非饱和红壤土降雨入渗室内模拟试验

以江西省域范围内典型红壤土为研究对象,利用自行研制开发的降雨模拟试验设备与渗透试验装置,设计了大雨工况下土体初始含水率、干密度、降雨累积时间及降雨后土体静置时间等对其渗透性影响的室内试验。试验结果显示,土体渗透性随初始含水率的升高逐渐降低,给出的宏观渗透系数公式定量化描述了不同初始含水率的可渗透性强弱程度;在初始含水率相对固定的情况下,土体渗透性随干密度的增大逐渐减小,且干密度增大到一定程度后其渗透性锐减,各水平之间的差异性不再明显;累积降雨时间会显著影响深部土体的渗透性,降雨历时越长,深部土体的含水率越高;雨水的在降雨过程停止后继续沿土体纵深入渗,致使表层含水率降低,深部含水率提高,含水率特征曲线趋向竖直。     

Reproductive biology of the spiny lobster, <Emphasis Type="Italic">Panulirus Penicillatus</Emphasis>, in the southeastern coastal waters off Taiwan

The reproductive biology of spiny lobster, Panulirus penicillatus, was studied based on 2,068 lobsters, ranging from 34.28 to 131.60 mm carapace length (CL), sampled in Taitung coastal waters from September 2003 to December 2004. The overall sex ratio approximated 1:1 (χ² = 0.02, P > 0.05), but the monthly sex ratios in 2004 showed significant differences and males were predominant in sizes larger than 80 mm CL. Reproductive activity, assessed using histology, a gonadosomatic index and percentage of ovigerous females, indicated that the mature females could be found in every month and that the major spawning occurred from May to September. The presence of re-developing/re-ripe ovaries by month and size-specific spawning time suggest that larger mature females (>60 mm CL) spawn at least three times a year while smaller new mature females spawn at least once a year. For females, the estimated sizes at 50% physiological and functional maturity were (mean ± SE) 56.46 ± 0.56 mm CL and 66.63 ± 1.07 mm CL. The estimated sizes at functional maturity were between 72 and 74 mm CL for males. The number of eggs per spawning event (brood size, BS) was related to CL by the equation Y _BS = 2.4 × 10^-3CL^4.18 (r ² = 0.902, n = 12). Female lobsters with CL ranging from 60 to 80 mm made the greatest contributions to egg production because of their high brood size and active reproductive activity. A minimum legal size should be established for the fishery to protect egg production potential of lobster population in the southeastern coastal waters off Taiwan.     

Inhalation health effects of fine particles from the co-combustion of coal and refuse derived fuel

This paper is concerned with health effects from the inhalation of particulate matter (PM) emitted from the combustion of coal, and from the co-combustion of refuse derived fuel (RDF) and pulverized coal mixtures, under both normal and low NO_x conditions. Specific issues focus on whether the addition of RDF to coal has an effect on PM toxicity, and whether the application of staged combustion (for low NO_x) may also be a factor in this regard.

Ash particles were sampled and collected from a pilot scale combustion unit and then re-suspended and diluted to concentrations of 1000 μg/m³. These particles were inhaled by mice, which were held in a nose-only exposure configuration. Exposure tests were for 1 h per day, and involved three sets (eight mice per set) of mice. These three sets were exposed over 8, 16, and 24 consecutive days, respectively. Pathological lung damage was measured in terms of increases in lung permeability.

Results show that the re-suspended coal/RDF ash appeared to cause very different effects on lung permeability than did coal ash alone. In addition, it was also shown that a “snapshot” of lung properties after a fixed number of daily 1-h exposures, can be misleading, since apparent repair mechanisms cause lung properties to change over a period of time. For the coal/RDF, the greatest lung damage (in terms of lung permeability increase) occurred at the short exposure period of 8 days, and thereafter appeared to be gradually repaired. Ash from staged (low NO_x) combustion of coal/RDF appeared to cause greater lung injury than that from unstaged (high NO_x) coal/RDF combustion, although the temporal behavior and (apparent) repair processes in each case were similar. In contrast to this, coal ash alone showed a slight decrease of lung permeability after 1 and 3 days, and this disappeared after 12 days. These observations are interpreted in the light of mechanisms proposed in the literature. The results all suggest that the composition of particles actually inhaled is important in determining lung injury. Particle size segregated leachability measurements showed that water soluble sulfur, zinc, and vanadium, but not iron, were present in the coal/RDF ash particles, which caused lung permeabilities to increase. However, the differences in health effects between unstaged and staged coal/RDF combustion could not be attributed to variations in pH values of the leachate.     

