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991.
久效磷对黄鳝乙酰胆碱酯酶、羧酸酯酶和磷酸酶活性的影响 总被引:5,自引:0,他引:5
采用静态急性毒性实验方法,研究了久效磷对黄鳝脑乙酰胆碱酯酶及肝脏、肾脏羧酸酯酶、碱性磷酸酶、酸性磷酸酶活性的影响.结果表明,在水温(20±2)℃条件下,经0.25 mg·L-1、0.50 mg·L-1、1.00mg·L-1和2.00mg·L-1的久效磷暴露96 h,黄鳝肝脏、肾脏羧酸酯酶和脑乙酰胆碱酯酶活性均显著下降,但两者表现出不同的抑制模式.随着暴露质量浓度的升高,肝脏和肾脏羧酸酯酶活性的下降幅度逐渐变小,而脑乙酰胆碱酯酶活性下降幅度却由小变大.久效磷暴露黄鳝96 h,肝脏、肾脏酸性磷酸酶活性均升高;而肝脏碱性磷酸酶活性升高;肾脏碱性磷酸酶活性降低.久效磷暴露质量浓度与脑乙酰胆碱酯酶和肝脏、肾脏羧酸酯酶活性之间具有剂量-效应关系,酸性磷酸酶和碱性磷酸酶可能在鱼体抵御有机磷农药毒性作用中有着重要的作用,其机理有待进一步研究.此外,本文还探讨了有机磷农药靶标酶乙酰胆碱酯酶和解毒酶羧酸酯酶、磷酸酶之间的相关性. 相似文献
992.
Phytoremediation of Cadmium-Contaminated Soils by Rorippa globosa Using Two-Phase Planting (5 pp) 总被引:1,自引:0,他引:1
Background Phytoextraction of contaminated soils by heavy metals can provide a great promise of commercial development. Although there
are more than 400 species of hyperaccumulators found in the world, phytoremediation technology is rarely applied in field
practice for remedying contaminated soils, partially due to low biomass and long growth duration for most of discovered hyperaccumulating
plants. In order to enhance the metal-removing efficiency in a year, the two-phase planting countermeasure of phytoextraction
by harvesting anthesis biomass was investigated on the basis of the newly found Cd-hyperaccumulator Rorippa globosa (Turcz.)
Thell. with 107.0 and 150.1 mg/kg of the Cd accumulation in stems and leaves, respectively, when soil Cd added was concentrated
to 25.0 mg/kg.
Methods The field pot-culture experiment was used to observe the distribution property of R. globosa aboveground biomass and to examine
characteristics of accumulating Cd by the plant at different growth stages. The concentration of Cd in plants and soils was
determined using atomic absorption spectrophotometry (AAS).
Results and Discussion The results indicated that the total dry stem and leaf biomass of R. globosa harvested at the flowering phase was up to 92.3%
of that at its full maturity and the concentration of Cd in stems and leaves harvested at the flowering phase was up to 73.8%
and 87.7% of that at the mature phase, respectively. The Cd-removing ratio by shoots of R. globosa harvested at the flowering
phase was up to 71.4% of that at the mature phase. It was also found, by observing the growth duration of R. globosa, that
the frostless period at the experiment site was twice as long as the growth time from the seedling-transplanted phase to the
flowering phase of the hyperaccumulator.
Conclusion R. globosa could be transplanted into contaminated soils twice in one year by harvesting the hyperaccumulator at its flowering
phase based on climatic conditions of the site and traits of the plant growth. In this sense, the extraction efficiency of
Cd in shoots of R. globosa increased 42.8% compared to that of at its single maturity when the plant was transplanted into
contaminated soils after it had been harvested at its flowering phase and the plant accumulated Cd from soil at the same extraction
ratio at its second flowering phase. Thus, the method of anthesis biomass regulation by the two-phase planting is very significant
to increase the Cd-removing efficiency by phytoremediation used in practice over the course of a year.
