Showing papers on "Saline water published in 2012"

Effect of Piriformospora indica and Azospirillum strains from saline or non-saline soil on mitigation of the effects of NaCl

Abstract: Salinity toxicity is a worldwide agricultural and eco-environmental problem. The intent of this study was to determine the salt tolerance of Piriformospora indica and strains of Azospirillum, isolated from non-saline and saline soil, as well as to determine their affect on the tolerance of wheat to soil salinity. In this study, an experiment was conducted to investigate the salt stress tolerance abilities of the endophytic fungi, P. indica, and Azospirillum strains, isolated from non-saline and saline soil, at five NaCl levels (0, 0.1, 0.2, 0.3, 0.4, 0.5 mol L−1). Additionally, a greenhouse experiment was conducted to test the effects of these selected microorganisms under increasing salinity levels on seedling growth, solute accumulation (proline and sugars), and photosynthetic pigments (Chl a, b, ab) of seedling wheat. Azospirillum strains were isolated in Iran from the root of field-grown maize from non-saline soil with an EC = 0.7 dS m−1 and from saline soil with an EC = 4.7 dS m−1. Plants were irrigated with non-saline water–tap water with an electrical conductivity water (ECw) value of 0.2 dS m−1, as well as low, moderate and severe saline water-irrigation with saline water with an ECw of 4 dS m−1, 8 dS m−1 and 12 dS m−1, respectively. The upper threshold of P. indica salinity tolerance was 0.4 mol L−1 NaCl in both liquid and solid broth medium. The upper thresholds of the salt adapted and non-adapted Azospirillum strains were 0.2 and 0.4 mol L−1 NaCl, respectively. The results indicated a positive influence of the organisms on salinity tolerance, more with the saline-adapted Azospirillum strains than the non-adapted strains. P. indica was more effective than the Azospirillum strains. These results could be related to a better water status, higher photosynthetic pigment contents and proline accumulation in wheat seedlings inoculated with P. indica. The benefits of both isolates and P. indica depended on two factors: water salinity and growth stage of the host plant. Inoculation with the two isolates increased salinity tolerance of wheat plants; the saline-adapted Azospirillum strains showed better performance with respect to improved fresh and dry weights at 80 and 100 days after sowing under both non-saline and saline conditions. When compared to plants inoculated with non-saline-adapted Azospirillum strains, those inoculated with adapted Azospirillum strains had much better performance with respect to the presence of photosynthetic pigment (Chl a, b and ab) and proline accumulation. Overall, these results indicate that the symbiotic association between P. indica fungus and wheat plants improved wheat growth, regardless of the salinity. It is concluded that the mechanisms for protecting plants from the detrimental effects of salinity by P. indica fungus and Azospirillum strains may differ in their salinity tolerance and influence the uptake of water, photosynthetic pigment contents and proline accumulation in wheat seedlings.

Yield and Quality Characteristics of Quinoa Grown in Open Field Under Different Saline and Non-Saline Irrigation Regimes

Abstract: A possible alternative to minimize the effects of salt and drought stress is the introduction of species tolerating these conditions with a good adaptability in terms of quantitative and qualitative yield. So quinoa (Chenopodium quinoa Willd.) cultivar Titicaca was grown in an open field trial in 2009 and 2010 to investigate the effects of salt and drought stress on quantitative and qualitative aspects of the yield. Treatments irrigated with well water (Q100, Q50 and Q25) and corresponding treatments irrigated with saline water (Q100S, Q50S and Q25S) with an electrical conductivity (ECw) of 22 dS m−1 were compared. Salt and drought stress in both years did not cause significant yield reduction, while the highest level of saline water resulted in higher mean seed weight and as a consequence the increase in fibre and total saponin content in quinoa seeds.

