Showing papers on "Saline water published in 2001"

Irrigation with saline water improves carotenoids content and antioxidant activity of tomato

Abstract: SummaryThe combined effect of increasing concentrations of NaCl in the irrigation water and fertilization with different nitrogen sources on the chemical composition of tomato (Lycopersicon esculentum Mill.) fruit was investigated. Increasing water salinity from 0.5.dS m-1 (non-salinized control) to 15.7.dS m-1 resulted in both reduced fruit size and fruit water content, whereas it caused an increase in soluble solids, carbohydrates, sodium and chloride concentrations. Titratable acidity increased upon irrigation with saline water, whereas the fruit redness significantly decreased. In addition, salinity reduced P, K+, Mg2+ and NO3- fruit concentrations. Total carotenoids and lycopene concentrations expressed on both fresh- and dry-weight basis gradually increased from the non-salinized control to the 4.4.dS m-1 treatment (approximately 0.25% NaCl w/v) and they decreased at electrical conductivities of the irrigation water higher than 4.4.dS m-1. Overall these data show that it is possible to improve carot...

Field Studies of Crop Response to Water and Salt Stress

Abstract: Studies of crop response to water and salt stress vary either salinity with a high leaching fraction or irrigation in the absence of salinity to isolate and quantify the effects of the two types of stress. Under deficit irrigation with saline water, a water conserving practice, the crop experiences simultaneous matric and osmotic stress, and it is not known if experiments designed to isolate stress effects may he used to predict crop response to simultaneous stresses. Thus, a study was conducted wherein yields were determined under varying levels ol' salinity and irrigation. Corn (Zea mays L.) and melon (Cucumis melo L.) were grown at the Arava Research and Development Farm in Yotvata, Israel, and alfalfa (Medicago sativa L.) at the Utah Power & Light Research Farm in Huntington. UT. Corn and melon plots were drip irrigated at six ratios of potenital evapotranspiration ranging from 0.2 to 1.7 in combination with four salinity levels. Alfalfa was irrigated with water of 0.2 and 4.0 dS m 1 from a line-source sprinkler. For all three crops, the salinity treatments consisted of a control treatment with a salinity level less than published salt-tolerance thresh-olds. Interactive effects of salinity and water stress were not observed in these field experiments. At low irrigation levels (70% of potential evaporation), yields were unaffected by the salinity level. AT the higher irrigation levels, the salinity level caused significant differences in yield. Yield data were fit to piecewise linear models that emphasized the limiting nature of the effects of salt and water stress.

Does the Yellow Sea Warm Current really exist as a persistent mean flow

Abstract: Does saline water of Kuroshio origin intrude into the Yellow Sea interior by a persistent mean current through the Yellow Sea Warm Current or by an intermittently generated wind-driven current? This very fundamental question is discussed by analyzing comprehensive conductivity-temperature-depth data collected over the entire southern Yellow Sea basin and by analyzing satellite-tracked drifter trajectories collected in 1996 and 1997. In the southwestern Yellow Sea, relatively saline water (33.0–34.0 psu) persists year-round, implying a northwestward intrusion of Cheju Warm Current water (CWCW). This water is a mixture of saline CWCW, with salinity higher than 34.0 psu, and fresh Yellow Sea waters, with salinity <33.0 psu. During the winter monsoon the mixed water distribution is tongue-shaped, apparently intruding from the CWCW area. At the same time a strong thermohaline front with a horizontal form similar to the Greek letter Γ forms across the southern entrance of the central Yellow Sea trough and separates the mixed water area from the CWCW. During the summer monsoon the CWCW intrusion is weak, and the mixed water that intruded in the previous winter monsoon remains inside the trough as its salinity decreases. In winter, occasional collapses of part of the front on the western side of the trough are observed, presumably in response to an imbalance between northwest currents generated by strong northerly wind bursts and southeast, tide-induced residual currents. Saline water in the frontal zone may then flush into the southwestern Yellow Sea through the collapsed area of the front. We conclude that the YSWC is not a persistent mean current. We also conclude that CWCW may be transported to the southwestern Yellow Sea in winter by the intermittently generated northwest currents on the western slope of the trough, which override the tide-induced residual currents that flow to the southeast in this part of the basin.

