Combined Effect Of Water Research Articles

Application of Response Surface Methodology for Optimization of Potato Tuber Yield

The Author investigates the operating conditions required for optimal production of potato tuber yield in Kenya. This will help potato farmers to safe extra cost of input in potato farming. The potato production process was optimized by the application of factorial design 23 and response surface methodology. The combined effects of water, Nitrogen and Phosphorus mineral nutrients were investigated and optimized using response surface methodology. It was found that the optimum production conditions for the potato tuber yield were 70.04% irrigation water, 124.75Kg/Ha of Nitrogen supplied as urea and 191.04Kg/Ha phosphorus supplied as triple super phosphate. At the optimum condition one can reach to a potato tuber yield of 19.36Kg/plot of 1.8meters by 2.25 meters. Increased productivity of potatoes can improve the livelihood of smallholder potato farmers in Kenya and safe the farmers extra cost of input. Finally, i hope that the approach applied in this study of potatoes can be useful for research on other commodities, leading to a better understanding of overall crop production.

Tolerant pearl millet (Pennisetum glaucum (L.) R. Br.) varieties to low soil P have higher transpiration efficiency and lower flowering delay than sensitive ones

Background and aim In the West African Sahel low soil phosphorus (P) and unpredictable rainfall are major interacting constraints to growth and grain yield of pearl millet. Investigating the relationship between transpiration and final yield under the combined effect of water and P stress is fundamental to understand the underlying mechanisms of tolerance and improve breeding programs.

Interactions Between Surface Water and Groundwater: Key Processes in Ecological Restoration of Degraded Coastal Wetlands Caused by Reclamation

Interactions between surface water and groundwater (SW-GW), composed of complex hydrological networks, maintain a dynamic balance between water regimes and salinity in coastal wetlands. Impacted by reclamation activity, however, changes in water regimes and salinity have resulted in wetland degradation. To mitigate such reclamation impacts on coastal wetlands, it is vital to understand the role of SW-GW interactions involved in maintaining the integrity of coastal wetlands. The objectives of this review were to: (i) outlining SW-GW interactions; (ii) addressing ecological responses to changes in water regimes and salinity; and (iii) exploring modeling techniques used to ascertain interactions between groundwater and coastal wetlands. Key findings are as follows: SW-GW interactions control water regimes and salinity while maintaining the integrity of coastal wetlands; the combined effects of water and salinity have an impact on ecological processes and patterns disturbed by hydrological pulses; and the distribution of physically-based models is an approach that can provide a profound means by which to understand the vital role in maintaining hydrological connectivity. Further research is required to fully reveal SW-GW interactions in maintaining coastal wetlands integrity and the mitigating effects reclamation has on coastal wetlands.

Towards the assessment of the shear behaviour of masonry in on-site conditions: A study on dry and salt/water conditioned brick masonry triplets

In this paper an experimental study conducted on fired-clay brick masonry triplets built with cement- and hydraulic lime-based mortars and subjected to artificial weathering cycles is presented. A cycle is constituted by (1) a wetting phase by capillary rise of either a saline solution or deionized water and (2) a drying phase in oven. The aim of the accelerate weathering cycles is to simulate on-site conditions of masonry structures subjected to rising damp and salts attack due to daily and seasonal microclimatic changes. For comparison purposes, triplets subjected to drying cycles only were also considered. At the end of the weathering process, the triplets were shear tested in order to quantitative assess the separate and combined effect of water and salts within the pores on the mechanical behaviour. Shear parameters were interpreted on the basis of the microstructural characteristics of the constituent materials. Particular attention was given to the pore size distribution, salt amount, and distribution within the specimens after the conditioning procedure, finding significant correlations. Results show that the triplets shear behaviour is influenced by the damp/salts presence to a different extent depending on the materials involved.