Effect of salinity on the dielectric properties of water

Abstract: The complex permittivity ∈=∈′− j∈′′ of distilled water and NaCl solutions of concentrations varying from 5000 to 35000 ppm have been measured in the frequency range from 200 MHz to 1.4 GHz using a Vector Network Analyzer (VNA). The complex permittivity of saline water collected from Kanyakumari sea bank has also been measured in this frequency range. It has been observed that the dielectric constant of water decreases slowly with increase in frequency from 200 MHz to 1.4 GHz for given salinity of water. At given frequency, the dielectric constant decreases slowly with increase in salinity from 5000 to 35000 ppm. The dielectric loss of distilled water increases with increase in frequency from 200 MHz to 1.4 GHz, but for saline water it decreases with increase in frequency, over this frequency range. The decrease in dielectric loss with increase in frequency is more for higher salinity in water. The variation of complex permittivity of water with salinity and frequency is calculated using the Stogryn equations [IEEE Trans. On Microwave Theory and Techniques, August 1971, pp. 733-736] as well as with the Klein and Swift [IEEE Transactions on Antennas and Propagation, Vol. AP25, No.1, January 1977, pp. 104-111] equations, and the results are found to be in good agreement with corresponding experimental values. The variation of emissivity with variation of salinity calculated at fixed frequencies of 0.5, 0.9 and 1.4 GHz have also been presented in the paper, which is very much useful for remote sensing applications of oceans.

Crescimento inicial do milho sob diferentes concentrações de biofertilizante bovino irrigado com águas salinas

Abstract: The purpose of this study was to evaluate the effect of irrigation with water of high and low salinity on the initial growth of corn plants grown in soil fertilized with bovine bio-fertilizer. The experiment was conducted in a greenhouse of the Department of Soil Science - UFC. The seeds were planted in vessels with a 12 kg capacity, containing Alfissol as substrate and one plant per pot. The experiment followed a completely randomized design, in a 5x2 factorial scheme, with four replications, referring to five concentrations of bio-fertilizer: C1 = 50% biofertilizer + 50% water (1:1), C2 = 33.33% biofertilizer + 66.67 + water (1:2), C3 = 25% biofertilizer + 75% water (1:3), C4 = 20% biofertilizer + 80% water (1:4) and C5 = 11.12% biofertilizer + 88, 88% water (1:5) and two salinity levels of irrigation water for S1 = 0.8 dS m-1 (low salinity) and S2 = 3.4 dS m-1 (high salinity). We analyzed the early growth of plants as compared to the readings of electrical conductivity of water saturated soil extracts (ECse) by using the collected data on plant height, stem diameter, leaf area, shoot dry matter, root dry matter and total dry matter. Irrigation with low salinity water was found more efficient in promoting the initial growth of plants under increasing concentrations of biofertilizer, except for root dry matter. Under the same concentrations of biofertilizer, plus irrigation with saline water, soil salinity increased, but did so with less intensity in soil irrigated with low salinity water.

Complementary techniques to assess physical properties of a fine soil irrigated with saline water

Abstract: Water flow and solute transport numerical modeling is strongly limited due to the lack and difficulty in obtaining hydraulic property data in saline soils. A comparison of different techniques for physical characterization of soil structure is carried out in this study aiming to emphasize the complementarities and the synergy of the different approaches and their suitability for soils affected by salinization. In situ measurements of hydraulic conductivity (HC) by tension disc infiltrometer, water retention (WR) characteristics and pore size distribution by image analysis on undisturbed soil samples and aggregates stability have been measured in lab on a light clay soil of an experimental field undergone to two extreme irrigation treatments, NS (not-saline water, ECw = 0.9 dS m−1) and S (saline water with 1% of NaCl; ECw = 15 dS m−1). Following, the replicates have been denoted with the under script 1 and 2. The results show: a strong reduction of the index of aggregate stability in water, equals to 37 and 34% for NS1 and NS2, respectively, against the values of 18.9% for S1 and 18.5% for S2, respectively. The water retention curves of the S soils, for all the pressure heads investigated, are above those measured on not-saline soils. The image analysis has showed a larger quantity of pores (>36 μm) on the not-saline soils with respect to the saline ones. The total porosity (>36 μm) was 21.8% for NS2 and 11.9% for S1. This porosity reduction (9.9%) was spread over the entire ranges of pores with the greatest reduction in pore classes lying in the size range between 700 and 2,000 μm. The unsaturated hydraulic conductivity of the not-salines samples shows higher values respect to those of the saline samples. All the techniques applied showed converging results and provided a specific contribution towards the demonstration of a process of clogging of macropores under saline condition. Furthermore, the direct measurement of the pore changes provided by soil image analysis allowed a detailed interpretation of the mechanisms behind soil pore-structure worsening due to salinity. Combined use of the tension disc infiltrometer and image analysis methods showed the highest potential to overcome difficulties in hydraulic characterization close to saturation in salinized horizons.

