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排序方式: 共有409条查询结果,搜索用时 15 毫秒
1.
Ren Reiser Viktor Stadelmann Peter Weisskopf Lina Grahm Thomas Keller 《植物养料与土壤学杂志》2020,183(3):316-326
Oxygen diffusion rate (ODR) and redox potential (EH) are quantitative indices representing oxygen availability and redox status in soils, which is valuable information for better understanding causes and effects of soil aeration. Because these indices are spatially and temporally highly variable, continuous measurements and adequate numbers of repetitions are essential for accurate in situ monitoring. Here, we present a new, fully automated recording system for in situ measurements where ODR and EH are measured at the same platinum electrode. The conflict between electrode polarization for ODR and the resulting biased EH readings is solved by reducing the polarization time and introducing a recovery interval between two consecutive measurement cycles. The shorter polarization time ensures accurate EH readings. It also results in moderately overestimated ODR readings, but this can be corrected before data analysis. The recovery interval restricts temporal resolution of the EH‐ODR data pairs to 8 h. We illustrate the use of the system with measurements in a field experiment in Zürich, Switzerland. ODR curves at different depths ran roughly parallel to the corresponding curves of O2 concentration in soil air but ODR was much more sensitive to precipitation. Low ODR was a necessary but not a sufficient condition for declining EH. EH ran parallel to O2 concentration in soil air rather than to ODR. The fully automated system allows for time series of replicate measurements in multifactorial field studies with reasonable labor requirements. It may be particularly suitable for studies examining the effects of soil tillage, compaction, and irrigation, where structure‐related soil properties such as porosity, gas permeability, and soil aeration play a dominant role. 相似文献
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根际通气对盆栽番茄生长及水分利用率的影响 总被引:1,自引:0,他引:1
为探索适宜作物生长的水气环境,在3种土壤水分水平下,采用50%土壤孔隙率的1.6,1.2,0.8,0.4,0五种通气系数等处理方法,研究了根际通气对盆栽番茄生长指标与根系生长,以及水分利用率的影响.结果表明:适宜的土壤水分与适宜的通气量相结合对番茄生长具有显著的促进作用,通气处理促进了番茄植株的生长,提高了番茄的根系活... 相似文献
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The venturi aeration is an effective practice to increase the dissolved oxygen accessibility in the water bodies. This study aims to optimize the various geometrical parameters of the venturi aeration system. A non-dimensional technique was applied to find the optimum performance of various geometric parameters i.e. throat lengths (tl), number of air holes (N), and converging and diverging angles (α and β). These experiments have been carried out using 1124 L capacity of tank having dimensions of 105 cm long, 105 cm wide and 102 cm deep. The experiments were conducted at a constant flow velocity of water (1.096 m/s) with varying throat length (tl = 20–100 mm keeping 20 mm as interval between two consecutive length), number of air holes (N = 1–17 at an equal hole to hole distance of 5 mm between them), and converging and diverging angles (α and β = 10°, 15°, 20° and 25°). Multiple non-linear regression equations were also developed from the linear relation with the dependent variable (Non-dimensional form of standard aeration efficiency, NDSAE) and independent variables (tl and N). With the geometrically optimized venturi aerator the optimum performance was found for tl =100 mm, N = 17, and α and β = 15°. The maximum value of standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) obtained was 0.0216 kgO2/h and 0.611 kgO2/kWh respectively. From the non-dimensional study, it was found that the NDSAE is the function Reynolds number (Re) and Froude number (Fr). The simulation equations were developed on the basis of Re and Fr for NDSAE, and subjected to 7.378 × 10−6 < Re < 3.689 × 10-5 and 0.163 < Fr < 0.817, respectively. 相似文献
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Through introducing the principle of bubbleless aerated membrane bioreactor, the traditional membrane bioreactor was improved. It could be obtained that the removal efficiency of COD and NH3 - N in bubbleless aerated membrane bioreactor increased 4% and 2% than that in traditional membrane bioreactor, respectively. Adopting bubbleless aeration as reflushing air which not only increased DO in the MBR, but also advanced the oxygen utilization, and the energy consumption decreased as well. 相似文献
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Discussion of the Application and Foreground of Falling Water Aeration with the Process of Sewage Treatment 下载免费PDF全文
The engineering design of sewage treatment plant for the Chongqing city, P. R. China is analyzed in this paper. Considering the situation of China and other projects, the characteristics of falling water reactor for the environment protection project and economy of investment is introduced ; the application and foreground of falling water aeration in the process of sewage treatment is discussed, such as Oxidation - ditch, SBR, and so on. The conclusion indicated that the falling water aeration can be designed and used as an independent aeration, and, it is an upgraded technology of sewage treatment which is adaptive for city water environment control in middle and small towns in China. The falling water aeration may reduce running cost of the sewage treatment plant, is adaptive for foothill and the mountainous areas, and reduces project investment and environments damage. 相似文献
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