Basin Water Mass Research Articles

Hydrography of Northern Thermaikos Gulf based on an integrated observational-modeling approach

The Northern Thermaikos Gulf is a semi-enclosed coastal region of the Aegean Sea, characterized by anthropogenic and natural stresses such as intense industrial and agricultural activities, urban outflows, and several river discharges facing severe pollution events. The main motivation of this study is to investigate the prevailing oceanographic conditions of Northern Thermaikos Gulf, which are associated with the quality of the semi-enclosed basin's water masses. The hydrography and the hydrodynamic circulation patterns are revisited, based on the findings of a multi-platform observational study, conducted during a recent annual cycle, from June 2021 until May 2022. The observational findings are supported by a three-dimensional high-resolution hydrodynamic model (Deltf3D-Thermaikos) with updated freshwater input from all important land sources. The physical connectivity between the sub-basins of Thermaikos, the renewal of its northern coastal areas and the seawater quality are strongly related to the variability of wind-induced circulation. Northerly and southerly winds affect the spreading of the nutrient-rich riverine waters, discharged at the west coast of the gulf. The prevailing northerly winds contribute to the southward removal of the polluted sea surface and riverine waters, enhancing the cyclonic circulation around the gulf, allowing the inflow of clearer Aegean Sea Waters along the eastern coasts of the gulf. Northerlies also promote a connectivity pathway between the environmentally stressed Thessaloniki Bay (urban seafront) and the commonly less polluted southeastern coasts of the central basin. Southerlies mainly confine riverine waters in the western and northern coastal regions, weaken the renewal ability of the enclosed basins, and impose the formation of anticyclonic, mesoscale, circulation eddies in the outer and central areas.

Inverted Solar Stills: A Comprehensive Review of Designs, Mathematical Models, Performance, and Modern Combinations

Fresh water is scarce, making it a worldwide issue. In order to address global freshwater demand, a filtration technique is needed. Solar distillation (SD) that purifies brackish and subterranean water has been proven to be a promising green technology. It produces distilled water which can be used as potable water for drinking and other purposes. The designs, operations, and configurations of several inverted solar stills are thoroughly examined in this article. All techniques for solar water distillation to separate saltwater from freshwater have the same fundamental idea. It has been demonstrated that for a specified mass of water in the top basin, the daily output of an inverted absorber double-basin solar still (IASS) grows with increasing water depth in the bottom basin. Nevertheless, as the water depth in the bottom basin rises from 1 cm to 5 cm, the output of an inverted absorber double-basin solar system falls by about 27%. At water depths of 4, 6, and 8 cm, the daily yields from inverted absorber solar stills paired with a refrigeration cycle (RIASS) were 6.4, 10.08, and 9.5 L/day, respectively. The results also showed a substantial rise in water temperature in the inverted absorber solar still as a result of lower bottom heat loss and larger absorptivity. In this study, the emphasis on energy, efficiency, and environmental concerns remains with the modified multi-wick basin-type inverted absorber solar panel. The performance of the inverted trickling solar still was assessed with a 60 ppm average salinity under various sun radiation, feed water flow rate, and existence conditions for natural convection. It was found that the still could produce 2.55 L/day m2 of fresh water, a 15% increase. Brackish water with a salinity of 6000 ppm was used to test the still in November at tilt angles of 47° and 32°. Condensate production at the specified angles was 2.8 and 2 L/d, respectively. A total output of 6.907, 5.681, and 4.650 kg/m2/day was also generated using the modified multi-wick basin-type inverted absorber solar still (MMWBIASS) at water depths of 1, 2, and 3 cm, respectively. With black cotton wicks, the MMWBIASS had a total thermal efficiency of 34.04%, 28.17%, and 23.61%.