Performance of single-slope single-basin solar still with sensible heat storage materials

Abstract: A single-slope single-basin solar still with an inner basin size of 1 × 1 m has been fabricated with a layer of copper sheet in the basin. The still has been provided with a dripping arrangement to pour saline water drop by drop into the basin. The system has been tested with the dripping of saline water and with different sensible heat storage materials like white marble stones, pebbles, black stones, calcium stones, and iron scraps. It has been found that the calcium stones in the basin with dripping of saline water to maintain the least water depth have a significant effect on the production and validated with the experimental results.

Response of tomato to irrigation with saline water applied by different irrigation methods and water management strategies

Abstract: In a field experiment the effects of irrigation with saline drainage water (seasonal average of 4.5 dS/m) and non-saline water (0.55 dS/m) applied by two different water management strategies (cyclic or blended saline water with non-saline water in different ratios) and two different irrigation methods (drip or furrow) were studied on growth and productivity of tomato (Lycopersicon esculentum Mill cv Floradade), salinity distribution in root zone and water use efficiency. The results indicated that salinity (at 3 dS/m and above) significantly reduced leaf area, height and dry weight of plant as well as fruit weight and number and hence total yield, but increased fruit T.S.S. content. Water use efficiency (WUE) was increased by using water with low and moderate salinity levels (2 and 3 dS/m) as compared to those obtained with non-saline water (0.55 dS/m) or the highest salinity level (4.5 dS/m). Salinity increased Na, Cl and Mg contents as well as dry matter percentage, but decreased N, P, K and Ca contents in leaves of plants. Drip irrigation enhanced tomato growth, yield and WUE under both saline and non-saline conditions, but showed more advantages under saline conditions as compared with furrow irrigation. Drip irrigation method did not allow salt accumulation in root zone (wetted area beneath the emitters and the plants). However, more salt accumulated in root zone (30 cm apart from irrigation source) of furrow irrigated plants. Mixing saline with non saline waters (blending) produced better results in terms of more vigorous vegetative growth and highest yield, than that produced by alternate saline with non saline water (cyclic). Using saline water up to 3 dS/m produced yield that was not significantly differ than that produced by non saline water if applied by drip irrigation and blended water management.

The demonstration of a novel sulfur cycle-based wastewater treatment process: sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI®) biological nitrogen removal process.

Abstract: Saline water supply has been successfully practiced for toilet flushing in Hong Kong since 1950s, which saves 22% of freshwater in Hong Kong. In order to extend the benefits of saline water supply into saline sewage management, we have recently developed a novel biological organics and nitrogen removal process: the Sulfate reduction, Autotrophic denitrification, and Nitrification Integrated (SANI®) process. The key features of this novel process include elimination of oxygen demand in organic matter removal and production of minimal sludge. Following the success of a 500-day lab-scale trial, this study reports a pilot scale evaluation of this novel process treating 10 m(3) /day of 6-mm screened saline sewage in Hong Kong. The SANI® pilot plant consisted of a sulfate reduction up-flow sludge bed (SRUSB) reactor, an anoxic bioreactor for autotrophic denitrification and an aerobic bioreactor for nitrification. The plant was operated at a steady state for 225 days, during which the average removal efficiencies of both chemical oxygen demand (COD) and total suspended solids (TSS) at 87% and no excess sludge was purposefully withdrawn. Furthermore, a tracer test revealed 5% short circuit flow and a 34.6% dead zone in the SRUSB, indicating a good possibility to further optimize the treatment capacity of the process for full-scale application. Compared with conventional biological nitrogen removal processes, the SANI® process reduces 90% of waste sludge, which saves 35% of the energy and reduces 36% of fossil CO(2) emission. The SANI® process not only eliminates the major odor sources originating from primary treatment and subsequent sludge treatment and disposal during secondary saline sewage treatment, but also promotes saline water supply as an economic and sustainable solution for water scarcity and sewage treatment in water-scarce coastal areas.

