Low Water Mass Research Articles

Effect of ten different physical parameters on solar still productivity: Theoretical modeling

AbstractSolar distillation using solar stills is widely recognized as a clean and cost‐effective method for producing freshwater. However, due to its straightforward design, solar still performance is greatly influenced by various physical characteristics. Many researches have evaluated solar still parameters, while only a few articles have concerned physical ones. Therefore, this article aims to investigate the effect of different physical parameters on solar still productivity through thermal modeling. The theoretical results were validated with those of a previous experimental model, showing a good agreement with each other. The results reveal that daily productivity experiences significant improvement with an increase in plate emissivity or insulation thickness. Conversely, an increase in water mass, glass absorptivity or insulation thermal conductivity leads to a substantial reduction in productivity. Notably, water transmissivity and plate absorptivity do not affect productivity. Modest enhancements in productivity can be achieved by reducing the effective emissivity between water and glass. While the initial temperature of water has a minor impact on productivity at low water mass, it exhibits a substantial improvement effect at high water mass. These results can be a good guidance for the designers and manufacturers to develop more efficient designs that maximize the production of clean water.

Waste heat recovery of air conditioning on thermal efficiency enhancement of water heater

Air conditioning units are used to deliver comfortable air in households for the daily life of humans. This generates waste heat into the surroundings, that can cause global warming. This study investigated the thermal performance of water heaters recovering waste heat from air conditioners. A double-tube heat exchanger was installed between the compressor and the condenser to recover heat from the air conditioner. The inlet water temperature ranges from 15 °C to 40 °C, mass flow rates range from 2.5 L/m – 12.5 L/m, and water heater power input of 880 W – 3520 W is investigated. The results showed that water heaters have high thermal efficiency at low water mass flow rates. The waste heat of the air conditioner was recovered, which increased the thermal efficiency of the water heater by 12 % – 180 %, higher than the conventional type by approximately 50 %. The inlet water temperature ranges from 15 °C to 25 °C, and the input power range from 880 W to 1760 W has a significant impact on the thermal efficiency of the water heater. The energy consumption of the air conditioner decreased significantly when it was integrated with the heat recovery system. In addition, the water mass flow rate affected the energy consumption of the air conditioner. This study provides guidelines for improving the thermal efficiency of water heaters to reduce carbon dioxide emissions and heat rejection from air conditioners, leading to a reduction in global warming.

Effects of pin shapes on gas-liquid transport behaviors in PEMFC cathode

In this work, three pin-type flow field (FF) designs for a proton exchange membrane fuel cell (PEMFC) cathode with the circle, diamond, and square pins are proposed. The gas-liquid transport phenomena inside the PEMFC cathode are investigated to evaluate the water management performance of the designs. The volume of fluid model is used for the observance of the liquid water behaviors. A validated dynamic contact angle model is applied to improve the accuracy of the numerical simulation. From the results, it can be concluded that the pin shape affects greatly the emergence of liquid water from the catalyst layer, gas diffusion layer (GDL) to the FF. The study also offers insights into the airflow and liquid behaviors inside the pin-type FFs. Among the three FFs, the diamond pins remove water fastest with the lowest pressure drop. The square-pin FF also has low water mass in the computational domains but suffers from the highest pressure drop and uneven velocity, water, and pressure distributions. The circle pins have the most water content but can provide low pressure drop with the most uniform distributions. Thus, considerations for water removal ability should be taken for the pin-type FF designs regarding PEMFC performance and reliability.

