Subsoil Water Research Articles

Modeling the Impact of Biopores on Root Growth and Root Water Uptake

Core Ideas A 3D soil–root model was used to investigate root–biopore interactions. Known effects of biopores on root growth, i.e., increased root length and depth were reproduced. Despite reducing root–soil contact, biopores led to increased water uptake in dry periods. Biopores had a larger impact on water uptake for more compact and less conductive soils. Roots are known to use biopores as preferential growth pathways to overcome hard soil layers and access subsoil water resources. This study evaluates root–biopore interactions at the root‐system scale under different soil physical and environmental conditions using a mechanistic simulation model and extensive experimental field data. In a field experiment, spring wheat (Triticum aestivum L.) was grown on silt loam with a large biopore density. X‐ray computed tomography scans of soil columns from the field site were used to provide a realistic biopore network as input for the three‐dimensional numerical R‐SWMS model, which was then applied to simulate root architecture as well as water flow in the root–biopore–soil continuum. The model was calibrated against observed root length densities in both the bulk soil and biopores by optimizing root growth model input parameters. By implementing known interactions between root growth and soil penetration resistance into our model, we could simulate root systems whose response to biopores in the soil corresponded well to experimental observations described in the literature, such as increased total root length and increased rooting depth. For all considered soil physical (soil texture and bulk density) and environmental conditions (years of varying dryness), we found biopores to substantially mitigate transpiration deficits in times of drought by allowing roots to take up water from wetter and deeper soil layers. This was even the case when assuming reduced root water uptake in biopores due to limited root–soil contact. The beneficial impact of biopores on root water uptake was larger for more compact and less conductive soils.

Restoring Natural River Flows, Through Optimal Ground WaterRecharge and Improved Drainage Prevention of Pollution in Rivers

Prevention of pollution in rivers and water bodies involves proper treatment of the sewage, drainage and other liquid effluents joining the river streams,as well as maintaining the natural river flows which have been diminishing due to the excessive drawl of river stream waters for the purpose of drinking water schemes, irrigation and some industrial uses, where ground water could be used, if available. Sub-soil ground water levels have also been going down on account of the excessive population growth in the last six decades, resulting into more and more dependence on river waters. This situation needs to be changed by enhancing the rain water harvesting and ground water recharge volumes with innovative and special measures so as to return to minimum drawl of river waters for drinking and other uses. The proposed measures could be summarized as follows. (i) Restoring Natural River Flows would involve (a) Reducing the surface water Drawl to a minimum. (b) Optimal Utilization of Ground Water for Drinking Water Supply, Irrigation and other uses. (c) Enhancing River Flows through improved surface drainage. (ii) Synchronized Water Supply and Precipitation Storage-cum- Recharge Systems in Water Scarcity areas. (a) Water Supply Schemes equipped with simultaneous rain water harvesting structures. (iii) Optimal Ground Water Recharge and Improved Drainage by innovative and special methods such as (a) Optimal Ground Water Recharge through Village Ponds, equipped with precipitation overflow diversion and recharge system. (b) Waste Water Drainage Treatment at discharge points before outfall into rivers.

Crop responses to subsoil manuring. I. Results in south-western Victoria from 2009 to 2012

Subsoil manuring is a practice that involves placing high rates of organic amendments in bands at the base of rip-lines that extend down into the subsoil to a depth of 30–40cm, in order to ameliorate poorly structured clay subsoils. The objective of this study was to determine whether the increases in crop yield from this practice, which occurred at one site in the high-rainfall zone in Victoria from 2005 to 2007, would occur at other sites and in other seasons in south-western Victoria. On-farm field experiments were therefore carried out at three sites in south-western Victoria between 2009 and 2012 to measure the yield responses to subsoil manuring. The study found that subsoil manuring with poultry litter resulted in consistent and recurring increases in estimated grain yield at these sites, with responses occurring with consecutive crops. Increases in estimated grain yield continued for 4 years, with average increases in hand-harvested yield of 3.5 t ha–1 for wheat, 1.6 t ha–1 for canola and 2.3 t ha–1 for faba beans. The estimated increases in grain yield were frequently associated with the increased extraction of deep subsoil water after anthesis. A treatment involving deep-banded nitrogen (N) and phosphorus (P) fertilisers and additional in-crop N, which matched the N and P in the poultry litter, yielded less than the full rate of subsoil manuring in seven of the eight site-years. This suggests that yield responses from subsoil manuring were not solely due to the release of N and P from the deep-banded poultry litter.