Response of Rice to Different Salinity Levels during Different Growth Stages

Abstract: Salt accumulation in irrigated soils is one of the main factors that diminish crop productivity since most of the crops are not halophytic. A greenhouse experiment was conducted in Rasht, North of Iran during May to June 2010 as a complete randomized block design with three replications. The treatments in this study were application of four levels of saline irrigation water (2, 4, 6 and 8 dS/m, respectively) at four growth stages (tillering, panicle initiation, panicle emergence and ripening). The aim of this study was to determine the effect salinity levels on some agronomic characters of rice. The results of this study showed that increase in salinity levels of irrigation water significantly decreased length of filled panicle, number of filled grains per filled panicle, number of spikelets per filled panicle and total number of spikelets per panicles but effect of different salinity levels on percentage of ratio of filled panicle number to tiller number and percentage of ratio of yield to straw weight was not significant. The least of these yield components were observed at the highest salinity level (8 dS/m). In different growth stages of rice, all yield components were different. Final growth stages, i.e., panicle emergence and ripening showed less sensitivity to salinity but primary stages, i.e., tillering and panicle initiation were more sensitive to salinity. Therefore, irrigation with saline water can be used in the final stages of plant growth, i.e. panicle emergence and ripeness.

Effect of Salinity on Larval Rearing of Pacu, Piaractus mesopotamicus, a Freshwater Species

Abstract: The aim of this study was to evaluate the growth and survival of pacu, Piaractus mesopotamicus, larvae reared in different salinities and to determine the Artemia nauplii life span in freshwater and in saline water. First feeding 5-d-old pacu larvae were reared in freshwater or at 2, 4, 6, 8, 10, 12, and 14 ppt salinities. The larvae were reared in 1.5-L aquaria at a density of 10 larvae/L with three replicates per treatment. After 10 d of rearing, significant differences (P < 0.05) were observed for growth and survival. Larval growth was higher at 2 and 4 ppt, and survival at 2 ppt was 100%. In freshwater and at 4, 6 and 8 ppt, the survival was 91.1, 93.3, 73.3, and 39.9%, respectively. At higher salinities, there was 100% mortality after 2 h (12 and 14 ppt) and 8 h (10 ppt) of exposure. The slightly saline water of at least 2 ppt increased the Artemia nauplii life span compared to the life span in freshwater. Later, in a second trial, 5-d-old pacu larvae were reared in freshwater and at 2 and 4 ppt salinities during the first 5 or 10 d of active feeding, and then the fish were transferred to freshwater. At the end of 15 d, larval growth was lower in freshwater (42 mg) than in treatments 2 and 4 ppt (59–63 mg). The abrupt transfer of fish from freshwater to slightly saline water and the return to freshwater did not affect the survival rates (89–97%). The larvae were able to adapt to these saline environments and handle abrupt changes in salt concentration. We concluded that salinity concentration of 2 ppt can be used for pacu larval rearing, allowing the Artemia nauplii lifetime to last longer and cause faster fish growth.