Antioxidative enzyme responses under single and combined effect of water and heavy metal stress in two Pigeon pea cultivars

Heavy metal toxicity and water stress are the two frequently co-occurring abiotic stresses restraining the growth of crop plants as the metal contaminated sites are over alarmingly increasing due to industrial pollution. The present study is to evaluate the effect of heavy metals (Cadmium, Chromium), PEG induced water stress and their combination on antioxidative enzyme activities in two Pigeon pea cultivars LRG-41 and Yashoda-45. The activities of antioxidative enzymes Superoxide dismutase, Catalase, Ascorbate peroxidase, Polyphenol Oxidase and Glutathione Reductase registered higher values in both roots and shoots with all the single stress treatments when compared to their controls. The levels of antioxidative enzyme activities and lipid peroxidation were high in cv. Yashoda-45 than cv. LRG-41. Overall, cv Yashoda-45 has shown better tolerance to both heavy metal and water stress. These results may show the novel insight in to the responses associated with combined stress in the cultivars of economically important crop, Pigeon pea.

Experimental studies on the short term effect of CO2 on the tensile failure of sandstone

Abstract The injection of CO2 to the formation may cause the tensile failure of the formation rock. The short term effect of CO2 on the tensile failure behavior of sandstone with or without the combined effect of water was investigated in this paper. Hollow cylinder method was adopted to fracture the sandstone samples under four types of pore fluid condition: dry, dry with CO2, water wet and wet with CO2. The experimental results indicated that the effective fracturing pressure of the samples under the same pore fluid condition varied linearly with the effective confining pressure in the range of 1.0-6.0 MPa. Existence of water resulted in a slight weakening of 5.638% on the tensile strength. But the tensile fracturing behavior of the sandstone was not obviously affected by gaseous CO2 with or without the combined effect of water. The findings can be a reference for the mechanical stability evaluation of the formation in CO2 storage.

灌溉对沙拐枣幼苗生长及氮素利用的影响

Water and nitrogen( N) are two primary factors controlling plant growth in desert ecosystems. Most studies have focused on water stress resulting from the low rainfall and high evaporation rates in arid areas. However,irrigation has become the main strategy for vegetation recovery in the southern rim of Tarim Basin. Many studies have shown that irrigation is most effective when nutrients are not limited,and fertilization is most effective when plants are not water-stressed. In addition,N not only affects drought tolerance through changing dry matter partitioning,but also plays an important role in ecosystem functioning and vegetation succession. Therefore,the combined effects of water and N on vegetation recovery and reconstruction in this area should be evaluated. We conducted a pot experiment to study characteristics of N allocation,use, and resorption,and growth of Calligonum caput-medusae Schrenk seedlings under different irrigation treatments( 4.6,6.1, 7.7,9.2,13.0 kg / plant per irrigation event). The results showed that the amounts of both N and dry matter per whole plant significantly increased with increasing amounts of irrigation. However,C. caput-medusae Schrenk seedlings were infected with powdery mildew at the high irrigation level( 13.0 kg / plant). During the early growth stage,irrigation promoted drymatter accumulation in and N allocation to,assimilating branches. On average,these assimilating branches accounted for 39.5% of whole-plant dry matter accumulation and 66.1% of whole-plant N-allocation. During the late growth stage,stems and older branches became the main organs for dry matter and N accumulation,on average accounting for 54.7% and 47.8% of whole-plant dry matter accumulation and N accumulation,respectively. The dry matter accumulation in and N allocation to stems and older branches was positively affected by irrigation at the end of the growing season. The plants allocated more dry matter and N into assimilating branches in their early growth stage to obtain more photosynthates,and to stems and older branches at the late growth stage to accumulate more energy for plant growth the following year. The root / shoot ratio of C. caput-medusae Schrenk seedlings was markedly higher under dry conditions than under irrigated conditions. The mean value of N resorption efficiency( NRE) at the early and late growth stages was 64.4% and 58.1%,respectively. The NRE was positively affected by irrigation at the early growth stage,but negatively affected by irrigation at the late growth stage( at the end of the growing season). There was a clear seasonal variation in N use efficiency( NUE),with a low mean value( 120.5 g / g) at the early growth stage and a high mean value( 235.8 g / g) at the late growth stage. Irrigation significantly enhanced the NUE of assimilating branches,stems,and older branches,and roots at the late growth stage. Although the whole-plant NUE increased significantly under higher irrigation levels,excessive irrigation did not increase the NUE. These findings suggested that both N and biomass could be distributed to the most appropriate organ of C. caput-medusae Schrenk at different growth stages to adapt to the arid and barren natural environment. Since plant growth and N use could be limited by over-irrigation and water stress,medium irrigation levels( 7.7—9.2 kg / plant) were appropriate for establishing C. caputmedusae Schrenk seedlings in this area.