Performance analysis of a solar still driven by a packed bed thermal storage tank during off-sunshine period

During cloudy or rainy days, when sunlight is absent, a solar still cannot operate in its natural mode. In such circumstances, the still can be run using energy stored in thermal storage systems during sunshine hours. This work presents an analytical investigation of such a scenario in which a packed bed sensible thermal storage tank is used to provide the input energy for desalination via a double basin solar still during off sunshine season. Closed form solutions are derived for the temperature profile in storage tank, and of temperatures in both upper and lower basins of the still. Using these solutions, a closed form solution is obtained for the net mass of distillate produced until the cessation of operation. Parametric studies reveal that the present system can produce appreciable quantity of pure water that remains unchanged with any variation in mass of water in ether basin of the double basin still, mw1, mw2. The net distillate increases linearly with an increase in the initial tank excess temperature,θ0. Further, the analysis tells that there is optimum mass flow rate of the working fluid that delivers heat from storage tank to the still,m˙athat maximizes net distillate production. The reason of existence of such an optimum mass flow rate is discussed in detail. For the values considered, it is seen that a storage tank of 1 m3 vol, at an initial temperature of 50 °C above ambient, can produce 11.69 kg of potable water, yielding a thermal efficiency of about 68%. This work is a first ever investigation of the viability of a packed bed thermal storage tank for operating a solar still, and can serve as a guiding study for further, more comprehensive research work in this direction.

Submesoscale flows impact Agulhas leakage in ocean simulations

Agulhas leakage, the warm and salty inflow of Indian Ocean water into the Atlantic Ocean, is of importance for the climate-relevant Atlantic Meridional Overturning Circulation. South of Africa, the eastward turning Agulhas Current sheds Agulhas rings, cyclones and filaments of order 100 km that carry the Indian Ocean water into the Cape Basin and further into the Atlantic. Here, we show that the resolution of submesoscale flows of order 10 km in an ocean model leads to 40 % more Agulhas leakage and more realistic Cape Basin water-masses compared to a parallel non-submesoscale resolving simulation. Moreover, we show that submesoscale flows strengthen shear-edge eddies and in consequence lee cyclones at the northern edge of the Agulhas Current, as well as the leakage pathway in the region of the filaments that takes place outside of mesoscale eddies. This indicates that the increase in leakage can be attributed to stronger Agulhas filaments, when submesoscale flows are resolved.

Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations.

The chemical conditions of the Argentine Basin (western South Atlantic Ocean) water masses are evaluated with measurements from eleven hydrographic cruises to detect and quantify anthropogenic and natural stressors in the ocean carbon system. The database covers almost half-century (1972-2019), a time-span where the mean annual atmospheric carbon dioxide concentration (CO2atm) increased from 325 to 408ppm of volume (ppm). This increase of atmospheric CO2 (83ppm, the 64% of the total anthropogenic signal in the atmosphere) leads to an increase in anthropogenic carbon (Cant) across all the water column and the consequent ocean acidification: a decrease in excess carbonate that is unequivocal in the upper (South Atlantic Central Water, SACW) and intermediate water masses (Sub Antarctic Mode Water, SAMW and Antarctic Intermediate Water, AAIW). For each additional ppm in CO2atm the water masses SACW, SAMW and AAIW lose excess carbonate at a rate of 0.39±0.04, 0.47±0.05 and 0.23±0.03μmol·kg-1·ppm-1 respectively. Modal and intermediate water masses in the Argentine Basin are very sensitive to carbon increases due low buffering capacity. The large rate of AAIW acidification is the synergic effect of carbon uptake combined with deoxygenation and increased remineralization of organic matter. If CO2 emissions follows the path of business-as-usual emissions (SSP 5.85), SACW would become undersaturated with respect to aragonite at the end of the century. The undersaturation in AAIW is virtually unavoidable.

WITHDRAWN: Performance on single basin square pyramid solar still

Abstract Solar still is widely used in Industries as well as Domestic. Single basin square pyramid is experimentally analysed with and without porous materials like clay pot pieces and chalk pieces. The outside ambient, inside and outside temperature of glass surfaces, basin water and condensate temperature and mass of condensate collected were recorded, for hourly intervals with thermocouple. The experiments were conducted with a constant depth of 1 cm in the basin. The system performance was found to be maximum 36% and it is strongly suggests a good capability of the system to convert solar thermal energy for desalination process.

