Showing papers on "Saline water published in 2004"

Salinity tolerance of diapausing eggs of freshwater zooplankton

Abstract: SUMMARY 1. Many freshwater zooplankton produce diapausing eggs capable of withstanding periods of adverse environmental conditions, such as anoxia, drought and extreme temperature. These eggs may also allow oligostenohaline species to survive increased salinity during periods of tidal flux or evaporation, and here we test the ability of diapause eggs to withstand such conditions. 2. Salinity tolerance may also enable organisms to invade new environments. The increased rate of introduction of non-indigenous species to the Laurentian Great Lakes since 1989, when ballast water exchange regulations (to replace fresh/brackish water at sea with full seawater) were first implemented for transoceanic vessels, has stimulated studies that explore mechanisms of introduction, other than of active animals, in ballast water. One hypothesis proposes that freshwater organisms transported in ballast tanks as diapausing eggs may be partially responsible for the increased rate of species introduction, as these eggs may tolerate a wide array of adverse environmental conditions, including exposure to saline water. 3. We collected ballast sediments from transoceanic vessels entering the Great Lakes, isolated diapausing eggs of three species (Bosmina liederi, Daphnia longiremis and Brachionus calyciflorus), and measured the effect of salinity on hatching rate. In general, exposure to salinity significantly reduced the hatching rate of diapausing eggs. However, as nonindigenous species can establish from a small founding population, it is unclear whether salinity exposure will be effective as a management tool.

How do salinity and water stress affect transport of water, assimilates and ions to tomato fruits?

Abstract: The study was conducted in order to determine whether water stress affects the accumulation of dry matter in tomato fruits similarly to salinity, and whether the increase in fruit dry matter content is solely a result of the decrease in water content. Although the rate of water transport to tomato fruits decreased throughout the entire season in saline water irrigated plants, accumulation rates of dry matter increased significantly. Phloem water transport contributed 80-85% of the total water transport in the control and water-stressed plants, and over 90% under salinity. The concentration of organic compounds in the phloem sap was increased by 40% by salinity. The rate of ions transported via the xylem was also significantly increased by salinity, but their contribution to fruit osmotic adjustment was less. The rate of fruit transpiration was also markedly reduced by salinity. Water stress also decreased the rate of water transport to the tomato fruit and increased the rate of dry matter accumulation, but much less than salinity. The similar changes, 10-15%, indicate that the rise in dry matter accumulation was a result of the decrease in water transport. Other parameters such as fruit transpiration rates, phloem and xylem sap concentration, relative transport via phloem and xylem, solutes contributing to osmotic adjustment of fruits and leaves, were only slightly affected by water stress. The smaller response of these parameters to water stress as compared to salinity could not be attributed to milder stress intensity, as leaf water potential was found to be more negative. Measuring fruit growth of girdled trusses, in which phloem flow was inactive, and comparing it with ungirdled trusses validated the mechanistic model. The relative transport of girdled as compared to ungirdled fruits resembled the calculated values of xylem transport.

Integrated Geophysical and Chemical Study of Saline Water Intrusion

Abstract: Surface geophysical surveys provide an effective way to image the subsurface and the ground water zone without a large number of observation wells. DC resistivity sounding generally identifies the subsurface formations—the aquifer zone as well as the formations saturated with saline/brackish water. However, the method has serious ambiguities in distinguishing the geological formations of similar resistivities such as saline sand and saline clay, or water quality such as fresh or saline, in a low resistivity formation. In order to minimize the ambiguity and ascertain the efficacy of data integration techniques in ground water and saline contamination studies, a combined geophysical survey and periodic chemical analysis of ground water were carried out employing DC resistivity profiling, resistivity sounding, and shallow seismic refraction methods. By constraining resistivity interpretation with inputs from seismic refraction and chemical analysis, the data integration study proved to be a powerful method for identification of the subsurface formations, ground water zones, the subsurface saline/brackish water zones, and the probable mode and cause of saline water intrusion in an inland aquifer. A case study presented here illustrates these principles. Resistivity sounding alone had earlier failed to identify the different formations in the saline environment. Data integration and resistivity interpretation constrained by water quality analysis led to a new concept of minimum resistivity for ground water-bearing zones, which is the optimum value of resistivity of a subsurface formation in an area below which ground water contained in it is saline/brackish and unsuitable for drinking.

Exploring potentials and constraints of low-cost drip irrigation with saline water in sub-Saharan Africa

Abstract: Irrigation with saline water could provide an interesting opportunity to meet increasing food demands without competing with other pressing needs for fresh water such as domestic and industrial wat ...