Road Salt Impact on Lake Stratification and Water Quality

Abstract: Runoff from roadways on which road salt (NaCl) has been applied for driving safety in winter can form a saline water layer at the bottom of a lake, pond, reservoir, or river impoundment. Natural vertical mixing of lentic surface water bodies can be hindered by the presence of a benthic saline layer and thereby affect lake water quality and ecology. To study the formation and disappearance of the saline layer, temperature and specific conductance profiles were measured intermittently over two years (2007, 2008) and at high frequency during one year (2009) in an urban lake of the northern temperate region (Tanners Lake, Oakdale, Minnesota). Erosion of the saline layer in the spring occurred only in year 2007. In years 2008 and 2009, the saline layer persisted throughout the summer only to be removed during fall turnover when thermal stratification was at a minimum. In all three years, salinity dominated density stratification after ice-out, but was quickly overtaken by temperature stratification as the epilimnion warmed. The deterministic, unsteady dynamic one-dimensional (1D) lake temperature and dissolved oxygen (DO) model MINLAKE was modified by including vertical salinity gradients, and it was used to simulate summer stratification and mixing dynamics in Tanners Lake. The daily adjustment of the hypolimnetic eddy diffusion as a function of lake number was an important component in the developed model. This addition allowed mixing in the hypolimnion to be stronger in the fall and spring when the lake stratification was weaker than in the summer after thermal stratification formed. Model results of dissolved oxygen in the water column demonstrated that the saline benthic layer can prevent dissolved oxygen from reaching lake sediments. The adverse consequences of dissolved oxygen depletion on phosphorus recycling from the sediments, benthic microbial communities, and fish habitat are well known. Overall, the results show how salinity from road salt applications can influence water quality and natural mixing in urban lakes.

Hydrogeochemistry and water quality assessment of the Kor–Sivand Basin, Fars province, Iran

Abstract: In order to assess the quality and suitability of waters in the Kor–Sivand river basin, 60 water samples from the Kor river and 90 water samples from wells in the basin were studied. Assessments were based on Piper’s and Gibbs’ diagrams for water quality, Food and Agricultural Organization’s (FAO) guidelines, and US Salinity Laboratory diagram for water suitability. The results showed that the river water is of Ca–HCO3 type, while well water is of Ca–Cl and Na–Cl type. Based on Gibbs’ diagram, the source of soluble ions in the river water samples is the weathering of stones over which water flows, while evaporation was found to be the dominant process in the ion concentration of the well samples. According to the FAO Guidelines, the salinity of surface water for irrigation did not cause great restrictions; however, many of these waters could create potential permeability problems. In the groundwater samples, a high salt concentration is more important than the infiltration problem. Mg hazard values at some sites limit its use for agricultural purposes. One third of the river water samples and two thirds of well waters had more than 50% magnesium. Saturation indices showed that 94% of the analyzed water samples are supersaturated with calcite, aragonite, and dolomite. Based on the US Salinity Laboratory diagram, river water samples were classified as C2S1 and C3S1, while C4S3, C4S4, C2S1, and C3S1 were the most dominant classes in well samples. Some management practices necessary for sustainable development of water resources in the study area were discussed briefly, including appropriate selection of crops, adequate drainage, leaching, blending and cyclic use of saline water, proper irrigation method, and addition of soil amendment.

Physiological characterization of rice under salinity stress during vegetative and reproductive stages

Abstract: Salinity is one of the major environmental factors limiting crop productivity. For this reason, a greenhouse experiment was conducted in Rasht, North of Iran during 2010 growing season to evaluate the salinity levels of irrigation water at different growth stages on the some physiological characterization of rice. Treatments were arranged in a randomized complete block design with two factors and three replications. Factor one included four levels of saline water (2, 4, 6, and 8 dS m -1 ); factor two consisted of four growth stages (tillering, panicle initiation, panicle emergence and ripening). The results of this work showed that effect of different salinity levels on the all yield components except percentage of filled grains per panicle was not significant. Increase in salinity levels decreased this component. Effect of different growth stages on total number of empty grains per panicles, percentage of filled grains per panicle, number of unfilled panicles and percentage of ratio of number of unfilled panicles to tillers was significant but effect of different saline water on length of unfilled panicle and number of spikelets per unfilled panicle was insignificant. Resistance of final growth stages, i.e. panicle emergence and ripening stages against salinity was more than primary growth stages, i.e. tillering and panicle initiation. Therefore, in irrigation with saline water the final growth stages were important and irrigation with saline water should be applied at final growth stages.

