Humble View on Soil Water Resources

Soil water is one of renewable water resources.Some properties of soil water concerning with its availability to plant are briefly described.An equation for estimating the amount of soil water resource is presented.Based on the evaporation demand of atmosphere,the evaluation coefficient for soil water resource is suggested.     

Soil Water Balance Measurement in Field Scale

A 5-year experiment on water balance has been conducted in a flat rainfed wheat field with an area of 66×100m² in Fengqiu, Henan Province in China. Based on the analysis of semi-variance functions conducted with soil moisture samples taken from 77 nodes of a 10×10m² grid, the soil moisture distribution in the field was structural with a temporal stability. According to the autocorrelation range of the semi-variance function, S sites were selected for the determination of soil water conditions. The characteristic of probability density function of the differences of water storage in two sets of measurements showed that the distribution of these variables in the field was a normal one. The error in the estimation of the average of S random samples was 14% (α=0.10), and the errors of water consumption by wheat during the experiments were estimated to be 6-13%.Since the experimental field was large enough to avoid any edge effect, the results obtained should tally with the actual situation.     

Effect of Irrigation Water Quality on Soil Hydraulic Conductivity

The effect of irrigation water quality on unsaturated hydraulic conductivity (HC) of undisturbed soil in field was studied.Results show that within the operating soil suction range (0-1.6 KPa) of disc permeameters,the higher the electric conductivity (EC) of irrigation water,the higher the soil HC became.The soil HC doubled when EC increased from 0.1 to 6.0ds m^-1.High sodium-adsorption ratio(SAR) of irrigation water would have an unfavorable effect on soil HC.Soil HC decreased with the increasing of SAR,especially in the case of higher soil suction.An interaction existed between the effects of EC and SAR of irrigation water on soil HC.The HC of unsaturated soil dependent upon the macropores in surface soil decreased by one order of magnitude with 1 KPa increase of soil suction.In the study on the effect of very low soluble salt concentration (EC=0.1 ds m^-1 of irrigation water on soil HC,soil HC was found to be lowered by 30% as a consequence of blocking up of some continuous pores by the dispersed and migrated clay particles.Nonlinear successive regression analysis and significance test show that the effects of EC and SAR of irrigation water on soil HC reached the extremely significant level.     

Water Security Problem in North China： Research and Perspective

This paper addresses the emergence of water security problems in North China with the aim of highlighting key water resources management and water security issues for the long-term development of North China. Three key problems related to water resources and security issues in North China in the 21st century are addressed, namely 1） the water cycle under environmental change, 2） agricultural water saving, and 3） water security. Development of international research related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences （CAS） is discussed and suggestions on research and development of water resources science in North China are presented. Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle on North China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquire hydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In the well irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have had widespread application, and reduced water use 60-150 mm while they increased water use efficiency （WUE） by 20%-30%. Furthermore, preventing water pollution is the most essential step to ensure North China＇s water security.     

Is Oil-Well Produced Water Effective in Abating Road Dust?

Energy development in the Bakken and Three Forks formations of the USA has led to an increase in fugitive dust from unpaved roads. A dust abatement alternative that has been considered in this region is oil-well produced waters. The objectives of this study were to compare dust loading at sites abated with produced water to non-abated control sites and to determine if the elemental constituents in released dust are different compared to control roads. Three previously untreated unpaved roads were selected, and passive dust collectors were placed at 10, 20, 40, and 60 m from the road on the downwind side of the dominant prevailing wind in each mile section. Eighty-four days post-application, two sections treated with produced waters failed to reduce dust when compared to the controls. Dust elemental changes were found on two of the three roads. Elements that were found to have differences included Mo, Mn, Fe, As, Au, and Hg. Overall results indicated that oil-well produced water is not effective at controlling road dust. Results of this study are important to road managers who are contemplating the usage of produced waters to reduce dusts from unpaved roads.     