Interactive effects of salinity, flooding, and soil type on panicum hemitomon

Abstract: It is well documented that Louisiana is experiencing wetland loss at rates greater than any other locale in the world. High rates of relative sea-level rise, a combination of eustatic sea-level rise and subsidence, is anticipated to compound this problem further in the future through increased flooding and encroachment of saline water into freshwater wetlands. The research presented in this paper examines the interactive effect of increased salinity level, flooding depth, and soil type on the growth responses of a dominant Louisiana fresh-water marsh plant, Panicum hemitomon, whose prevalence in Louisiana is currently in decline. This study was conducted under greenhouse conditions and employed a factorial design consisting of three salinity levels (0, 1.5, 3.0 ppt), three hydrologic regimes (0, 10, 20 cm), and two soil types (high organic content, low organic content). Panicum hemitomon productivity was significantly reduced even under the relatively small increases in salinity level (1.5 and 3.0 ppt) imposed in this study. Interestingly, moderate flooding tended to increase productivity, although this relationship was not statistically significant. Significantly greater productivity was observed for plants grown in mineral soil compared with organic soil. These results indicate that any degree of saline influx into P. hemitomon-dominated wetlands will result in decreased vigor and localized decline of this species. Moderate increases in the degree of freshwater inundation may not be as damaging as originally expected and, in fact, may actually stimulate production. However, if increased flooding is accompanied by increased salinity levels, which is anticipated to occur, then the overall effect on this species will be detrimental.

Significance of Dar-Zarrouk parameters in the exploration of quality affected coastal aquifer systems

Abstract: The interpreted Earth subsurface resistivity layer parameters of 55 vertical geoelectrical soundings are analyzed over a fan shaped area of 1,700 km2 from Pipli-Astrang-Bhramgiri, Orissa, India. In this study, Dar-Zarrouk (D-Z) parameters, namely the longitudinal conductance (S), transverse resistance (T) and longitudinal resistivity (Rs) are analyzed and we encountered the resistivity regime of the clay layers, saline and fresh water bearing formations. The significance of these parameters in establishing an easily decipherable vision about the occurrence and distribution of fresh and saline water aquifers, while dealing with complicated situations of intermixing of the resistivity ranges of saline and fresh water aquifers has been illustrated. The results show that the Dar-Zarrouk (D-Z) parameters provide a useful and confident solution in delineating the saline and fresh water aquifers. The behavior of the D-Z parameters S, T and Rs, and its patterns in space over large areas with respect to the occurrence of saline water and fresh water aquifer systems in the deltaic coastal aquifer system has been demonstrated.

Identification of sea-water ingress using strontium and boron in Krishna Delta, India

Abstract: The distribution trends of trace elements over North and South Krishna delta were examined in relation to fresh-, brackish- and saline-water zonations. Strontium and boron have shown significant variations in fresh-, brackish- and saline-water environment. Strontium has shown a variation from 23 to 1500 μg/l in freshwater, 1650 to 2760 μg/l in brackish water and 1679 to 3180 μg/l in saline water. Similarly, boron has shown a variation from 71 to 199 μg/l in freshwater, 211 to 422 μg/l in brackish water and 695 to 2929 μg/l in saline water. The groundwater of these delineated zones when compared with the zonations of total dissolved solids are in good agreement. Therefore, strontium and boron could be used as sensitive chemical parameters responding to changes in fresh- to saline-water environment.

Effect on growth performance and biochemical contents of Salvadora persica when irrigated with water of different salinity

Abstract: An experiment was conducted in pots to study the effects of saline water of different salinity on growth performance, salt-accumulation and biochemical contents in Salvadora persica at establishment stage using calcareoussoil. The observations indicated that all the growth parameters such as height, stump diameter and plant biomass decreased with the increase in the salinity of irrigation water and a total reduction in dry biomass of the plant was 31.59% when irrigated with water of 16 dS m - 1 as compared to good quality tap water. Concentration of sodium in different parts of plant indicated that maximum retention was in root followed by stem, leaf and minimum in thin branches and it increased with the increase in salinity of irrigation water. Potassium content was maximum in leaf in all the treatments and almost evenly distributed in other parts. Its accumulation decreased with increase in salinity of irrigation water. Both calcium and magnesium contents were maximum in leaf followed by root. These were almost equal in stem and thin branches. In leaf samples, proline and other amino acids increased and chlorophyll, protein and sugar contents decreased with the increase in salinity of irrigation water.

