we study simultaneous transport of pollutant, the water that provides transport and the heat transfer in a 200 cm long cylindrical column full of sand taken as a non-saturated porous medium. We consider two kinds of conditions on the temperature at the column surface: the case of constant temperature and the case of sinusoidal temperature. We evaluate the influence of this temperature on the transfers. This study is purely numerical. We use the control volume method to determine hydrous, thermal and pollutant concentration profiles.

Yield Compounds and Nutrient Elements of Carnation (Dianthus caryophyllus L.) under Different Growing Media

Production of cut flowers is very prevalent in Iran. Carnation is most famous for its use as a cut flower. This study was carried out in the research greenhouse of Islamic Azad University, Isfahan (Khorasgan) Branch, to explore the effect of different growing media on some vegetative and reproductive traits of carnation. The experimental design was randomized complete, using 50% perlite and different growing media including: mineral soil and coco peat in 6 proportions (50% coco peat, 10% soil + 40% coco peat, 20% soil + 30% coco peat, 30% soil + 20% coco peat, 40% soil + 10% coco peat, 50% soil). During growth period, irrigation rate, humidity and temperature were similar. The growth characteristics of carnation were determined at the end of growth period. The results indicated that although there were no significant differences between studied growing substrates in chlorophyll a, b. Statistical analysis showed fresh weight of flower was far greater in coco peat 10% + soil 40% and soil 50% compared to other growing media. Fresh and dry weight of root and shoot in soil 50% were higher than other growing media. The results showed that highest concentration of Fe and Zn was observed in coco peat 40% + soil 10%. The concentration of Mn in coco peat 10% + soil 40% was higher than other growing media. The results showed that the highest Ca concentration was observed in soil 50% and the lowest concentration of this element was obtained in coco peat 50%. According to the obtained results, mineral soil can be used as a suitable alternative to cocopeat for cultivation and growth of carnation in greenhouse.

DYNAMIC BEHAVIOR OF PILES EMBEDDED IN TRANSVERSELY ISOTROPIC LAYERED MEDIA

Dynamic behavior of single pile embedded in transversely isotropic layered media is investigated using the finite element method combined with dynamic stiffness matrices of the soil derived from Green's function for ring loads. The influence of soil anisotropy on the dynamic behavior of piles is examined through a series of parametric studies.

Analysis on the Phase Frequency Characteristic of Soil Impedance

Soil is a typical porous media and its impedance characteristic directly determines the performance of grounding system. Soil phase frequency characteristic measurements were carried out on various soil types and water content. This paper finds that the impedance angle of soil specimen presents a capacitive performance when power frequency (f) is low. As the frequency increases, soil impedance angle goes up rapidly. Furthermore the frequency characteristic while f > 1000 Hz is distinct in terms of different water content. In particular, at low moisture content, soil impedance angle would be higher than 0?, that is, the inductive component is obvious. The study result indicates that porous media possesses the unique conductivity property dif-ferent from conductor and solution. Its mechanism needs further study.

Development of an Ontology-Based Knowledge Network by Interconnecting Soil/Water Concepts/Properties, Derived from Standards Methods and Published Scientific References Outlining Infiltration/Percolation Process of Contaminated Water

The present work deals with the development of an Ontology-Based Knowledge Network of soil/water physicochemical & biological properties (soil/water concepts), derived from ASTM Standard Methods (ASTMi,n) and relevant scientific/applicable references (published papers—PPi,n) to fill up/bridge the gap of the information science between cited Standards and infiltration discipline conceptual vocabulary providing accordingly a dedicated/internal Knowledge Base (KB). This attempt constitutes an innovative approach, since it is based on externalizing domain knowledge in the form of Ontology-Based Knowledge Networks, incorporating standardized methodology in soil engineering. The ontology soil/water concepts (semantics) of the developed network correspond to soil/water physicochemical & biological properties, classified in seven different generations that are distinguished/located in infiltration/percolation process of contaminated water through soil porous media. The interconnections with arcs between corresponding concepts/properties among the consecutive generations are defined by the relationship of dependent and independent variables. All these interconnections are documented according to the below three ways: 1) dependent and independent variables interconnected by using the logical operator “depends on” quoting existent explicit functions and equations;2) dependent and independent variables interconnected by using the logical operator “depends on” quoting produced implicit functions, according to Rayleigh’s method of indices;3) dependent and independent variables interconnected by using the logical operator “related to” based on a logical dependence among the examined nodes-concepts-variables. The aforementioned approach provides significant advantages to semantic web developers and web users by means of prompt knowledge navigation, tracking, retrieval and usage.

