Mean Electrical Conductivity Research Articles

Assessment of groundwater occurrence in Olomoro, Nigeria using borehole logging and electrical resistivity methods

The objective of this study was to assess the subsurface strata and groundwater situation of Olomoro, Nigeria using borehole logging and electrical resistivity techniques. The borehole logging consisting of resistivity and spontaneous potential logs were conducted by using the Johnson Keck logger on a drilled well in the study area. The electrical resistivity survey involving 17 vertical electrical soundings (VES) with a maximum current electrode spacing of 100 to 150 m was conducted using the Schlumberger electrode configuration. Analysis of the well cuttings revealed that the lithology of the subsurface consist of topsoil, clay, very fine sand, medium grain sand, coarse sand and very coarse sand. Results of the downhole logging also revealed that the mean electrical conductivity and the total dissolved solid of the groundwater was obtained as 390 μS/cm and 245 mg/cm3 respectively. These values are within the acceptable limit set by the Standard Organization of Nigeria (SON) for drinking water. The result of the vertical electrical sounding interpreted using the computer iterative modeling revealed the presence of four to five geoelectric layers which showed a close correlation with result from the lithology and downhole logging. Results further showed that the resistivity of the subsurface aquifer ranged between 1584 and 5420 Ωm while the aquifer depths varied between 27.8 and 39.3 m. Groundwater development of the area is suggested using the depth and resistivity maps provided in this study.

Measurement of Anode Arc Attachment Movement in DC Arc Plasma Torch at Atmospheric Pressure

Direct current (DC) arc plasma torches are widely used in various industrial applications. Studying processes in their anode area helps to extend their lifetime, and stabilize the plasma flow for plasma applications. This paper reports detailed observations of the fast movement (above 100 m/s) of the anode arc attachment in a hybrid water-argon DC arc plasma torch with an external anode. We measured a mean electrical conductivity of a plasma volume above the anode and found a relation between the attachment movement and the anode erosion. Further, we measured average attachment speed, the average period of the restrike process and the average distances travelled by the attachment under different experimental conditions such as different values of the arc electric current, argon flow rate and different anode configurations. For our measurements, we used a high-speed camera and a high-voltage probe. Our results are in agreement with a model of plasma generated by a hybrid plasma torch and with spectroscopy measurements. The results describe the movement of the anode arc attachment in detail and provide experimental data on average plasma electrical conductivity in hot anode areas. Both the measurements of the mean electrical conductivity and the procedure for quantitative comparisons of anode erosion can be used also in water plasma torches and theoretically also in gas plasma torches.

Conditioning in the promotion and uniformization of Umbu seed germination

Abstract Seed dormancy may decrease during storage and some environmental conditions may accelerate this process. The aim of this work was to determine efficient techniques to condition umbu seeds in order to promote and standardize their germination. Seeds were stored for 180 days in paper bags kept in five ambient conditions: laboratory (25 ºC and 55% RH); warm oven (40 °C and 53% RH); hot oven (50 °C and 49% RH); dry chamber (18 °C and 65% RH) and cold chamber (10 °C and 65% RH). Seed quality was evaluated every 60 days by means of the following tests and determinations: water content; germination test (25 °C and 55% RH, weekly evaluated up to 91 days after sowing); first count test (14 days); germination rate index; mean germination time and electrical conductivity. The conditioning of umbu seeds in laboratory, or in warm oven (40 ºC) used efficient techniques to promote and standardize germination; under these conditions, after six months of storage, germination increased from 31% to 84 and 74%, respectively.

A new method for optimal fabrication of carbon composite paper as gas diffusion layer used in proton exchange membrane of fuel cells

Carbon Papers (CPs) have been widely used as a Gas Diffusion Layer (GDL) for high performance fuel cells. Herein we report a novel method for production of GDL, without the need to carbonization and graphitization steps that is common steps in GDL production. CP is provided by a dry-laying of carbon fibers (CFs) and expanded graphite (EG) in the phenolic resin and the composites are compared with carbon paper of Toray Co., Ltd. The effect of paper thickness, aspect ratio of CF and EG value of the composite are investigated. The characterizations are performed by scanning electron microscope, maximum pore size, mean pore size, permeability, electrical conductivity, flexibility, and performance (I-V) curve. The results shown that in the optimized state of the composition in the manufactured composite, the values of mean pore size, permeability, electrical conductivity, and performance curve is reasonable and near the Toray paper, however the manufactured composite show a much higher flexibility than that of Toray paper in a qualitative test. In addition, due to removing the graphitization and carbonization steps for production of carbon paper, the produced carbon paper costs are much lower than Toray paper.