Geophysical and Hydro-Chemical Investigations of Oke Asunle Dumpsite in Ile-Ife, Southwestern Nigeria for Subsoil and Surface Water Pollution.

Background.Waste deposited in dumpsites immediately becomes part of the hydrological system. Over time, waste components bio-accumulate and/or decompose into contaminant liquid, leading to pollution of soil and water and posing a risk to human health.Objectives.The present study employed integrated hydro-chemical and geophysical methods to assess surface water and soil/subsoil within the premises of the Obafemi Awolowo University waste dumpsite in Ile-Ife, southwest Nigeria, for possible leachate pollution.Methods.The electrical resistivity method involving 1D vertical electrical sounding (VES) and 2D dipole-dipole profiling techniques and hydro-chemical analysis were used. Two-dimensional profiling data were gathered along two orthogonal traverses and inverted into 2D resistivity images. Schlumberger VES data were gathered and quantitatively interpreted using partial curve matching and computer assisted 1D forward modeling. Hydro-chemical analysis was carried out on three water samples collected from the Asunle River for water quality testing. Anthropogenic pollution determinant parameters such as pH, conductivity, total dissolved solid, cations (calcium, magnesium, sodium, and potassium), anions (chloride, sulphate, biocarbonate, and nitrate) and the less abundant heavy metals in granitic gneiss-derived soil such as cadmium, copper, iron, manganese and lead were analyzed.Results.Three geologic layers: topsoil, weathered basement and fresh basement were identified. Within the topsoil and weathered layer, two zones with contrasting geoelectrical characteristics were observed. The first zone, outside the dumpsite boundary, was characterized by relatively high resistivities (78–178 Ωm), typical of unimpacted soil. The second zone, within the dumpsite boundary, was characterized by relatively low resistivity values (15–47 Ωm) up to depth levels between 2.5 and > 15 m. The analyzed physico-chemical parameters, except for turbidity, fell within set limits for potable water quality. However, the concentration levels of heavy metals such as cadmium (0.017 - 0.018 mg/l); iron (0.544 - 0.739 mg/l) and lead (0.501 -0.551 mg/l) significantly exceeded standard limits.Conclusions.The results of the present study indicate that subsoil and surface water within and around the dumpsite can be considered to be polluted.Competing Interests.The authors declare no competing financial interests.

A Model of Mixing of Four River Runoff Recharge Sources Using Hydrochemical Tracers in the Problem of Hydrograph Separation

Methods for the analysis of the formation of river water chemistry based on mixing models are discussed. An analytical solution for a mixing model of four recharge sources is given along with the results of its adaptation based on the materials of hydrochemical and hydrological observations over 2013 and 2014 in drainage basins in Primorski Krai. The analysis and calculations revealed four components of river recharge in these years: rainwater, two types of subsoil water, and groundwater, the latter forming the base runoff. The estimates of the mixing model with four sources and its tests showed a high quality of modeling.

Emerging Pleiotropic Mechanisms Underlying Aluminum Resistance and Phosphorus Acquisition on Acidic Soils.

