Non-saline Water Research Articles

Gross alpha and beta activity analysis in water—a routine laboratory method using liquid scintillation analysis

The generally accepted method for gross alpha and beta activity analysis of drinking water in Australia is based on ISO methods; ISO9696, water quality—measurement of gross alpha activity in non-saline water—thick source method, and ISO9697, water quality—measurement of gross beta activity in non-saline water. A liquid scintillation (LSA) based method that requires smaller sample quantities, less sample preparation time and operator intervention, and produces adequate minimum detection levels for local drinking water guidelines has been developed. A synthetic groundwater sample was analysed using the LSA method and compared with results from ISO method techniques used by two independent Australian laboratories. The results show that the LSA method exceeds performance of the ISO methods in measurement accuracy.

Growth and Chemical Composition of Pistachio Affected by Salinities and Depths of Water Table

Pistachio may be grown around the central desert of I.R. Iran with adverse conditions such as shallow saline water tables, which limit its growth and production. The effects of saline (13 dS m−1) and non-saline (0.5 dS m−1) shallow water table depths of 30, 60, 90, and 120 cm under irrigated and not irrigated conditions on growth and chemical composition of a local pistachio cultivar (Badami–Zarandi) were studied in a greenhouse experiment. The results indicated that appropriate growth of pistachio may occur at water table depth of 60 cm under irrigated condition. Only at this depth, the difference in plant growth between irrigated and not irrigated conditions were significant, and low plant growth was obtained at not irrigated condition. At saline water table (13 dS m−1) and not irrigated condition water table depth should be kept below 60 cm for normal pistachio production.

Field Crop Production in Areas with Saline Soils and Shallow Saline Groundwater in the San Joaquin Valley of California

SUMMARY Salinity in soil and water is irrevocably associated with irrigated agriculture throughout the world and as a result requires that salt management becomes an integral part of the production system. With careful water management, it is possible to sustain irrigated agriculture in areas with saline soil and saline groundwater with and without subsurface drainage. The results from two field projects conducted in an area with saline soils and saline groundwater demonstrated the type of irrigation systems and management needed to sustain production of moderately salt tolerant and tolerant crops. During the first study at Murrieta farms, yields of cotton and sugar beet were maintained using both saline and non-saline water for irrigation when pre-plant irrigation and rainfall were adequate to maintain soil salinity at a tolerable level. Wheat production was reduced in areas that used saline water for irrigation. Use of saline water containing toxic elements such as boron for irrigation poses a threat to...

Short term effects of saline irrigation on evapotranspiration from lysimeter-grown citrus trees

Eight-year-old Murcott orange trees grown in greenhouse lysimeters filled with sandy soil were subjected to irrigation with saline water to investigate the influence of salinity on daily evapotranspiration (ET). The study was conducted in Japan from 1 August to 15 September 2000. The study duration was divided into three periods of about 2 weeks each. In period I, all lysimeters planted with a tree were irrigated with 60 mm of non-saline water at the water content of 70% of field capacity (FC). Salinity treatments for period II started on 14 August. The treatments during period II were as follows: Lysimeter 1 (L1) had 32 mm non-saline water with an electrical conductivity (EC I) of 1.0 dS/m applied. At the same time Lysimeter 2 (L2) had 32 mm of saline water with an EC I of 8.6 dS/m applied when the water content decreased to 70% of FC. Lysimeter 3 (L3) had 16 mm saline water (EC I=8.6 dS/m) applied at 85% of FC. The irrigation amounts during period II were equal to those corresponding to 1.2 times of water required to reach FC. Treatments in period III were the same as in period I. Daily ET was similar for all weighing lysimeters during period I. The average relative ET for L2 and L3 with respect to L1 (L2/L1 and L3/L1) were similar during this period, with a mean value of 0.99. During period II, ET from L1 was consistently higher than that from L2 and L3. In addition, L3 with a higher irrigation frequency because of irrigation at higher soil water content resulted in higher ET than L2. The average relative ET of period II was 0.71 and 0.88 for both L2 and L3. During the last half of period III, reductions occurred in the ET differences between the saline treatments (L2 and L3) and non-saline control (L1). Evaporation rates from soil did not exceed 0.7 mm per day. Transpiration rates from L1, L2 and L3 during period II varied between 6.3 and 3.1 mm per day, 4.5 and 2.2 mm per day, and 5.8 and 3.0 mm per day, respectively. The results reflected a tangible difference of water extraction by roots from individual soil layers. Maximum water uptake by these trees was observed at layer of 30–60 cm. Nevertheless, no clear differences in water extraction pattern between trees were observed. Approximately, 95% of drainage occurred during the first 2 days following irrigation. The electrical conductivity of soil water (EC S) and the electrical conductivity of drainage water (EC D) for the saline water treatments (L2 and L3), compared to the control (L1) were significantly different during period II. EC S values were 2–5 times higher in saline treatments compared to the control treatment. After irrigating trees with saline water, EC S increased from 5 to 14 and 16 dS/m in L2 and L3, respectively. Similarly, in both saline treatments, EC D values were greatly increased after irrigation. During period III, EC D values increased from 5 to 8 dS/m in L2, and from 3 to 11 dS/m in L3. By contrast, EC S declined from 14 to 5 dS/m in L2, and from 16 to 3 dS/m in L3 over the same period.