Effects of road-deicing salt (NaCl) and saline water on water quality in the Urmia area, northwest of Iran

Abstract: Increased application of road salt for winter maintenance has resulted in increased concentration of deicer constituents in the environment. The runoffs from the deicing operation have a deteriorating effect on water quality. The existence of salt super saturated Urmia lake and easy access to it, causes Urmia municipality to over use the super saturated water of this lake and salt (NaCl) during winter for snow melting, freezing prevention and traffic load facilitation. The aim of this study was investigation of surface and groundwater contaminations in consequence of salt (NaCl) and saline water usage in Urmia city and its surroundings. Studying the chloride ion concentration as a tracer in runoff result snowmelts during winter shows that its amount is differential with respect to time and place sampling. Results indicate that runoff result of snowmelts effected groundwater, soil and plant growth. The contamination of groundwater in study area by road salt and saline water is a slow process and directly related to the amount of road salt and saline water applied.

Water quality assessment of a tropical coastal lake system using multivariate cluster, principal component and factor analysis

Abstract: Statistical techniques represent a reliable tool for classifying, modelling and interpreting surface water quality monitoring data, particularly for lakes The complexity associated with the analysis of a large number of measured variables, however, is a major problem in water quality assessments Multivariate analysis, such as cluster analysis and factor analysis (FA), was utilized in this study for the analysis of water quality data (including water discharges and 28 water quality parameters) for Akkulam–Veli Lake, a tropical coastal lake system in Kerala, India This lake is partially divided into two sub-systems, namely Veli Lake and Akkulam Lake Akkulam Lake exhibits freshwater characteristics, in contrast to Veli Lake, which exhibits saline water characteristics because of its close proximity to the sea Thus, studying this lake provides insights into water quality variations in both a freshwater and saline water lake in a tropical region Water quality patterns and variations in Akkulam–Vela Lake over three seasons, including pre-monsoon (PRM), monsoon (MON) and post-monsoon (POM), also were studied, utilizing multivariate techniques The organic pollution factor played a significant role on lake water quality during PRM The influence of organic pollution tends to decrease during MON and POM, a particular situation faced by urban lakes in tropical regions Polluted stretches in a lake system during different seasons can easily be ascertained by hierarchical cluster analysis Further, the factors affecting a lake system as a whole, as well as for a particular sampling site, can easily be identified by FA Improved water quality can be observed during POM Akkulam and Vela lakes exhibit a wide variation in water quality during all seasons, a finding that corroborates a water flow obstruction from Akkulam Lake to Veli Lake because of the bund existing between the two lakes The location of the bund is identified as the major reason for different hydrochemical processes in A–V Lake

Yield Response of Drip-Irrigated Onion under Full and Deficit Irrigation with Saline Water in Arid Regions of Tunisia

Abstract: A two-year study was conducted in arid region of Tunisia to evaluate the effects of deficit irrigation regimes with saline water on soil salinity, yield, and water use efficiency of onion grown in a commercial farm on a sandy soil and drip-irrigated with water having an EC𝑖 of 36 dS/m Irrigation treatments consisted in water replacements of accumulated ET𝑐 at levels of 100% (SWB-100, full irrigation), 80% (DI-80), 60% (DI-60), when the readily available water in the control treatment (SWB-100) is depleted, deficit irrigation during ripening stage (SWB100-MDI60) and farmer method corresponding to irrigation practices implemented by the local farmers Results on onion production and soil salinization are globally coherent between the two-year experiments and show significant difference between irrigation regimes Higher soil salinity was maintained in the root zone with DI-60 and farmer treatments than full irrigation (SWB-100) SWB100-MDI60 and DI-80 treatments resulted also in low EC𝑒 values No significant differences were observed in bulbs fresh and dry yields, bulbs number·ha−1 and weight from the comparison between full irrigation (SWB-100) and deficit treatments (DI-80, SWB100-MDI60) DI-60 irrigation treatment caused significant reductions in the four parameters considered in comparison with SWB-100 The farmer method caused significant reductions in yield components and resulted in increase of water usage 45 and 33% in 2008 and 2009, respectively Water use efficiency was found to vary significantly among treatments, where the highest and the lowest values were observed for DI-60 and farmer treatments, respectively The full irrigation (SWB-100) and deficit irrigation (DI-80 and SWB100-MDI60) strategies were found to be a useful practice for scheduling onion irrigation with saline water under the arid Mediterranean conditions of southern Tunisia