Effect of Various Plasticizers in Different Concentrations on Physical, Thermal, Mechanical, and Structural Properties of Wheat Starch-Based Films

Biocomposite materials are essential for environmental protection, as they have the ability of substituting synthetic plastic with natural materials. This work investigated how different plasticizers (Glycerol (G), Fructose (F), Sorbitol (S), and Urea (U)) affect the morphological, mechanical, thermal, and physical characteristics of films made of wheat starch at various concentrations (0%, 15%, 25%, and 35%). Plasticizers were added to improve the flexibility and homogeneity of the wheat starch-based bioplastic. Control film exhibited high tensile strength (38.7 MPa) with low elongation (1.9%). However, films plasticized with 35% sorbitol showed the highest elongation, which was 60.7% at break. At 35% of all plasticizers, fructose showed the highest tensile strength, with 7.6 MPa. The addition of different plasticizers shows improvement in water resistance; films plasticized with glycerol had the lowest water absorption at 35% fructose (187.4%) and also showed coherent surfaces. Glycerol, sorbitol, and urea films showed a higher mass loss compared to fructose films. Fructose showed the highest performance after the analysis of the results, with low water absorption, water content, and mass loss and with high mechanical performance at 35% of fructose. SEM images show that the addition of fructose and glycerol improves the surface homogenate, while sorbitol and urea have a less compact structure with large pores.

Response of Spatial and Temporal Variations in the Kuroshio Current to Water Column Structure in the Western Part of the East Sea

Using geographic sea surface current data, long-term changes in spatial and temporal variations in the Kuroshio Current 1993–2021 were analyzed, and the relationship between the Kuroshio Current and oceanic conditions, such as water column structure and intensity of East Korea Warm Current (EKWC) in the western part of the East Sea (WES), was investigated. Long-term changes in the Kuroshio Current intensity were positively correlated with the Pacific Decadal Oscillation and East Asian Winter Monsoon indices. When the Kuroshio Current was strong, its main axis passing around the Ryukyu Islands moved eastward, and the intensity of EKWC separated from the Kuroshio Current and flowed into the WES, indicating weakened conditions. When the intensity of the EKWC was weakened, its main axis moved away from the inshore area of the WES. As a result, the vertical distribution range of the cold and low saline water mass located in the bottom layer extended to shallower depths in the inshore area of the WES with increasing chlorophyll-a.

The Mode‐Water‐Induced Interannual Variation of the North Pacific Subtropical Countercurrent and the Corresponding Winter Atmospheric Anomalies

AbstractCombining several reanalysis and in situ data sets, the low potential vorticity (PV) water masses are Lagrangian tracked in the subsurface ocean southwestwardly from the midlatitude Pacific in winter, which have significant interannual variations. The subsurface low PV water transport is proved to be closely related to the interannual variation of atmospheric North Pacific westerly jet by changing the subtropical countercurrent (STCC) and the sea surface temperature gradient adjacent. Specifically, the enhanced subsurface low PV water mass transported to the west of STCC causes strengthened northeastward warm water transport of STCC branching, and the weakened eastward branching. Therefore, significant negative temperature gradient anomalies of sea surface and lower atmosphere generate in the midlatitude to the east of 170°E. The corresponding local weakened lower atmospheric baroclinity and wave activities then lead to the convergence of anomalous downward atmospheric baroclinic Rossby waves and eventually the upper westerly jet deceleration.

Observational Analysis of the Formation Reasons and Evolution Law of Winter Counter-Wind Current in Jiazi Sea Area of Northeastern South China Sea

Based on the observational data of wind, current, and sea surface temperature in the Jiazi sea area of the northeastern South China Sea in 2018 and the satellite remote sensing data of sea surface temperature in the northern South China Sea, this paper explores the formation reasons and evolution law of winter counter-wind currents in the Jiazi sea area of the northeastern South China Sea. The results show that: (1) The counter-wind current in the Jiazi sea occurs only in certain time periods instead of the entire winter; (2) When the eastern component of wind stress weakens, the eastern component of seafloor friction also weakens to some extent. A high-frequency northeast current often occurs in the bottom layer of the sea area, indicating that the formation of winter counter-wind current in the Jiazi sea area is a result of the concerted action of wind stress, the baroclinic effect, and geostrophic effect; (3) When the counter-wind current is formed, there is a low temperature water mass in the northwest of Jiazi and a high-temperature water mass in the southeast. The baroclinic effect causes the sea water to flow to the shore and produce a westward flow on the shore, and northeastward counter-wind current occurs on convergent sea water on the shore due to the baroclinic effect and geostrophic effect (Ekman effect). Therefore, two different current systems are formed in the northeastern South China Sea in winter with 116° E as the boundary. The appearance of cold water masses in the northwest of 116° E sea area and warm water masses in the southeast of the South China Sea is the key to the formation of both the two different current systems with 116° E as the boundary and the winter counter-wind flow; (4) The formation and disappearance of the counter-wind current can be divided into four stages: in the first stage, the northeast monsoon gradually relaxes to become the southeast wind, forming the northwest current; in the second stage, the warm water masses on the west side of the Luzon Strait flow to the coastal waters due to the northwest current, forming a significant onshore pressure gradient force; in the third stage, a high-temperature seawater convergence zone is formed in the Jiazi sea area, forming southwest and northeast pressure gradient forces, and the northwest coastal current forms a counter-wind current under the combined action of pressure gradient force and geostrophic effect; in the fourth stage, the northeast monsoon intensifies and the counter-wind current weakens gradually until it disappears, and the sea water flows to the southwest again.

Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea

The flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore and onshore currents over the east- and west-side slopes in the channel, respectively, is suggested. A bottom intensified flow characteristic was observed at the offshore stations in the Yamato Basin. The asymmetric current system in the channel is also suggested by the asymmetric distribution of water characteristics across the TDSC in Toyama Bay; a cold dense water mass with higher dissolved oxygen (DO) and higher transmittance (Tr) was found over the west-side slope of the channel, whereas a water mass with lower DO and lower Tr was distributed over the east-side slope, suggesting a turbidity current from the head of Toyama Bay. The currents facing the shallower depth on their right-hand-side, along with the density distribution in the TDSC, suggest a density current system under the influence of the earth’s rotation. The dissolved oxygen concentration in the TDSC was significantly lower than that in the offshore region of the same temperature range. This suggests that the water mass over the west-side slope in the TDSC is a modified offshore water mass which experienced significant mixing with the low DO water mass over the east-side slope in the TDSC, probably due to strong shear between the offshore and onshore currents in the narrow channel.

Verification and Improving the Heat Transfer Model in Radiators in the Wide Change Operating Parameters

Laboratory measurements and analyses conducted in a wide range of changes of water temperature and mass flow rate for different types of radiators allowed to provides limitations and assessment of the current radiators heat transfer model according to EN 442. The inaccuracy to determinate the radiator heat output according to EN 442, in case of low water mass flow rates may achieve up to 22.3% A revised New Extended Heat Transfer Model in Radiators NEHTMiRmd is general and suitable for different types of radiators both new radiators and radiators existing after a certain period of operation is presented. The NEHTMiRmd with very high accuracy describes the heat transfer processes not only in the nominal conditions—in which the radiators are designed, but what is particularly important also in operating conditions when the radiators water mass flow differ significantly from the nominal value and at the same time the supply temperature changes in the whole range radiators operating during the heating season. In order to prove that the presented new model NEHTMiRmd is general, the article presents numerous calculation examples for various types of radiators currently used. Achieved the high compatibility of the results of the simulation calculations with the measurement results for different types of radiators: iron elements (not ribbed), plate radiators (medium degree ribbed), convectors (high degree ribbed) in a very wide range of changes in the water mass flow rates and the supply temperature indicates that a verified NEHTMiRmd can also be used in designing and simulating calculations of the central heating installations, for the rational conversion of existing installations and district heating systems into low temperature energy efficient systems as well as to directly determine the actual energy efficiency, also to improve the indications of the heat cost allocators. In addition, it may form the basis for the future modification of the European Standards for radiator testing.