Aluminum (Al) toxicity on acidic soils significantly damages plant roots and inhibits root growth. Hence, crops intoxicated by Al become more sensitive to drought stress and mineral nutrient deficiencies, particularly phosphorus (P) deficiency, which is highly unavailable on tropical soils. Advances in our understanding of the physiological and genetic mechanisms that govern plant Al resistance have led to the identification of Al resistance genes, both in model systems and in crop species. It has long been known that Al resistance has a beneficial effect on crop adaptation to acidic soils. This positive effect happens because the root systems of Al resistant plants show better development in the presence of soil ionic Al3+ and are, consequently, more efficient in absorbing sub-soil water and mineral nutrients. This effect of Al resistance on crop production, by itself, warrants intensified efforts to develop and implement, on a breeding scale, modern selection strategies to profit from the knowledge of the molecular determinants of plant Al resistance. Recent studies now suggest that Al resistance can exert pleiotropic effects on P acquisition, potentially expanding the role of Al resistance on crop adaptation to acidic soils. This appears to occur via both organic acid (OA)- and non-OA transporters governing a joint, iron-dependent interplay between Al resistance and enhanced P uptake, via changes in root system architecture. Current research suggests this interplay to be part of a P stress response, suggesting that this mechanism could have evolved in crop species to improve adaptation to acidic soils. Should this pleiotropism prove functional in crop species grown on acidic soils, molecular breeding based on Al resistance genes may have a much broader impact on crop performance than previously anticipated. To explore this possibility, here we review the components of this putative effect of Al resistance genes on P stress responses and P nutrition to provide the foundation necessary to discuss the recent evidence suggesting pleiotropy as a genetic linkage between Al resistance and P efficiency. We conclude by exploring what may be needed to enhance the utilization of Al resistance genes to improve crop production on acidic soils.

Elevated [CO2] mitigates the effect of surface drought by stimulating root growth to access sub-soil water.

Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in shallow soil versus sub-soil on agronomic and physiological responses of wheat to e[CO2] in a glasshouse experiment. Wheat (Triticum aestivum L. cv. Yitpi) was grown in split-columns with the top (0–30 cm) and bottom (31–60 cm; ‘sub-soil’) soil layer hydraulically separated by a wax-coated, root-penetrable layer under ambient [CO2] (a[CO2], ∼400 μmol mol-1) or e[CO2] (∼700 μmol mol-1) [CO2]. Drought was imposed from stem-elongation in either the top or bottom soil layer or both by withholding 33% of the irrigation, resulting in four water treatments (WW, WD, DW, DD; D = drought, W = well-watered, letters denote water treatment in top and bottom soil layer, respectively). Leaf gas exchange was measured weekly from stem-elongation until anthesis. Above-and belowground biomass, grain yield and yield components were evaluated at three developmental stages (stem-elongation, anthesis and maturity). Compared with a[CO2], net assimilation rate was higher and stomatal conductance was lower under e[CO2], resulting in greater intrinsic water use efficiency. Elevated [CO2] stimulated both above- and belowground biomass as well as grain yield, however, this stimulation was greater under well-watered (WW) than drought (DD) throughout the whole soil profile. Imposition of drought in either or both soil layers decreased aboveground biomass and grain yield under both [CO2] compared to the well-watered treatment. However, the greatest ‘CO2 fertilisation effect’ was observed when drought was imposed in the top soil layer only (DW), and this was associated with e[CO2]-stimulation of root growth especially in the well-watered bottom layer. We suggest that stimulation of belowground biomass under e[CO2] will allow better access to sub-soil water during grain filling period, when additional water is converted into additional yield with high efficiency in Mediterranean-type dryland agro-ecosystems. If sufficient water is available in the sub-soil, e[CO2] may help mitigating the effect of drying surface soil.

Irrigation and Deep Tillage Effects on Productivity of Dry-Seeded Rice in a Subtropical Environment

Dry-seeded rice has a potential to save water, but may entail loss in yield. A 2-year field study examined the combined effects of irrigation frequency and deep tillage on water use and productivity of rice cultivars differing in duration to maturity. Mean grain yield was greater in shorter (5.4 t ha−1) than in medium-duration (4.0 t ha−1) cultivar. Yield gain was more with deep tillage over conventional tillage (25–42%) than with full irrigation over partial irrigation regime (11–16%). Benefits of deep tillage were greater with partial (35–55%) than with full-irrigation regime (15–35%) for the two cultivars. Harvest-time soil water in top 0.30-m-depth layer was 0.2–1.0% (absolute) less with deep tillage than with conventional tillage. It implies that deep tillage enhanced profile water depletion component of crop water use. These effects can be attributed to denser rooting below 0.10 m depth due to a reduction in soil penetration resistance under deep tillage that helped in better mining of subsoil water suggesting that deep tillage could be used as a water-saving intervention.