CHEMICAL COMPOSITION AND SALT LOAD IN RAINWATER OF MOSUL CITY-NINEVEH GOVERNORATE

The present study reports the chemical composition and atmospheric salt load rainwater of Mosul city/ Nineveh Governorate / Iraq. The sampling were done from October 2012 to March 2013. Twenty six samples were collected and analyzed for pH, ion concentration (Ca++, Mg++, K+, Na+, CI-, HCO3-, SO4--) and electrical conductivity. Total rainwater was 338.55mm. The results show that the volume weighted mean (VWM) pH and electrical conductivity in the rainwater were 6.83 and 114.22µS.cm-1 respectively. Cation and anion concentration took the following order : Ca++ ˃ Mg++ ˃ Na+ ˃ K+ and HCO3- ˃ CI- ˃ SO4=. HCO3- and Ca++ contributed 65.3% of the total ions in the rainwater. Equivalents ratios for different ionic components to sodium, revealed higher values in rainwater than that of seawater. This indicates the dominance of non-marine in studied samples. Analyses revealed that loads delivered from the fallen precipitation in the urban city of Mosul was about 0.1167kg cl-/m3 of chloride in rainwater which equal numerically to 395kg NaCI. h-1 of land.

Extensive reclamation of saline-sodic soils with flue gas desulfurization gypsum on the Songnen Plain, Northeast China

Previous studies have reported that flue gas desulfurization (FGD) gypsum can be used as an amendment for saline-alkali soils. However, little information is available regarding the effects of FGD gypsum on soil quality and crop production at large scales. Thus, we evaluated the changes in the soil salinity, sodicity, soluble ion levels, paddy rice (Oryza sativa L.) yield and heavy metal levels in soil and rice after reclamation with FGD gypsum and paddy planting over three years. Data (90 samples) were also collected from three neighbouring saline-sodic fields (1780 ha). As expected, soil salinity and sodicity decreased significantly after two years of reclamation. The levels of electrical conductivity (EC) and the sodium absorption ratio (SAR) decreased rapidly in the first year, and the pH and exchangeable sodium percentage (ESP) decreased substantially in the second year. Averaged across the experimental sites, the mean EC, pH, ESP and SAR levels of the soils two years after reclamation decreased by 38.6%, 14.6%, 61.2% and 87.8%, respectively, compared to those of the initial soils. In addition, the concentrations of water-soluble Na+ and CO32− + HCO3− were 97.5% and 96.8% lower, respectively, two years after reclamation than the concentrations before reclamation. The paddy rice yield increased over time with reclamation; the mean level in the second year was 7.4 t ha−1 or 80% of the yield harvested from the managed fields of neighbouring farmers. Moreover, the heavy metal (Cd, Cr, Hg, Pb and As) contents of both soils and rice were lower than the established standards and below detectable limits after FGD gypsum application. These results confirm that FGD gypsum is a safe and effective way to reclaim saline-sodic soils and worthy of widespread application on the Songnen Plain in Northeast China and in similar ecological areas.

Acidic Wet Deposition in Bandung City Indonesia

Acidic deposition (acid rain) has been known to cause negative impact to environment. Measurement of rain chemical composition was done in March to August 2016 to investigate temporal variation of atmospheric deposition in Bandung City. Rainwater samples are collected at four sampling sites. The chemical properties of the rain determined were pH and ionic concentrations of SO42-, NO3-, Cl-, Ca2+, Mg2+, Na+, K+ and NH4+. The rainwater was typically acidic with the range of mean pH between 5.29 – 5.56 and mean electric conductivity value range between 16.37 – 19.96 μS/cm. Temporal variation showed higher SO42+, NO3+ and NH4+ concentration in August when rainfalls were the lowest (214.88 mm). Similar temporal variation for the mean pH (5.98) and electric conductivity (25.36 μS/cm) in August. Ca2+ highest concentration was observed in June. Generally, the the major component of precipitation chemistry were SO42- and NO3-, Ca+ and NH4+, for anion and cations, respectively. The largest proportions of the total anions in all sampling sites was SO42- ranged from 32% (Lembang) to 37% (Buah Batu) followed by NO3- (13 – 15%) and and Cl- (4 – 7%). For cations, NH4+ dominated with proportion ranged between 21 – 27% and subsequently Ca2+ (13 – 19%) and followed by Na+, Mg+, K+ and H+. The Neutralizing Factor (NF) results reveal that Ca2+ and NH4+ are the dominant neutralization substances in the rainwater. However it should be noted that reduced nitrogen (NH4+) act as mobile nitrogen that further will acidify the environment, particularly to soil ecosystem downstreams.