Intrusion of Less Saline Shelf Water into the Kuroshio Subsurface Layer in the East China Sea

Abstract: The possible origin and cause of the less saline shelf water detected in the Kuroshio subsurface layer around the shelf edge of the East China Sea are investigated using observational results obtained in May 1998–2001 in conjunction with a dataset archived by Japan Oceanographic Data Center and a numerical model. The observations show that subsurface intrusions of less saline water are always detected in May in layers above 24.5σθ isopycnal surface, and that salinity inversions (i.e., areas in which the less saline water lies beneath the saline water) are detected around the trough of the Kuroshio frontal eddy (or wave). Analyses of the archived dataset reveal that the isopycnal surface of 24.5σθ is the deepest layer of the Kuroshio pycnocline outcropping to the sea surface on the shallow shelf in early spring. Outcropping isopycnals above 24.5σθ encounter a less saline water plume originating from the Changjiang, especially in the western East China Sea. Thereafter, the less saline water moves along isopycnal layers and reaches the Kuroshio front around the shelf edge. Numerical models demonstrate that, when the frontal wave captures the less saline water, the shelf water takes the form of a salinity inversion in the trough because isohalines in the frontal wave have a phase lag between the upper and lower layers in consequence of the baroclinic instability.

Cation exchange processes and human activities in unconfined aquifers

Abstract: During the 1999–2002 water years, a hydrogeological research project was carried out on the unconfined aquifer of Trifilia in the Peloponnese. Seawater intrusion due to overpumping, and intensive use of fertilizers caused the groundwater quality degradation that is a typical case for the coastal aquifers in Greece. Isopiezometric maps along with ion distribution balances, ion distribution maps and factor analysis indicate the existence of three zones of groundwater quality. In the first zone of saline water, a cation exchange process between the Ca2+ of sediments and the Na+ of groundwater contribute to the formation of the water type Na+-Ca2+-Cl−. In the second zone, which is considered as a transition zone, dominate the Ca2+-Na+-HCO3 −-Cl− water type. In the third zone of Ca2+-HCO3 −-SO4 2− water type, relationships among Ca2+, SO4 2−, NO3 − and NH4 can be attributed to the dissociation of ammonium nitrate and sulfate fertilizers on one hand, and Ca2+ derivation from cation exchange processes between water, rocks and clay minerals, such as smectite and illite, on the other.

The role of diatom resting stages in the onset of the spring bloom in the East China Sea

Abstract: The abundance and species composition of diatoms were investigated along the PN line from the Okinawa Islands to the inner continental shelf in the East China Sea in the early spring of 1996. Viable diatom resting stages in sediments on the shelf were also enumerated by the extinction dilution method (most probable number method). Clear differentiation in the water masses was observed, with less saline, cold water (shelf water) on the shelf region, and warm, saline water (Kuroshio water) prevalent off the shelf and on the shelf edge. In the Kuroshio water, the abundance of diatoms was generally low but species diversity of diatoms was relatively high. In contrast, the spring bloom of diatoms was clearly observed in the shelf water where the water column was weakly stratified. The bloom was dominated by Chaetoceros debilis, contributing occasionally >80% of the diatom community. Resting stages of this species were also the most abundant taxon in the sediments on the shelf. Resuspension of the sediment during winter mixing of the water column should have enabled the resting stages to germinate at the surface. Subsequent vegetative growth after germination led to the formation of an early spring bloom of C. debilis when the water column was stratified and light availability had increased. Intermittent resuspension of sediment on the shelf, driven by strong winds and tidal currents, probably provides opportunities for diatoms with a resting stage to exploit favorable conditions for their germination and subsequent vegetative growth. It is further suggested that complex hydrographic conditions in the East China Sea result in a dynamic bloom with contributions by both autochthonous and allochthonous species.

Effects of increasing salinity and 15N-labelled urea levels on growth, N uptake, and water use efficiency of young tomato plants