Effects of immersion and sustained bending on water absorption and thermomechanical properties of ultraviolet cured glass fiber-reinforced acylate polymer composites

An ultraviolet cured glass fiber-reinforced acylate polymer composite can be cured in several 10 sec, which is potentially used for quick repair of concrete structures. In the present paper, combined effects of water or alkaline solution immersion and sustained bending on its water absorption and thermomechanical properties were investigated. With increasing the sustained bending levels, water uptake and diffusion rate monotonically increased in ultraviolet cured glass fiber-reinforced acylate polymer. The combined effects lead to remarkable decreases in the tensile properties. More serious degradation of the tensile strength was found in the cases of higher sustained bending levels and/or alkaline solution immersion. After removal of sustained bending, residual deformation of samples was observed and depended on the bending levels and immersion medium, attributed to the orientation of the resin molecules. In all, 1% of water uptake led to about 8–9℃ reduction in the glass transition temperatures, regardless of sustained bending or immersion medium. The height of tan delta decrease with sustained bending levels indicates the occurrence of fiber debonding or delamination.

Particle breakage of argillaceous siltstone subjected to stresses and weathering

Particle breakage is an important phenomenon that is observed in high rockfill dams as the dam material is subjected to both weathering and stresses. This paper presents a study of the particle breakage of an argillaceous siltstone used in a rockfill dam in southwest China that is 261.5m in height. The region is characterized by abundant rainfall and a wide variation in temperature (10–60°C). A series of oedometer tests were performed with specimens subjected to different types of weathering. The study aims to examine the development of particle breakage of an argillaceous siltstone and the manner in which the particle size distribution of the weathered material changes over time. The results highlight that the combined effect of water and thermal weathering is a major factor controlling the disintegration of soft rocks. Particle breakage is characterized by three mechanisms: angular fracture, particle cracking and particle breakup. The weathering rate, defined as the rate of particle breakage over a weathering cycle, declines as the number of cycles increases. The ultimate particle breakage induced by weathering approaches a constant despite different axial stresses.

High temperature steam investigation of cobalt oxide silica membranes for gas separation

In this work we investigate the effect of high temperature steam on cobalt and cobalt oxide derived silica with an aim to providing an understanding of the permeation and gas separation performance of cobalt silica membranes exposed to simulated industrial wet gas streams. Cobalt silica (CoSi) and cobalt oxide silica (CoO x Si) xerogels were synthesized and exposed to steam at 500 °C for varying time periods. Subsequent characterization with FTIR and N 2 adsorption revealed that CoO x Si xerogels were significantly more hydrostable than CoSi xerogels, with few structural changes observed and only moderate densification (∼43%) of the CoO x Si matrix experienced even after the longest steam exposure. In comparison the CoSi matrix experienced severe densification (∼89%) after only short term steam exposure. CoO x Si was therefore selected as the optimal material for further membrane tests and CoO x Si membranes were subsequently synthesized using sol–gel techniques and exposed to steam in both high temperature long term stability studies and during temperature cycling tests. Exposure to steam had an adverse effect on membrane performance with the largest effect occurring during the initial stages where He permeance dropped from 3.95 × 10 −8 to 2.05 × 10 −10 mol m −2 s −1 Pa −1 and He/N 2 ideal selectivities from 123 to 45, respectively after 135 h of testing. However, following this initial period of steam conditioning, these membranes were able to oppose further deterioration and maintain acceptable steady state performance. Further tests with an increased steam rate showed that nitrogen permeation decreased more significantly than helium, leading to a rise in membrane ideal selectivity, suggesting that steam was competitively blocking the pores available to nitrogen adsorption and/or reducing the diffusion of nitrogen. Steam testing under cycling temperature conditions showed that below 400 °C, the membrane ideal selectivity was low. However, above 400 °C the membrane consistently exhibited a molecular sieving mechanism. In addition water permeation through the membrane varied with temperature suggesting that the membrane matrix continuously underwent reversible structural modification by the combined effect of water and temperature.