Plant uptake and transport models for neutral and ionic chemicals

BACKGROUND: Models for predicting uptake and transport of chemicals in plants are applied in pesticide design, risk assessment, and environmental biotechnology. OBJECTIVE: This review considers the theoretical basics of the most popular models, and discusses what they have in common. The line is drawn between models for neutral compounds, and models for weak and strong electrolytes. MAIN FEATURES: Neutral Compounds. Neutral compounds undergo only very few processes inside plants (lipophilic interactions, metabolism), in contrast to weak electrolytes. The models developed for neutral compounds are widely applied in the risk assessment of environmental contaminants, but are not of much use for weak electrolytes, such as pesticides. Weak electrolytes. A very important process for weak electrolytes is the 'ion trap', which traps chemicals that dissociate inside plant cells. This is considered in the popular models of Kleier, Satchivi and Briggs. Other relevant processes for electrolytes are electrophilic interactions, speciation and complex formation. None of the currently used models considers these processes. CONCLUSIONS: The accuracy of models for neutral compounds is satisfactory, but the prediction of electrolyte behavior inside plants is still quite difficult due to gaps in knowledge.     

盐间非砂岩低渗透油藏中原油运移动力学分析

独特的江汉盆地潜江凹陷潜江组盐间非砂岩油藏生储同层 ,盐岩封盖条件极佳 ,但储集层渗透能力极低 ,油气运移条件差。目前的众多证据表明 ,就是在渗透能力如此低下的盐间层中 ,非断裂区的原油也顺层发生了一定规模的运移。在压实作用、流体热增压、有机质生烃生气增压以及毛细管压差等应力作用下 ,盐间原油得以从烃源岩层中排除 ,并在低渗透的盐间层运移主干道中顺层侧向 (或断裂区垂向穿层 )从生烃次洼向构造高部位等低势区聚集。从动力学的角度证明了盐间非砂岩低渗透油藏中原油顺层运移的可能性 ,并指出了盐间石油的运移方向和有利聚集区。     

孔隙介质中生物膜空间分布及其对渗透性影响研究

孔隙介质地下水污染的生物修复过程中,微生物附着在介质颗粒表面,造成生物堵塞,影响生物修复的效率.对二维砂箱中的生物堵塞实验数据进行了统计分析,统计结果表明生物膜厚度在空间上服从正态分布.现有的定量刻画多孔介质生物膜与渗透率的模型一般均假设生物膜均质等厚地覆盖在颗粒表面,与实验结果不符.为探讨多孔介质中生物膜厚度变化对渗透率计算结果的影响,本文选择常用的Taylor模型中二大类六种模型进行比较分析研究.计算结果表明:生物膜厚度参数对模型计算结果影响显著,利用最小生物膜厚度计算得到的相对渗透率比利用最大生物膜厚度计算时的结果大1～4个数量级;不同模型对生物膜厚度参数的敏感性不同,其中Mualem模型最为敏感;Mualem Model利用平均值计算所得相对渗透率与实验测量结果相符,基于正态分布的生物膜厚度统计均值具有一定的代表性;Mualem模型更适用于计算孔隙介质中生物堵塞时对渗透率的影响.     

危险废物填埋场环境风险控制的地质实践

危险废物填埋场工程的经验之一是选址颇费周折,周期长。对环境地质条件的理解与重视不够,以及利用不当,常常会造成选址失误以至失败。在扬州危险废物填埋场选址中,应用环境地质条件级序论证的办法,将场址选在一个比较完整、稳定的上升型断块内,处于独立水文地质单元内,并择定巨厚隔水泥质砂岩为填埋库基础。由于充分利用和发挥了场地环境地质条件的优越性,大大降低了危废填埋场的环境风险,奠定了设计战略性危废填埋大库的基础。环境地质条件优越的危废填埋场场址本身日益稀缺而逐渐资源化。     

煤层水力压裂合理参数分析与工程实践

煤层水力压裂技术是近年来应用于高瓦斯低透气性突出煤层的一种卸压增透消突技术,人们对水力压裂的卸压增透消突机理有了较充分的认识,现场工程应用的效果也较好,但有关煤层水力压裂参数是如何确定的系统分析却是很少。笔者在阐述水力压裂机理及压裂过程的基础上,系统地阐述高瓦斯低透气性突出煤层水力压裂所需的注水压力、流量、注水时间、注水速度、孔间距、封孔长度等技术参数以及煤体内在因素的影响作用;最后在义安矿FD003工作面进行了水力压裂试验研究和效果考察,得出适合义安矿的水力压裂合理注水参数。通过水力压裂,煤层瓦斯抽放量和抽放浓度得到大幅度提高,达到了卸压增透防突效果,同时起到了润湿煤体和降尘效果。     

高阶煤孔隙特征的低场核磁共振实验研究

研究孔裂隙特征对煤层中甲烷的产出及运移具有重要的意义。为了得到高阶煤的孔裂隙特征信息,采用低场核磁共振仪对高阶煤样做低场核磁共振实验,测得煤样的T2图谱,进一步分析得到了煤样的核磁渗透率、核磁孔隙度、可动流体饱和度、束缚流体饱和度以及孔径分布等参数的实验结果,并测出煤样的工业分析参数。分析结果得出:原煤中孔隙体积与煤的挥发分含量呈正比的关系;高阶煤孔隙发育而裂隙不发育,并且在孔隙中微孔和小孔占有较大的比例而中孔和大孔占有较少的比例;煤样渗透率与煤样内小孔和大孔所占的比例成正比,与煤样内微孔所占的比例成反比等结论。