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Mohamed Galal Eltarabily Abdelazim M. Negm Chihiro Yoshimura Jiro Takemura 《Environmental Modeling and Assessment》2018,23(3):289-308
Different scenarios of recharge and discharge were assessed for sustainable management of groundwater in Quaternary aquifer east of Nile Delta. MODFLOW was utilized to investigate the effect of land use change and damming construction in the upstream of the Nile River on the current and short-term groundwater management strategies. The interpretive transient simulation was performed between 2004 and 2016 after steady-state calibration in 2004, and transient state from 2004 to 2013 with different irrigation recharges associated with land use change in this period. Sensitivity analysis was performed for hydraulic conductivities, recharge, and conductance parameters. The predictive transient simulation was run till 2023 under three scenarios of increasing pumping rates by 15, 30, and 50% for agriculture expansion and specified head reduction of Port Said Canal by 0.2, 0.4, and 0.6 m associated with the reduction of Nile water levels after Grand Ethiopian Residence Dam, GERD operation in 2017. Results from the in- and out-flow budgets showed that groundwater aquifer is stable at the current rate of pumping till 2023. Groundwater heads decreased by 0.2 and 0.42 m in the southern section, and a slight increase in the northern part was noticed for the first and second scenarios, respectively. When additional pumping stress is applied (50% increase), groundwater head dropped by 0.66 m, and the storage is no longer able to maintain the aquifer capacity after 2020 (worst-case scenario). 相似文献
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Hideo Nakajima Akihiko Hirooka Jiro Takemura Miguel A. Mario 《Journal of the American Water Resources Association》1998,34(6):1415-1425
ABSTRACT: One-dimensional contaminant transport through a saturated soil is modeled using a 1.2-m radius geotechnical centrifuge. Small-scale physical modeling in the centrifuge is achieved in relatively short time, at stress distributions that are similar to those experienced in the prototype (actual site). A 0.05 mol/l of sodium chloride solution is used as a contaminant and conductivity cells measure the concentration of the contaminant throughout the porous medium. Scaling analysis for centrifuge modeling and 1-g modeling are briefly discussed and it is concluded that centrifuge modeling simulates the effect of molecular diffusion; however, scaling of the effect of mechanical dispersion may be violated in the centrifuge if the interstitial fluid velocity is high. Centrifuge test results show good agreement with the predicted relationship between the coefficient of hydrodynamic dispersion and the Peclet number using column tests. Centrifuge modeling can be used as a complement of numerical modeling although the effect of mechanical dispersion may be overestimated in the former. 相似文献
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Masanori Terasaki Yoshiharu Takemura Masakazu Makino 《Environmental Chemistry Letters》2012,10(4):401-406
This article reports the first identification of paraben-chlorinated derivatives in river water. Parabens are widely used as preservatives in pharmaceuticals and personal care products. Parabens can be easily chlorinated by chlorinated tap water. The resulting chlorinated derivatives might pose a higher potential risk to humans and ecosystems than the corresponding parent parabens. However, the occurrence of such derivatives in rivers remains unknown so far. We studied 23 parabens and their chlorinated derivatives from rivers receiving effluents from sewage treatment plants in Shizuoka city, in the central Pacific region of Japan. The compounds were extracted by solid-phase extraction with a styrene polymer sorbent, trimethylsilyl-derivatized, and then identified by gas chromatography–mass spectrometry. Six chlorinated parabens and their primary degradation products, two chlorinated hydroxybenzoic acids, were found for the first time in river water. Moreover, in river water, chlorinated derivatives preferentially partition into the suspended-solid phase. 相似文献
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Michihiro Mochida Kimitaka Kawamura Pingqing Fu Toshihiko Takemura 《Atmospheric environment (Oxford, England : 1994)》2010,44(29):3511-3518
Levoglucosan is considered as a useful molecular tracer of biomass-burning aerosols in the atmosphere. To characterize the seasonal variation of its concentrations over the Pacific Ocean and to assess its usefulness as a tracer after long-range transport, we investigated long-term variations of levoglucosan over Chichi-jima in the western North Pacific, from 2001 to 2004. Organic carbon (OC), elemental carbon (EC) and d-glucose were analyzed for comparison. The seasonal variation of levoglucosan concentrations showed a maximum in the winter, which is consistent with the enhanced Asian outflow to the Pacific indicated by backward air-mass trajectories. The concentration levels of levoglucosan estimated from global aerosol model outputs in the winter are, on average, comparable to the observed levels, suggesting that a considerable fraction of levoglucosan did not decompose during long-range transport from the Asian continent by westerly/northwesterly winds. This result is supported by comparable ratios of levoglucosan to EC in Chichi-jima and the East Asian coastal region. Conversely, the measured concentrations of levoglucosan in the summer were significantly lower than the modeled one. This implies a degradation of levoglucosan in the air masses that stagnated over the Pacific, although uncertainties in the model estimate may also be partly responsible for this discrepancy. One possible degradation pathway is oxidation by OH radicals; the contribution of acid-catalyzed reactions needs further investigation. 相似文献
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Recycled Natural Fiber Polypropylene Composites: Water Absorption/Desorption Kinetics and Dimensional Stability 总被引:1,自引:0,他引:1
Detailed analysis of the effects of recycling process on long-term water absorption, thickness swelling and water desorption
behavior of natural fiber polypropylene composites is reported. Composite materials containing polypropylene and wood flour,
rice hulls or bagasse fibers were produced at constant fiber loading and were exposed to a simulated recycling process consisting
of up to five times grinding and reprocessing under controlled conditions. A wide range of analytical methods including water
absorption/desorption tests, thickness swelling tests, density measurement, scanning electron microscopy, image analysis,
contact angle, fiber length analysis and Fourier transform infrared spectroscopy was employed to understand the hygroscopic
behavior of the recycled composites. Water absorption and thickness swelling behaviors were modeled using existing predictive
models. Results indicated that generally the recycled composites had considerably lower water absorption and thickness swellings
as compared with the original composites which were attributed to changes in physical and chemical properties of the composites
induced by the recycling process. 相似文献
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Ryutaro Ohtsuka Tetsuro Hongo Toshio Kawabe Tsuguyoshi Suzuki Tsukasa Inaoka Tomoya Akimichi Hideo Sasano 《Environment international》1985,11(6):505-508
This study presents concentration of nine minerals (Na, K, Mg, Ca, Cl, Mn, Zn, Cd, Pb) in 31 drinking water samples collected in the Papua New Guinea lowland, where coastal villagers draw water from artificial wells blended with sea water, riverside villagers utilize brackish river water, and inland villagers fetch creek or swamp water whose chemical composition is close to rain water. During the dry season, the coastal well water contains 500 mgL−1 of sodium and 50–90 μgL−1 of lead. The inland creek or swamp water contains very small amount of minerals; on the average, for instance, 0.64 mgL−1 of magnesium, 0.84 mgL−1 of calcium, and 4.78 mgL−1 of water hardness (as CaCO3). From some epidemiological evidence in industrialized countries, these mineral concentrations are judged to be indicative of high risk of cardiovascular disorders. 相似文献