Combined effect of water and KOH on rapeseed oil methanolysis

This paper deals with the effect of water and catalyst (KOH) amount on the quantity and quality of transesterification products of rapeseed oil by methanol, the methyl ester phase (i.e. yield, conversion), and the side-product, the glycerol phase (i.e. density, viscosity, the mass fraction of glycerol, esters, soaps). The dependencies were described by statistical models. The transesterification was carried out at constant reaction conditions (90 min reaction time, 400 rpm, 60 °C). Twelve experiments with the independent factors, amount of potassium hydroxide (0.65–0.9 mg per gram of oil) and total amount of water (0.24–1.42 mg per gram of oil) naturally present in the reaction components or formed by the neutralisation reaction of free fatty acids and of added water. The data were analyzed by linear regression with respect to regression triplet (complex critical analysis of the model, data and regression method). The analysis resulted in a set of linear and/or quadratic models consisting of statistically proven terms at a statistical significance level of 0.05 and demonstrated that ester in the glycerol phase increases with increasing amount of soaps.

Melting in the deep upper mantle oceanward of the Honshu slab

We examine the upper mantle and transition zone beneath the western Pacific using multiple ScS reverberations. A low-velocity zone (LVZ) is found above the 410-km discontinuity oceanward of the subducting Honshu slab at an average depth of 356 km, with a thickness that ranges from 50 to 75 km assuming the LVZ continues to the 410-km discontinuity, which is locally elevated. The low-velocity region is evident in previous tomographic studies, and our results suggest that the anomaly is best explained by a layer of partial melt. The layer may be entrained from above by subduction or produced in situ by the combined effects of water and temperature. A self-consistent model that explains local P-wave velocities (Obayashi, M., Sugioka, H., Yoshimitsu, J., Fukao, Y., 2006. High temperature anomalies oceanward of subducting slabs at the 410-km discontinuity. Earth and Planetary Science Letters 243, 149–158) and our observations calls for a maximum temperature anomaly of ∼150 °C and a resulting maximum olivine water content after melting of 0.100 wt. %.

Microbial soil respiration and its dependency on carbon inputs, soil temperature and moisture