Metal Contamination in Nullah Dek Water and Accumulation in Rice

A research study was carried out to determine the electrical conductivity （EC）, residual sodium carbonate （RSC）, sodium adsorption ratio （SAR）, pH and metals in metal-polluted irrigation water from a nullah and those in soils over a period of time, and the effect of metals on rice yield and metal concentrations in rice grain and straw. Two sites （I and If） were selected on the bank of Nullah Dek at Thatta Wasiran in Sheikhupura District （Pakistan）, with two rice varieties, Super Basmati and Basmati 385, at both sites. Water samples were collected during rice crop growth at 15-day intervals from August 3 to November 1, 2002. The results showed that Nullah Dek water had an EC 〉1.0 dS m^-1 and RSC of 2.78-4.11 mmolc L^-1, which was hazardous for crops, but the SAR was within the safe limit. Cu, Mn Cd and Sr were also within safe limits. The soil analysis showed that Site Ⅱ was free from salinity/sodicity, whereas Site Ⅰ was saline sodic. Among metals, Zn was sometimes deficient, Cu, Mn and Fe were adequate, and St, Ni and Cd were within safe limits in the soil at both the sites. After the rice crop harvest, concentrations of all metals tested were usually slightly increased, being higher in the upper soil layer than the lower. In addition, Basmati 385 produced higher rice grain and straw yield than Super Basmati. Chemical analysis of rice grain indicated the presence of Zn, Cu, Fe, Mn, Pb and Sr, whereas rice straw contained Zn, Cu, Fe, Mn and Sr, with Cd and Ni both being found in minute quantities.     

Treatment Efiiciencies of Constructed Wetlands for Eutrophic Landscape River Water

The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic landscape river water were studied in the western section of the Qingyuan River at the Minhang campus of Shanghai Jiaotong University. The first wetland was a single-stage system using gravel as a filtration medium, and the second was a three- stage system filled with combinations of gravel, zeolite, and fly ash. Results from parallel operations of the wetlands showed that the three-stage constructed wetland could remove organics, nitrogen, and phosphorus successfully. At the same time, it could also decrease ammoniacal odour in the effluent. Compared to the single-stage constructed wetland, it had better nutrient removal efficiencies with a higher removal of 19.37%-65.27% for total phosphorus （TP） and 21.56%- 62.94% for total nitrogen （TN）, respectively, during the operation period of 14 weeks. In terms of removal of chemical oxygen demand （COD）, turbidity, and blue-green algae, these two wetland systems had equivalent performances. It was also found that in the western section of the test river, in which the two constructed wetlands were located, the water quality was much better than that in the eastern and middle sections without constructed wetland because COD, TN, and TP were all in a relatively lower level and the eutrophication could be prevented completely in the western section.     

Phosphorus Extraction Methods for Water Treatment Residual–Amended Soils

Abstract

Water treatment residuals (WTR) can adsorb tremendous amounts of phosphorus (P). A soil that had biosolids applied eight times over 16 years at a rate of 6.7 Mg ha^?1 y^?1 contained 28 mg kg^?1 ammonium–bicarbonate diethylenetriaminepentaacetic acid (AB‐DTPA), 57 mg kg^?1 Olsen, 95 mg kg^?1 Bray‐1, and 53 mg kg^?1 Mehlich‐III extractable P. To 10 g of soil, WTRs were added at rates of 0, 0.1, 1, 2, 4, 6, 8, and 10 g, then 20 mL of distilled deionized H₂0 (DI) were added and the mixtures were shaken for 1 week, filtered, and analyzed for soluble (ortho‐P) and total soluble P. The soil–WTR mixtures were dried and P extracted using DI, AB‐DTPA, Olsen, Bray‐1, and Mehlich‐III. Results indicated that all methods except AB‐DTPA showed reduced extractable‐P concentrations with increasing WTR. The AB‐DTPA extractable P increased with increasing WTR rate. The water‐extractable method predicted P reduction best, followed by Bray‐1 and Mehlich‐III, and finally Olsen.     