寒区冻土层含冰孔隙结构导热模型构建及应用分析

冻土主要由固、液和气三相物质构成,其中固体可以看成骨架,另外两相物质填充在孔隙中,是典型的多孔介质。寒区冻土层融沉过程中,其中的孔隙结构、矿物颗粒和含冰量等参数变化幅度较大,导热系数等热物性参数随之变化,目前在精细表征和分析研究方面存在一定不足。针对含冰冻土,采用多孔介质描述方法,考虑其相态变化特性,将其分为未冻区、融化区、固结区及已冻区;基于表征单元体(representative elementary volume,REV)方法,结合冻土物理学和传热传质学理论,构建了冻土层导热分析模型,包括微观模型和宏观分析模型;以寒区土壤冻融过程为例进行模拟计算,分析了孔隙率、含水率、含冰率以及通道构成系数等对冻土导热系数的影响规律。所建模型可为寒区冻土传热机理分析及导热特性研究提供理论基础。

Comparative study on production,purification of penicillin by Penicillium chrysogenum isolated from soil and citrus samples

Objective:To explore various unexplored locations where Penicillium spp.would be available and study the production of penicillin from the isolated Penicillium spp.in different media with altered carbohydrate source.Methods:The collected soil samples were screened for the isolation of Penicillium chrysogenum(P.chrysogenum) by soil dilution plate.The isolated Penicillium species were further grown in different production media with changes in the carbohydrate source.The extracted penicillin from various isolates was analyzed by HPLC for the efficacy of the product.Further the products were screened with various bacterial species including methicillin resistant Staphylococcus aureus(MRSA).And the work was extended to find the possible action on MRSA,along with characterization using other pathogens.Results:From the various soil and citrus samples used for analysis,only the soil sample from Government General Hospital of Bangalore,India,and Sanjay Gandhi Hospital,Bangalore,India,showed some potential growth of the desired fungi P.chrysogenum.Different production media showed varied range of growth of PenicilUum.Optimum production of penicillin was obtained in maltose which proved maximum zone of inhibition during assay.Characterization of penicillin on pathogens,like wild Escherichia coli strain,Klebsiella spp.,and MRSA,gave quite interesting results such as no activity on the later strain as it is resistant.HPLC data provided the analytical and confirmation details of the penicillin produced.Accordingly,the penicillin produced from the soil sample of Government General Hospital had the high milli absorbance unit of 441.5 mAu compared with that of the penicillin produced from Sanjay Gandhi Hospital sample,8S.S2 mAu.Therefore,there was a considerable change in quantity of the penicillin produced from both the samples.Conclusions: The Penicillium spp.could be possibly rich in hospital contaminants and its environments.This research focuses on various unexplored sources of medical ailments,and also shows that the growth of penicillin is high in maltose rich media that could possibly enhance the growth.

高温、高含冰量冻土中弹性波的传播特性

考虑了高温、高含冰量冻土在弹性波激励下表现出的冰晶黏滞性与未冻水流动性,并融入温度对介质物理性质的2种影响机制,通过结合Burgers黏弹性本构关系、BISQ模型和热力学理论推导了冻土中快P波、慢P波和S波传播的相速度及衰减因子的解析表达式,形成了针对该类冻土温度依赖的双相黏弹性孔隙介质理论。在此基础上开展了数值算例分析,明确了3种体波相速度和衰减因子的典型响应模式,并依次讨论了土孔隙度、冰晶黏滞性和地温等因素对它们传播特性的影响方式及敏感程度。证实了温度对快P波的相波速、衰减频带及峰值均有显著影响;对慢P波传播影响较小;对S波仅影响其相速度及低频衰减峰值。通过对比理论模型预测与实验室测试数据,证明了与传统基于弹性介质假设的冻土模型相比,基于黏弹性介质理论提出的新模型可以更好地描述高温、高含量冻土中弹性波的速度和衰减响应特征。

下凹式绿地对周边地下水动态影响的试验研究

为探究下凹式绿地对周边地下水动态的影响,本文选取了细砂、中细砂和粗砂三种不同粒径的砂土,开展不同下凹深度与不同土壤含水量条件下的室内下凹式绿地槽试验研究。试验结果表明,含水介质为粗砂且下凹深度为10 cm时,地下水动态变化最显著,水位埋深变幅达22.7%,影响范围约58 cm,其影响效果随介质渗性和下凹深度的降低而减弱。同时地下水动态变化程度与土壤含水量有关,17%含水量条件下的水位埋深变幅约是45%含水量条件的1.5倍。