Enhancing tubular solar still performance using double effect with direct sunrays concentration

Water scarcity, energy and demographic nature are real challenges facing many countries worldwide. These are maximized in rural communities where using the conventional energy resources for freshwater production may not be available. Thus the present study develops a novel double-effect tubular solar still installed at a focal line of a parabolic concentrator solar tracking system as an efficient solution. The developed device is experimentally examined under the climatic conditions of Ha'il city, Saudi Arabia. The results showed a significant enhancement in the performance of the developed device compared with the conventional single-effect device. The developed device increased the freshwater productivity and efficiency by 31.65% and 26.65%, respectively, with almost no increase in the freshwater production cost. A 5.2 L/m 2 day freshwater productivity was achieved with almost 40.4% daily thermal efficiency. Under the same operating conditions, the developed device presented 13%–50% higher productivity compared with the related published studies. The freshwater yield of the second effect was 25.8% of the total device yield, with a tube surface temperature of 73 °C compared with 88.6 °C for that of the single-effect device. This lower temperature along with the lower water mass in the second effect led to a significant decrease in the heat loss to the surrounding. It can be said that one square meter of the developed system can produce the essential freshwater needs per day for one person in rural and isolated communities. • Novel double-effect tubular solar still with concentrated sunrays is developed. • Novel system increased the device yield and efficiency by 31.7% & 26.7%. • Developed device produced 5.2 L/m 2 day with 40.4% thermal efficiency.

Contiguous Low Oxygen Waters between the Continental Shelf Hypoxia Zone and Nearshore Coastal Waters of Louisiana, USA: Interpreting 30 Years of Profiling Data and Three-Dimensional Ecosystem Modeling.

The multidecadal expansion of northern Gulf of Mexico continental shelf hypoxia is a striking example of the adverse effects of anthropogenic nutrient enrichment on coastal oceans. Increased nutrient inputs and widespread shelf hypoxia have resulted in numerous dissolved oxygen (DO) water quality problems in nearshore coastal waters of Louisiana. A large hydrographic dataset compiled from research programs spanning 30 years and the three-dimensional hydrodynamic-biogeochemical model CGEM (Coastal Generalized Ecosystem Model) were integrated to explore the interconnections of low DO waters across the continental shelf to nearshore coastal waters of Louisiana. Cross-shelf vertical profiles showed contiguous low DO bottom waters extending from the shelf to coastal waters nearly every year in the 30+ year time series, which were concurrent with strong cross-shelf pycnoclines. A threshold Brunt-Väisälä frequency of 40 cycles h-1 was critical to maintaining the cross-shelf subpycnocline layers and facilitating the formation of a contiguous low DO water mass. Field observations and model simulations identified periods of wind-driven bottom water upwelling lasting between several days to several weeks, resulting in both physical advection of oxygen-depleted offshore waters to the nearshore and enhanced nearshore stratification. Both the upwelling of low DO bottom waters and in situ respiration were of sufficient temporal and spatial extent to drive DO below Louisiana's DO water quality criteria. Basin-wide nutrient management strategies aimed at reducing nutrient inputs and shelf hypoxia remain essential to improving the nearshore coastal water quality across the northern Gulf of Mexico.

The Characteristics of Near‐Equatorial North Pacific Low PV Water and Its Possible Influences on the Equatorial Subsurface Ocean

AbstractUsing SODA oceanic reanalysis data, the subduction rate and low potential vorticity (PV) water masses in the North Pacific are investigated from January 1870 to December 2008. A new low PV water mass with a large subduction rate is found near‐equatorial North Pacific, which is named as the near‐equatorial North Pacific low PV water mass (NELPVW), and it is the only one low PV water mass in North Pacific that appears an increasing trend under global warming. Among all the low PV water masses in North Pacific, only Eastern Subtropical Mode Water (EMW) and NELPVW can migrate to the equatorial Pacific and effect subsurface oceanic temperature (SOT) there. Further research shows that the subducted low PV water mass in EMW generation region can migrate to equatorial Pacific through two transport paths, which are called the Western‐EMW path and the Central‐EMW path. The analysis of Lagrange tracking shows that EMW can migrate and bring SOT anomaly to equatorial Pacific along these paths in 7 years and lead to the almost precisely opposite distributions of equatorial Pacific SOT anomaly between the strong and weak EMW subduction years, while it takes the newly discovered NELPVW less than 3 years to reach the equatorial Pacific along the Western‐NELPVW path or the Eastern‐NELPVW path after subduction. The distributions of equatorial Pacific SOT anomaly in the strong and weak NELPVW subduction years are approximately reverse too. The actual distribution of the equatorial Pacific SOT is affected by these two low PV water masses at the same time.

