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Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes (PPMMs). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FT-IR) and scanning electron microscope (SEM) were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor (MBR), filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied. 相似文献
94.
Benchmarking Optical/Thermal Satellite Imagery for Estimating Evapotranspiration and Soil Moisture in Decision Support Tools
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Jan M.H. Hendrickx Richard G. Allen Al Brower Aaron R. Byrd Sung‐ho Hong Fred L. Ogden Nawa Raj Pradhan Clarence W. Robison David Toll Ricardo Trezza Todd G. Umstot John L. Wilson 《Journal of the American Water Resources Association》2016,52(1):89-119
Generally, one expects evapotranspiration (ET) maps derived from optical/thermal Landsat and MODIS satellite imagery to improve decision support tools and lead to superior decisions regarding water resources management. However, there is lack of supportive evidence to accept or reject this expectation. We “benchmark” three existing hydrologic decision support tools with the following benchmarks: annual ET for the ET Toolbox developed by the United States Bureau of Reclamation, predicted rainfall‐runoff hydrographs for the Gridded Surface/Subsurface Hydrologic Analysis model developed by the U.S. Army Corps of Engineers, and the average annual groundwater recharge for the Distributed Parameter Watershed Model used by Daniel B. Stephens & Associates. The conclusion of this benchmark study is that the use of NASA/USGS optical/thermal satellite imagery can considerably improve hydrologic decision support tools compared to their traditional implementations. The benefits of improved decision making, resulting from more accurate results of hydrologic support systems using optical/thermal satellite imagery, should substantially exceed the costs for acquiring such imagery and implementing the remote sensing algorithms. In fact, the value of reduced error in estimating average annual groundwater recharge in the San Gabriel Mountains, California alone, in terms of value of water, may be as large as $1 billion, more than sufficient to pay for one new Landsat satellite. 相似文献
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The Effect of Water Harvesting Techniques on Runoff,Sedimentation, and Soil Properties 总被引:1,自引:0,他引:1
This study addressed the hydrological processes of runoff and sedimentation, soil moisture content, and properties under the
effect of different water harvesting techniques (treatments). The study was conducted at three sites, representing environmental
condition gradients, located in the southern part of the West Bank. For each treatment, the study evaluated soil chemical
and physical properties, soil moisture at 30 cm depth, surface runoff and sedimentation at each site. Results showed that
runoff is reduced by 65–85% and sedimentation by 58–69% in stone terraces and semi-circle bunds compared to the control at
the semi-humid site. In addition, stone terraces and contour ridges significantly reduced the amount of total runoff by 80%
and 73%, respectively, at the arid site. Soil moisture content was significantly increased by water harvesting techniques
compared to the control in all treatments at the three study sites. In addition, the difference between the control and the
water harvesting structures were higher in the arid and semi-arid areas than in the semi-humid area. Soil and water conservation,
via utilization of water harvesting structures, is an effective principle for reducing the negative impact of high runoff
intensity and subsequently increasing soil moisture storage from rainfall. Jessour systems in the valley and stone terraces
were effective in increasing soil moisture storage, prolonging the growing season for natural vegetation, and decreasing the
amount of supplemental irrigation required for growing fruit trees. 相似文献
96.
Gas/particle partitioning of atmospheric PCDD/Fs in a satellite town in Eastern China 总被引:3,自引:0,他引:3
Meng-xia Xu Jian-hua Yan Sheng-yong Lu Xiao-dong Li Tong Chen Ming-jiang Ni Hui-fen Dai Fei Wang Ke-fa Cen 《Chemosphere》2009,76(11):1540-1549
Gas/particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air was investigated in a satellite town in Eastern China from April 2007 to January 2008 comprehending large temperature variations (from 3 to 34 °C, daily average). Molecular weight, molecular structure and ambient temperatures are the three major factors that govern the gas/particle partitioning of atmospheric PCDD/Fs throughout the year. Generally, good agreements were obtained (except for winter) between measured particulate fractions and theoretical estimates of both the Junge–Pankow adsorption model and Harner Bidleman absorption model using different sets of subcooled liquid vapor pressure and octanol–air partition coefficient (Koa), respectively. Models utilizing estimates, derived from gas chromatographic retention indices (GC-RIs), are more accurate than that of entropy-based. Moreover, during winter, the Koa-based model using the GC-RIs approach performs better on lower chlorinated PCDD/Fs than that of -based. Furthermore, possible sources of mismatch between measured and predicted values in winter (3–7 °C) were discussed. Gas adsorption artifact was demonstrated to be of minor importance for the phenomena observed. On the other hand, large deviations of slopes (mr) and intercepts (br) in logKp vs. plots from theoretical values are observed in the literature data and these are found to be linearly correlated with ambient temperatures (P<0.001) in this study. This indicates that the non-equilibrium partitioning of PCDD/Fs in winter may be significantly influenced by the colder temperatures that may have slowed down the exchange between gaseous and particulate fractions. 相似文献
97.
Profile of Methane Concentrations in Soil and Atmosphere in Alpine Steppe Ecosystem on Tibetan Plateau 总被引:1,自引:1,他引:0
Pei Zhiyong Ouyang Hua Zhou Caiping Xu Xingliang . The Administrative Center for China’s Agenda Beijing China . Interntional Center for Integrated Mountain Development Kathm a Nepal . Institute of Geographical Sciences Natural Resources Research CAS Beijing 《中国人口.资源与环境(英文版)》2009,7(1):3-10
The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe located in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occurring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steadystable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were significantly correlated (R^2〉0.6) with each other comparing to the weak correlations (R^2〈0.2) between the atmospheric concentra- tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were determined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area. 相似文献
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Alexei V. Uvarov 《Environmental monitoring and assessment》2000,60(3):337-357
Long-term charcoal production in small private charcoal kilns (CK) in Eastern Bieszczady Mts. (SE Poland) can cause local smoke contamination of the ambient forest environment. Responses of model soil systems, contaminated or not contaminated by CK smoke, to contrasting combinations of hydrothermic regimes were compared in laboratory microcosms (respiration of soil community, decomposition rate of soil organic matter and cotton stripes, herb seeds germination were studied). The majority of the obtained data show a markedly higher level of soil biological activity in the CK versus the control series. In some cases CK and control soil systems show different patterns of reactions to the tested combinations of microclimate regime. These phenomena should at least partly be attributed to the effects of CK pollution. 相似文献