Water Remediation by Columns Filled with Micelle–Vermiculite Systems

Photodegradation of four pharmaceuticals (i.e. carbamazepine, ibuprofen, ketoprofen and 17α-ethinylestradiol) in aqueous media was studied using a solar light simulator (Xe lamp irradiation) and sunlight experiments. These experiments were carried out in river and seawater and compared to distilled water. The latter was used to evaluate the direct photodegradation pathways. Irradiation time was up to 400 min and 24 days for the solar light simulator and sunlight assays, respectively. Pharmaceutical photodegradation followed a first-order kinetics and their half-lives calculated in every aqueous matrix. Moreover, the sensitizing effect of DOC was evaluated by comparison with the kinetics obtained in distilled waters. Ketoprofen was rapidly transformed via direct photolysis in all the waters under both sunlight (t _1/2?=?2.4 min) and simulated solar light simulator test (t _1/2?=?0.54 min). Under xenon lamp radiation, ibuprofen and 17α-ethinylestradiol were photodegraded at moderate rate with half-lives from 1 to 5 h. Finally, carbamazepine had the lowest photodegradation rate (t _1/2?=?8–39 h) attributable to indirect photodegradation. Indeed, its elimination was strongly dependent on the DOC concentration present in solution. Finally, several ketoprofen photoproducts were identified and plotted against solar light simulator irradiation time. Accordingly, the photodegradation pathway of ketoprofen was postulated.     

Water Budget Analysis of Red Soils in Central JiangxiProvince, China

The daily soil water budgets in the red soil areas of central Jiangxi Province, southern China, were investigatedwith a large-scale weighing lysimeter and runoff plots. From 1998 to 2000, peanuts (Arachis hypogaea L.) and rape(Brassica napus L.) were planted in the lysimeter and in 1999, peanuts were planted in the runoff plots. The soil waterbudget components including rainfall, runoff, percolation and evapotranspirat.ion were measured directly or calculated by Richards‘ equation and water balance equation. The results showed that most rainfall, including rainstorms, occurredfrom March to July, and induced the greatest soil water percolation during the year. The evapotranspiration was stilllarge from July to September when rainfall was ininimal. Thus, the lack of synchronization in soil water inputs and losseswas disadvantageous to crops growing in this region. Among the soil water losses, percolation was the largest, followed byevapotranspiration, and then soil runoff. Runoff was very small on farmland with crops. It was significantly different, fromthe uncultivated uplands where large-scale runoff was usually reported. The soil water storage fluctuated sinusoidally,with a large amplitude in the rainy season and a small amplitude in the dry season.     

SW—Soil and Water: Climate Change and Water Resources Management in Arid and Semi-arid Regions: Prospective and Challenges for the 21st Century