Halophytes – A resource for the future

Abstract: One of the more urgent global problems, particularly in arid and semi-arid regions of the world, is finding enough water and land to support the world’s growing food needs. By some estimates, an additional 500 million acres of new croplands are required over the next thirty years to feed burgeoning populations of the tropics and subtropics. Yet only 230 million acres are available in these areas for farming to expand. And, much of this land is forested and should realistically be preserved to maintain the integrity of remaining natural stands and ecosystem functioning. Furthermore, saline soils are a major problem of cultivated lands in semi-arid and arid areas. About 23% of the world’s 1.5 × 10 9 ha of cultivated land is saline and 37% is sodic. Approximately one third of the world’s irrigated land is salt-affected due chiefly to unsustainable irrigation practices. Freshwater resources are also being rapidly depleted and current agricultural irrigation practices are steadily increasing salinity levels in many regions. Rapid increases in population pressure are leading to greater utilization of remaining meager freshwater supplies for drinking, leaving even less for agriculture. In this complex scenario, it has become imperative to consider development of non-conventional agricultural technologies which might more effectively utilize degraded, marginal and saline lands for agriculture by using, the ‘so-called’, poor quality water (brackish water, seawater, and wastewater). An attractive option is the use of seawater or brackish water agriculture, and this has worked well in both inland and coastal sandy soils of some desert environments. Saline water aquifers exist in many arid lands of the world but these have been greatly under-utilized. This brackish water could be a major resource in saline agriculture to produce food, feed, and fiber and oil seeds on currently non-productive, saline arid lands. In further support of saline agriculture, there would be no shortage of water since seawater in the oceans makes up 97% of water on earth. Desert land is also plentiful, with around 43% of the earth’s total land surface being arid or semi-arid. A small portion of this (about 15%) is close to the sea and this would be convenient for growing crops using saline agriculture. This amounts to 130 million hectares of ‘new’ land that could arguably be brought into human or animal food production – without cutting down more forests or diverting scarce fresh water resources from current agricultural and community needs. Salt tolerant plants (halophytes, including salt marsh and mangrove plants) are highly evolved and specialised organisms with well-adapted morphological and physiological characteristics allowing them to proliferate in the soils possessing high salt concentrations. It is tempting to think we might exploit these plants for the better utilization of saline water, and for the rehabilitation of highly saline soils. Saline agriculture, however, must fulfill two conditions to be cost-effective. First, it must produce useful crops at yields high enough to justify the expense of pumping salty water. Second, researchers must develop successful agronomic techniques for growing saline, water-irrigated crops in a sustainable manner. These methods must also not contribute to further damage of natural environments. If applied successfully, this approach would lead to the domestication of wild, salttolerant plants for use as food, forage, and oilseed crops.

Use of Bacillus subtilis as biocontrol agent. IV. Salt-stress tolerance induction by Bacillus subtilis FZB24 seed treatment in tropical vegetable field crops, and its mode of action