Influence of water mass on the performance of spherical basin solar still integrated with parabolic reflector

Continuous availability of fresh drinking water to meet the growing social, economic and environmental need of society is one of the major concern for present situation. Solar desalination is sustainable device to get the potable water from brackish water. However, the lower productivity of solar desalination is the major obstacle for worldwide applicability. In the present paper, an ingenious amendment in form of spherical basin solar still has been integrated with parabolic reflector. The spherical basin solar still has been developed and performance has been investigated for various water mass such as 1 L, 2 L, 3 L, 4 L and 5 L in basin. The daily yield of 3.5409 L/m2, 4.7860 L/m2, 6.7174 L/m2, 7.4744 L/m2 and 8.2596 L/m2 was obtained for 1 L, 2 L, 3 L, 4 L and 5 L water mass in basin respectively. The daily average efficiency of spherical basin solar still was obtained 19.56%, 23.92%, 30.83%, 34.49%, 39.06% for the 1 L, 2 L, 3 L, 4 L, 5 L water mass in basin respectively. From experimental results, it has found that the distilled output increases with increase in mass of water in basin.

Large accumulations of 34S-enriched pyrite in a low-sulfate marine basin: The Sturtian Nanhua Basin, South China

The Cryogenian of the Nanhua Basin (eastern Guizhou Province, South China) consists of a continuous succession of glacial and post-glacial deposits from the Sturtian Glaciation, including diamictite of the Tiesi’ao Formation and Mn-carbonate and black shale of the overlying lower Datangpo Formation. Here, we analyzed the sulfur chemistry of these units with the goal of understanding regional to global changes in the marine sulfur cycle accompanying a Snowball Earth event. The study units are characterized by elevated carbonate-associated sulfate (CAS) δ34S (mean +56.0‰, range +49.6 to +62.6‰) and pyrite δ34S compositions (mean +57.5‰, range +48.8 to +66.8‰). Both CAS and pyrite δ34S show water-depth gradients, with mean values increasing from the shallower Lijiawan area (CAS: +49.3‰; pyrite: +44.5‰) to the deeper Xixibao (CAS: +57.9‰; pyrite: +59.8‰) and Gaodi areas (CAS: +62.4‰; pyrite: +61.6‰), reflecting a density-stratified water column with limited vertical mixing. △34S values (i.e., δ34SCAS – δ34Spy) range from −6.5‰ to +8.0‰ with a mean of +0.7‰. These features, which are similar to those for coeval strata globally, are consistent with low seawater sulfate concentrations, but several additional features of the Nanhua Basin deposits do not conform to existing Cryogenian sulfur-cycle models: (1) high total sulfur contents (mean 2.2 ± 1.1%), which are difficult to reconcile with low seawater sulfate, and (2) frequent negative △34S values, which indicate that in situ microbial sulfate reduction (MSR) cannot have been the sole control on pyrite δ34S. These features point to quantitatively important hydrothermal sulfur inputs to the Nanhua Basin watermass. Based on these considerations, we propose a new sulfur-cycle model for the Sturtian Nanhua Basin in which hydrothermal emissions supplied large amounts of 34S-enriched H2S to the water column. The released H2S was partly precipitated as syngenetic framboidal pyrite and partly oxidized to sulfate that was removed to the sediment as CAS, thus accounting for the unusual combination of high total sulfur concentrations, similar strongly 34S-enriched sulfur-isotopic compositions for CAS and pyrite, and frequent negative △34S values. As a result of low seawater sulfate concentrations, both δ34SCAS and δ34Spy developed water-depth gradients through vertical mixing of strongly 34S-enriched hydrothermal sulfide from deep-graben vents with moderately 34S-enriched sulfate from the global ocean. Our model provides new insights into Sturtian-glacial sulfur cycling processes within a semi-restricted marine basin that are likely to have wider applicability to Neoproterozoic marine systems.

Seasonal changes of water mass, circulation and dynamic response in the Kuril Basin of the Sea of Okhotsk