The overgrowing population and the recent droughts are putting water resources under pressure and calling for new approaches for water planning and management if escalating conflicts are to be avoided and environmental degradation is to be reversed. As countries are using their water resources with growing intensity, poor rainfall increasingly leads to national water crises as water tables fall and reservoirs, wetlands and rivers empty. Global warming could cause further changes, further variability and further uncertainty. The UK Hadley Centre's global climate model was run at a spatial scale of 2·5 by 3·75° (latitude and longitude) grid squares to simulate the global climate according to scenarios of greenhouse gas concentration emission. Runs of the model assuming the emission scenario proposed by the Intergovernmental Panel on Climate Change in 1995 are analysed here for the 2050s time horizon. Outputs provide estimations of climate variables, such as precipitation and temperature, at a monthly time step. Those results, assumed representative of future climatic conditions, are compared to mean monthly values representative of the current climate and expressed in terms of percentage change. The results show that, for the dry season (April–September), by the 2050s, North Africa and some parts of Egypt, Saudi Arabia, Iran, Syria, Jordan and Israel, are expected to have reduced rainfall amounts of 20–25% less than the present mean values. This decrease in rainfall is accompanied by a temperature rise in those areas of between 2 and 2·75°C. For the same period, the temperature in the coastal areas of the Mediterranean countries will rise by about 1·5°C. In wintertime, the rainfall will decrease by about 10–15% but would increase over the Sahara by about 25%. Given the low rainfall rate over the Sahara, the increase by 25% will not bring any significant amount of rain to the region. In wintertime, the temperature in the coastal areas will also increase but by only 1·5°C on average, while inside the region it will increase by 1·75–2·5°C.In southern Africa (Angola, Namibia, Mozambique, Zimbabwe, Zambia, Botswana and South Africa), results suggest an increase of the annual average temperature ranging between 1·5 and 2·5°C in the south to between 2·5 and 3°C in the north. The summer range is between 1·75 and 2·25°C in the south, and increases towards the north to between 2·75 and 3·0°C while the winter range is between 1·25 and 2°C in the south, and increases towards the north to between 2·5 and 2·75°C. On the other hand, the annual average will decrease by 10–15% in the south and by 5–10% in the north. The annual average decrease is 10%. However, some places will have an increase i.e. by 5–20% in South Africa in wintertime. In the Taklimakan region (Tarim Basin) west of China, the annual average temperature is shown to increase by 1·75–2·5°C. Annual average rainfall should increase by 5–>25% in most of the region but decrease by 5–10% in some small parts. In summer, an increase by 5–15% is indicated in most of the region, and an increase by up to 25% or more during the wintertime.In the Thar Desert (India–Pakistan–Afghanistan), estimations suggest that the annual average increase in temperature ranges from 1·75 to 2·5°C, ranging from 1·5 to 2·25°C in winter and from 2 to 2·5°C in summer. Annual average precipitation is shown to decrease by 5–25% in the region. The winter will have values closer to the annual average but the summer will have more decrease and most of the region will see a decrease closer to 25%.In the Aral Sea basin (Kazakhstan, Turkmenistan and Uzbekistan), estimates suggest an annual average increase in temperature ranging from 1·75 to 2·25°C, higher in summer (between 2 and 2·75°C) than in winter (between 1·5 and 2°C). Rainfall should increase by 5–20% annually, in summer increasing by 5–10% in the north but decreasing by up to 5% in the south, while in wintertime, both south and north should undergo increases of 5–10% and 20–25%, respectively.In Australia, results indicate an increase in the annual average temperature ranges of 1–1·5°C in the south to 2·5–2·75°C in the north, slightly higher during the summer than in the winter. The summer range is between 1 and 2°C in the south and increases towards the north to 2·5–3·0°C while the winter range is between 1 and 1·5°C in the south, and increases towards the north to between 2 and 2·25°C. Rainfall annual average is shown to decrease by 20–25% in the south and by 5–10% in the north.Given the above-mentioned facts, in order to meet the water demands in the next century, some dams and water infrastructure will be built in some countries and a new paradigm by rethinking the water use with the aim of increasing the productive use of water will have to be adopted. Two approaches are needed: increasing the efficiency with which current needs are met and increasing the efficiency with which water is allocated among different uses. In addition, non-conventional sources of water supply such as reclaimed, recycled water and desalinated brackish water or seawater is expected to play an important role.     

Water Environmental Issue in Three Gorges Reservoir Area and Its Protective Countermeasures

By single-factor-index evaluation on water of earth＇s surface, the result shows that the water-quality keep Ⅲ grade on the whole in Yang-tze River, Jia-ling River and Wu River of the Three Gorges reservoir, it occurs no obviously deteriorated tendency in 2005. But some sub-grade rivers are polluted badly, cross-section amount of water-quality Ⅰ, Ⅱ ,Ⅲ only has 64 percent, their water-quality is bad. It is clear that the gap between the water environmental state and the object of keeping water- quality Ⅱin the Three Gorges reservoir is very big. This paper thoroughly analyses the problems and causes of the water environment, points out that the main factors resulting in the water pollution in recent years include the industrial sewage, solid wastes, soil and water loss, domestic rubbish and agricultural non-point source pollution, and finally puts forward the countermeasures for protecting of the water environment in the Three Gorges Reservoir.     