Abstract: The rhizobacterium Bacillus subtilis FZB24 registered as biocontrol agent was field tested as a promoter for salt- tolerance to two cultivars of eggplant and pepper in saline soil in the Sinai region (Egypt) under the condition of irrigation with ground saline water. The use of Bacillus subtilis for root bacterization was realized by watering the seedlings with bacterial spore-(preparation-)suspension, titer 10 8 spores/ml. Starting from 8 weeks after transplanting and for 4 weeks, fruit yield (kg/m2), number of fruits/plant, average fruit fresh weight, dry weight percentage and fruit size were evaluated. Compared with the unsaline-irrigated control the yield was reduced in both vegetable crops in all used cultivars, due to irrigating the plants with saline groundwater to more than 90 %. By using Bacillus subtilis FZB24 in the plots irrigated with saline groundwater, the yield increased up to 550 % in eggplants, and up to 430 % in the pepper cultivars, as compared with unbacterized ones. Also in the other plant growth parameters, significant promotions could be found in the bacterized plants in the saline plots. So, the bacterization caused 50 and 25 % reduction in salinity effect on the yield of eggplants and pepper, respectively, and consequently resulted in a remarkable salt-stress tolerance induction, which varied its degree according to the used plant species. To have insight on the mode of actions of the salt stress tolerance-inducing effect of Bacillus subtilis FZB 24, model experiments have been conducted with auxin precursors and IAA in tomato seedlings under controlled, axenic conditions and under salt-stress conditions similar to the field experiment. Up to now, it has been hypothesized for the mode of action of Bacillus subtilis FZB24, which acts as plant growth and health promoter, and stress tolerance inducer, that the given bacterial production of auxin and auxin precursors during root colonization induces a push in the plant auxin synthesis with changing regulation of the appropriate mechanisms. In the model experiments, the pretreatment of seedlings with millimolare amounts of auxin precursors, tryptophan, indole-3-pyruvic acid or indole-3-acetic aldehyde, 75 % growth reduction in untreated seedlings under salt stress could be compensated completely after 1 week. That was not observed to the same degree after preapplication of auxin (IAA). So, the presented model experiment could support the hypothesis of salt-stress tolerance induction in Bacillus subtilis FZB24-treated plants. The results are discussed from the aspect of a general anti-stress effect of Bacillus subtilis FZB24.

Saline fresh water interface structure in Mahanadi delta region, Orissa, India

Abstract: Saline/fresh water interface structure is one of the most important and basic hydrogeological parameter that needs to be estimated for studies related to coastal zone management, well-field design and understanding saline water intrusion mechanism/processes. The success and stability of a groundwater structure in a coastal region depend upon an accurate estimate of interface structure between saline and fresh water zones, aquifer-aquiclude boundaries and their lateral continuities and the interstitial water qualities of aquifers. Self-potential and resistivity logs provide a reasonably good basis for such estimates and for sustainable development of fresh groundwater resources. The interface depth structure for the Mahanadi delta region, as obtained and interpreted through self-potential and resistivity logs, provides a fairly clear picture of the regional extensions and boundaries of aquifers, aquicludes and interstitial water quality patterns. Aquifers in the northern sector of the basin and within the framework of Birupa and Mahanadi are characterized by an interface depth range that varies between 40 and 280 m below ground level (bgl) with brackish water on the top underlain by freshwater aquifers. The aquifers in the southern sector within the framework of Khatjori/Devi and Koyakhai/Daya/Kushbhadra/Bhargavi are characterized by an interface depth range that varies from 10 to 120 m with freshwater aquifers near the surface underlain by saline, brackish water aquifers. The inversion of these major fluid systems appears to have taken place over a narrow zone between Mahanadi and Khatjori tributaries, possibly over a wide subsurface ridge with separate basin characteristics.

Foliar damage to ornamental trees sprinkler-irrigated with reuse water

Abstract: The extent of foliar damage to ornamental trees irrigated with treated sewage effluent (reuse water) may be a significant factor dictating the extent of reuse water implementation on golf courses, schools and parks in the arid southwestern United States. An experiment was conducted on 20 tree species to determine the extent of foliar damage when sprinkler-irrigated with reuse water, municipal water or a synthesized saline water. Irrigations (168) were applied over a 16-month period via 183-cm raised sprinkler heads, to plots that contained the trees in a dual-pot system. Plant water status, growth, tissue ion concentrations and an index of visual damage (IVD) were assessed at different times throughout the experiment. A higher IVD (greater foliar damage) was reported for most species when sprinkler-irrigated with either reuse or synthesized saline water. However, six species showed significant foliar damage even when irrigated with municipal water. The accumulation of Cl in the tissue was shown to be a species-dependent response, with tissue Cl concentrations varying by as much as a factor of 5. When a backward stepwise multiple regression analysis was conducted on the normalized (reuse-municipal) IVD and tissue ion concentrations, all ions except Na were eliminated from the correlation (Index (reuse – municipal)=0.79+0.62Na (reuse – municipal), r=0.72***, n=20). Wax content on the leaves in the reuse (0.310 mg cm–2) and saline treatments (0.546 mg cm–2) and the increase in wax content with time (young leaves/May vs mature leaves/July) suggested a possible stress response. Based on the results of this experiment, we believe the number of woody ornamental trees that can tolerate spray irrigation of reuse water in the hot dry environment of southern Nevada to be limited.

