Water Excess Conditions Research Articles

Numerical and Experimental Research on Gas Production from Methane Hydrate under Water–Excess Conditions

A combination of experimental observations and numerical simulations was used to investigate the methane hydrate dissociation properties. To study the impact of water saturation heterogeneity on hy...

Efecto de la temperatura y la precipitación durante el llenado de grano sobre la dormición y sensibilidad al agua en granos de cebada (Hordeum vulgare L.)


 Los granos de cebada (Hordeum vulgare L.) pueden presentar dormición y sensibilidad al agua poscosecha, que retrasan su utilización industrial. Ambas dependen del genotipo y del ambiente durante la maduración del grano. Con el fin de analizar el efecto de la temperatura media y las precipitaciones acumuladas durante y en el tercio final del llenado de grano, sobre la dormición y la sensibilidad al agua y la relación entre ellas, fueron sembrados tres cultivares de cebada en cuatro fechas durante el 2009 y dos durante 2011. Se registraron temperaturas y precipitaciones diarias desde antesis a madurez fisiológica. La dormición se evaluó como la germinación a los 12 días pos-madurez fisiológica y la sensibilidad al agua como la germinación en exceso de agua, a los 100 días pos-madurez fisiológica. Las variables que presentaron mejor correlación con germinación y sensibilidad al agua fueron la temperatura media y las precipitaciones acumuladas durante el llenado de grano. Ambientes con mayores temperaturas medias durante el llenado de grano disminuyeron la dormición, pero la disminución de la sensibilidad al agua dependió del cultivar. El incremento de las precipitaciones durante el llenado de grano disminuyó la dormición, pero aumentó la sensibilidad al agua en los tres cultivares. 

Variabilidad climática y disponibilidad hídrica en los valles de Ubaté, Chiquinquira y Alto Chicamocha, Colombia

En este estudio se analiza la variabilidad climática de dos regiones de importancia agropecuaria en los departamentos de Boyacá y Cundinamarca (Colombia). Se identifican comportamientos modales de variables climáticas de interés agropecuario, así mismo, se realiza el análisis intra-anual de eventos extremos y se identifican áreas con deficiencias y excesos hídricos a través de un balance hidroclimático. Además, se identifican zonas con mayor frecuencia de condiciones de deficiencias y excesos hídricos en el suelo a escala mensual por medio del Índice de Severidad de Sequía de Palmer (PSDI). Los resultados indican que ambas zonas de estudio no muestran grandes diferencias climáticas entre sí, sin embargo, es importante realizar el estudio por separado con la intención de proporcionar información local de utilidad para los productores. Saboyá en el Valle de Ubaté y Chiquinquirá y Sotaquirá en el Alto Chicamocha son altamente afectados por eventos tanto de deficiencia como exceso hídrico. El evento El Niño 1997 tuvo un impacto más fuerte en el área del Valle de Ubaté y Chiquinquirá, mientras que en el Alto Chicamocha se registró la mayor reducción de la precipitación en 1992, lo que coincidió con un evento El Niño. En cuanto a excesos hídricos, 2011 registró aumentos superiores a 50% en la precipitación en las regiones del estudio, este comportamiento responde al evento La Niña registrado ese año.

Goosegrass: Morphophysiological Characterization Under Water Excess Conditions

ABSTRACT: Eleusine indica (L.) Gaertn. (goosegrass) is a grass species that has global prominence as a weed in areas typical of the soybean crop. However, its dispersion in recent years has been reported expressively for areas of poorly drained soil, in which irrigated rice is cultivated (lowlands). Little is known on its behavior and biology in this different ecosystem. This study aimed to evaluate if Eleusine indica can survive and withstand flooding. The experimental design was a completely randomized (two-way), in which two E. indica biotypes, one from the uplands (without flooding) and the other from the lowlands (with flooding), were submitted to three soil water conditions: 50 and 100% water retention capacity and soil under water depth. Photosynthetic and gas exchange parameters (photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration, water use efficiency, and assimilation rate by Rubisco) were determined. Morphological diversity of biotypes was evaluated through descriptors. The existence of typical lowland biotype could not be characterized. However, both biotypes were able to survive, develop, and generate seeds in a flooded environment in the irrigated rice system.