Recommendation and Outlook As for some hyperaccumulators that the growth duration from the seedling-transplanted phase to the flowering phase are short
and the concentrations of heavy metals accumulated in their shoots at the flowering phase are high, the efficiency of phytoremediation
can greatly be improved using the method of the two-phase planting. 相似文献
993.
近年来我国大气重污染频发,严重影响民生,其中以京津冀最为严重.2017年"总理基金"启动,同年冬防效果显著.衡水市作为"2+26"城市之一,空气质量排名常年处于倒数十名之内.经过2017年的冬防,空气质量明显改善,衡水市大气污染的改善在"2+26"城市中很具有代表性.本文以衡水作为切入点,利用后向轨迹和浓度权重轨迹分析(CWT)探讨了2017年衡水冬防效果及潜在源区变化,分别从气象轨迹和本地排放初探了潜在原因.结果表明,2017年冬防效果显著,PM_(2.5)浓度降低33%,优良天数增加32 d,重污染天数减少22 d.PM_(10)浓度降低41%,优良天数增加40 d.2017年冬季PM_(2.5)潜在源区由2016年同期衡水北部及以北地区向衡水南部及以南地区转移.PM_(10)潜在源分布变化与PM_(2.5)相似.两年气象条件的对比结果表明,气象变化较小,对潜在源分布影响不大,本地排放是潜在源区分布变化的主要原因,其中衡水北部工业锅炉和扬尘减排量显著高于衡水南部.研究表明,2017年衡水冬防效果显著,相比于气象条件,本地排放对大气颗粒污染及来源影响更大,本研究可为"2+26"城市大气颗粒污染研究提供参考. 相似文献
994.
油层注水过程中水质不合要求的危害及保护措施 总被引:1,自引:0,他引:1
分析了油田在二次采油注水过程中,对水质的要求,讨论了水质不合格带来的危害并提出了保护措施. 相似文献
995.
北京市天然气公交车的发展现状及前景 总被引:2,自引:0,他引:2
随着石油资源短缺、城市空气污染问题的日益严重,天然气汽车作为一种实用的低排放汽车逐渐得到了重视和应用。本文首先通过汽车与能源、汽车与环境两个方面,分析说明了北京市发展天然气汽车的重要性;然后简要介绍了北京市天然气公交车的发展现状、未来几年的发展规划,最后指出了实现发展规划的条件和政策。 相似文献
996.
997.
998.
The paper outlines an experimental study on influence of the spark duration and the vessel volume on explosion parameters of premixed methane–air mixtures in the closed explosion vessels. The main findings from these experiments are: For the weaker ignition the spark durations in the range from 6.5 μs to 40.6 μs had little impact on explosion parameters for premixed methane–air mixtures in the 5 L vessel or 20 L vessel; For the same ignitions and volume fractions of methane in air the explosion pressures and the flame temperatures in both vessels of 5 L and 20 L were approximately the same, but the rates of pressure rises in both vessels of 5 L and 20 L were different; The explosion indexes obtained from the measured pressure time histories for both vessels of 5 L and 20 L were approximately equal; For the weaker ignition with the fixed spark duration 45 μs the ignition energies in the range from 54 mJ to 430 mJ had little impact on the explosion parameters; For the same ignition and the volume fractions of methane in air, the vessel volumes had a significant impact on the flame temperatures near the vessel wall; The flame temperatures near the vessel wall decreased as the vessel volumes increased. 相似文献
999.
1000.
尾矿库能否安全运行的影响因素之一就是渗流问题。而降雨又是影响尾矿库渗流场的一个重要因素。运用ANSYS有限元软件的热力学模块建模,计算了3种干滩长度、3种降雨量及7种雨型,共计63种组合工况。分析计算发现,降雨时干滩长度越长,尾矿库出口节点渗透压上升越高。由此可知降雨时,如果尾矿库干滩面未做防渗排水防护措施,那么干滩长度越长对坝体的稳定越不利。建议尾矿库工程设计过程中考虑在干滩面设置防渗排水设施。 相似文献