Gendered participation in water management: Issues and illustrations from water users‘ associations in South Asia

The widespread trend to transferirrigation management responsibility from the stateto communities or local user groups has byand large ignored the implications ofintra-community power differences for theeffectiveness and equity of water management. Genderis a recurrent source of such differences. Despitethe rhetoric on womens participation, a review ofevidence from South Asia shows that femaleparticipation is minimal in water usersorganizations. One reason for this is that theformal and informal membership criteria excludewomen. Moreover, the balance between costs andbenefits of participation is often negative forwomen because complying with the rules and practicesof the organization involves considerable time costsand social risks, whereas other ways to obtainirrigation services may be more effective for femalewater users. Although effective, these other andoften informal ways of obtaining irrigation servicesare also typically less secure. More formalparticipation of women can strengthen womensbargaining position as resource users withinhouseholds and communities. Greater involvement ofwomen can also strengthen the effectiveness of theorganization by improving womens compliance withrules and maintenance contributions. Furtherdetailed and comparative research is required toidentify the major factors that affect womensparticipation and control over resources, ifdevolution policies are to address the tensionbetween objectives of transferring control overresources to community institutions, and ensuringthe participation of all members of the community,especially women.     

Xylem-tapping mistletoes: water or nutrient parasites?

Most mistletoes parasitize higher plants by tapping the xylem (a conduction tissue) of their hosts. Field observations of diurnal gas exchange parameters and carbon isotope ratios in xylem-tapping mistletoes from three continents support the hypotheses that water use efficiency and carbon isotope composition are related and that mistletoes which are parasitic for water are also nutrient parasites, differing in their water use efficiency relative to that of their hosts on the basis of host nitrogen supply in the transpiration stream.     

How do small water clusters bind an excess electron?

The arrangement of water molecules around a hydrated electron has eluded explanation for more than 40 years. Here we report sharp vibrational bands for small gas-phase water cluster anions, (H2O)(4-6)- and (D2O)(4-6)-. Analysis of these bands reveals a detailed picture of the diffuse electron-binding site. The electron is closely associated with a single water molecule attached to the supporting network through a double H-bond acceptor motif. The local OH stretching bands of this molecule are dramatically distorted in the pentamer and smaller clusters because the excited vibrational levels are strongly coupled to the electron continuum. The vibration-to-electronic energy transfer rates, as revealed by line shape analysis, are mode-specific and remarkably fast, with the symmetric stretching mode surviving for less than 10 vibrational periods [50 fs in (H2O)4-].     

Deep oxygenated ground water: anomaly or common occurrence?

Contrary to the prevailing notion that oxygen-depleting reactions in the soil zone and in the aquifer rapidly reduce the dissolved oxygen content of recharge water to detection limits, 2 to 8 milligrams per liter of dissolved oxygen is present in water from a variety of deep (100 to 1000 meters) aquifers in Nevada, Arizona, and the hot springs of the folded Appalachians and Arkansas. Most of the waters sampled are several thousand to more than 10,000 years old, and some are 80 kilometers from their point of recharge.     

A single molecule of water encapsulated in fullerene C₆₀

Water normally exists in hydrogen-bonded environments, but a single molecule of H(2)O without any hydrogen bonds can be completely isolated within the confined subnano space inside fullerene C(60). We isolated bulk quantities of such a molecule by first synthesizing an open-cage C(60) derivative whose opening can be enlarged in situ at 120°C that quantitatively encapsulated one water molecule under the high-pressure conditions. The relatively simple method was developed to close the cage and encapsulate water. The structure of H(2)O@C(60) was determined by single-crystal x-ray analysis, along with its physical and spectroscopic properties.     

Phosphorus sources for aquatic weeds: water or sediments?

Nine common species of aquatic macrophytes took all their phosphorus from the sediments when grown in situ in both a mesotrophic and a mildly eutrophic bay. Even under hypertrophic conditions, the sediments contributed an average of 72 percent of all the phosphorus taken up during growth. These experiments unambiguously demonstrate for the first time that submergent macrophytes in nature over-whelmingly depend on the sediments for their phosphorus supply and characterize them as potential nutrient pumps to the open water.     

Changes in ocean water mass properties: oscillations or trends?

A new transindian hydrographic section across 32 degrees S reveals that thermocline mode waters have become saltier and colder since 1987. This change almost entirely reverses the observed freshening of mode waters from the 1960s to 1987 that has been interpreted to be the result of anthropogenic climate change on the basis of coupled climate models. Here, we compare five hydrographic sections from 1936, 1965, 1987, 1995, and 2002 to show that upper thermocline waters (10 degrees C to 17 degrees C) changed little from 1936 to 1965, freshened from 1965 to 1987, and since 1987 have become saltier. These results demonstrate substantial oscillations in mode-water properties.     