AbstractThis experiment was designed to study three determinant factors in decomposition patterns of soil organic matter (SOM): temperature, water and carbon (C) inputs. The study combined field measurements with soil lab incubations and ends with a modelling framework based on the results obtained. Soil respiration was periodically measured at an oak savanna woodland and a ponderosa pine plantation. Intact soils cores were collected at both ecosystems, including soils with most labile C burnt off, soils with some labile C gone and soils with fresh inputs of labile C. Two treatments, dry‐field condition and field capacity, were applied to an incubation that lasted 111 days. Short‐term temperature changes were applied to the soils periodically to quantify temperature responses. This was done to prevent confounding results associated with different pools of C that would result by exposing treatments chronically to different temperature regimes. This paper discusses the role of the above‐defined environmental factors on the variability of soil C dynamics. At the seasonal scale, temperature and water were, respectively, the main limiting factors controlling soil CO2 efflux for the ponderosa pine and the oak savanna ecosystems. Spatial and seasonal variations in plant activity (root respiration and exudates production) exerted a strong influence over the seasonal and spatial variation of soil metabolic activity. Mean residence times of bulk SOM were significantly lower at the Nitrogen (N)‐rich deciduous savanna than at the N‐limited evergreen dominated pine ecosystem. At shorter time scales (daily), SOM decomposition was controlled primarily by temperature during wet periods and by the combined effect of water and temperature during dry periods. Secondary control was provided by the presence/absence of plant derived C inputs (exudation). Further analyses of SOM decomposition suggest that factors such as changes in the decomposer community, stress‐induced changes in the metabolic activity of decomposers or SOM stabilization patterns remain unresolved, but should also be considered in future SOM decomposition studies. Observations and confounding factors associated with SOM decomposition patterns and its temperature sensitivity are summarized in the modeling framework.

Effect of Water on Nano-rheology of Dioctylphthalate Confined between Surfaces Coated with Long Alkyl Chains

To study rheological properties of precipitated calcium carbonate (PCC) dispersion in dioctylphthalate (DOP) in the presence of a small amount of water, ca. 770-2600 ppm, the macroscopic viscosity was measured using a B-type viscometer. The PCC coated with stearic acid dispersed in DOP exhibited higher viscosity than the uncoated PCC. To know the mechanism of this high viscosity, the rheological properties of DOP in nanometer space were investigated using the shear resonance measurement. For this measurement, we used mica surfaces modified with dioctadecyldimethylammoniumbromide (DODA) as a model of PCC surfaces which bears long alkyl chains, and the effects of the surface modification and the addition of water to DOP were examined. For the 1164 ppm water content, we observed that the viscosity of DOP between DODA modified surfaces started to increase at the distance of 57.1 nm, which is much longer than the value for bare mica surfaces, 10.7 nm. When the water content was decreased to 469 ppm, the viscosity started to increase at small distances, 1.1 nm and 8.0 nm for the DODA modified and bare mica surfaces, respectively. These distances were compared with the average particle distance in a DOP sol employed for the macroscopic rheological measurement. Results of the current study indicated that a mechanism of the high viscosity of dispersion of PCC coated with long alkyl chains in DOP would be due to the increasing viscosity of DOP by the combined effects of water and long alkyl chains of the PCC surfaces.

Photosynthesis, Light Acclimation of Photosynthesis and Chlorphyll Fluorescence of Lemon in Response to Water Stress and Shading

The combined effects of water and light on net photosynthesis (A) of rooted cuttings of lemon (Citrus limon L. Burm.f. Eureka) were investigated to determine if the effects of water stress and shading are interactive. Treatments investigated included sufficient water +full light (control), water stress + full light, sufficient water + shade and water stress + shade. Under ambient conditions, the main effects of water stress significantly decreased A, gs, and chlorophyll content. It increased Ci. Mean effects of shading decreased A and NPQ. It significantly increased Fm, and Fv/Fm. Water×light interactions were not significant for A, gs, Ci, chlorophyll content, Fo, FvFm, qP and NPQ. But they were significant for Fm, and Yield. Under controlled environment, the mean effects of water stress on A were as for ambient conditions, but the effects of shade were reversed. Water×light interactions significantly influenced A at irradiance of 50 and 300μmol m-2 s-1 but not at 600 μmol m-2 s-1. At 300 μmol m-2 s-1, shaded sufficiently watered plants had significantly higher A than plants grown under the other water×light combinations. Water stressed plants grown in full light were photoinhibited at 50-600μmol m-2 s-1. Water stress and shading effects on A are interactive if leaf environment is controlled.

