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911.
表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征 总被引:1,自引:0,他引:1
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。 相似文献
912.
913.
Xie Bin Luo Hang Tang Qing Du Jun Liu Zuohua Tao Changyuan 《Environmental science and pollution research international》2017,24(27):21761-21769
Environmental Science and Pollution Research - Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was... 相似文献
914.
Xiaoguo Jiao Zhanqi Chen Jun Wu Hongyan Du Fengxiang Liu Jian Chen Daiqin Li 《Behavioral ecology and sociobiology》2011,65(2):325-332
Although the effects of male mating history on female reproductive output and longevity have been studied in insects, few
such studies have been carried out in spiders. In a mating system in which females are monandrous while males are polygynous,
females may incur the risk by mating with successful males that have experienced consecutive matings and suffer from the possible
depletion of sperm and/or associated ejaculates. Here, we examine the effects of male mating history on male courtship and
copulation duration, female reproductive fitness, and female adult longevity of the wolf spider, Pardosa astrigera. Results indicated that male mating frequency had little effect on their subsequent copulation success, and of 35 males tested,
about half of the males were able to copulate with five virgin females successively at an interval of 24 h. Male mating history
had little effect on their courtship duration. However, male mating history significantly affected male copulation duration,
female adult longevity, and reproductive output. Males that mated more frequently copulated longer and more likely failed
to cause their mates to produce a clutch, although there was no significant difference in the number of eggs laid and the
number of eggs hatched regardless of the first clutch or the second one. Multiple mating of male P. astrigera resulted in significant reduction in female adult longevity. Our results indicate that monandrous females mating with multiple-mated
males may incur substantial fitness costs. 相似文献
915.
916.
湿法烟气脱硫喷淋塔的阻力特性研究 总被引:1,自引:0,他引:1
以装配有自行设计的湍流装置的冷态喷淋塔为研究对象,考察了气速、喷淋量、液气比(L/G)、湍流装置垂直和水平间距对其阻力特性的影响。结果表明,当湍流装置结构形式一定时,喷淋塔的湍流层阻力(ΔP)均随气速、喷淋量和L/G的增大而增大;当气速、喷淋量、L/G一定时,湍流层阻力均随湍流装置垂直与水平间距的增大而减小。当气速、喷淋量、L/G、湍流装置垂直与水平间距分别为2.0 m/s、100 m~3/h、10 L/m~3、120 mm、120 mm时,湍流层的最小阻力为0.14 kP a;而当气速、喷淋量、L/G、湍流装置垂直与水平间距分别为3.6 m/s、240 m~3/h、25 L/m~3、90 mm、100 mm时,湍流层的最大阻力为0.62 kP a。对实验数据进行多元线性回归分析,得出该喷淋塔湍流层阻力的经验公式为ΔP=0.000 46V ~(0.724)Q~(0.930)D~(-1.860)f~(-5.480),其拟合优度与显著性良好,对工业应用具有一定的理论指导意义和实际参考价值。 相似文献
917.
城市生态文明建设评价指标体系构建 总被引:1,自引:1,他引:0
城市作为人类环境问题和危机产生的重要策源地,建立反映城市生态环境问题和生态文明建设状态的评价指标体系,依据评价结论,指导城市生态文明建设十分必要。文章在城市作为社会—经济—自然复合人工生态系统的理论基础上,分析了社会生态亚系统、经济生态亚系统及自然生态亚系统相互作用关系和城市生态系统主要生物成分组成、结构与功能关系,系统的构建了符合中国国情的城市生态文明评价指标体系。该体系以生态经济、生态环境质量、生态社会为评价要素,下设12个一级指标及42个二级指标,为评价中国城市生态文明建设水平提供科学依据。 相似文献
918.
Feihu Yao Hailong Liu Guangquan Wang Liming Du Xiaofen Yin Yunlong Fu 《环境科学学报(英文版)》2013,25(6):1245-1251
Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (ΔF) showed a good linear relationship with PQ concentrations from 1.0×10-8 to 1.2× 10-5 mol/L with a detection limit of 3.35×10-9 mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by 1H NMR spectroscopy. 相似文献
919.
920.
Biological invasions have incurred serious threats to native ecosystems in China, and soil N-fixing bacteria communities (SNB) may play a vital role in the successful plant invasion. Meanwhile, anthropogenic acid deposition is increasing in China, which may modify or upgrade the effects that invasive plant species can cause on SNB. We analyzed the structure and diversity of SNB by means of new generation sequencing technology in soils with different simulated acid deposition (SAD), i.e., different SO4 2? to NO3 ? ratios, and where the invasive (Amaranthus retroflexus L.) and the native species (Amaranthus tricolor L.) grew mixed or isolated for 3 months. A. retroflexus itself did not exert significant effects on the diversity and richness of SNB but did it under certain SO4 2? to NO3 ? ratios. Compared to soils where the native species grew isolated, the soils where the invasive A. retroflexus grew isolated showed lower relative abundance of some SNB classes under certain SAD treatments. Some types of SAD can alter soil nutrient content which in turn could affect SNB diversity and abundance. Specifically, greater SO4 2? to NO3 ? ratios tended to have more toxic effects on SNB likely due to the higher exchange capacity of hydroxyl groups (OH?) between SO4 2? and NO3 ?. As a conclusion, it can be expected a change in the structure of SNB after A. retroflexus invasion under acid deposition rich in sulfuric acid. This change may create a plant soil feedback favoring future A. retroflexus invasions. 相似文献