Influence of long-term donor irrigation on quality of underground water in the south-steppe zone of Ukraine (case of the Baraboy River, Odessa Region)

The article presents the results of in-situ studies of the chemical composition and quality of underground (subsoil and artesian) water within the basin of the Baraboy River where irrigation of agricultural areas using the water resources of the Dniester River has been carried out since 1967. These water resources are fed into the network of reservoirs and channels of the Lower Dniester Irrigation System. Filtration losses of water from irrigation areas and water supply and sewage systems of settlements replenish the reserves of underground (subsoil) waters increasing the ingress therein of dissolved substances from the sedimentary rocks which leads to increase in the concentrations of certain ingredients included in chemical composition of surface and underground waters within the basin of the Baraboy River. It is shown that groundwater is enriched with nitro-gen compounds containing high concentrations of chlorides, sulfates, calcium and magnesium. Mineralization, toxicity and degree of contamination of underground water increase along the length of the Baraboy River. The chemical composition of the groundwater coming to the riverbed of the Baraboy River does not meet the fishing requirements and worsen the water quality of fish farming water bodies. The results of assessment of groundwater quality at the stations under study give reason to consider these sources of groundwater as an important factor affecting the hydrochemical regime and the quality of the water of the Baraboy River and its reservoirs which should be taken into account when developing the recommendations for optimization of the current hydroecological state of the Baraboy River as a whole. If high mineralization and significant content of principle ions in groundwater can be explained by natural factors, the high level of contamination by biogenic substances is resulted from entering of industrial, domestic and return waters from irrigated areas into aquifers. Such contamination is not a temporary but a permanent phenomenon. In terms of magnesium content artesian waters used for utility and drinking water supply are recognized as «mediocre, suitable with limitations and having undesirable quality». In addition, after 50 years of operation compounds of nitrogen and phosphorus were found in artesian water, and this was not a case in 1960s of the last century. A conclusion on the negative effect of long-term donor irrigation on the quality of underground water and on the need for additional treatment of water of artesian aquifers of the Sarmatian Stage used for centralized water supply was made.

Hydrochemical Regime and Quality of Subsoil Water in Built-Up Territories in the Southern Rostov Oblast

Seasonal dynamics of the mineralization, ionic composition, and the concentrations of specific pollutants in subsoil water are studied in populated localities in the southern Rostov oblast. Four major water types are identified: hydrocarbonate–sulfate (sulfate–hydrocarbonate), sulfate, chloride–sulfate (sulfate–chloride), and mixed type of subsoil water. The quality of subsoil water was found to fail to meet the sanitarytoxicological standards in terms of many characteristics. The values of MAC are exceeded for calcium, magnesium, sodium, chloride and sulfate ions, oil products, cadmium, total iron, silicon, and nitrate and ammonium nitrogen. Relationships were found to exist between the concentrations in water of cadmium, potassium, and phosphorus ions; oil products; pH values; water mineralization and total hardness; and seasonal variations of subsoil water levels. The identified relationships were substantiated.

Purification of subsoil water from iron compounds in Zhytomyr region

The most valuable type of water resources are fresh water supply. These resources are, in general, much cleaner than surface water. Its runoff is stable and its quality (excl. infiltration waters) is almost independent from the weather (seasonal) changes. Almost all Ukrainian subsoil water-bearing horizons have a high concentration of iron ions, ranging from 0.5 mg/l to 50 mg/l and more. By analyzing known methods of water neutralization, we can conclude that at low concentrations of activated earth ions in the initial water proved to be quite well established. The most common method of water deironing is the process of filtering, using natural or artificial granular loads, with up to 10 m/h water filtration rate.