Characteristics of the ecological environment in upwelling area adjacent to the changjiang river estuary

Abstract: Accoding to the comprehensive investigation data for the Changjiang River Estuary area of August, 1985, the upwelling and its impacts on the ecological environment were analyzed. Outside the Changjiang River Estuary, in the area of 122°20′—123°10′E,31°00′—32°00′N, an upwelling of cold and saline water was present. With this upwelling a low dissolved oxygen and high nutrient water appeared in the same area in the 5—10m layers. The low dissolved oxygen and high nutrient water did not come directly from the Changjiang River diluted water in the upper layer, rather it comes from the modified high saline Taiwan Warm Current Water in the deep and bottom layers. Further, the area with high chlorophyll a centents and high phytoplankton cells was deviated to the southeast about 15—20km from the upwelling centre part. A possible reason for this location deviation may be the upwelling which results in a decrease the water temperature in the upper layer, thus slowing down the phytoplankton growth.

Salinity and Temperature Tolerances of Black Sea Bass Juveniles

Abstract: The salinity and temperature tolerances of black sea bass Centropristis striata juveniles (46 ± 10.3 mm total length [mean ± SD]) were estimated to assist in decisions concerning location of culture facilities and types of production systems. At 21°C, all exposed fish survived for 7 d in salt concentrations of 10, 20, or 35 g/L. All fish exposed to salt concentrations of 5 g/L died within 3 d. Temperature extremes were estimated after acclimation of fish to 24–25°C. Half of the juveniles exposed to a gradual increase (+0.65°C/d) or decrease (–0.51°C/d) in temperature (at a nominal salt concentration of 20 g/L) were dead when the water temperature reached 33.3°C and 3.7°C, respectively. Results of this study indicate that this species requires saline water at or above a salt concentration of 10 g/L and that it may not be practical to keep black sea bass over winter or over summer in shore-based outdoor facilities located in temperate climates.

Surface water distribution of pico- and nanophytoplankton in relation to two distinctive water masses in the North Water, northern Baffin Bay, during fall

Abstract: Distribution of pico- and nanophytoplankton in surface waters was investigated in relation to environmental factors at 10 stations in the North Water (NOW), northern Baf- fin Bay, and at 4 more southerly stations in Baffin Bay in fall 1999. Water temperature (T), salinity (S), dissolved inorganic nitrogen (DIN), phosphate concentrations and pico- and nanophytoplankton abundances were measured in the sur- face waters in the studied area. A clustering analysis was per- formed on these data and allows 2 major ecological regions to be distinguished. An eastern region was characterized by warmer, more saline, surface waters (T > -0.04°C, 31.1 3000 cells ml -1 ) in the northern sub-region and their distributions fol- lowed the change in DIN concentrations. DIN and phosphate concentrations were higher in the northern sub-region than in the eastern region and the western sub-region, although DIN and phosphate concentrations were low in the NOW, with values ranging from 0.1 to 1.0 and 0.09 to 0.69 µM, respec- tively. Based on these ecological results, it is hypothesized that a surface current flows northward along the western coast of Greenland in fall, bringing warm, more saline water to the eastern part of the NOW. In contrast, surface Arctic water (colder, less saline) coming from the Kane Basin flows southward along the western part of the NOW. These 2 dis- tinct water masses, with their different physical and chemical characteristics, govern pico- and nanophytoplankton distribu- tions in the NOW during the fall.