The combined effects of water and fluorine on the viscosity of silicic magmas

The Newtonian viscosity of water-plus-fluorine-bearing silicate melt of haplogranitic composition (HPG8) has been determined. Viscosities of HPG8 melt with addition of 3.11 and 4.25 wt.% of F and up to 3 wt.% H 2O have been obtained using a micropenetration technique in the interval 10 9.74 to 10 11.84 Pa · s and temperatures varying from 370 to 700°C, at ambient pressure. Determination of the temperature dependence of viscosity from this and previous studies permits the parameterization of the viscosity of melts containing water and fluorine, having similar composition, within a 0.3 log units standard error. The viscosity of water-bearing, F-rich haplogranitic samples is represented by a modified Vogel-Fulcher-Tammann (VFT) equation which provides a non-Arrhenian description of the temperature dependence of the viscosity. The results of this study indicate that, taken individually or together, both H 2O and F − have a strong and similar effect on the viscosity of SiO 2-rich compositions. This similarity between F 2O −1 and H 2O greatly simplifies the task of predicting viscosity for volatile-rich, highly silicic magmas. The low viscosities of hydrous fluorine-bearing granitic melts favour efficient crystallization-fractionaction paths for these liquids, controlling degassing paths and consequently the eruptive behaviour. Numerical simulations of eruptive events normally do not take into account the contribution of fluorine; this may introduce a significant error in the description of the fluid-dynamic properties of magma and, therefore, in the accurate prediction of eruptive scenarios, as well as in hazard assessment studies. Fluorine, unlike water, remains dissolved in the melt at high concentrations and low confining pressures. The incorporation of fluorine data and the modelling of fluorine-bearing viscosity data are therefore of fundamental importance for simulations of magma dynamics and prediction of eruptive scenarios.

Combined effect of water and organic matter on phosphorus availability in calcareous soils

Phosphorus removal from soil solution is mainly due to adsorption and precipitation. For calcareous soils, with a large reservoir of exchangeable calcium, precipitation of insoluble Ca-P phases is the predominant process that reduces P availability to plants. Soil water content positively affects P-precipitation, while the addition of organic matter (OM) has an opposite effect. Little information on the effect of soil organic matter on P-insolubilisation as a function of soil water contents has prompted this study of the variation of extractable P, after addition of mineral P fertiliser. Columns packed with a calcareous soil were enriched with different levels of OM, extracted from Irish peat, and subjected to different rainfall simulations. After 102 days of experimentation and 171 mm of accumulated rainfall, the Olsen-P was 53% of the initially applied amount in 6.2% OM-enriched soil, 37% in 4.1% OM-enriched soil, and 20% in untreated soil (1.9% of OM). While the curve describing Olsen-P decrease as a function of accumulated rainfall was clearly exponential for untreated soil, the curves for OM-enriched samples were flatter, evidence that OM addition modified P-insolubilisation. The P-insolubilisation, after P-fertilisation, at several constant values of soil moisture for (i) calcareous soil, (ii) calcareous soil after removing carbonates and saturating the exchange complex with Ca, and (iii) calcareous soil after addition of different levels of OM followed first-order kinetics. The Kobss followed the order: Ca-saturated soil > untreated soil > OM-enriched samples. Results from rainfall simulation experiments and kinetics of Olsen-P decrease at several constant soil moisture contents indicated that the soil water amount was the main factor in reducing extractable P after P fertilisation and that the soil OM content was the main factor in keeping P in extractable forms. On the other hand, the addition of OM to calcareous soil increased the extractable P at each soil moisture regime, decreasing P-insolubilisation more effectively at lower soil water contents. P-sorption isotherms of calcareous soil after addition of different levels of OM showed that the presence of OM mainly influences P-insolubilisation, but not the adsorption process.