Arc Motion in Low Voltage Circuit Breaker (LVCB) Experimental and Theoretical Approaches

This paper is related to the study of the arc motion in simple low voltage circuit breaker geometry. Experimental and theoretical approaches are investigated respectively by fast camera and by a magneto hydrodynamic model. Two theoretical methods have been developed to characterize the arc movement called MECM (Mean Electrical Conductivity Method) and GCRM (Global Current Resolution Method). The results obtained by the two models are in good agreement with the experimental observations. The MECM allows obtaining faster results but the stagnation phases are well represented with the GRCM and this last method is easier to implement in more complex geometry. The results show also the importance of the exhaust description on the arc behavior.

Helminths and heavy metals in soils from a dumpsite in Ibadan city, Nigeria.

SummaryWaste generation is inevitable because humans continue to generate waste due to increase in population, urbanization and advancement in technology. This generation of waste is of public health concern especially when the waste materials are deposited on dumpsites. This study assessed the helminths and heavy metal content of Awotan dumpsite in Ibadan city. Surface soils (0-15cm depth) of the dumpsite were randomly sampled at different dumpsite areas with the aid of a quadrat. Helminth content was determined using the zinc floatation method and the heavy metal concentrations of the soil were determined using Atomic Absorption Spectrophotometry (AAS). Some physicochemical properties of the soil were also determined. Results showed that the dumpsite soil was slightly alkaline with an average pH of 8.1 ± 0.2 while the overall mean electrical conductivity, temperature, moisture content and height above sea level were 545.9 ± 235.3μS/cm, 32.6 ± 2.2oC, 17.2 ± 4.8 % and 236±4.6 m respectively. The overall prevalence of soil helminths was 10.4% with Ascaris lumbricoides being more prevalent (8.8%). The heavy metal concentration of the soil followed the trend Pb (709.7± 1574.9mg/g) > Cu (316 ± 227.1mg/g) > Cr (48.8 ± 17.7mg/g) > Cd (9.7 ± 10.9mg/g). There was a low overall prevalence of soil helminths. However, the heavy metal concentrations exceeded USEPA permissible limits providing a possible source for underground water contamination in residential areas around the dumpsite. Human settlements close to the dumpsite should be discouraged by the government.

Physicochemical Characteristics of Soil from Selected Solid Waste Dump Sites in Port Harcourt, Rivers State, Nigeria

This study examined the nutrient status and textural characteristics of soil from solid waste dumpsites in the city of Port Harcourt. The study was carried out in five solid waste dump sites alongside their respective controls located at Iwofe, Eliozu, Choba, Rumuokwuta and Ozuoba within the city of Port Harcourt for two seasons (wet and dry). A systematic sampling technique was employed for field sampling. Soil sample was collected with soil auger and analysis was done using standard methods. Results showed mean pH value (4.86±0.18 – 7.66±0.44) and; cation exchange capacity (2.2±0.3 -18.11±0.8 meq/100g). The mean electrical conductivity indicated higher conductivity in the control sites (125±5.5 - 492±16 μs/cm) than the dump sites (32.06±2.5 – 299.5±1.5μs/cm).There was high nutrient concentrations in the dump site soils of total nitrogen (0.04±0.01 – 0.62±0.13%); phosphorus (0.041±0.01 – 4.07±0.02mg/kg); potassium (9.19±2.5 – 326±51.91mg/kg) than the controls. On the contrary, there was no significant difference between the soil particle size distribution of the dump site soil and their respective controls. The soil particle size distribution indicated an average of 83% sand, 11% clay and 5% silt, while the soil texture was loamy sandy for all the dump sites except the dump site located at Iwofe. Therefore, solid dumps alter the soil nutrient contents with no significant change in the textural nature of soil. Key words: Solid wastes, Soil, Particle size, Nitrogen, Nutrient, Dump sites