Quality of Groundwater Resources in Chikhwawa, Lower Shire Valley, Malawi

Abstract: Groundwater resources in some parts of the lower section of the Shire River valley, Malawi, are not potable for rural domestic water supply due to high salinity. Knowledge of spatial variation of water quality is essential in locating and sustaining usable water supplies. In this study, a comprehensive assessment of the quality of groundwater from the area has been conducted to establish a spatial variation of major ions and general groundwater quality. World Health Organisation (WHO) guidelines for sodium (200 mg/l), chloride (250 mg/l), sulphate (250 mg/l), magnesium (30 mg/l) and calcium (75 mg/l) in drinking water were exceeded by 42%, 29%, 15%, 70% and 53% for all groundwater samples, respectively. The concentrations of analysed solutes are very wide in range, suggesting that the hydrochemistry is controlled by several intermixed processes such as saline water mixing and water–rock interaction. Based on the interpretation of the cumulative probability curve for TDS content, groundwater samples are grouped into three groups, as follows: (1) Group 1 waters (51%) that are relatively poor in Cl−, representing fresh groundwater affected mainly by weathering reactions; (2) Group 2 waters (45%) relatively enriched in Cl−, indicating considerable effects of rock-water interaction and mixing with saline water; (3) Group 3 waters (4%) enriched in Cl−, representing the saline groundwater resources. High total hardness (TH) and total dissolved solids (TDS) (in several places) render the groundwater, in large sections of the study area, unsuitable for domestic and irrigation purposes. Results reported in this study provide baseline data towards the utility of groundwater resources in the area.

Effects of long-term salt stress on antioxidant system, chlorophyll and proline contents in pea leaves

Abstract: The effects of long-term salt stress on the contents of chlorophyll, proline, protein, hydrogen peroxide (H2O2), and malondialdehyde (MDA) in terms of lipid peroxidation, and on the changes in activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) in leaves of pea (Pisum sativum cv Rona) were investigated in field conditions. Salinity and irrigation water regime experiments were set up in pots as randomized plot experimental designs with five replications. The experiment focused on pea responses to irrigation water salinity by irrigating the crops using 6 different levels of saline water (0.7, 2.0, 3.0, 4.0, 5.0 and 7.0 dS m -1 ) with a constant leaching fraction (LF = 0.30). The pots were located in the experimental area under a polyethylene cover which was about 1.8 m height from the surface for the purpose of eliminating rainfall effect on the experiments. Chlorophyll and protein contents were significantly decreased while accumulation of proline was enhanced with increased electrical conductivity (EC). Both MDA and H2O2 contents were reduced in the result of high salts application. All of the salt treatments increased total SOD activity significantly, as a remarkable increase in POD activity was observed especially at 5.0 and 7.0 dS/m EC. CAT and APX activities generally decreased in salt stressed seedlings. Our study indicates that its acquisition of salt tolerance may be a consequence of improved resistance to oxidative stress via increased activities of peroxidase and the superoxide dismutase/ascorbate-glutathione cycle.

Integrated approach for demarcating subsurface pollution and saline water intrusion zones in SIPCOT area: a case study from Cuddalore in Southern India.

Abstract: This paper deals with a systematic hydrogeological, geophysical, and hydrochemical investigations carried out in SIPCOT area in Southern India to demarcate groundwater pollution and saline intrusion through Uppanar River, which flows parallel to sea coast with high salinity (average TDS 28, 870 mg/l) due to back waters as well as discharge of industrial and domestic effluents. Hydrogeological and geophysical investigations comprising topographic survey, self-potential, multi-electrode resistivity imaging, and water quality monitoring were found the extent of saline water intrusion in the south and pockets of subsurface pollution in the north of the study area. Since the area is beset with highly permeable unconfined quaternary alluvium forming potential aquifer at shallow depth, long-term excessive pumping and influence of the River have led to lowering of the water table and degradation of water quality through increased salinity there by generating reversal of hydraulic gradient in the south. The improper management of industrial wastes and left over chemicals by closed industries has led surface and subsurface pollution in the north of the study area.