Irrigating perennial pasture with saline water: effects on soil chemistry, pasture production and composition

In response to a local survey that revealed that many farmers in the Goulburn Valley region of Victoria did not adhere to recommendations for safely applying saline irrigation water to perennial pasture, an experiment was conducted at Tatura. Six irrigation water quality treatments, which differed in the timing of the application of saline water, were applied to perennial pasture plots over 4 irrigation seasons. Measurements made included soil EC1:5, soil SAR1:5, soil ESP, pasture dry matter production and composition, dry matter digestibility, tissue ion concentrations and mineral ash content. After 4 seasons, in which the winter rainfall for each season was significantly lower than the long-term average, soil sodicity and salinity levels appeared to reach steady values. Plots irrigated with non-saline water (0.1 dS/m, treatment 1) performed the best in terms of lower soil salinity and sodicity levels and higher dry matter production and pasture quality levels. However, for most of these measurements and for most seasons, there were no significant differences between the control plots and those irrigated with water at 1.2 dS/m (treatment 2). Soil EC1:5 and SAR1:5 levels were highest, and dry matter production and dry matter digestibility levels the lowest (particularly for the clover component), in plots irrigated with water at 2.4 dS/m throughout the season (treatment 6). There were no significant differences in soil characteristics or biomass production between the remaining 3 treatments (treatments 3, 4 and 5) or between treatment 2. These treatments had the same amount of salt applied throughout the season but differed in the pattern of salt application — whether it occurred at the beginning or end of the season, or was alternated with fresh water throughout the season. This study confirmed that in the long term, there is a reduction in the yield of perennial pastures when saline irrigation water at levels greater than 0.8–1.2 dS/m is used on the red-brown earths of the Shepparton Irrigation Region. However, the soil and pasture were more sensitive to the total amount of salt applied rather than to the pattern of salt application throughout the season. It was concluded that farmers should monitor the salinity levels of their irrigation water to avoid a build up of Na+ and Cl– in the soil profile and consequent long-term reductions in herbage production and quality.

Determination of the 234U/ 238U ratio in water samples by inductively coupled plasma mass spectrometry

234U belongs to the 238U natural radioactive decay series, and at equilibrium, the abundance ratio, 234U/ 238U, corresponds to the ratio of their half-lives, i.e. 54.8×10 −6. In natural waters, deviations from this ratio reflect radioactive and geochemical processes and can be correlated with the flow path of the water. Alpha spectrometry or thermal ionization mass spectrometry require tedious procedures for separation and preconcentration of the uranium prior to analysis. Inductively coupled plasma quadrupole mass spectrometry can yield reliable results for the 234U/ 238U ratio without any treatment of the sample (except acidification). Here, we show that combining a flow-injection sample introduction system with an ultrasonic nebulizer, significantly increases the sensitivity and enhances the ability to cope with a relatively high salt content in non-saline water samples. The relative standard deviation attained is 5% at 50 pg l −1 234U. The method is extremely fast (1 min per measurement), pre-treatment is not required and 1 ml of the sample is needed for triplicate measurements. Therefore, it may be used as a fast screening method.

Long-Term Reuse of Drainage Waters of Varying Salinities for Crop Irrigation in a Cotton-Safflower Rotation System in the San Joaquin Valley of California—A Nine Year Study: II. Safflower (Carthamus tinctoriusL.)