Different Influences of Mesoscale Oceanic Eddies on the North Pacific Subsurface Low Potential Vorticity Water Mass Between Winter and Summer

AbstractThe generation and dissipation of North Pacific subsurface low potential vorticity water mass (SLPVW) affect various ocean‐atmosphere dynamic and thermodynamic processes on a wide range of time scales. Mesoscale oceanic eddies are believed to play an important role in the variation of SLPVW. National Centers for Environmental Prediction (NCEP)/NCEP‐Climate Forecast System Reanalysis coupled data set during 1979–2010 has been analyzed to investigate the different influences of mesoscale oceanic eddies on the SLPVW between winter and summer. It is found that the correlation between the sea surface height and SLPVW volume in winter is positive on the north of 30°N but negative on the south of 30°N, which is mainly caused by the eddy vorticity strength. The negative correlation value region has more strong anticyclones than the positive correlation value region, so the mixed layer depth in the negative (positive) correlation value region tends to be deeper (shallower) caused by stronger (weaker) anticyclones, which leads to the decreasing (increasing) of the low PV water mass under mixed layer depth (namely, SLPVW). Eddies also have obvious impacts on the subduction rate. The climatological eddy subduction rate can reach to 1.88 Sv in the NCEP‐Climate Forecast System Reanalysis, which accounts for 36.4% of the total subduction rate. In summer, the correlation between the sea surface height and SLPVW volume is remarkably negative. It is found that water diverges (converges) in the composite anticyclone (cyclone), which leads to the increasing (decreasing) of PV value in the composite anticyclone (cyclone), finally accelerates (hinders) the dissipation of SLPVW.

Picophytoplankton variability: Influence of Rossby wave propagation in the southeastern Arabian Sea

The westward propagating Rossby waves and associated currents transport low salinity nutrient-rich water mass from the Bay of Bengal into the southeastern Arabian Sea (SEAS) during winter monsoon, and ensuing changes in physicochemical properties of water column regulate phytoplankton distribution in the latter region. Herein, we elucidate the influence of Rossby wave propagation on picophytoplankton community composition in the SEAS. We compare the picophytoplankton community structure between the Rossby front (low saline, high nitrate concentration and strong current) and the surrounding non-frontal regions (high saline, low nitrate and weak current) along a cruise track in the SEAS during early winter monsoon (November 2016). The higher abundance of phycoerythrin-rich Synechococcus (‘dim’ and ‘bright’ types) and lower abundance of Prochlorococcus in the frontal region than the non-frontal regions suggest that salinity and nitrate concentration in the water column significantly influence the picophytoplankton community dynamics. We argue that the advection of low saline water mass from the Bay of Bengal associated with Rossby wave propagation introduces a ‘dim’ phycoerythrin-rich Synechococcus group in the frontal region, and the ensuing physicochemical changes in water column favor their growth, whereas low cell abundance of Prochlorococcus and Phycocyanin-rich Synechococcus suggests restricted growth of both the groups. These inferences indicate that Rossby wave associated circulation pattern and physicochemical changes in the water column regulate picophytoplankton community composition and its contribution to food web dynamics in the SEAS.

Chemical composition of planet building blocks as predicted by stellar population synthesis