Factores que intensifican el riesgo toxicológico en comunidades expuestas al arsénico en agua

La exposición prolongada al arsénico (As), a través de los alimentos y el agua de consumo, incrementa el riesgo de padecer cáncer, diabetes e hipertensión arterial, entre otras enfermedades. Las familias marginadas, que reemplazan el agua potable comercial por agua de pozo o de la llave, en zonas contaminadas con As, presentan mayores riesgos. El objetivo de este trabajo fue identificar los principales factores de riesgo toxicológico por exposición a la contaminación con arsénico presente en agua, en población que habita en zonas donde se han detectado altos niveles de este metaloide, del estado de Guanajuato. Se realizó́ un estudio analítico y transversal. Se aplicó una encuesta a 30 jefas de familia encargadas de la alimentación. La seguridad alimentaria se midió con la aplicación de la escala Latinoamericana y Caribeña. El 93 % de las familias tenía acceso a agua de la llave no potable. En relación a la preparación de alimentos, el 26.7 % de las familias utilizaba agua de la llave, el 13.3 % agua de pozo y el 43.3 % aguadepipa. El 70 % de las familiasestudiadas presentaron algún nivel de inseguridad alimentaria. Otro factor de riesgo a considerar fue el nivel de escolaridad de la jefa de familia. La identificación de los principales factores de riesgo, incluyendo ausencia de seguridad alimentaria, permitirá diseñar una escala de validación, con la cual se obtendrá un tamizaje oportuno para prevenir posibles intoxicaciones por arsénico en comunidades en donde el agua del subsuelo está contaminada.

Free LNAPL Volume Estimation by Pancake Model and Vertical Equilibrium Model: Comparison of Results, Limitations, and Critical Points

Light nonaqueous phase liquids (LNAPLs), due to their low solubility, dissolve slowly, acting as a long-term source of water contamination, and consequently they represent an important environmental issue. In the subsoil, more than 99% of spilled LNAPL remains as adsorbed and free phase; therefore, the volume estimation of free phase, obtained in this case through two different conceptual models (Pancake Model and Vertical Equilibrium Model), is considered a fundamental step for a correct site remediation. According to the first model, the LNAPL floating on the water table and its saturation is up to 100%; instead, according to the second one, the LNAPL can penetrate below the water table and the coexistence of LNAPL, water, and air in the pore fraction, leads to a lower LNAPL saturation, variable with the depth. Actually, in subsoil LNAPL and water saturations vary with depth due to the influence of capillarity, leading to the inaccuracy of Pancake Model assumption. Despite the evident limitation of Pancake Model, both models were applied, coupled with area calculations with Thiessen polygons and grid at regular mesh, to roughly estimate the free LNAPL volume existing in a contaminated site. The volume estimation carried out, considering the LNAPL type and its features, the soil type, and relative effective porosity, provides estimates of volumes having differences up to thousands of cubic meters. The results analysis shows that this estimation has several critical points such as area definition and the lack of site-specific data (e.g., porosity). Indeed, the sensitivity analysis for porosity shows that a reduction of this parameter provides a 20% reduction of estimated volume.

Crop yield responses to surface and subsoil applications of poultry litter and inorganic fertiliser in south-eastern Australia