On the impact of water activity on reversal tolerant fuel cell anode performance and durability

Abstract Durability of polymer electrolyte fuel cells in automotive applications can be severely affected by hydrogen starvation arising due to transients during the drive-cycle. It causes individual cell voltage reversal, yielding water electrolysis and carbon corrosion reactions at the anode, ultimately leading to catastrophic cell failure. A popular material-based mitigation strategy is to employ a reversal tolerant anode (RTA) that includes oxygen evolution reaction (OER) catalyst (e.g., IrO 2 ) to promote water electrolysis over carbon corrosion. Here we report that RTA performance surprisingly drops under not only water-deficient but also water-excess conditions. This presents a significant technical challenge since the most common triggers for cell reversal involve excess liquid water. Our findings from detailed electrochemical diagnostics and nano-scale X-ray computed tomography provide insight into how automotive fuel cells can overcome critical vulnerabilities using material-based solutions. Our work also highlights the need for improved materials, electrode designs, and operation strategies for robust RTAs.

Physiologycal Responses of Rice Crop to Water Deficit and Water Excess Conditions

Physiologycal Responses of Rice Crop to Water Deficit and Water Excess Conditions

Protonation in germanium equivalents of ringwoodite, anhydrous phase B, and superhydrous phase B

To gain insight into hydroxyl solubilities and possible hydration mechanisms of mantle silicates, as well as to test the utility of germanium analog models in studies of water-related defects, our present work is focused on the protonation of germanium analogs of silicates. For this purpose Ge-analogs of ringwoodite, anhydrous phase B (anhB), and for the first time, superhydrous phase B (shyB), were synthesized in a piston cylinder device at 2 GPa and 950-1000 °C under water-excess conditions. Electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and X-ray diffraction as well as Raman and infrared (IR) spectroscopy were used to characterize the experimental products. Ge-ringwoodite incorporates from 900 to 2200 ppm H 2 O by weight, which is much less than Smyth et al. (2003) observed for the Si-equivalent synthesized at 22 GPa and 1500 °C, but 200× more than published for γ-Mg 2 GeO 4 by Hertweck and Ingrin (2005). In addition to this discrepancy, the incorporation mechanism of H in Ge-ringwoodite also differs from that of Si-ringwoodite. Ge-anhB, which is currently believed to be anhydrous in the Si-system, contains from 2400 to 5300 ppm water by weight. A hydration model for germanate anhB was constructed based on single-crystal X-ray diffraction analysis and IR spectroscopy, in which OH is incorporated via the hydrogarnet substitution [V Ge ·4(OH) O ] x and via vacant Mg sites [V Mg ·2(OH) O ] x . For Ge-shyB the water concentration and incorporation mechanism obtained in this study are identical to results reported for the silicate phase synthesized at 22 GPa and 1200 °C (Koch-Müller et al. 2005). Thus, germanates are good low-pressure analogs for hydrous mantle silicates in which protonation is controlled by stoichiometry. However, for nominally anhydrous minerals we cannot recommend the use of germanates as high-pressure models in water-related studies. In these Ge-analogs, which are usually synthesized at much lower pressures, i.e., lower water fugacities, OH incorporation seems to differ from the high-pressure silicate equivalents qualitatively and quantitatively, as hydroxyl solubility is governed by other factors such as water fugacity and intrinsic defects.

Deficit and excess of soil water impact on plant growth of Lotus tenuis by affecting nutrient uptake and arbuscular mycorrhizal symbiosis

The impact of deficit and excess of soil water on plant growth, morphological plant features, N and P plant nutrition, soil properties, Rhizobium nodulation and the symbiosis between arbuscular mycorrhizal (AM) fungi and Lotus tenuis Waldst. & Kit. were studied in a saline-sodic soil. Water excess treatment decreased root growth by 36% and increased shoot growth by 13% whereas water deficit treatment decreased both root and shoot growth (26 and 32%, respectively). Differences between stress conditions on shoot growth were due to the ability of L. tenuis to tolerate low oxygen concentration in the soil and the sufficiency of nutrients in soil to sustain shoot growth demands. Water excess treatment decreased pH, and increased available P and labile C in soil. Water deficit treatment decreased available P and also increased labile C. In general, N and P acquisition were affected more by water excess than water deficit. The number of nodules per gram of fresh roots only increased in water excess roots (97%). Under both stress conditions there was a significant proportion of roots colonized by AM fungi. Compared to control treatment, arbuscule formation decreased by 55 and 14% under water excess and water deficit, respectively. Vesicle formation increased 256% in water excess treatment and did not change under water deficit treatment. L. tenuis plants subjected to water deficit or excess treatments could grow, nodulated and maintained a symbiotic association with AM fungi by different strategies. Under water excess, L. tenuis plants decreased root growth and increased shoot growth to facilitate water elimination by transpiration. Under water deficit, L. tenuis plants decreased root growth but also shoot growth which in turn significant decreased the shoot/root ratio. In the present study, under water excess conditions AM fungi reduced nutrient transfer structures (arbuscules), the number of entry points and spore, and hyphal densities in soil, but increased resistance structures (vesicles). At water deficit, however, AM fungi reduced external hyphae and arbuscules to some extent, investing more in maintaining a similar proportion of vesicles in roots and spores in soil compared to control treatment.