Abstract: A greenhouse experiment was conducted to investigate the response of tomato plants (Lycopersicon lycopersicum L.) to salinity and to determine the interactive effects of salinity and nitrogen fertilisation on yield, nitrogen uptake, water use efficiency (WUE), and root-zone salinity during early plant growth. Furthermore, the effects of salinity and N fertilisation were evaluated by measurement of carbon isotope discrimination (∆). Tomato plants were grown in pots filled with 8 kg (dry weight equivalent) of Krumbach sandy loam. Salinity treatments were imposed by irrigation water containing Na, Ca, and Mg salts and having electrical conductivity of 0, 3, 6, 9, and 12 dS/m at 25°C. 15 N-labelled urea (10 atom % excess) was also applied at 0, 80, 160, and 240 mg N/kg soil. Increasing salinity reduced plant growth; fresh and dry weights of shoots and roots decreased significantly, except for the non-fertilised plants. The maximum growth reduction in shoots occurred due to salinity-N fertilisation relationships at 12 dS/m (59.4% reduction compared with 0 dS/m in 160 mg N/kg). Root growth was less affected than shoots. Vegetative growth and N content increased with increasing nitrogen treatment. However, salinity generally reduced N uptake by plants. ∆ was negatively correlated with WUE at all salinity levels in young tomato plants. Similar correlations were also obtained between WUE and ∆ at various N treatments; the result suggests that ∆ is a useful tool for assessing stress conditions. Smaller ∆ values were obtained when salinity or N level increased. Increasing N fertiliser increased WUE in plants, whereas increasing salinity increased WUE at 3 dS/m and decreased WUE to some extent at other salinity levels. Electrical conductivity of the root-zone increased due to increasing salinity and time, whereas pH decreased. It was concluded that the early stage of development was a salt sensitive period for tomato plants. SR02 C. Ku t et al Sa li f

Sources and transformations of nitrogen compounds along the Lower Jordan River.

Abstract: tions from small springs and rare flood events. Currently, the only two water sources at the starting point The Lower Jordan River is located in the semiarid area of the of the Lower Jordan River are the effluent of the Bitania Jordan Valley, along the border between Israel and Jordan. The implementation of the water sections of the peace treaty between wastewater treatment plant and the Saline Water CarIsrael and Jordan and the countries’ commitment to improve the rier (Sites 1 and 2 in Fig. 1). The Bitania source includes ecological sustainability of the river system require a better under- poorly treated human and animal waste effluents. The standing of the riverine environment. This paper investigates the Saline Water Carrier contains a mixture of saline spring sources and transformations of nitrogen compounds in the Lower water diverted from the Sea of Galilee and urban sewage Jordan River by applying a combination of physical, chemical, isoto- effluent. As a result of the degradation of water quantity pic, and mathematical techniques. The source waters of the Lower and quality, the Lower Jordan River has become brackJordan River contain sewage, which contributes high ammonium loads

Sub-surface investigations on deep saline groundwater of Charnockite rock formation, Kalpakkam, India.

Abstract: Investigations on geohydrological aspects of coastal aquifer are important in order to understand the mechanism of ground water salinisation. The present study describes the salinity variations of ground water in deep boreholes drilled in Charnockite rock formation of Kalpakkam, on the eastern coast of India. Water samples collected up to 600m depth were analyzed for salinity variation. It is noticed that in one of the boreholes, (borehole K1), the salinity level is found to be 74 parts per thousand (ppt) at 400 m depth. Influence of surface saline water bodies viz., sea (26–28.5 ppt), backwaters (27–30 pt) and Buckingham canal (27–32 ppt) as the possiblesources of recharge of fresh waters through joint and fracture system ofthe rock are discussed in this paper. Studies would assist in understandingthe geohydrological characteristics of deep geological formation.

Multi-layer structure in the Youngsan Estuary, Korea

Abstract: Repeated hydrographic observations were undertaken to examine the spatial structure and temporal variation of temperature and salinity in the Youngsan Estuary during summer. A multi-layer structure with four water masses was observed. Fresh water was frequently observed at the surface in summer, when a large volume of river water was discharged from the sea dike. The coldest water, which occupied the entire water column due to vertical mixing in spring, was preserved in the middle layer during summer. The bottom layer, which was warmer than the middle layer, became warmer in summer due to an intrusion of warm saline water, along the bottom from the open sea. The surface water was a mixture of discharged fresh water and cold water from the middle layer. Long-term monitoring data showed that the spreading of discharged fresh warm water over the pre-existing surface water and the intrusion of warm saline water along the bottom from the open sea produced a multi-layer structure. Large Richardson number, due to strong stratification and a weak tidal current, suggested that the multi-layer structure remained throughout the summer. The multi-layer structure disappeared in fall due to an inflow of cold water from the river and surface cooling.

Can the desert bloom? Lessons learned from the Israeli case.

Abstract: Despite the central management of Israel's water resources and the highly planned strategy for a sustainable water supply, Israel has twice faced an acute water crisis during the past decade. Although the visible problem is related to a lack of additional quantities of water, the deterioration of water quality appears to be endangering the future use of available water quantities as well. A long-term policy of ground water mining (translated to salt water encroachments), and irrigation with relatively saline water and recycled waste water, among other damage, account for this deterioration. Enhanced flushing of the salt and contaminant load from the aquifers (using various techniques) is proposed as a solution to the problem.