Context. Future space missions (TESS, CHEOPS, PLATO, and the JWST) will considerably improve our understanding of the formation and history of planetary systems by providing accurate constraints on planetary radius, mass, and atmospheric composition. Currently, observations show that the presence of planetary companions is closely linked to the metallicity and the chemical abundances of the host stars. Aims. We aim to build an integrated tool for predicting the planet building blocks (PBBs) composition as a function of the stellar populations to interpret ongoing and future large surveys. The different stellar populations we observe in our Galaxy are characterized by different metallicities and α-element abundances. We here investigate the trends of the expected PBBs composition with the chemical abundance of the host star in different parts of the Galaxy. Methods. We synthesized stellar populations with the Besançon galaxy model, which includes stellar evolutionary tracks that are computed with the stellar evolution code STAREVOL. We integrated a previously published simple stoichiometric model into this code to determine the expected composition of the PBBs. Results. We determine the expected PBB composition around FGK stars for the four galactic populations (thin and thick disks, halo, and bulge) within the Milky Way. Our solar neighborhood simulations are in good agreement with the recent results obtained with the HARPS survey for firon, fw, and the heavy element mass fraction fZ. We present evidence of a clear dependence of firon and fw on the initial alpha abundances [α/Fe] of the host star. We find that the different initial [α/Fe] distributions in the different galactic populations lead to a bimodal distribution of PBB composition. Our simulations show an iron valley that separates PBBs with high and low iron mass fractions and a water valley that separates PBBs with high and low water mass fractions. Conclusions. We linked host star abundances and expected PBB composition in an integrated model of the Galaxy. The trends we derive are an important step for statistical analyses of expected planet properties. In particular, internal structure models may use these results to derive statistical trends of rocky planet properties, constrain habitability, and prepare an interpretation of ongoing and future large-scale surveys of exoplanets.

Distribution Trend of the Bottom Water at the Bay Mouth of Jiaozhou Bay

Based on the survey data of Jiaozhou Bay in May, June, July, August, September and October of 1980, the bottom water temperature and its horizontal distribution in Jiaozhou Bay were studied. The results showedthat the bottom water temperaturein Jiaozhou Bay rangedat a high level between 12.35℃to 25.72℃and a low level between 10.18℃to 24.58 ℃in May, June, July, August, September and October. From May to October, the bottom water temperature in Jiaozhou Bay was moderately high. In May, June, July and August, a high temperature zone formed around the waterinside the bay mouth, and the bottom water temperaturereached 12.35℃to 25.72℃.From May to August, the bottom water temperaturefirst increased in the watersinside the bay mouth, followed by the water at the bay mouth, withthe water outside the bay mouthas the end. In September and October, the temperature of the eastern coastal water outside Jiaozhou Bay ranged from 20.00℃to 24.43℃, and a high temperature zone formed around there. From September to October,the bottom water temperaturefirst decreased in the water inside the bay mouth, followed by the water at the bay mouth, with the water outside the bay mouthas the end. According to Yang Dongfang's definition of “Cryogenic Low Water Mass”, a cryogenic water mass formed in the bottom water at the bay mouthin September and extended widely among the water inside the bay mouth-at the bay mouth-in the southern part outside the bay mouthwith a temperature of 23.79℃to 23.91℃.

Spray, combustion and soot of water-in-fuel (n-dodecane) emulsions investigated in a constant volume combustion chamber part 1: Influence of low water content

This experimental study focuses on the characteristics of water-in-fuel-emulsions (WFE) with low water mass fractions (⩽10wt%) on injection, spray combustion and soot in regard to direct-injection (DI) diesel fuel engines. Investigations have been performed in an optically accessible constant volume combustion chamber (CVCC) at engine relevant conditions (Tgas=860K/ρgas=22.8kg/m3) with n-dodecane as a reference diesel fuels surrogate fuel. Optical diagnostics has been applied to characterize the influences related to the water content in the fuel on injection such as spray momentum flux and hence, air entrainment as well as on spray combustion and soot formation/oxidation.In order to further enhance the fundamental understanding of the fuel mixing and chemical effects of WFE, two injection strategies have been employed: first, a constant injection pressure as for neat fuel and thus a prolonged injection duration was employed. Second, a constant energy input flow has been obtained by increasing injection pressure dependent on water content while keeping the injection duration constant. The injection is described by injection rate/momentum analysis. The spray parameters (penetration length, cone angle) have been assessed by Schlieren imaging and the combustion characteristics (ignition delay, flame lift-off length) were acquired by OH∗-chemiluminescence. To investigate the (temporal and spatial) soot behaviour two-color pyrometry has been applied and is compared with diffused back-illumination extinction imaging (DBIEI).n-Dodecane and WFE show nearly equal momentum flux and spray penetrations for constant injection pressure, i.e. the first injection strategy. Compared to neat fuel, ignition delay is gradually increased with addition of water. Measured quasi-steady lift-off lengths (LOL) increased and evaluated fuel-to-air ratios Φ at axial LOL decreased, however, for both WFEs differences of Φ are within their respective standard deviation. Increasing water contents reduce axial and radial soot extension as well as the optical soot densities (KL factor). Moreover, the injection strategy of constant injected energy input flow further decreased soot area and optical soot densities (KL). Decreasing fuel-to-air ratios Φ on the spray centerline at the axial soot inception location and increasing fuel flow residence times from LOL to axial start of soot formation with increasing water mass fractions indicate a direct influence of the water content in WFE on soot formation/oxidation processes.