Heavy‐Metal Concentration of Sewage‐Contaminated Water and Its Impact on Underground Water,Soil, and Crop Plants in Alluvial Soils of Northwestern India

Abstract

Heavy‐metal concentration in underground and surface water, soil, and crop plants growing in farmers' fields near the industrial city of Ludhiana, Punjab, India, that receive irrigation with water contaminated with sewer and untreated industrial effluents was studied. The concentrations of lead (Pb), chromium (Cr), cadmium (Cd), and nickel (Ni) in sewage‐contaminated water were 18, 80, 88, and 210 times higher than in shallow handpump water, and 21, 133, 700, and 2200 times higher than in deep tube‐well water, respectively. The concentrations of Cd and Ni in shallow handpump underground water were significantly higher than in deep tube‐well underground water. The concentrations of Pb, Cr, Cd, and Ni in deep tube‐well water were 0.017, 0.003, 0.0002, and 0.0002 mg L^?1, respectively. Soils irrigated with sewage‐contaminated water had higher electrical conductivity, cation exchange capacity, organic carbon (C), and clay content but had lower pH and calcium carbonate content compared to soils irrigated with deep underground water. The concentrations of diethylenetriamine pentaacetic acid (DTPA)–extractable Pb, Cr, Cd, and Ni in soils irrigated with sewage‐contaminated water were 1.8, 35.5, 3.6, and 14.3 times higher, and total concentrations of these heavy metals were 1.5, 3.0, 3.7, and 2.2 times higher than that in soils irrigated with deep underground water. The mean concentrations of Pb, Cr, Cd, and Ni in crop plants growing on soils irrigated with sewage‐contaminated water were 4.88, 4.20, 0.29, and 3.99 mg kg^?1, which were 1.2, 2.1, 8.7, and 1.9 times higher than in plants irrigated with deep tube‐well water, respectively. The amounts of potentially toxic metals were significantly and positively correlated with cation exchange capacity and organic C content and negatively correlated with soil pH. In conclusion, long‐term accumulation of toxic metals in soils and their uptake by crop plants has a high potential for phytotoxicity as well as for entering into the food chain. The findings also suggest contamination of underground shallow drinking water through leaching of some highly mobile metals.     

Salt-Water Dynamics in Highly Salinized Topsoil of Salt-Affected Soil During Water Infiltration

Continuous monitoring of salt and water movement in the soil profile of highly salinized topsoil under steadystate infiltration was conducted.It gives that salt and water dynamics during convection-diffusion period can be divided into three stages:1.formation of a salt peak,2.the salt peak moving downwards till the appearance of the summit of the salt peak,3.the salt peak moving further downwards with the peak value decreasing.Results show that the maximum salt peak appears at the same depth if soil texture and outflow condition are the same.Factors affecting salt and water movement and ion components in the outflow solution underinfiltration are discussed.     

Defluoridation of Drinking Water Using PURAL® MG-20 Mixed Hydroxide Adsorbent

Water, Air, &; Soil Pollution - High applications of P fertilizers and manure are general practice in intensive agriculture and may cause eutrophication in adjacent streams. Bioavailability of P...     

Removal of Hexavalent Chromium from Water by Polyurethane�CKeratin Hybrid Membranes

The feasibility of employing a porous polyurethane?Ckeratin hybrid membrane for the removal of hexavalent chromium was investigated. Keratin was extracted from chicken feathers and incorporated onto a synthetic polyurethane polymer to synthesize a hybrid membrane. Keratin supply active sites to bioadsorb Cr(VI) and polyurethane play an important role as the support to protein. Also, polyurethane?Ckeratin biofiber membranes were synthesized. Biofibers obtained from chicken feathers were modified to activate their surface. The effective pore in membranes is less than 50 nm, which places these materials in the mesopore range. Scanning electron microscopy (SEM) was used to study the morphology of membranes, and mechanical dynamical analysis (DMA) was used to evaluate the viscoelastic properties. NH, C=O, S?CS and C?CS were determined via Fourier-transform infrared (FTIR) analysis as functional groups of keratin, which participate in the linking sorption of hexavalent chromium. Adsorption of Cr(VI) was carried out in a filtering system at low contact time in continuous flux; the maximum removal reached was 38% at neutral pH of chromium solution. Results indicate that the isoelectric point of keratin is relevant in the adsorption process. pH of keratin solution above the isoelectric point brings about higher adsorption of heavy metals, whereas lower pH causes minor adsorptions, due to the functional groups?? ion charges. Based on the results, keratin extracted from feathers is a natural biosorbent that can be incorporated onto synthetic polymers to develop novel membranes and improve its applications in the heavy metal separation process.     