The initiation of subduction: criticality by addition of water?

Subduction is a major process of plate tectonics; however, its initiation is not understood. We used high-resolution (less than 1 kilometer) finite-element models based on rheological data of the lithosphere to investigate the role played by water on initiating subduction. A solid-fluid thermomechanical instability is needed to drive a cold, stiff, and negatively buoyant lithosphere into the mantle. This instability can be triggered slowly by sedimentary loading over a time span of 100 million years. Our results indicate that subduction can proceed by a double feedback mechanism (thermoelastic and thermal-rheological) promoted by lubrication due to water.     

Drip irrigation incorporating water conservation measures: Effects on soil water–nitrogen utilization,root traits and grain production of spring maize in semi-arid areas

The Northeast Plain is the largest maize production area in China, and drip irrigation has recently been proposed to cope with the effects of frequent droughts and to improve water use efficiency (WUE). In order to develop an efficient and environmentally friendly irrigation system, drip irrigation experiments were conducted in 2016–2018 incorporating different soil water conservation measures as follows: (1) drip irrigation under plastic film mulch (PI), (2) drip irrigation under biodegradable film mulch (BI), (3) drip irrigation incorporating straw returning (SI), and (4) drip irrigation with the tape buried at a shallow soil depth (OI); with furrow irrigation (FI) used as the control. The results showed that PI and BI gave the highest maize yield, as well as the highest WUE and nitrogen use efficiency (NUE) because of the higher root length density (RLD) and better heat conditions during the vegetative stage. But compared with BI, PI consumed more soil water in the 20–60 and 60–100 cm soil layers, and accelerated the progress of root and leaf senescence due to a larger root system in the top 0–20 cm soil layer and a higher soil temperature during the reproductive stage. SI was effective in improving soil water and nitrate contents, and promoted RLD in deeper soil layers, thereby maintaining higher physiological activity during the reproductive stage. FI resulted in higher nitrate levels in the deep 60–100 cm soil layer, which increased the risk of nitrogen losses by leaching compared with the drip irrigation treatments. RLD in the 0–20 cm soil layer was highly positively correlated with yield, WUE and NUE (P<0.001), but it was negatively correlated with root nitrogen use efficiency (NRE) (P<0.05), and the correlation was weaker in deeper soil layers. We concluded that BI had advantages in water–nitrogen utilization and yield stability response to drought stress, and thus is recommended for environmentally friendly and sustainable maize production in Northeast China.     

Magnetic field increase weight and water content in date palm （Phoenix dactylifera L.）

Magnetic field effects on different plant species have been subject of many studies in the last decade. Magnetic fields are known to induce changes in plant metabolism, growth and productivity. In this study, effect of magnetic field on date palm weight and water content has been investigated. Seedlings of date palm were treated with two types of magnetic fields in two separate experiments. In the first experiment, seedlings were treated with static magnetic field SMF using electromagnetic circuit set to produce three levels of magnetic field intensities 10, 50 and 100 mT for different durations （0, 30, 60, 120, 180 and 240 min）. In the second experiment seedlings were treated with alternating magnetic field AMF, using magnetic resonance imaging providing 1500 mT for 0, 1, 5, 10 and 15 min. After two months of exposure, plants growth parameters （fresh, dry weights and water content for both leaves and roots） were recorded. The measurements revealed that leaf fresh, dry weight and water content increased significantly in response to SMF treatment. Similarly, roots fresh weight and water content were increased significantly; however roots dry weight increasing were insignificant. In the second experiment, AMF has affected plant growth all parameters were increased significantly. Measurements reached the highest level at 15 min of exposure. This study revealed that magnetic fields affect date palm growth parameters by increasing osmotic pressure and water potential which increase water absorption and enhance flesh weight.     

Enhancing hydrogen evolution activity in water splitting by tailoring Li⁺-Ni(OH)₂-Pt interfaces

Improving the sluggish kinetics for the electrochemical reduction of water to molecular hydrogen in alkaline environments is one key to reducing the high overpotentials and associated energy losses in water-alkali and chlor-alkali electrolyzers. We found that a controlled arrangement of nanometer-scale Ni(OH)(2) clusters on platinum electrode surfaces manifests a factor of 8 activity increase in catalyzing the hydrogen evolution reaction relative to state-of-the-art metal and metal-oxide catalysts. In a bifunctional effect, the edges of the Ni(OH)(2) clusters promoted the dissociation of water and the production of hydrogen intermediates that then adsorbed on the nearby Pt surfaces and recombined into molecular hydrogen. The generation of these hydrogen intermediates could be further enhanced via Li(+)-induced destabilization of the HO-H bond, resulting in a factor of 10 total increase in activity.