Influence of drip irrigation level on salt leaching and vegetation growth during reclamation of coastal saline soil having an imbedded gravel–sand layer

Water resources are very scarce in coastal saline areas; as such, water-saving irrigation regimes are needed. Drip irrigation combined with an imbedded gravel–sand layer has been proved to be a good method for constructing ecological landscapes in coastal saline soils. A 3-yr experiment (2009–2011) was conducted to evaluate the effects of different drip irrigation amounts controlled by soil matric potentials (SMP) (−5, −10, −15, −20, and −25kPa) on soil salinity and landscape species growth in coastal saline soils with an imbedded gravel–sand layer in Northeast China. The mean electrical conductivity of the saturated paste extract (ECe) of the soil profile significantly decreased to less than 4dSm−1 for SMP treatments higher than −20kPa after two months, then remained at the low level. No significant differences in the extent of desalinization occurred among the drip irrigation treatments based on −5, −10, −15, and −20kPa SMP. The −20kPa treatment could reduce irrigation water usage by 150–610mm in the first three years of reclamation compared with higher SMPs (−5, −10, and −15kPa). Variations of pH of the saturated paste extract (pHe) in the soil profile were relatively moderate. After the 3-yr experiment, the landscape species that are moderately sensitive or sensitive to salt grew well, with an average survival rate of 72%. To balance salt leaching and water saving, a SMP of −20kPa could be used to guide landscape construction in the first three years of reclamation.

Modern and fossil diatom assemblages from Bol’shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia)

This article discusses the results of a taxonomic and ecological investigation of diatoms from polygonal ponds and Quaternary permafrost deposits of Bol’shoy Lyakhovsky Island (New Siberian Archipelago) and the reconstruction of climatic changes on the Island during late Pleistocene/Holocene transition using fossil diatom assemblages from the permafrost deposits. The taxonomic list of diatoms includes 159 diatom species. The main ecological factors that determine the distribution of diatoms in the investigated data set are mean July air temperature, рН, electrical conductivity, water depth, and concentrations of Si4+ and Al3+. An increase in water depth and stable lacustrine conditions in the Lateglacial–Holocene in the ancient thermokarst lake relate to Lateglacial warming before 11860 ± 160 years BP and during the early Holocene between 11210 ± 160 and 7095 ± 60 years BP.

Groundwater salinization in Graciosa and Pico islands (Azores archipelago, Portugal): processes and impacts

Study regionGraciosa and Pico islands, Azores, Portugal Study focusSeawater intrusion is a main driver of groundwater salinization in the Azores archipelago. In order to characterize the associated geochemical processes through major-ion and determination of stable (δ18O; δ2H; δ11B) and radiogenic isotopic ratios (δ87Sr) a total of 46 wells were sampled in Graciosa and Pico, as well as 51 wells from other islands. New hydrological insights for the regionThe overall groundwater chemistry is mainly controlled by Cl and Na, which account respectively for 10.4%–46.9% and 16%–39.7% of the relative major-ion content. Mean electrical conductivity (EC) in Graciosa is in the range 308 − 3462μS/cm, while hand-dug wells in Pico are highly mineralized (1758–9732μS/cm). Drilled wells in Pico are in the range of 186μS/cm to 5625μS/cm. Besides mixture with seawater, groundwater chemistry is also influenced by dissolution of silicate minerals which also contributes to water composition. Moreover, 18O and 2H stable isotope data show that a few samples depict an evaporative effect, resulting in heavier isotopic compositions besides mixing with a marine source. About 70% of the wells in Graciosa and Pico exceed the 200mg Cl/L and the EC Portuguese reference values, severely constraining water supply. The impact on water quality is also shown by exceedances of the groundwater threshold values derived for the Azores River Basin District (89%).