Medium-term evolution of a gully developed in a loess-derived soil

Field surveys in the Belgian loess belt revealed the presence in many forested areas of large, permanent gully systems, most of which are currently inactive. In cultivated areas, such gullies can only be observed in cross-sectional soil profiles through hollows, as virtually all such large gullies are currently infilled with colluvium. Little is known about the spatial distribution, initiation and temporal evolution of these large, permanent gully systems on loess-derived soils. Therefore, the medium-term evolution of a gully initiated in a cultivated area on loess-derived soils southwest of Leuven (Belgium) in May–June 1986, was studied over 13 years. Two intense rainfall events created this (ephemeral) gully, which was not erased by subsequent tillage. Between June 1986 and the December 1999, eight field surveys were conducted to measure gully dimensions. During two surveys, topographic indices (e.g., slope and drainage area) were also measured. Daily rainfall for the measuring period were obtained from a rainfall station located some 10 km southwest of the gully. Analysis of rainfall data showed that no extreme rainfall event was required to initiate such large (permanent) gullies, as observed in forested areas and through cross-sectional profiles in cultivated fields in the Belgian loess belt. Return periods of the event that caused the gully varied between <1 year and 25 years, depending on the assumptions used for defining event rain intensity. Once established, length, surface area and volume of the studied gully evolved with time, cumulative rainfall or cumulative runoff, following a negative exponential relation. This accords with observations reported for gullies in Australia and the USA. This study shows that a degressive increase of gully extension, can be largely explained by the evolution of a “slope–drainage area” factor ( S× A, which is proportional to stream power) with time. While gully length and gully surface area asymptotically evolve towards a final value, gully volume decreased at a given point in time. From this, it is inferred that sediment deposition will potentially infill the gully to such an extent that the farmer can drive across it. From this moment on, the combined effect of water and tillage erosion in the gully drainage area, will lead towards rapid infilling. This expected evolution of a gully in cultivated fields accords with observations of large infilled gully systems in cultivated areas in eastern Belgium. The permanent gullies observed under forest are attributed to the fact that after severe gully erosion, this area was reforested or abandoned. Therefore, the sediment source was cut off and the gully was not filled in by sediment deposition.

The role of zeolite type on the lean NO x reduction by methane over Pd loaded pentasil zeolites

The lean selective catalytic reduction of NO x by methane over protonic palladium loaded ZSM-5, FER and MOR, as well as, on bimetallic Pd–Pt-HMOR was examined. Special emphasis was paid on the combined effects of water and SO 2 in the feed stream. Under dry conditions and in the absence of SO 2, the degree of NO x conversion at 450°C decreases as follows: Pd-HZSM-5>Pd-HMOR>Pd-HFER. Sulfur dioxide alone has no apparent effect on the activity for NO x reduction, but the coexistence of water and SO 2 inhibits both NO x and methane conversions. The extent of inhibition by water and SO 2 on NO x reduction is Pd-HFER>Pd-HZSM-5>Pd-HMOR. Acid mordenite doped with low levels of Pt and Pd leads to an active catalyst that is more tolerant to the presence of either water or SO 2 than the corresponding monometallic Pt- and Pd-HMOR. Nevertheless, NO x reduction is also inhibited at temperatures below 450°C when SO 2 and water are both present. TPD experiments of water over calcined samples of protonic Pd supported pentasil zeolites, Pd/γ-Al 2O 3 and Pt–Pd-HMOR with and without pretreatment in SO 2+O 2 indicate that sulfation of the surface increases water chemisorption by the support. Therefore, the observed decrease of NO x reduction on Pd-loaded zeolite catalysts when SO 2 and H 2O coexist in the feed stream may be due to enhanced water inhibition and presumably active site poisoning.

Application of a Computable General Equilibrium (CGE) Model to Evaluate Surface Water Reallocation Policies

This study uses a computable general equilibrium (CGE) model to calculate the economic impacts of reallocating surface water from irrigated agriculture to recreational use at the Stillwater National Wildlife Refuge in Churchill County, Nevada. In this study, we consider three alternative assumptions about how the proceeds from water rights sales are spent. Model results show that under all three alternative assumptions, the combined effect of water rights compensation and the increase in recreation-related expenditures does not offset the reduction in agricultural production.