Water‐retention capability as a selection criteria for drought resistance in wheat

Four durum wheat cultlvars (Triticum turgidum spp. durum Desf.) from different countries of origin (Austria, Ethiopia, and Italy) were investigated. Plants were grown in pots under glasshouse conditions. Immediately after the full development of the flag leaves, these leaves were detached for the screening. Distinct differences in water‐retention capabilty among the cultivars was observed. The drought‐resistant (hardy) types, Valgerardo and Boohai, showed better water retention capabilty than the drought‐sensitive ones, such as DZ‐04–688. Poor yielding cultivars under field conditions were also found to be poor in water‐retention capability and vice versa. The applied method is simple and inexpensive. It adds another procedure when screening for drought resistance. However, it needs further confirmation by cultivars covering a broader range of genetic diversity.     

Salt—Water Dynamics in Soils：Ⅲ.Effect of Crop Planting

Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamics in situ,using soil salinity sensors and tensiometers.The results indicated that the amount of water absorbed by crops from the soil was generally larger than the decrement of water consumption from soil surface evaporation reduced by the crop covering the soil surface and improving the soil structure,therefore,under the conditions of crop growing and non-irrigation,water content in soil profile was less than that without crop growing,and the gradient of negative pressure of soil water in soil profile especially in the root zone was enlarged,thus causing the water flowing from subsoils into root zone and increasing the groundwater moving upwards into soil layer via capillary rise,so that the groundwater evaporation increased.Consequently,under the condition of crop growing,the salt was mainly accumulated towards the root zone rather than to the top soil.the accumulating rate of salt in groundwater via capillary rise of soil water to subsoils was increased thereby.     

Water content or water activity: what rules crispy behavior in bread crust?

A dry crust loses its crispness when water migrates into the crust. It is not clear if it is the amount of water absorbed or the water activity ( a w) that leads to a loss of crispness. The hysteresis effect observed when recording a water sorption isotherm allowed us to study the effects of a w and moisture content separately. All experiments were carried out on model bread crusts made from Soissons bread flour. The effect of water content and water activity on the glass transition of model bread crusts was studied in detail using two complimentary techniques: phase transition analysis (PTA) and nuclear magnetic resonance (NMR). The results were compared with sensory data and results from a puncture test, which provided data on acoustic emission and fracture mechanics during breaking of the crusts. The water content of the crust was found to be decisive for the transition point as measured by PTA and NMR. However, both water content and water activity had an effect on perceived crispness and number of force and sound peaks. From this may be concluded that the distribution of the water in the samples with a history of high water content is more inhomogeneous, which results in crispy and less crispy regions, thus making them overall more crispy than samples with the same water content but higher a w.     

Double Health Risk in Arsenic Contaminated Drinking Water – Evidence of Enhanced Alpha Radioactivity

The presence of alpha emitting radionuclides in the environment assumes importance since they are found to be carcinogenic. This paper reports the results of an exhaustive and systematic measurement of alpha radioactivity using solid state nuclear track detector (SSNTD) in drinking water in different parts of India covering the entire Ganges Basin – West Bengal, Bihar and Uttar Pradesh where arsenic contamination is severe. The alpha activity in the samples was found in the range of 8 to 800 Bq/l in West Bengal, 90 to 1,000 Bq/l in Uttar Pradesh and 60 to 1,000 Bq/l in Bihar – much higher alpha activity value than MCL value given by US EPA. The concentration of alpha activity has a positive correlation with that of arsenic.