In the high-rainfall zone of south-eastern Australia, deep incorporation of organic matter has previously been reported to increase crop yields by improving access to subsoil water and nutrients, resulting from the amelioration of subsoil constraints. However, previous experiments did not separate the yield response resulting from nutrients contained in the amendment from yield response due to amelioration of subsoil constraints. In order to separate these effects, eight field experiments were conducted on a range of soil types across the medium- and high-rainfall zones of south-eastern Australia between 2014 and 2016. Grain yield and quality responses of a range of annual crops (canola, wheat, barley and lentil) to surface and deep placement of poultry litter and inorganic fertilisers with matched nutrition were assessed. Over 15 site × year combinations, there was no consistent, significant positive interaction between amendment and incorporation treatments necessary to demonstrate that deep placement of amendment (i.e. subsoil manuring) had advantages over surface application of the same amendment. Differences in crop yield in these experiments are attributed to nutrients (particularly nitrogen) supplied by the amendment, and not to the amelioration of subsoil constraints. Future research, including analysis of subsoil physicochemical properties and plant nutrient concentrations after treatment, is necessary to confirm the role of nitrogen and other nutrients in the crop response to subsoil manuring.

Comparative analysis on performance of vertical drain improved clay deposit under vacuum or surcharge loading

This paper presents two well-instrumented large-scale field tests of PVD-improved soft soil with vacuum and surcharge preloading, respectively. The two large-scale field tests were conducted adjacent to each other with the same preload. A comparative analysis was performed to investigate the performance of subsoil (i.e., the ground settlement, the layered settlement, the lateral displacement of subsoil and pore water pressure) under vacuum preloading and equivalent surcharge preloading. Some design methods were verified based on the field data. Cone Penetration Tests (CPT) and Vane Shear Tests (VST) were conducted to assess the improvement effects on subsoil after preloading. The results showed that as compared with surcharge preloading, vacuum preloading mitigated the differential settlement of the ground. The vacuum pressure transmitted into the soil with a minor loss through the PVD length. From a practical point of view, the improvement effects by vacuum preloading and surcharge preloading were similar in terms of influence depth and soil strength based on the in-situ tests.

Dynamics, Cxtent, and Causes of Underflooding of Populated Localities in the Southern Rostov Oblast

Underflooding of different extent was recorded in 133 populated localities in southern Rostov oblast, among which 4 such localities are always partly underflooded, and 77 localities suffer underflooding during spring floods and freshets. Minimal estimates show that the area of the territories underflooded every year and only in wet years is 282 km2 or 19% of the total built-up area in the southern Rostov oblast. Technogenic factors were found to dominate as the causes of underflooding in the majority of the populated localities. However, natural or slightly disturbed subsoil water regime is typical of the built-up territories in the southern Rostov oblast, where it implies annual periodicity of level variations with a peak in spring and a minimum in autumn.

Insulin-like Effects of Mt. Fuji Subsoil Water which Conta ins Vanadium on Cultured Cells: Insight from Japan

Background: It was reported that vanadium compounds possess insulin-like activity, although suitable vanadium compounds have not yet developed as anti-diabetes mellitus drugs. Objective: As Mt. Fuji subsoil water contains high levels of vanadium, this study aimed to assess whether it showed insulin-like effects. Method: Insulin-like effects of vanadium ions have been investigated in cultured cells, using rat fibroblasts (Py-3Y1-S2), human esophageal cancer cells (TE-13), and other established cell lines. To evaluate insulin-like effects, glucose consumption in the cultured media and cell growth based on cellular protein content were measured, and cytotoxic effects on cells were assessed. Results: The vanadium concentration in the commercially available Mt. Fuji subsoil water ranged from 56–144 ppb, and the highest concentration (144.2 ± 1.2 ppb) was observed in Healthy Vana Water. The vanadium concentration in other water samples derived from wells, ravine rivers, and cities ranged from 0.5 to 27 ppb, and a comparatively high vanadium concentration (27.1 ± 0.0 ppb) was observed in the well water at Kayayama-Machi, which is close to Mt. Fuji. The largest insulin-like effect on glucose consumption was observed in Healthy Vana Water among the various water samples tested. The effects of vanadium at low concentrations of 200-500 µg/l seemed to accelerate cell growth, while high concentrations of vanadium (> 500 µg/l) had a cytotoxic effect. Conclusion: Mt. Fuji subsoil water possesses higher insulin-like activity than other water samples derived from wells, ravine rivers, and cities, suggesting a potential future role in diabetes mellitus therapy. Keywords: Insulin-like effects, diabetes, vanadium, Mt. Fuji subsoil water, glucose consumption, cell growth, cytotoxicity.

