镉与S-异丙甲草胺对斜生栅藻的联合毒性作用

采用毒性标准实验方法研究了Cd2+与S-异丙甲草胺单独及联合作用对斜生栅藻急性毒性、总可溶性蛋白含量、超氧化物歧化酶(SOD)活性和细胞膜通透性的影响.结果表明Cd2+与S-异丙甲草胺单独作用时EC50均随时间的延长而减小,且S-异丙甲草胺的急性毒性大于Cd2+;Cd2+、S-异丙甲草胺的EC50-24h分别为0.27 mg·L-1、0.24 mg·L-1,EC50-96h分别为0.16mg·L-1、0.13 mg·L-1.Cd2+与S-异丙甲草胺联合作用时低浓度表现为协同作用,高浓度表现为拮抗作用.暴露96 h后,Cd2+与S-异丙甲草胺单独及联合作用下,随有毒物质浓度升高,斜生栅藻总可溶性蛋白含量降低,SOD酶活性先激活后抑制,细胞膜通透性逐渐增大.     

坡地赤红壤物理退化及其机理研究──Ⅱ.土壤水分性能退化特征

探讨了坡地赤红壤水分性能退化的特征、结果表明,与地带性自然植被下坡地赤红壤比较,次生植被或人工植被下坡地赤红壤水分性能变劣：表现在导水性降低,2h饱和渗水量明显减少,自然赤红壤比耕型赤红壤的减幅大;持水能力下降,在同样吸力下,土壤持水量较少;供水能力下降,在同样吸力段,表土释放的水量较少;亚表土在低吸力段释放水量较少。     

Estimating the hydraulic properties of the fracture network in a sandstone aquifer

The potential hydraulic behaviour of the fracture network in a major Triassic sandstone aquifer in the UK has been evaluated. The properties of the fracture network were determined using results from detailed scan line surveys at 10 sites, television and geophysical borehole logging, and packer testing. Six sets of discontinuities common to all sites were identified and statistically characterised (dip, strike, orientation, density, size, and estimated transmissivity). A discrete fracture network model was then used stochastically to investigate the properties of the network. In general, the network is poorly connected: it is estimated that 9% of the discontinuities intersecting boreholes are transmissive. The hydraulic behaviour of the network is generally dominated by one sub-horizontal bedding plane fracture set, although when present, a relatively infrequent north-south striking, sub-vertical set modifies the bulk flow properties significantly. Ignoring this latter set, the network's minimum representative volume is about 35 x 35 x 35 m. The upscaled permeability is anisotropic, being typically 23 times greater in the horizontal than in the vertical. Tortuosity in the north-south direction is around 1.6.     

Air quality and respiratory health in Delhi

Delhi is an instructive location for studying the impact of air pollution since it is a rapidly expanding centre of government, trade commerce and industry. We have made an attempt to (1) determine the association between environmental pollution and respiratory morbidity in Delhi for the period 1998–2004, (2) assess the impact on hospital admission of the implementation of recent governmental regulations and (3) calculate the relative risk of hospitalization due to respiratory ailments caused by air pollutants. Seven hospitals from different parts of Delhi were selected. The pollution profiles of these areas were assessed and subsequently Poisson regression model was performed for the patient population. There was a remarkable decrease in monthly average concentration of sulphur dioxide (from 17.9 to 11.1 μg m⁻³) and increase in monthly average concentration of nitrogen dioxide (from 34.2 to 49.1 μg m⁻³) after the newly introduced regulations. Particulates were observed to have marginal fall in their concentration but still remained above the permissible limits. Gaseous pollutants, in spite of being at a level lower than the permissible level, showed more consistent significant association with respiratory admissions. The relative risks of hospitalization due to respiratory diseases were in the range of 1.07–2.82 in residential cum commercial areas. Comparative study of pre and post new stringent governmental regulation showed significant positive association of NO₂ with respiratory disorders in southern (RR: 1.10; CI: 1.09–1.12) and northern regions (RR: 1.33; CI: 1.27–1.39), both mixed use areas. In spite of the improvement in the air quality, the associated health effects were found to be substantial.     

鄂东南崩岗不同层次土壤分形特征及抗蚀性研究

崩岗是鄂东南地区极其严重的土壤侵蚀类型,影响范围广,破坏性强。选择鄂东南通城县花岗岩崩岗不同层次土壤进行研究,主要分析崩岗剖面土壤颗粒分形维数、可蚀性、渗透性及水稳性,并通过回归分析等方法建立其与土壤性质之间的拟合关系。结果表明:鄂东南通城县崩岗土层表土层、红土层、斑纹层以及碎屑层的性质存在较大差异,土壤颗粒分形维数D由表土层至碎屑层呈减小的趋势,土壤可蚀性K值由表土层至碎屑层呈增加的趋势,水稳性指数则呈现减小的趋势,渗透性则表现为红土层小而表土层和碎屑层大的规律。同时,相关性分析以及多元线性回归分析显示,崩岗剖面土壤颗粒分形维数、可蚀性、渗透性以及水稳性之间关系密切,抗蚀性与土体性质之间的相关性显著。研究旨在明确了崩岗发生的内在因素,为阐述崩岗的发生机理提供了依据。     

Enhanced cytotoxicity of pentachlorophenol by perfluorooctane sulfonate or perfluorooctanoic acid in HepG2 cells

Chlorinated phenols and perfluoroalkyl acids (PFAAs) are two kinds of pollutants which are widely present in the environment. Considering liver is the primary toxic target organ for these two groups of chemicals, it is interesting to evaluate the possible joint effects of them on liver. In this work, the combined toxicity of pentachlorophenol (PCP) and perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA) were investigated using HepG2 cells. The results indicated that PFOS and PFOA could strengthen PCP’s hepatotoxicity. Further studies showed that rather than intensify the oxidative stress or promote the biotransformation of PCP, PFOS (or PFOA) might lead to strengthening of the oxidative phosphorylation uncoupling of PCP. By measuring the intracellular PCP concentration and the cell membrane properties, it was suggested that PFOS and PFOA could disrupt the plasma membrane and increase the membrane permeability. Thus, more cellular accessibility of PCP was induced when they were co-exposed to PCP and PFOS (or PFOA), leading to increased cytotoxicity. Further research is warranted to better understand the combined toxicity of PFAAs and other environmental pollutants.     