The seasonal variability of the hydrography and anticyclonic circulation in the Kuril Basin of the Sea of Okhotsk, from which the North Pacific ventilation originates, is studied from bi-monthly climatologies of temperature, salinity, dynamic height and current velocity. The subsurface hydrography of the Kuril Basin is characterized by the dominant role of fresh and cold waters transported by the East Sakhalin Current during winter and spring, and relatively warm and saline waters flowing with the Soya Warm Current. At the intermediate layer, the influence of dense shelf water is maximum from May to August, and this water mixes with surrounding waters in around half a year to form a well homogenized Okhotsk Sea Intermediate Water, the source of North Pacific ventilation. The anticyclonic circulation typical of the Kuril Basin exhibits a strong seasonality, being absent in winter and showing a maximum amplitude in summer. Its formation is mainly related to the dynamic response of isopycnals to wind forcing. A dynamic height maximum appears along the coastal regions from Sakhalin Island to the southern Kuril Straits in winter, likely migrates towards the Kuril Basin in March–April and forms the anticyclonic system between May and October. The dynamic height – and thus the flow field – is mainly determined by isopycnal displacement in and around the Kuril Basin, whereas advection of water masses has a negligible effect. Surface intensification and decay of the anticyclonic circulation seems to be related to other processes such as heat exchange with the atmosphere.

ANALYSIS OF LONG-CIRCUIT TYPE CAISSONS FOR ATTENUATION OF LONG-PERIOD WAVES

Breakwaters provide convenient shelter for short-period waves, thus limiting the amount of energy entering the harbor. This wave energy in the port basins may be amplified, due to the wave reflection, disturbing port operations. Anti-reflective Jarlan-type (ARJ) structures (see Jarlan, 1961) have been proposed in the literature, along with other structures, to alleviate wave disturbance within port basins. ARJ anti-reflective mechanism is based on the destructive interference of waves. An anti-reflective zone width, B, must be almost a quarter of the wavelength for maximum efficiency. Longer waves easily enter the port-sheltered area where resonance phenomena could magnify its energy under certain conditions. This low-frequency energy is much more difficult to dissipate. Port resonance is the phenomenon of energy amplification that takes place in a harbor or port basin if the incident waves have frequencies close to those of the natural oscillation of the mass of water in the port basin. These infragravity long waves are frequently reported as causing trouble in cargo handling areas of many ports (see Rabinovich, 2009), even causing breakages of mooring lines and other relevant damage (see Thotagamuwage and Pattiaratchi, 2014).

An experimental investigation of a v-corrugated absorber single-basin solar still using PCM

In this paper, a new design of a v-corrugated absorber solar still with built-in phase change material (PCM) is presented. This design allows for the expansion of melting wax through a net of tubes extended inside the storage tank. The system is tested with and without the PCM using different water masses. Adding wick over the corrugated plate using PCM is also investigated. Paraffin wax is chosen as a PCM due to its medium storage, safety, reliability, uniform melting and moderate cost. The experimental investigation shows that the solar still with using the PCM beneath the corrugated plate with less basin water mass achieves the best thermal performance among other studied configurations. Using the PCM causes a little decrease in the daylight productivity with a considerable increase in the still overnight productivity. The daily productivity of the still with the PCM when mw=25kg is 12% and 11.7% better than those for the v-corrugated still without the PCM and with the PCM using wick, respectively. Cost analysis is also performed where the cost per liter (CPL) for the still without PCM, with PCM and with PCM using wick are estimated as 0.07182, 0.08369 and 0.09558 $/l, respectively.

A Pliocene to recent history of the Bering Sea at Site U1340A, IODP Expedition 323

Fossil diatoms are the principal component of Bering Sea sediments and reflect the paleoceanographic history of the region. Diatom accumulation rates and relative abundances at International Ocean Discovery Program (IODP) Site U1340A are presented. Overall, the total diatom productivity record from 4.9 Ma to the present day reveals a fourfold reduction at circa 4.2 Ma from ~45 × 107 down to 11 × 107 valves/g (wet sediment), signifying a major shift in the upwelling and/or nutrient regime, coinciding with the end of the late Miocene-early Pliocene bloom identified in the eastern equatorial Pacific and California margin. Further abrupt shifts in the diatom assemblage occur at (1) 2.78–2.55 Ma, (2) 2.0–1.8 Ma, and (3) 1.0–0.88 Ma. (1) At 2.78–2.55 Ma, the appearance of sea ice-related species marks the regional cooling associated with the expansion of Northern Hemisphere ice sheets, subsequent development of stratified, nutrient-depleted waters, and increased influence of Western Basin Water masses (most likely due to the suppressed inflow of the Alaskan Stream). (2) Rapid cooling between 2.0 and 1.8 Ma indicates increased sea ice duration and/or frequency. This, coupled with low sea level stands caused prolonged closure of the Aleutian Passes, coupled with further increased Western Basin Water inflow. (3) The shift to 100 ka glacial/interglacial cycles at the middle-Pleistocene transition (1.0–0.88 Ma) marked an increase in upwelling-related species, indicating enhanced surface water mixing. These records confirm that the development and changing dynamics of sea ice in the Bering Sea played a major role in sub-Arctic Ocean circulation and is an integral component of global climate change.