Macroalgae and submerged macrophytes from fresh and saline waterbodies of ephemeral streams ('ramblas') in semiarid south-eastern Spain

Abstract: Semiarid saline streams are uncommon and hence are seldom studied. Moreover, most studies on filamentous algae have been carried out in permanent freshwaters. Seventeen waterbodies from ephemeral streams of semiarid south-eastern Spain (‘ramblas’) were surveyed from a botanical, phycological and ecological point of view over a four-year period. Gradients of environmental conditions ranged from fresh to saline water (0.27 to 47 mS cm–1), from ephemeral to permanent and from pools to streams. Most of the sites were springs or streams that appeared in certain reaches as a result of the upwelling of groundwater. In total, 47 species of submerged macrophytes and macroalgae were recorded, with 1–18 species per site. The most diverse orders were Zygnematales, Oedogoniales and Charales, although the importance and diversification of Vaucheriales in some places was also of note. Multivariate analysis identified salinity as the main factor explaining species distribution. Conductivity ranges for species were compared with other saline habitats such as saline lakes, saltmarshes or coastal lagoons. Finally, this study broadens the ecological range of some taxa and highlights the ecological importance of these kinds of systems for the preservation of biodiversity in arid lands.

Saline Drainage Water, Irrigation Frequency and Crop Species Effects on Some Physical Properties of Soils

Abstract: This field study evaluated the effects of water quality, irrigation frequency and crop species on some physical properties of soils. The experiment had a split-split-plot design, with three irrigation water qualities (normal water, drainage water and a 1: 1 mixture of freshwater and drainage water) as the main treatments, two irrigation frequencies (at 7- and 14-day intervals) as the subtreatments and two crops (barley and alfalfa) as the subsubtreatments. The soil infiltration rate was highest in the barley plot receiving freshwater irrigation at weekly intervals. The lowest soil infiltration rate was found in alfalfa plots receiving saline irrigation water at 14-day intervals. Bulk density and proportions of micropores [pore radius (r) 1.4 μm] were higher and the proportion of macropores (r > 14.4 μm) was lower in barley than in alfalfa. Saline irrigation caused the greatest decrease in total porosity. The soil infiltration rate was higher with more frequent irrigation, and was highest in alfalfa plots receiving freshwater irrigation. The decrease in soil bulk density and infiltration rate was greater with saline drainage water, irrespective of the crop grown and the irrigation frequency.

Caracterização dos frutos de maracujá amarelo irrigados com água salina

Abstract: With the purpose of characterizing fruits of yellow passion fruit (Passiflora edulis f. flavicarpa Deg) in plants irrigated with saline water, an experiment was conducted at Santa Cruz, RN, in the semi-arid zone of Brazil. The treatments were distribuited in randomized blocks, with four repetitions, using factorial design 5 x 2 corresponding the planting pits without coating (R0) and with side coatings (R1; R2; R3; R4; respectively one, two, three and four lateral sides), irrigated daily with volumes of 5 and 10 L of water. The water salinity higher then 3.0 dS m-1 did not show effect on the external and internal quality of the fruits. The increase of the volume of water resulted in larger mean weight of the fruits. The protection of the planting pits did not influence the length, diameter or number of seeds for fruit and neither the peel thickness, pulp percentage, total soluble solids, total titratable acidity or total vitamin C contents.