液态 CO2 相变致裂煤层增透技术布孔方式研究

液态CO2相变致裂技术是一种新颖的低透煤层增透技术。为了更好地将液态CO2相变致裂技术运用到低透气煤层增透领域中,在平煤十三矿进行了液态CO2相变致裂的穿层强化预抽煤层瓦斯现场试验,通过煤层致裂后的瓦斯抽采效果反映出的不同布孔方式下的致裂差异,确定液态CO2的爆破孔的合理布孔方式。现场试验表明液态CO2相变致裂在交错的梅花孔布置方式下由于能量分布均匀,致裂效果优于矩形孔布置方式,研究结果为该技术在煤层增透强化预抽领域的推广应用奠定了基础。     

氧化石墨烯对邻苯二甲酸二丁酯藻毒性的影响

以海洋微藻青岛大扁藻(Platymonas helgolanidica var.tingtaoensis)为受试对象,研究了氧化石墨烯(graphene oxide,GO)与邻苯二甲酸二丁酯(dibutyl phthalate,DBP)单独及共同对青岛大扁藻的急性毒性效应,考察了藻细胞的生长状况,光合色素产量,细胞通透性,氧化应激指标及扫描电镜,以探讨GO的加入对DBP藻毒性的影响.结果表明,低浓度GO(0.1~10 mg·L~(-1))对青岛大扁藻的藻密度和叶绿素产量无明显影响,但藻细胞通透性随GO浓度升高显著增加(P0.05),10mg·L~(-1)时达到空白组的2.2倍.DBP对青岛大扁藻的EC50,96 h为(11.14±0.80)mg·L~(-1),其毒性远大于GO(EC50,96 h大于100mg·L~(-1)).1 mg·L~(-1)GO的加入使DBP的EC50,96 h降低到(4.93±2.14)mg·L~(-1),低浓度GO对DBP藻毒性表现出一定的增强作用.1 mg·L~(-1)的GO加入时,对低浓度DBP组(0.1~2 mg·L~(-1))的藻密度、叶绿素产量、细胞通透性水平没有显著性影响,但加剧了高浓度DBP组(4 mg·L~(-1))对藻密度、叶绿素产量的抑制,使单个藻细胞内ROS和SOD平均增加了21%和7%.扫描电镜结果发现GO对藻细胞具有覆盖,包裹及聚集作用,这些可能是DBP藻毒性增强的主要原因.该结果为揭示新型污染物碳纳米材料对海洋生物的风险提供了数据支持.     

垃圾填埋场抽气竖井周边气体运移规律研究

通过建立填埋场抽气竖井周边气体轴对称稳态运移模型,分析了单层和分层垃圾体中气压力分布,并提出“降压百分比”的概念用于判定抽气影响范围,研究了垃圾产气率、气体渗透率、覆盖层厚度、覆盖层气体渗透率、抽气井深度和抽气负压对抽气影响范围和抽气量的影响,获得了竖井深度和井间距的确定方法.分析结果表明,抽气井的降压作用明显,抽气井深度和抽气负压越大,则抽气影响范围和抽气量越大.覆盖层厚度增加或其渗透率降低有助于扩大抽气影响范围和提高抽气量.抽气影响范围随气体渗透率的增加而增大,但随垃圾产气率的增加而减少;抽气量则随气体渗透率和产气率的增大而增加.抽气井深度是控制抽气影响范围的关键参数,建议竖井深度取垃圾填埋厚度的65％～75％,井间距取1.5～2.5倍竖井深度.     

表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征

为明确表面活性剂强化抽出处理含水层中DNAPL污染物过程中表面活性剂的增强修复效果,及DNAPL自身理化性质和介质孔径的影响,利用数码图像分析技术对1,2-二氯乙烷和四氯乙烯2种DNAPL在石英砂填充的二维砂箱中的抽取迁移过程进行了实验模拟研究,并对抽出水样中DNAPL的浓度进行了测试分析。结果表明,实验条件下加入低浓度(0.18%)的十二烷基苯磺酸钠(SDBS)大幅提高了对弱透水层截留的2种DNAPL聚集体的抽出处理效率。1,2-二氯乙烷在该表面活性剂溶液中的表观溶解度远高于四氯乙烯,因此其短时间内的绝对去除率更高。SDBS强化抽出处理DNAPL的作用机理以增溶作用为主,而其增流作用使DNAPL迁移流动后分布面积增大,增加了与表面活性剂溶液接触的面积,对增溶作用起到促进效果。细粒介质中DNAPL迁移后的最大分布面积较大,因此体系中DNAPL的溶解速率较高。在DNAPL聚集体质量与水力梯度固定的条件下,油水界面张力越低,DNAPL的密度越大,DNAPL垂向迁移的风险就越大。本研究为修复工程中如何依据DNAPL种类与场地多孔介质的情况选择表面活性剂提供了参考。