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991.
992.
2,4-二硝基苯肼固相吸附/高效液相色谱法测定车内空气中醛酮类物质 总被引:3,自引:0,他引:3
建立了2,4-二硝基苯肼固相吸附/高效液相色谱同时测定车内空气中4种醛酮类物质的方法,研究了固相吸附采样和前处理方法,优化了试验条件。4种醛酮类物质在一定质量范围内工作曲线线性良好,甲醛、乙醛、丙烯醛、丙酮的检出限分别为0.075μg/m^3、0.207μg/m^3、0.715μg/m^3、0.159μg/m^3(按采样体积12L计),实际样品测定的RSD为7.5%-9.7%。 相似文献
993.
变色酸比色法测定甲胺生产废水中甲醇 总被引:4,自引:0,他引:4
建立了变色酸比色测定甲胺生产废水中甲醇的方法,确定了最大吸收波长,优化了试验条件。方法在0mg/L-7.00mg/L范围内线性良好,检出限为0.07mg/L,标准溶液测定的RSD≤0.9%,废水样品的加标回收率为98.8%-101%。 相似文献
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为了研究使用随机化Pushover方法进行RC框架结构整体抗震可靠度计算过程中相关参数的适应性,使用Matlab调用SAP2000编制出基于随机化Pushover的结构整体抗震可靠度程序,以一榀11层RC框架结构为例,通过该程序统计出不同参数下结构最大层间位移角的分布情况及整体失效概率,并以大样本实际地震波进行时程分析所统计出的相应结果为基准进行对比。结果表明,在常规参数设置下随机化Pushover方法统计出的最大层间位移角分布情况和结构整体失效概率与大样本时程分析结果有较大差异,然后提出了一种修正方式,有效地减小了两者的差异,并以某算例验证了该修正方式的适用性。 相似文献
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The littoral zone in the Three Gorges Reservoir, China: challenges and opportunities 总被引:3,自引:0,他引:3
Xing-zhong Yuan Yue-wei Zhang Hong Liu Sen Xiong Bo Li Wei Deng 《Environmental science and pollution research international》2013,20(10):7092-7102
For flood control purpose, the water level of the Three Gorges Reservoir (TGR) varies significantly. The annual reservoir surface elevation amplitude is about 30 m behind the dam. Filling of the reservoir has created about 349 km2 of newly flooded riparian zone. The average flooding period lasts for more than 6 months, from mid-October to late April. The dam and its associated reservoir provide flood control, power generation, and navigation, but there are also many environmental challenges. The littoral zone is the important part of the TGR, once its eco-health and stability are damaged,which will directly endanger the ecological safety of the whole reservoir area and even the Yangtze River Basin. So, understanding the great ecological opportunities which are hidden in littoral zone of TGR (LZTGR) and putting forward approaches to solve the environmental problems are very important. LZTGR involves a wide field of problems, such as the landslides, potential water pollution, soil erosion, biodiversity loss, land cover changes, and other issues. The Three Gorges dam (TGD) is a major trigger of environmental change in the Yangtze River. The landslides, water quality, soil erosion, loss of biodiversity, dam operation, and challenge for land use are closely interrelated across spatial and temporal scales. Therefore, the ecological and environmental impacts caused by TGD are necessarily complex and uncertain. LZTGR is not only a great environmental challenge but also an ecological opportunity for us. In fact, LZTGR is an important structural unit of TGR ecosystem and has special ecosystem services function. Vegetation growing in LZTGR is therefore a valuable resource due to accumulation of carbon and nutrients. Everyone thinks that the ecological approach to the problem is needed. If properly designed, dike–pond systems, littoral woods systems, and re-created waterfowl habitats will have the capacity to capture nutrients from uplands and obstruct soil erosion. Ecological engineering approaches can therefore reduce environmental impacts of LZTGR and optimize ecological services. In view of the current situation and existing ecological problems of LZTGR, according to function demands such as environmental purification, biodiversity conservation, and vegetation carbon sink enhancement, we should explore the eco-friendly utilization mode of resources in LZTGR. Ecological engineering approaches might minimize the impacts or optimize the ecological services. Natural regeneration and ecological restoration in LZTGR are valuable for soil erosion decrease, pollutant purification, biodiversity conservation, carbon sink increase, and ecosystem health maintenance in TGR. 相似文献
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Feng XH Zhai LM Tan WF Liu F He JZ 《Environmental pollution (Barking, Essex : 1987)》2007,147(2):366-373
Several Mn oxide minerals commonly occurring in soils were synthesized by modified or optimized methods. The morphologies, structures, compositions and surface properties of the synthesized Mn oxide minerals were characterized. Adsorption and redox reactions of heavy metals on these minerals in relation to the mineral structures and surface properties were also investigated. The synthesized birnessite, todorokite, cryptomelane, and hausmannite were single-phased minerals and had the typical morphologies from analyses of XRD and TEM/ED. The PZCs of the synthesized birnessite, todorokite and cryptomelane were 1.75, 3.50 and 2.10, respectively. The magnitude order of their surface variable negative charge was: birnessite> or =cryptomelane>todorokite. The hausmannite had a much higher PZC than others with the least surface variable negative charge. Birnessite exhibited the largest adsorption capacity on heavy metals Pb(2+), Cu(2+), Co(2+), Cd(2+) and Zn(2+), while hausmannite the smallest one. Birnessite, cryptomelane and todorokite showed the greatest adsorption capacity on Pb(2+) among the tested heavy metals. Hydration tendency (pK(1)) of the heavy metals and the surface variable charge of the Mn minerals had significant impacts on the adsorption. The ability in Cr(III) oxidation and concomitant release of Mn(2+) varied greatly depending on the structure, composition, surface properties and crystallinity of the minerals. The maximum amounts of Cr(III) oxidized by the Mn oxide minerals in order were (mmol/kg): birnessite (1330.0)>cryptomelane (422.6)>todorokite (59.7)>hausmannite (36.6). 相似文献
1000.
4种沉水植物对白洋淀富营养化水体净化效果的研究 总被引:4,自引:0,他引:4
利用白洋淀富营养化的湖水和底泥与蓖齿眼子菜、马来眼子菜、金鱼藻和黑藻4种沉水植物分别组成室内静态模拟的生长体系,研究4种沉水植物在白洋淀富营养化环境下的生长状况,以及不同沉水植物生长体系对水体磷、氮及有机物的净化效果。结果表明:试验所用沉水植物对富营养化湖水、底泥具有一定的耐受能力,在试验条件中生长良好,长度与生物量都明显增加,并能有效地降低水体中的总磷、氨氮及总氮浓度。试验21 d后,蓖齿眼子菜、马来眼子菜、金鱼藻和黑藻所在的生长体系对水体中总磷的去除能力分别为:4.68、4.72、4.92和5.03μg·d-1·g-1,去除率分别为:83.59%、84.35%、87.84%和89.88%;对水体中氨氮的去除能力分别为:11.42、10.75、12.02和11.90μg·d-1·g-1,去除率分别为:74.98%、70.58%、78.96%和78.11%;对总氮的去除能力分别为:37.69、39.79、42.02和41.65μg.d-1.g-1,去除率分别为:79.40%、83.82%、88.51%和87.73%。沉水植物生长体系对CODcr的降解有所反复,但整体呈现下降趋势。不同沉水植物生长体系总磷、总氮含量随时间降解的拟合方程表明,水体总磷、总氮浓度随时间的变化呈负指数形式衰减。沉水植物对水体营养盐浓度的影响通过多种途径实现,底泥在营养盐的归趋中起着重要的作用。 相似文献