Numerical Simulation of the Movement of Saltwater under Skimming and Scavenger Pumping in the Pleistocene Aquifer of Gaza and Jericho Areas, Palestine

Abstract: The Pleistocene aquifers are important sources of water supply in both the Gaza and Jericho areas of Palestine. The aquifers are saline with freshwater lenses floating on saline bodies of water. It is important to investigate how to exploit these freshwater lenses without causing unnecessary mixing of the fresh and saline waters. The objective of this research is to investigate the feasibility of applying skimming and scavenger pumping as a means to exploit the freshwater lenses and to control saline water upconing in the aquifers. This study is the first to examine the movement of fresh and saline waters underneath skimming and scavenger wells in the aquifers of Gaza and Jericho. Two simulation models that couple density-dependent fluid flow and solute transport have been used to simulate and predict the movement of saltwater under different hydrogeological and operational conditions of skimming and scavenger wells in the two aquifers. The results show (for the Jericho Aquifer) that: the location of well screen has a strong control on the steady-state position of the fresh/saline water transition zone; the upconing mechanism appears to continue under skimming pumping until saline water enters the well screen even when the pumping rate is reduced; and for better salinity control it is necessary to place well screen against the gravel layers only and locate one screen segment in the saline water zone. The study shows (for the Gaza coastal aquifer) that the most important parameters affecting the movement of saline water under scavenger pumping are the relationship between recharge and pumping rates, the location of the well screen within the saturated thickness, the vertical permeability; and the transverse dispersivity. This study shows that saltwater upconing in Gaza aquifer can be controlled by operating a second well in the saline water zone so that the optimal ratio between saline water and freshwater pumping is 1:2 respectively.

Amending Sand with Isolite and Zeolite under Saline Conditions: Leachate Composition and Salt Deposition

Abstract: Understanding the possible influence of inorganic soil amendments on salt leaching and deposition is helpful in selecting soil amendments when salinity is a problem. Greenhouse experiments were conducted to: 1) evaluate the effects of isolite and zeolite on turf quality of Kentucky bluegrass (Poa pratensis L.) under three salinity levels; and 2) determine if soil amendments affected leachate composition, salt deposition, and soil sodium absorption ratio (SAR). 'Challenger' Kentucky bluegrass was grown in columns filled with 100% sand, 50 sand: 50 isolite, and 50 sand: 50 zeolite (v/v). Irrigation waters with three levels of salinity [0.25 (control), 3.5, or 6.5 dS.m -1 ] were applied daily for 3 months in Study I and for 6 months in Study II. Saline water reduced turf quality compared with control. Amendment of sand with isolite increased turf quality only during the third month of treatment with the most saline water in Study I. However, zeolite increased turf quality during both the second and third months at both salinity levels in both studies. The beneficial effects of zeolite on turf quality diminished 5 and 6 months after salinity treatments. Amending sand with zeolite reduced leaching of Na + and K + , but increased the leaching of Ca 2+ and Mg 2+ . Amending sand with zeolite increased SAR values by 0.9, 1.6, and 6.3 units in Study I and 0.9, 3.6, and 10.9 units in Study II, under control, 3.5, and 6.5 dS.m -1 salinity treatments, respectively. Isolite increased SAR by 1.1-1.6 units with 3.5 dS.m -1 and by 2.5-3.5 units with 6.5 dS.m -1 salinity treatments. Results indicate that amending with zeolite may buffer soil solution Na + concentration in the short- term. In the long-term, however, a substantial amount of Na + may be retained concurrent with Ca 2+ and Mg 2+ exchange, thereby increasing sodicity and salinity problems.

Laboratory model studies of flushing of trapped salt water from a blocked tidal estuary

Abstract: Results are presented from a series of laboratory model studies of the flushing of saline water from a partially- or fully-closed estuary. Experiments have been carried out to determine quantitatively the response of the trapped saline volume to fresh water Hushing discharges Q for different values of the estuary bed slope a and the density difference (Δρ)0 between the saline and fresh water. The trapped saline water forms a wedge within the estuary and for maintained steady discharges, flow visualisation and density profile data confirm that its response to the imposition of the freshwater purging flow occurs in two stages, namely (i) an initial phase characterised by intense shear-induced mixing at the nose of the wedge and (ii) a relatively quiescent second phase where the mixing is significantly reduced and the wedge is forced relatively slowly down and along the bed slope. Scalings based upon simple energy balance considerations are shown to be successful in (i) describing the time-dependent wedge be...