Summary This paper reports the results on safflower crops grown in a nine-year study, conducted on a 8 ha site, to determine the feasibility of using drainage water for irrigation in a 2-year cotton/1-year safflow-er rotation system. The cotton crops were irrigated with waters of 400, 1,500, 3,000, 4,500, 6,000, and 9,000 ppm total dissolved salts, and safflower was grown only with a preplant irrigation with nonsaline water. The use of drainage water for crop irrigation may be a means of decreasing its volume. Even though safflower was never irrigated with saline drainage water directly, the residual effect of using saline water for cotton irrigation adversely impacted safflower growth and development. Safflower seed yields were reduced in plots previously irrigated with waters of 4,500 ppm or higher salinity and even more severe effects on crop growth were seen as the numbers of years of irrigation with the saline water increased. After irrigating six cotton crops, the safflower seed yield in plots irrig...

Response of Sunflowers to Quantities of Irrigation Water, Irrigation Regimes and Salinities in the Water and Soil

Summary The production of sunflower grains for roasting was investigated in two soil types under different quantities of applied saline and non-saline irrigation water, different irrigation managements, soil salinity due to previous use of saline water or due to a raised water table. It was shown in one experiment, conducted in a loess type soil, that sunflowers extracted water at least to a soil depth of 120 cm, when the available water from the top layers was used up. The crop in this soil consumed all the available soil water from nearly the entire root zone, while in the clay soil limited water was consumed from deep layers, due to the high salinity and lack of aeration. No decrease in yield was found in the loess soil when 75% of the full amount of water (which was 0.8 of Class A pan evaporation rate) was applied. When only 50% was applied a significant decrease in yield was obtained. In contrast, in the clay soil even 75% of the full amount of water decreased the yield remarkably. Under dry-land con...

294 Comparative Studies of Local vs. Imported Tomato Cultivars under Saline Irrigation Water

Scarcity and high cost of good-quality water for irrigation in the Kuwait environment, which is located in an extremely arid region, necessitate the utilization of underground brackish water. However, productivity of most vegetable crops is reduced tremendously when irrigated with such low-quality water. Consequently, a tomato-breeding program had been launched to develop tomato cultivars that are well-adapted to the local conditions. The present work is a 2-year field study to compare the performance of four locally developed vs. eight imported tomato cultivars under saline irrigation water (brackish). The experiment was laid out in a completely randomized block design with four replications. Dimensions of each experimental unit was 2 × 2.5 m (5 m2). Fertilization and other cultural practices followed those recommended for the local environment and soil was sandy in texture. Prior to transplanting seedlings to field, they had been irrigated with nonsaline water. Total dissolved solutes of the brackish water used for irrigation was 7500 mg.L-1. A total of seven harvests were collected on a weekly basis. There were no significant differences among tomato cultivars in terms of total fruit weights in the first four harvests. However, beginning with the fifth harvest, two of the locally developed cultivars (Kuwait-16 and Kuwait-20) were among the highest in total yield for two consecutive years in this study. It is therefore recommended that these Kuwaiti tomato cultivars be used to replace the several expensively imported varieties, which, though high yielding, are not necessarily so in the Kuwait environment, or may be salt-sensitive cultivars. Combining the local varieties with the use of less expensive brackish water could reduce the expense of farming significantly in this region of the world.

Yield, earliness and fruit quality of pepino clones and their hybrids in the autumn–winter cycle

The success of the pepino (Solanum muricatum Aiton) as a new crop for intensive horticultural areas relies on shortening the growing cycle and on securing a high standard of fruit quality. Irrigation with saline water and ethephon sprayings could be useful in achieving these goals. Two consecutive pepino crops consisting of two hybrids and their four parents were grown in the autumn–winter cycle. Plants were irrigated with water having electrical conductivities of 3 or 8 dS m−1 and full sized fruits were sprayed with ethephon at 0 or 500 mg l−1 . Salinity reduced yield and fruit size, although this effect was less important in the hybrids, which showed heterosis for yield characters. Overall, yields and fruit size of hybrids irrigated with saline water were greater than in the parents irrigated with non-saline water. Ethephon had no effect on yield characters. Salinity and ethephon improved earliness. In most clones combination of salinity and ethephon shortened the growing cycle by 1 month. Salinity improved fruit quality as it increased the soluble solids content (SSC) and dry matter (DM) in all clones, and titratable acidity (TA) in some cases. Ethephon sprayings had no marked effects on quality characters, except for parental clone 9-1 in which ethephon treated fruits had a lower SSC and TA. Organoleptic tests conducted on the best flavoured clones (0-8 and 6-10) showed that salinity improved fruit aroma and flavour although not texture, while ethephon had no effects. Results show that irrigation with saline water and ethephon sprayings improve earliness and fruit quality without dramatic yield depressions, especially in the hybrid clones. © 1999 Society of Chemical Industry