Oceanic slab melting and mantle metasomatism.

Modern plate tectonic brings down oceanic crust along subduction zones where it either dehydrates or melts. Those hydrous fluids or melts migrate into the overlying mantle wedge trigerring its melting which produces arc magmas and thus additional continental crust. Nowadays, melting seems to be restricted to cases of young (< 50 Ma) subducted plates. Slab melts are silicic and strongly sodic (trondhjemitic). They are produced at low temperatures (< 1000 degrees C) and under water excess conditions. Their interaction with mantle peridotite produces hydrous metasomatic phases such as amphibole and phlogopite that can be more or less sodium rich. Upon interaction the slab melt becomes less silicic (dacitic to andesitic), and Mg, Ni and Cr richer. Virtually all exposed slab melts display geochemical evidence of ingestion of mantle material. Modern slab melts are thus unlike Archean Trondhjemite-Tonalite-Granodiorite rocks (TTG), which suggests that both types of magmas were generated via different petrogenetic pathways which may imply an Archean tectonic model of crust production different from that of the present-day, subduction-related, one.

GAS EXCHANGE, GROWTH, YIELD AND BEVERAGE QUALITY OF COFFEA ARABICA CULTIVARS GRAFTED ON TO C. CANEPHORA AND C. CONGENSIS

Gas exchange, leaf carbon isotope discrimination, growth, yield and beverage quality were evaluated for two Coffea arabica cultivars (Catuai and Mundo Novo), grafted on to C. canephora and C. congensis progenies growing in open fields. During the years 1994 to 1997, grafting resulted in an average increase in bean yield of 151 and 89% for Catuai and Mundo Novo respectively. As analysed by sensory analyses and by the ratio between the mono-isomers and di-isomers of caffeoylquinic acid, beverage quality of the C. arabica was not altered by grafting. Shoot growth was significantly greater in grafted plants, showing an increase of 52% in total leaf area compared with the non-grafted plants. Under conditions of water excess in the soil there was little difference in the transpiration and stomatal conductance rates between the grafted and non-grafted plants, but the net photosynthesis was higher in grafted plants. With an accentuated water deficit in the soil in the dry period, the grafted plants showed significantly higher transpiration and stomatal conductance rates than the non-grafted plants, and similar values to those of C. canephora. Carbon isotope discrimination was greater in the grafted plants, suggesting greater root hydraulic conductance. The results suggest that the better performance of the grafted plants during the dry period was due to the greater capacity of the root system of C. canephora to provide water to the shoot thereby maintaining greater gas exchange in the leaves and consequently a greater carbon gain.

Sequential Cropping as a Function of Water in a Seasonal Tropical Region

In the seasonal (wet–dry) tropics, yields of rainfed staple crops are usually low and variable. However, our simulations have indicated that rainfall could be used more efficiently, increasing the length of the rainfed cropping season, the number of crops grown, and their yields, while decreasing yield variability and risk. To evaluate these predictions, cropping schemes with two or three annual rainfed crops grown in sequence were field‐tested. Irrigated plantings were subsequently added to evaluate year‐round cropping. Work was conducted in Costa Rica during 4 yr at one site and 1 yr at a second site. Both sites have a half‐year‐long, bimodal rainy season, and have deep soils with high water‐holding capacity. The first crop of each year was planted early using preseason rains, and the last was planted to mature after the rainy season to maximize depletion of available soil water. Rainfed cropping sequences averaged 255 d long, which is from 50 to 100 d longer than local practices. Adding an irrigated planting during the dry season brought the mean length of the cropping season up to 346 d. Of 115 plantings, only 7 had low yields; all others had medium or high yields. Adding an irrigated crop increased yield potential of a year‐round cropping season composed of two or more plantings. All low yields were attributed here to extended water excess conditions. However, water excess effects do not remain after the rainy season, nor into the next rainy season.

Infra-red and X-ray diffraction study of the hydration process in the polymer electrolyte system M(CF 3SO 3) 2PEO n for M=Pb, Zn and Ni

Water uptake in the system M(CF 3SO 3) 2PEO n , where M=Ni, Zn and Pb, and n=6–24, has been investigated at room temperature using i.r. spectroscopy and X-ray diffraction. It has been found that the ion-pairing/clustering involving M 2+ and CF 3SO − 3 is highly affected by hydration, with water replacing CF 3SO − 3 at the cation. At intermediate degrees of hydration, the CF 3SO − 3 ions are hydrogen bonded to metal-ion coordinating water molecules. In conditions of water excess, features typical of CF 3SO − 3 ions in aqueous solution are observed. The interaction between PEO and M 2+ is also affected by hydration for M=Ni and Zn. The v(COC) a stretching band is shifted to higher wave numbers, indicating a weakening in the interaction between PEO and a hydrated cation. X-ray diffraction has shown that any crystalline component present in the anhydrous form is destroyed by water uptake.