Experimental Investigation and Thermodynamic Performance Analysis of a Solar Distillation System with PCM Storage: Energy and Exergy Analysis

This article presents the experimental performance investigation ofsolar still integrated with two types of phase change materials namelyLauric acid and Myristic acid independently, used as storage mediumof solar energy. The experiments were performed during the months ofApril-May 2011, under Indian climatic conditions. The effect of inputparameters such as mass of water in basin and mass of phase changematerial integrated with solar still basin on productivity of the solar stillhas been studied. Also on the basis of the experimental data the valuesof exergy and energy were calculated. It has been found that (i) produc-tivity of solar still integrated with Lauric acid is 22% more than the solarstill integrated with Myristic acid. (ii) the energy efficiencies for solarstill integrated with Lauric acid and Myristic acid are found to be 39.6%and 34.4% where as exergy efficiencies values are 0.29% and 0.74% re -spectively (iii) the cost of using Lauric acid is lesser than using Myristicacid for same amount of productivity.

Experimental Investigation and Thermodynamic Performance Analysis of a Solar Distillation System with PCM Storage: Energy and Exergy Analysis

ABSTRACTThis article presents the experimental performance investigation of solar still integrated with two types of phase change materials namely Lauric acid and Myristic acid independently, used as storage medium of solar energy. The experiments were performed during the months of April-May 2011, under Indian climatic conditions. The effect of input parameters such as mass of water in basin and mass of phase change material integrated with solar still basin on productivity of the solar still has been studied. Also on the basis of the experimental data the values of exergy and energy were calculated. It has been found that (i) productivity of solar still integrated with Lauric acid is 22% more than the solar still integrated with Myristic acid. (ii) the energy efficiencies for solar still integrated with Lauric acid and Myristic acid are found to be 39.6% and 34.4% where as exergy efficiencies values are 0.29% and 0.74% respectively (iii) the cost of using Lauric acid is lesser than using Myristic acid f...

Parametric study and heat transfer mechanisms of single basin v-corrugated solar still

A transient mathematical model was presented for a single basin solar still with v-corrugated basin liner. The model was based on an analytical solution of the energy balance equations for various elements of the still assuming the temperatures of the inner and outer surfaces of the still covers are not equal. The performance of the still was investigated by computer simulation using the climatic conditions of Tanta (lat. 30°47′N, long. 31°E), Egypt. The calculated results showed that the v-corrugated plate had improved both the daily productivity and daily efficiency by a relative percentage difference of approximately 24% compared to the case when a flat basin liner of the same area of 0.437 m2 was used. Effects of basin water mass and the number, height, and the half angle of the “vee” on the daily productivity and efficiency of the still were studied. To validate the proposed mathematical model, the simulated results were compared with the results presented in the literature for a v-corrugated solar still. It was concluded that the proposed model is able to predict the still performance during sunshine hours with good accuracy.

Performance analysis for passive single slope single basin solar distiller with a floating absorber – An experimental study

The availability of potable water per capita is contracting because of the growth of population. Solar distillation method is a promising method for supplying potable water to rural regions. Passive solar distiller is a simple device for the partial solution of the problem of shrinking potable water, because its simplicity in construction, operation and low cost. In this work, a detailed comparison between the thermal performance of single slope single basin solar distiller (SBD) and single slope single basin solar distiller with a floating absorber (SBDFA) has been investigated. The two units are designed, fabricated and tested under the same weather conditions of Tanta, Egypt (Lat 30° 47′N) during typical summer days. Effects of basin water mass and the type of the floating absorber plate on the daily productivity and efficiency of the proposed systems are investigated. For all investigated values of the mass of water above the floating absorber (mwu); the productivity of the SBDFA is found to be higher than that of the SBD. The improvement ratio of daily productivity is found to increase with the decrease of the value of mwu. The improvement ratio of daily productivity was found to be 42.2%, 15.2%, 20.1% and 17.2% when mica, stainless steal, aluminum and cooper are used as floating absorbers (mwu = 10 kg, mwL = 70 kg). The obtained experimental results indicated that the SBDFA can be used for supplying potable water with reasonable amounts.