Potential human health impact of groundwater in non-exploited uranium ores: The case of Horta da Vilariça (NE Portugal)

The anomalous concentration of chemical elements in rocks can have consequences on the human health population even in the absence of anthropogenic activities. Uranium contamination of groundwater is being increasingly recognized as a health threat to rural residents relying on home wells for their drinking water, not only in communities with a legacy of mining, but also where there's naturally occurring uranium. In the Horta da Vilariça region (Torre de Moncorvo, Northern Portugal), a few uranium (U) ores were recognized in the metamorphic aureole of a hercynian granite; the host rocks are metasedimentary schists and greywacks of the pre-ordovician “Complexo Xisto-Grauváquico”. To assess water-rock interaction 11 groundwater wells were selected and sampled, for major and trace elements as well as for radioisotopes 222Rn, 226Ra, 234U, 238U analyses. Analytical results point to Na-Ca-bicarbonate groundwater with a mean electric conductivity of 477μS·cm−1 and pH between 5.4 and 6.5. The concentration of dissolved arsenic (As) reaches 15μgL−1, mostly in the oxidized form of As(V), and is above the parametric value for drinking water (10μgL−1) in 3 wells used for drinking and/or irrigation. The radioisotope activity (U, 226Ra and 222Rn) is also very high in the most of collected water samples. About 65% of the samples are above the WHO recommended limit for drinking water with respect to U, with a median of 129mg·L−1 and a maximum of 3483mg·L−1. About 30% of the samples are above the EU (2013) recommended limit for drinking water for 222Rn (1000Bq·L−1), with a median of 400Bq·L−1 and a measured maximum of 9784Bq·L−1. The human health impact was evaluated only for the water ingestion vector through calculation of the annual effective dose. As the health impact depends of the body mass the dose was calculate for different age groups of the population. The results indicate that, in 60% of the samples, the effective dose exceeds the limits suggested by existing guidelines. The use of groundwater for drinking and crop irrigation in the studied region should be subject to previous assessment for U, Ra, Rn and As. In the activity concentrations found in the present work they are clearly a potential health risk for the population.

Chemical characteristics, deposition fluxes and source apportionment of precipitation components in the Jiaozhou Bay, North China

To systematically illustrate the chemical characteristics, deposition fluxes and potential sources of the major components in precipitation, 49 rainwater and snow water samples were collected in the Jiaozhou Bay from June 2015 to May 2016. We determined the pH, electric conductivity (EC) and the concentrations of main ions (Na+, K+, Ca2+, Mg2+, NH4+, SO42−, NO3−, Cl− and F−) as well as analyzed their source contributions and atmospheric transport. The results showed that the precipitation samples were severely acidified with an annual volume-weighted mean (VWM) pH of 4.77. The frequency of acid precipitation (pH<5.6) reached up to 71.4%, and the mean EC value was relatively higher at 64.9μScm−1, all of which suggested a higher atmospheric pollution level over the Jiaozhou Bay. Surprisingly, NH4+ (40.4%), which is higher than Ca2+ (29.3%), is the dominant species of cations, which is different from that in most areas of China. SO42− was the most abundant anions, and accounted for 41.6% of the total anions. The wet deposition fluxes of sulfur (S) was 12.98kgha−1yr−1. Rainfall, emission intensity and long-range transport of natural and anthropogenic pollutants together control the concentrations and wet deposition fluxes of chemical components in the precipitation. Non-sea-salt SO42− and NO3− were the primary acid components while NH4+ and non-sea-salt Ca2+ were the dominating neutralizing constituents. The comparatively lower rainwater concentration of Ca2+ in the Jiaozhou Bay than that in other regions in Northern China likely to be a cause for the strong acidity of precipitation. Based on the combined enrichment factor and correlation analysis, the integrated contributions of sea-salt, crustal and anthropogenic sources to the total ions of precipitation were estimated to be 28.7%, 14.5% and 56.8%, respectively. However, the marine source fraction of SO42− may be underestimated as the contribution from marine phytoplankton was neglected. Therefore, the precipitation components in the Jiaozhou Bay present complex chemical characteristics under the combined effects of natural changes and anthropogenic activities.