Melting and subsolidus reactions in the system K2O?CaO?MgO?Al2O3?SiO2?H2O: experiments and petrologic application

Experiments with synthetic starting materials of muscovite, phlogopite, zoisite, kyanite and quartz were performed in the pressure temperature range 10–25 kbar, 640–780° C under water excess conditions. The reaction muscovite+zoisite+quartz+vapor=liquid+kyanite was bracketed at 10.5 kbar/689–700° C, 15.5 kbar/709–731° C and 20 kbar/734–745° C. The equivalent reaction in the Mg-bearing system muscovitess +zoisite+quartz+vapor=liquid+kyanite+phlogopitess lies at the same temperature around 10 kbar and approximately 10° C higher around 20 kbar, compared with the Mg-free reaction. At slightly higher temperatures formation of melt and tremolitess was reversibly observed from the assemblage phlogopitess+zoisite +kyanite+quartz around 10.5 kbar/690–710° C, 15.5 kbar/720–750° C and 20.5 kbar/745–760° C. In the subsolidus region, the reaction muscovitess+talcss+ tremolitess=phlogopitess+zoisite+quartz+vapor were located in the range 700° C/16.7–19.0 kbar and 740° C/19.7–20.8 kbar. From these data, a wedge shaped stability field of phlogopitess+zoisite+quartz appears with a high P, T termination around 21 kbar/755° C. Muscovite+tremolite+talc or kyanite comes in at higher pressures. These phase relations are in qualitative accord with petrographic observations from high pressure metamorphic areas. Formation and crystallization of melts in rocks of a wide compositional range involving zoisite/epidote has been ascribed to relatively high pressures and is consistent with experimentally determined stability fields in the simplified KCMASH system.

The Effect of Different Water Regimes on Growth and Nodule Development of Greenhouse-GrownVicia faba

Plants of Vicia faba cv. Maris Bead were germinated under uniform conditions; some were then transferred to conditions of water excess or stress for the vegetative growth phase. Those on the excess water regime grew best, produced most root nodules, and fixed most nitrogen. Microscopic examination showed that control and water-stressed plants did not develop all those nodules which had previously been initiated. Average nodule weight and specific activity were unaffected, but nodules showed a progressive increase in size and a more open structure as water supply was increased. Transfer between treatments resulted in adaptation to the new environment within a few days. It is concluded that established plants of V.faba are far more likely to be adversely affected by

Investigation about the Necrosis Formation “Sharilka” (Aladja) on the Leaves of Field-Grown Tobacco Plants: Part I. About the Causes of the Phenomenon Part II. BiochemicaI Changes in the “Sharilka”-Affected Leaf

AbstractA specific dot-like necrosis formation on Oriental type tobacco, called "sharilka'' was studied. The phenomenon is of a physiological nature. It manifests itself under conditions of water excess during the time when the leaves begin to become overripe. It was established that susceptibility to "sharilka" is connected with a low content of pectins and proteins. The latter fact predetermines the lower water binding capacity of protoplasm or higher content of free water in the tissues which suffer from "sharilka''. The raised quantity of free water as a possible source of degenerative cell changes, which become apparent on the leaf in the form of "sharilka", was considered

The storage of extra water by various tissues of Uromastyx aegyptia (Forskal)

1. Retention of extra water by the tissues occurs under conditions of water excess. 2. Tissues are more able to retain extra water from saline injections than from distilled water injections. 3. The most suitable depots of water in the body were found to be the liver, skeletal muscles and peritoneal sacs. 4. The amount of extra water retained within the tissues differs according to the type of the tissue and to the total amount of injected saline. 5. Tissues of young animals are more able to retain extra amounts of water than those of adult animals.

The storage of extra water by various tissues of Varanus griseus daud

1. Under conditions of water excess, Varanus can retain extra water amounting to 15% of its body weight in its tissues. 2. Tissues of high metabolic activity as brain, heart and spinal cord and tissues of low metabolic activity as skin, bone and cartilage show no increase in their water content under conditions of water excess. 3. The remaining tissues show an increase in their water content in the presence of water excess. Among these tissues skeletal muscles. liver, parts of alimentary canal and blood can be looked upon as important water depots. 4. Degree of hydration of tissues was found to be proportional to the amount of added water and to the time elapsed for its absorption.