Law policy of European Union in the sphere of water conservation

In the light of such foreign policy goal as accession to the EU there was arised a need to thorough research of European Union’s water policy and legislation with the view of its adaptation to the national legislation.The basic issues of European Union’s water policy in water conservation were considered in this paper. During the three legislative waves a number of directives and decisions were made which pointed out: environmental standards of water quality for specific types of water and emission limit values; strict rules for the disposal of sewage and usage of nitrates in agriculture; regulations for prevention of subsoil water pollution from agricultural waste; protection of the marine environment; potable water standards and the like.For the purpose of concentration, rationalization, standardization and improvement of the European law effectiveness in the sphere of water protection Water Framework Directive was developed, which provided for multifaceted approach to effective water resources management at EU level, harmonized legal and institutional system, public participation and integrated water resources management. Herein directive became a framework for further legislative activity, nullified the antiquated laws and co-operated elements and obligations of other regulatory acts, such as directives deals with municipal sewage treatment and monitoring the usage of nitrates in agriculture. The rules were prescribed by Water Framework Directive focused on: 1) water protection (groundwater, surface, inland and transitional waters); 2) ecosystem restoration of water bodies; 3) pollution abatement of waters; 4) sustainable use of waters by individuals and enterprises.

Vibration velocity of X-section cast-in-place concrete (XCC) pile–raft foundation model for a ballastless track

This paper presents two case studies of the dynamic response of a ballastless track, X-section cast-in-place concrete (XCC) pile–raft (referred to as BTXPR) foundation embedded in sand subsoil. Model tests were conducted at a scale of 1/5 using a 7 m deep box with cross-sectional dimensions of 5 m × 4 m. In one case the box was filled with subsoil consisting of air-dried sand, whereas in the other case the box was filled with saturated sand. The tests involved measurement and analysis of the response in velocity under different applied cyclic load frequencies. It has been shown that the magnitude and variation of vibration velocity in the BTXPR foundation are closely related to the degree of saturation of the subsoil. Due to the existence of pore water in the saturated sand subsoil, the first natural frequency of the BTXPR foundation embedded in saturated sand is 5 Hz lower than that in air-dried sand. In addition, the amplitude of vibration velocity of the BTXPR foundation embedded in the saturated sand is about 9%∼36% higher than that of the air-dried sand. The research results provide an insight into BTXPR foundations with respect to theoretical analysis and calculation.

Changes in sub-soil river water quality upon its open storage-a case study.

A study was carried out to investigate the changes in the physicochemical and biological properties of sub-soil river water upon its storage in a man-made reservoir. Palar sub-soil and reservoir water samples were collated fortnightly for a period of 5years (2010-2014). The open reservoir is used as a reliable raw water source for condenser cooling systems and for the demineralizing (DM) plant input of Fast Breeder Test Reactor (FBTR), Madras Atomic Power Station (MAPS), and other laboratories at Kalpakkam, southeast coast of India. Relatively high nutrient concentration was observed in the Palar sub-soil water, and a significant reduction in average concentration (μmoll-1) of phosphate (Palar 1.92; open reservoir 1.54) and nitrate (Palar 9.78; open reservoir 5.67) was observed from Palar to open reservoir. Substantial increase in pH (Palar 8.05; open reservoir 8.45), dissolved oxygen (mgl-1) (Palar 6.07; open reservoir 8.47), and chlorophyll-a (mg m-3) (Palar 1.66; open reservoir 8.43) values were noticed from the Palar sub-soil water to open reservoir water. It is concluded that sub-soil water with higher nutrient concentrations when stored openly, exposing to the sun, resulted in growth of plants, planktonic, and macrophytes, which led to substantial deterioration in water quality from its utility point of view as a condenser cooling medium and raw water input for DM plant.