Urban dew and rain in Paris, France: Occurrence and physico-chemical characteristics

This paper summarizes one year (April 2011 to March 2012) measurements on planar condensing surfaces of dew and rain events and related physico-chemical characteristics in the urban environment of Paris (city center). Yearly collected water was 3.48mm for dew (63 events) and 593mm for rain (146 events). The latter value compares well with rain data (547mm and 107 events) collected within 12km at Paris-Orly airport. An estimation of dew yield based on meteo data gives 2.35mm and 74 events, to be compared with 17.11mm and 196 events at Paris-Orly. These differences highlight the large reduction in dew events and dew yields in an urban area as compared to a close rural-like area. This reduction is not due to a sky view reduction but to heat island that increases air temperature and decreases relative humidity.Analysis of dew (34) and rain (77) samples were done concerning pH, electrical conductivity (EC), major anions and cations as well as selected trace metals and other minor ions. Mean pH values are found similar for both, dew (6.5) and rain (6.1), rain being slightly more acidic than dew. The mean dew total ionic content (TIC 1.8meq/l) and EC value (124μS/cm) are about four times that of rain (0.45meq/l; 35μS/cm), meaning that total dissolved solids in dew is nearly four times that in rain. Sulfate and nitrate are the most acidifying components, calcium the most neutralizing constituent with ratio of mean total acidity/total alkalinity comparable for dew and rain (~0.9). Sulfate and nitrate have mainly anthropogenic sources, whereas chloride and magnesium are mostly connected with marine air masses. Dew is a considerable factor of wet deposition of pollutants; dew and rain ion concentrations, however, meet the WHO requirements for drinking water.

Physico-Chemical Quality of Selected Drinking Water Sources in Mbarara Municipality, Uganda

The study assessed the physico-chemical quality of selected drinking water sources (springs, boreholes, shallow wells and rainfall) in Mbarara municipality with respect to World Health Organization (WHO) drinking water guidelines and other guidelines in light of the increased anthropogenic activities in the municipality. A total of 70 water samples were collected from purposively selected boreholes, springs, wells and rainwater in Nyamitanga, Kamukuzi and Kakoba divisions of Mbarara municipality with various human activities. The samples were analysed for physico-chemical parameters: Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Electrical Conductivity (EC) and Total hardness using American Public Health Association (APHA) standard methods. The mean temperature and pH ranged between 18.07 °C - 23.45 °C and 5.74 - 7.54, respectively. The mean DO values were found to be between 4.84 and 12.86 mg/l; whereas mean BOD was within the range of 1.83 - 7.71 mg/l. The mean TDS and EC of the water samples ranged, between 33.40 - 569.20 mg/l and 29.30 - 1139.90 μS/cm respectively. Furthermore, the lowest and highest mean total hardness were 70.00 and 264.00 mg/l, respectively. The recorded mean water temperatures for each of the water sources were above the WHO threshold temperature (15 °C) which makes drinking water palatable. Boreholes in Nyamitanga and Shuhaddea Secondary Schools, spring in Kiswahili, well in Kisenyi and rainwater in Mbarara University of Science and Technology (MUST) had mean pH below the WHO minimum guideline value (6.5) hence acidic. Borehole in Nyamitanga secondary school, spring in Kisenyi, shallow well in Nyamitanga and the rainwater in MUST had mean DO values below the WHO range (10 - 12 mg/l). Borehole in Shuhaddea Secondary School and the well in Kisenyi had average BOD values above the range of European Union guideline values (3 - 6 mg/l). TDS and EC of all the water sources were below the WHO maximum guideline limits of 1000 mg/l and 1500 μs/cm respectively. Total hardness was also below the WHO harmless limit of 1000 mg/l. However rainwater in MUST was moderately soft while the other drinking water sources exhibited moderate to full total hardness. The physicochemical parameters of some of the selected water sources in Mbarara municipality have been compromised mainly by the increased human activities especially croplands, latrines, landfills, transportation, animal and municipal wastes at the vicinity of the water sources. Mbarara municipal council should therefore ensure proper sanitation and water safety plans for these drinking water sources to avoid further contamination from the human activities.