Theoretical and experimental investigation on double basin double slope solar still

This paper presents a theoretical and experimental work performed on a double slope single basin and double basin solar still. In this work, an additional basin is incorporated with conventional single basin still to improve the performance of the double slope solar still. Single basin and double basin double slope stills are fabricated with the same area and tested under the same climatic condition. This study investigates the effect of varying the water mass in both upper and lower basin on productivity of the double basin still. In addition, the results were compared with the single basin still. From this tests (theoretical and experimental), it was found that providing an additional basin increases the productivity significantly. A good agreement was made with theoretical and experimental results. The deviation between theoretical and experimental was within 10%. Double basin still production is higher than the single basin still by 85% for the same basin condition.

Comparative study of double basin and single basin solar stills

This paper presents a new approach to enhance the productivity of a solar still by introducing an additional basin in the double slope solar still. Two solar stills, single basin double slope and double basin double slope with the same basin area were fabricated and tested at Kovilpatti (9° 11′N, 77° 52′E), Tamil Nadu, India. The experiments were conducted with various depths of water, different wick materials, porous material and energy storing material. In double basin still, a mass of water in upper basin is constant for all experiments. For both stills, water production decreases with increase of water depth. The production rate is higher for both the stills, when mild steel pieces are used as storing material in the basin. For the same basin condition, double basin still production is 85% more than single basin still.

Spatial variation in right whale food, Calanus finmarchicus, in the Bay of Fundy

We quantified small- and basin-scale variation in the energy available in right whale (Eubalaena glacialis) food, Calanus finmarchicus Copepodite-5 (C5), as a function of depth, tidal variation and circulation during the late-summer feeding period in the Grand Manan Basin of the Bay of Fundy. Food energy density (kJ m �3 ) is a function of C5 concentration (m �3 ) and individual C5 lipid energy content (J) that increases by 2 orders of magnitude from near the surface to ~18 kJ m �3 at ~160 m depth; this observation helps explain why right whales concentrate their foraging efforts at depth. Food energy density can vary by a factor of 4 over a tidal cycle and 3.5 over a hor- izontal distance of ~2 km in the deeper strata of the Basin. By tracing water mass trajectories, we show that it is the warmer, saltier and denser water that contains the highest food energy density that is tidally advected within the Basin. At the scale of the Basin (10s of kilometres) we observed maximum food energy densities of ~25 kJ m �3 in the 140 to 160 m depth stratum where the highest energy densities spatially coincide with the highest historical right whale concentrations. We con- cluded that the tidal variation and tidally driven circulation represents the simplest explanation for the distribution of food energy density and for the distribution of right whales in the Grand Manan Basin region and that Basin topography and water mass excursions associated with tidal currents facilitate the persistence of C5 aggregations in the dense deep water.

On effect of wind speed on passive solar still performance based on inner/outer surface temperatures of the glass cover

The thermal performance of a passive single basin solar still was investigated by computer simulation using the climatic conditions of Jeddah (lat. 21° 42′ N, long. 39° 11′ E), Saudi Arabia under the two conditions: (a) the temperatures of the inner T gi and outer T go surfaces of the still cover are equal and (b) the temperatures of the inner T gi and outer T go surfaces of the still cover are not equal. Effect of wind speed V on the daily productivity P d of the still for these conditions was studied. It was indicated that for the condition T gi = T go , there is a critical mass (depth) of basin water beyond which P d increases as V increases until a typical velocity V t . For basin water masses less than the critical mass, P d was found to decrease with increasing V until V t . After V t , the change in P d becomes insignificant. When T gi ≠ T go , P d was found to be less dependent on wind speed V for all investigated values of mass of basin water m w in the range 0 < m w ≤ 100 kg. The rate of heat transfer by forced convection due to wind should be estimated on the basis of the temperature of the upper surface of the still cover.