Pebble Accretion at the Origin of Water in Europa

Abstract Despite the fact that the observed gradient in water content among the Galilean satellites is globally consistent with a formation in a circum-Jovian disk on both sides of the snowline, the mechanisms that led to a low water mass fraction in Europa (∼8%) are not yet understood. Here, we present new modeling results of solids transport in the circum-Jovian disk accounting for aerodynamic drag, turbulent diffusion, surface temperature evolution, and sublimation of water ice. We find that the water mass fraction of pebbles (e.g., solids with sizes of 10−2–1 m) as they drift inward is globally consistent with the current water content of the Galilean system. This opens the possibility that each satellite could have formed through pebble accretion within a delimited region whose boundaries were defined by the position of the snowline. This further implies that the migration of the forming satellites was tied to the evolution of the snowline so that Europa fully accreted from partially dehydrated material in the region just inside of the snowline.

Biomass recovery from invasive species management in wetlands

Reed represents an opportunity fuel that can be obtained from wetland restoration activities designed for reducing the dominance of invasive reed over native matrix vegetation. Equipment used for reed recovery must be light enough to negotiate soft terrain. At the same time, it needs to be versatile, so that investment cost is depreciated on a variety of different tasks, given the seasonal character of reed collection. The study tested a new system designed for harvesting reed during winter, under unfrozen soil conditions. This system was based on a modified snowcat (trail groomer) and on light orchard tractors, for maximum floatation. Reed chopping, windrowing, baling and extraction took 12 h ha−1 and incurred a cost of 500 € ha−1, or 111 € t−1 dry matter. Assuming that reed biomass would obtain a price of 80 € t−1 dry matter, the cost of reed control would amount to 160 € ha−1, which is better than the 242 € ha−1 required for chopping to waste. Furthermore, savings can be accrued by better operator selection (baling) and by improving extraction technique, which would bring reed collection cost below 100 € ha−1. Reed biomass has favourable fuel qualities, including low water mass fraction. For this reason, reed can be used to build a strategic reserve to be tapped in winter, at times of peak demand. Furthermore, reed grows on land that is not suitable for other uses, and therefore it is unlikely to compete with food crops.

Seasonal variations in the vertical structure of pelagian water stratum in the Southern Baikal

For the first time, T,S-analysis was used to determine the specifics of seasonal variations in the vertical structure of Lake Baikal active layer. In the under-ice period, the active layer includes the under-ice, top winter, and upper intermediate water masses. The under-ice water mass, unlike other masses, shows an increase in mineralization to 100.74 mg/kg, which corresponds to a release of 71.1 g salt under 1 m2 of water surface in a layer 0–40 m in the process of salt freezing out during ice cover formation and accretion. In the phases of mixing (homothermy), the water masses of the active layer transform into a surface homogeneous mass. In summer and autumn, surface and upper intermediate water masses, separated by a water mass of summer thermocline can be identified. A specific feature of the summer thermocline water mass is the increased sum of ions because of an increase in HCO 3 - concentration at the decay of organic matter accumulating in the bottom part of the thermocline. The existence of the under-ice water mass and the water mass of summer thermocline was established in Lake Baikal for the first time. In the deep-water zone (>250 m), except for the bottom parts, the lower water masses (the lower intermediate and the deep) are permanent, their characteristics remaining stable during the year. The changes in the bottom water mass are due to the character of the processes of bottom water renewal.