Enhancing Subsurface Drainage to Control Salinity in Dryland Agriculture

Abstract. Controlling the physical processes of soil salinization involves lowering ground water levels, draining the vadose zones, and leaching excess salts from root zones. Plastic drain tubing strategically placed 1.5 to 1.8 m below the surface in semiarid lands can lower water tables and drain phreatic water, but irrigation is usually required to satisfactorily leach the offending salts. In non-irrigated drylands, the leaching process depends on natural precipitation, but the drier the climate, the greater the need for more leaching water. Possible practices which tap complementary water in conjunction with subsurface drainage include: (1) establishment of roughness barriers to trap wind-borne snow, and (2) pumping water from near-surface, ground water mounds. The mean electrical conductivity of saturated soil paste extracts sampled yearly from a semiarid site in Saskatchewan averaged 14.1 dS m-1 during the six years before the drainage was installed, 13.0 dS m-1 for two years just after drainage but before capturing blowing snow, and 9.6 dS m-1 for the six years following. The average barley grain harvested during the six years prior to drainage yielded 330 kg ha-1 and 2414 kg ha-1 after installation of the enhanced drainage system. In a follow-up sub-study, fall applications of 4.6 dS m-1 mounded ground water from a shallow well fitted with a solar-powered pump within a drainage system preceded spring seeding of alfalfa. Enhanced drainage improved mean seedling emergence from 20% to 79%. Every 28 mm of ground water applied, up to 2273 mm, increased alfalfa emergence by 1%. Keywords: Agricultural drainage, Plant emergence, Pre-seeding irrigation, Solar-powered pumping, Soil reclamation, Soil salinity, Windbreaks.

Growth and Mineral Nutrition in Salt Stressed Guava ( Psidium guajava L.) cv . Allahabad Safeda

Guav a cv . Allahabad Safeda w as grown in saline soils and irrigated with the best av ailable w ater -1 -1 + -1 (EC 2.8 dS m ). Based on chemical composition (pH- 7.1, EC - 2.8 dS m , Na - 20.04 meq l and IW IW sodium adsorption ratio- 4.86), irrigation w ater w as categorized as marginally saline. The soil pH 2 -1 w as mostly below 8.5 but mean electrical conductivity (EC ) v alues ranged from 0.5-2 dS m 2 indicating moderate to high salinity in the experimental soil. After one-y ear of experimentation, fiv e plants randomly selected from each treatment and the data w ere recorded. Plant height -1 -1 significantly increased (LSD 5%) with increase in salinity from 0.5 dS m to 1.4 dS m . A similar -1 trend w as noted with respect to stem girth. The av erage plant height at 0.5, 0.9 and 1.4 dS m salinity lev els w as 98.3 cm, 108.3 cm and 123 cm, respectiv ely whereas the corresponding stem girth v alues -1 w ere 2.24 cm, 2.28 cm and 2.46 cm. At 2 dS m salinity ,how ev er , both av erage plant height (94.6 cm) and stem girth (2.24 cm) significantly decreased and w ere found to be comparable to control (0.5 dS -1 + -1 m ) v alues. Plants show ed negligible Na accumulation in leav es up to 1.4 dS m salinity , but -1 + exposure to elev ated salinity (2 dS m ) significantly increased leaf Na (0.16% DW). These data -1 indicated a salinity tolerance (EC )threshold of about 1.5 dS m inguav a cultiv ar Allahabad Safeda.

Determining the groundwater potential recharge zone and karst springs catchment area: Saldoran region, western Iran

Assessing the groundwater recharge potential zone and differentiation of the spring catchment area are extremely important to effective management of groundwater systems and protection of water quality. The study area is located in the Saldoran karstic region, western Iran. It is characterized by a high rate of precipitation and recharge via highly permeable fractured karstic formations. Pire-Ghar, Sarabe-Babaheydar and Baghe-rostam are three major karstic springs which drain the Saldoran anticline. The mean discharge rate and electrical conductivity values for these springs were 3, 1.9 and 0.98 m3/s, and 475, 438 and 347 μS/cm, respectively. Geology, hydrogeology and geographical information system (GIS) methods were used to define the catchment areas of the major karstic springs and to map recharge zones in the Saldoran anticline. Seven major influencing factors on groundwater recharge rates (lithology, slope value and aspect, drainage, precipitation, fracture density and karstic domains) were integrated using GIS. Geology maps and field verification were used to determine the weights of factors. The final map was produced to reveal major zones of recharge potential. More than 80 % of the study area is terrain that has a recharge rate of 55–70 % (average 63 %). Evaluating the water budget of Saldoran Mountain showed that the total volume of karst water emerging from the Saldoran karst springs is equal to the total annual recharge on the anticline. Therefore, based on the geological and hydrogeological investigations, the catchment area of the mentioned karst springs includes the whole Saldoran anticline.