The use of insulated time-domain reflectometry sensors to measure water content in highly saline soils

In a conducting medium, the energy of a time-domain reflectometry (TDR) pulse is dissipated and the signal is attenuated. Above a certain high conductivity, however, the signal is completely attenuated and the soil short-circuits the sensor. This behaviour of the signal with conductivity severely limits the TDR technique in measuring water content in highly saline soils. By reducing the direct contact between the conductive soil and the metallic sensor the energy of the pulse is better maintained. Different combinations were tried: we insulated the central wire, outer two wires, and all wires of a three-wire sensor with two different insulators. The first insulator was an adhesive polyethylene sheet usually used as a transparent cover and the second insulator was an adhesive tape. The insulated sensors were used to measure dielectric constants in non-saline soils and water and in saline soils. The sensors with the insulated centre wire preserve maximum energy and maintain a clear signal in saline soils. The insulating materials have very small dielectric constants. The TDR exerts a larger influence in the vicinity of the wires of the sensor during measurements. Therefore, the insulated sensor measures a dielectric constant which is smaller than the apparent dielectric constant of the surrounding medium. The type of insulating material also has an effect on the dielectric constant. Therefore, it is necessary to calibrate the sensors for the specific insulator.

INFLUENCE OF THE MODE OF SALINIZATION ON REPRODUCTIVE TRAITS OF FIELD-GROWN PROGENY IN SORGHUM BICOLOR

The offspring ofSorghum bicolor(L.) Moench plants exposed to 150 mM NaCl eight or twenty-one days following germination were grown in field conditions, and were irrigated with non-saline water. As compared to the offspring of non-treated plants, the progeny of plants early-exposed to NaCl displayed an increase in shoot dry weight and stem height, but some of them showed a significant decrease in fertility. Similar changes were observed, but to a lesser extent, in the offspring of plants late-exposed to salinity. A similar increase in phenotypic variability was observed in populations of progeny from early-and late-treated plants. After verifying that the changes observed did not result from an artifactual selection, it was concluded that the NaCl treatment is able to influence characters expressed during the late development of the plant progeny. The nature of the induced change is discussed in relation to the plant response, adaptation or resistance, induced by the early or late exposure to salinity in the parent generation.

Real‐time Soil Water Dynamics Using Multisensor Capacitance Probes: Laboratory Calibration

AbstractThere is a continued need for better methods to perform accurate, real‐time, nearly continuous soil water measurements at specific depth intervals, with minimal soil disturbance, and covering field‐scale areas. The objectives of this research were to assess the characteristics of a newly developed multisensor capacitance probe and to calibrate the sensors against a Mattapex silt loam (fine‐silty, mixed, mesic Aquic Hapludult) soil. The soil was uniformly packed in small increments, with the aid of a large hydraulic press, in a wooden box (35.5 by 35.5 cm, 40.5 cm deep). Probe installation in the boxed soil mimicked that required for correct field installation. A highly significant (r2 = 0.992 for n = 15, and RMSE = 0.009 cm3 cm‐3 water), nonlinear (θv = 0.490 SF2.1674) relationship was found between the soil volumetric water content (θv, cm3 cm‐3) and the scaled frequency [SF = (Fa − Fs)(Fa − Fw)‐1]. The SF represents the ratio of individual sensor's frequency (inside PVC pipe) response in soil (Fs) compared with sensor responses in air (Fa) and in nonsaline water (Fw) at room temperature (≈22°C). Axial and radial sensitivity studies showed that these capacitance sensors give integrated readings over a primary depth interval of 10 cm and a radial capacitance fringe within 10 cm of the wall of the access pipe. Temperature effects of air and water were measured, and the calculated effects on assessment of θv were less than the RMSE for a temperature range of 10 to 30°C. Our calibration studies indicate that these multisensor capacitance probes can be used to accurately measure volumetric soil water contents in a soil water monitoring system.