铀尾矿库氡析出机理及其影响因素研究进展

氡来源于土壤、铀尾矿、岩石等多孔射气介质,铀尾矿库滩面是尾矿堆积或沉积体与大气环境直接接触的暴露面,氡气从该交界面析出并经大气弥散而污染周边环境,覆盖处置是滩面控氡的主要手段。本文以典型铀尾矿库滩面为例,综述氡析出机理及其影响因素,阐述了多孔射气介质固有特性及外部气象环境条件对铀尾矿库滩面氡析出的影响机制。结果表明,国内外学者已对多孔射气介质固有特性影响氡析出的规律开展了大量研究,但由于实验尺度、研究方法存在差异,矿物颗粒特征影响氡析出机制的解释仍存在争议,外部气象环境等因素对铀尾矿库滩面氡析出的影响机制尚不明确。为此,提出今后研究的关注点:(1)真实条件下,氡析出过程的合理表征形式;(2)开展大尺度实验探究多孔介质固有特性对铀尾矿库滩面氡析出的影响机制。

镧改性生物炭在砂柱中单独运移及与Cr(Ⅵ)共运移

为探究稀土金属改性生物炭在土壤-地下水中的运移行为,本研究选择常见稀土元素镧制备改性生物炭,并经球磨后制成镧改性生物炭细颗粒(La-BC),采用柱实验分别从流速、pH、离子强度和腐植酸浓度4个方面来研究La-BC单独运移和与Cr(Ⅵ)共运移时其在饱和均质石英砂介质中的运移和滞留规律。研究表明:流速从1.0 mL·min^(-1)增至1.5 mL·min^(-1)时,单独运移实验出流液中La-BC的质量回收率由58.0%增至73.4%,共运移实验出流液中La-BC的质量回收率为78.7%~80.1%。pH从5升至7时,La-BC单独运移及共运移时的穿透曲线的相对浓度(Ct/C0)峰值分别从0.66增至0.93和从0.80增至0.85。离子强度增至5 mmol·L^(-1)时,La-BC单独运移时的Ct/C0峰值降低至0.05,与Cr(Ⅵ)共运移时La-BC的穿透峰值为0.81~0.75。腐植酸浓度由0增至10 mg·L^(-1)时,La-BC单独运移及与Cr(Ⅵ)共运移时出水中La-BC质量回收率分别减少了约13个和3个百分点。相较于La-BC单独运移,共运移中Cr(Ⅵ)的存在除了在中性实验条件下抑制La-BC运移能力外,其余实验条件下皆促进了La-BC在饱和介质中的运移。因此,较低的流速、较低的pH环境、一定的离子强度及腐植酸浓度有助于改性生物炭的滞留稳定。

植物挥发性单萜经土壤载体的化感作用--以三裂叶豚草(Ambrosia trifida L．)为例

植物释放的挥发性单萜在生态系统中起着重要的作用,这些单萜不仅能以空气为载体对其他植物显示直接的化感作用,而且也能以土壤为载体进行间接的化感作用。通过对三裂叶豚草挥发物对植物种子萌发和土壤微生物种群影响及其化学成分的鉴定研究,验证了以单萜类物质为主的三裂叶豚草挥发物可以经土壤载体对其他植物及土壤微生物显示化感效应。还对植物挥发物化学成分鉴定的GC(气相色谱)和GC-MS(气相色谱-质谱联用)方法存在的一些误区进行了澄清,这将有助于对生态系统中植物挥发物化感作用的研究和认识。

核电磁脉冲在岩土介质中的传播研究

综述了对非铁磁性、线性、各向同性介质中核电磁脉冲传播规律研究方面的一些成果。通过建立康普顿电流模型 ,采用 FDTD法 ,对地面核爆炸 SREMP数值分析的结果表明 ,厚度为几十米以上的具有一定导电性的岩土介质层 ,对于电磁脉冲峰值场强的衰减可达一个量级以上 ,且使脉冲上升沿变缓。采用两种模型对 HEMP的入地传播问题进行计算分析 ,将电磁脉冲模拟器架设于隧道顶上作试验研究 ,得出了类似的结论。