Using δ 87 Sr values to identify sources of salinity to a freshwater aquifer, Greater Aneth Oil Field, Utah, USA

Salinity increases in water from the freshwater Navajo aquifer in the Aneth area have been documented in recent years. Previous studies during the 1980s in the Aneth area suggested that brines associated with oil production and their subsequent re-injection were the probable source of salinity in the Navajo aquifer. Differences in the delta strontium-87 (δ 87Sr) composition of ground-water samples from southeastern Utah were used to determine if oil-field brine or water from the upper Paleozoic aquifer is a plausible source of salinity to the Navajo aquifer. The δ 87Sr values of the oil-field brine samples (mean = −0.95%, range = −1.06 to −0.79%, n = 5) are substantially more negative than the values in water samples from wells completed in the Navajo aquifer (mean = 0.73, range = −0.85 to 2.02%, n = 48), indicating that oil-field brine is not a source of salinity. The δ 87Sr values in water samples from wells completed in the upper Paleozoic aquifer (mean = 0.801% range = 0.34 to 1.10%, n = 4) are similar to the mean isotopic composition of the more saline water from the Navajo aquifer. The δ 87Sr values in water from the Navajo aquifer confirm that two distinct flow areas are present. Mixing models using the δ 87Sr values and Sr concentrations of non-saline water from the Navajo aquifer and saline water from the upper Paleozoic aquifer indicate that water from the upper Paleozoic aquifer is a plausible source of saline water to the Navajo aquifer. Most Navajo aquifer wells that contain water with a δ 87Sr signature similar to water from the upper Paleozoic aquifer are located within or adjacent to an area where the hydraulic gradient is favorable for upward movement of water from the upper Paleozoic aquifer into the Navajo aquifer.

Sorghum Response to Saline Industrial Cooling Water Applied at Three Growth Stages

AbstractSaline wastewater from industrial or agricultural sources may be an alternative irrigation supply in arid regions if effective crop and water management strategies for their use are developed. A field experiment was conducted to determine if grain yields of sorghum [Sorghum bicolor (L.) Moench] irrigated with undiluted saline waste‐water from cooling towers of an electrical power generation plant can be significantly increased by applying nonsaline water at a critical growth stage. The wastewater had an average electrical conductivity (EC) of 0.67 S m−1 and was high in CaSO4. Plot studies were conducted for 4 yr using conventional cultural practices and sprinkler irrigation on Tujunga loamy sand—Hanford fine sandy loam soil (mixed, thermic Typic Xeropsamment—coarse‐loamy, mixed, nonacid, thermic Typic Xerorthent). Highest grain yields were obtained from the nonsaline control plots and from treatments that received nonsaline water during either the vegetative or reproductive growth stages. Plant height decreased in response to salinity, and differences between treatments were apparent by 27 d after planting. Plant height and grain yield were both negatively correlated with soil salinity by the 3rd yr of the experiment. Over an extended length of time, the best treatment for maximizing yield and utilizing saline wastewater is the application of nonsaline water early in the season to germinate and establish seedlings, followed by saline water during the grain‐filling stage.

The effect of a saline and non-saline water table on peach tree water use, growth, productivity and ion uptake

The effect of salinity and shallow water tables (1.4 m depth) used in combination with Regulated Deficit Irrigation (RDI) on peach trees (Prunus persica, L. Batsch) was studied over 2 years. Under RDI management a non-saline water table contributed up to 30% of water use. A lack of control of vegetative growth in the first season indicated that a shallow water table may interfere with RDI management. A decline in tree health and growth under RDI and a non-saline water table in the following season may have resulted from salinity and/or waterlogging effects. Saline irrigation under RDI management caused an additional decline in tree growth compared with RDI under non-saline conditions, and resulted in a reduction in productivity (yield and fruit size) and increased uptake of sodium (Na) and chloride (Cl) ions in various plant tissues. Similarly, a saline water table caused a decline in tree growth and fruit size in the first season and increased uptake of Na and C1 ions. For all treatments, accumulation of C1 in the leaves, Na and C1 in the fruit, Na in the bark and storage of Na in the butt wood and structural roots was demonstrated. Differences in mechanisms of transport of Na and C1 and the importance of older wood as a storage organ for ions are proposed. The potential for butt wood as a precise indicator of past salinity treatment is suggested. A combination of a shallow water table and moderate salinity environment was shown to present a potential health hazard for peach trees. The need for refinement of RDI management to incorporate leaching in the presence of saline irrigation and/or water tables is proposed. The management of drainage is also essential.

Effect of Supplementary Saline Irrigation and Applied Nitrogen on the Performance of Dryland Seeded Indian Mustard (Brassica juncea)

SUMMARYField experiments were conducted for two years to evaluate the effects of combinations of saline irrigation (ECw 14.0 ds m-1) and nitrogen levels on the yield, seasonal water use and nitrogen use efficiencies of mustard. These showed that the use of saline water can boost the growth and yield of dryland mustard and that, within certain limits, a non-saline water supply can be substituted by applying nitrogen and saline water. It is suggested that fertilizer nitrogen rates should be adjusted in relation to the supply of water and its predicted salinity.Irrigación salina y los efectos del nitrógeno en la mostaza sembrada en las tierras de secano

Shoot growth and fruit development of muskmelon under saline and non-saline soil water deficit

In irrigated agriculture, the production of biomass and marketable yield depend largely on the quantity and salinity of the irrigation water. The sensitivity of field-grown muskmelon (Cucumis melo L. cv. “Galia”) to water deficit was compared, using non-saline (ECi= 1.2 dS m−1) and saline (ECi=6.3 dS m−1) water. Drip irrigation was applied at 2-day intervals at seven different water application rates for each water quality, including a late water-stress treatment. Neutron scattering measurements showed that the soil layers below the root zone remained dry throughout the experiment, indicating negligible deep percolation. Thus, the sum of the seasonal amount of applied water and the change in soil moisture approximated the cumulative evapotranspiration (ET). Gradual buildup of water and salt stresses resulted in small treatment effects on the size of the vegetative cover and large effects on leaf deterioration and fruit production. Crop responses to salinity may result from an osmotic component of the soil water potential or from other salt effects on the crop physiology. Relating plant data to cumulative ET allowed a distinction to be made between the effect on water availability and specific salinity effects. The relation between fruit fresh weight and ET was not sensitive to ECi. The slopes for fruit dry weights were also insensitive to ECi but the intercept was larger for saline treatments. At any given ET saline water increased fruit number, increased fruit dry matter content and decreased fruit netting, in comparison with non-saline water. The combination of salinity and soil-water deficit was detrimental to fruit quality. Saline soil-water deficit decreased the percentage of marketable (netted) fruit and caused an early end to the period of marketable fruit production. Non-saline soil-water deficit increased the percentage of marketable fruit and had no effect on the duration of the production period. Late non-saline water stress caused a pronounced increase in the percentage of marketable fruit.

Feasibility of Cyclic Reuse of Saline Drainage in a Tomato‐Cotton Rotation

AbstractUse of saline drainage water for crop irrigation has been proposed as a strategy to reduce drainage volume and conserve good quality water. Over a 6‐yr period, two cyclic drainage‐water reuse practices were tested in a 3‐yr rotation of processing tomato (Lycopersicon esculentum L.) and cotton (Gossypium hirsutum L.). In both practices, drainage water (ECi = 7.4 dS m−1 and 0.74 mmol L−1 B) was applied to processing tomato after first bloom to take advantage of salt‐induced enhancement of fruit quality and increased crop salt tolerance at later developmental stages. In one practice, drainage water was also applied to the following cotton crop after thinning. Nonsaline water was used for irrigation at all other times and throughout for the control. When saline water was applied once every 3 yr, yields of both crops were unaffected. Tomato yields were generally lowest when saline water was applied 2 out of 3 yr, but saline water improved tomato fruit quality by increasing °Brix in most years. Changes in soil chemical and physical quality may limit long‐term reuse. Both B and salts accumulated in the soil over time, particularly at depth (60–140 cm), whereas Se was more readily leached and showed greater fluctuations in the rootzone with irrigation treatment. Calculations using reclamation formulae estimated that for low B drainage water, the amount of drainage wager used exceeded that of nonsaline water needed to return soil ECe to control levels, resulting in significant water savings. For high B drainage water, more than twice the amount of nonsaline water was needed to fully reclaim the profile than was saved by reuse. However, moderately B‐tolerant crops could be successfully grown during the reclamation period, making cyclic reuse for at least 6 yr an attractive option for growers facing limited supplies of nonsaline water supplies, or as a means to reduce effluent volumes.

Investigation of uranium recovery from dilute aqueous solutions using silk fibroin.

The uranium uptake ability of silk fibroin was investigated. High ability to uptake uranium from nonsaline water containing 2.500 mg of uranium was observed with the silk fibroin tested. The uranium uptake was very rapid and was dependent on pH, uranium concentration, temperature, and retention time. Almost all uranium taken up is easily eluted with 1 mol/L CH3COONH4. This biomatrix, therefore, appears to have potential for use in a commercial process for uranium recovery from uranium-containing waste water.