Mass Balance Research Articles

Feasibility study of a metal hydride-based solar thermal collector system

The present study aims to assess the technical feasibility of a novel Metal Hydride-based Solar Thermal Collector (MH-STC) system. This system includes a flat-plate solar collector integrated with a metal hydride bed, a hydrogen compressor, a photovoltaic panel, a hydrogen tank, and a water storage tank. This system combines the principles of a conventional solar thermal collector with the energy storage capabilities of metal hydrides, enabling the storage of surplus thermal energy. The LaNi5 alloy was used as heat storage material. A 3D-mathematical model is established and a numerical code written in Fortran-90 is developed to simulate the dynamic behavior of the proposed solar thermal collector. It was shown that the developed 3D-model produces computational results that are consistent with experimental data. In addition, to check the accuracy of the mathematical model and numerical approach, the relative errors in the mass balance and energy balance were calculated and values of 0.054 % and 0.18 %, respectively, were obtained.The simulation results offer insights into the system's technical feasibility, revealing an overall efficiency of 90.6 %, the water temperature at the collector outlet can reach 357.3 K, and a water volume heated of 230.4 L under the considered operating conditions. Moreover, the results indicate that the proposed MH-STC system exhibits significant potential as a viable alternative for thermal storage in domestic hot water systems.

Computational study on the Maillard reactions of glucose and galactose with lysine.

Milk has nutrient-rich but thermal sensitive matrix that undergoes varying degrees of Maillard reaction (MR) at heating conditions. The MR mainly occurs between lysine residues (Lys) and lactose composed of glucose (Glc) and galactose (Gal), which are abundantly sourced from dairy products. In the present study, the MRs of Glc and Gal with Lys at the initial and intermediate stages have been investigated theoretically using density functional theory (DFT) to simulate the gaseous and aqueous phases. Reaction mechanisms have been proposed, and relative energy changes of different steps were calculated according to the total mass balance. The calculations reveal that both Nα- and Nε-amine groups of Lys can react with the carbonyl functional group of Glc and Gal with the similar potential energy profiles, and Gal is more reactive than Glc. However, the barrier in Nε-channel is lower than in Nα-channel, indicating a faster reaction rate through the former channel compared with the latter. The 5-hydroxymethyl-2-furfural (HMF) and derivative are formed under 3-deoxysone route in the intermediate stage. The calculation results are helpful for proposing a reasonable MR mechanism and suggesting possible control methods of the MRs. In this study, different levels of DFT calculations have been conducted to investigate the mechanisms and favorability of generating MR products in Glc-Lys and Gal-Lys models at initial and intermediate stages in the gaseous and aqueous conditions. In order to elucidate the molecular models from the perspectives of chemistry and geometry, DFT calculations were performed by the mean of B3LYP functional at basis sets of 6-311 + + G (d, p) and 6-311 + + G (2df, 2p) with optional solvation settings. To examine the solvation effect, the study further constructed models with solvent H2O and calculated in wB97XD functional with 6-31 + G (d) basis set. All computations were carried out Gaussian 09 suite of quantum chemistry software.

Dye Removal From Tannery Wastewater Utilizing Footwear Waste: A Sustainable Approach

ABSTRACTWaste‐to‐3R (reduce, reuse, and recycle) is a promising mass balance approach in the leather sector for addressing the current challenge of overproduction of rubber sole waste in the footwear industry and dye pollution in tanneries. In this study, low‐cost charcoal derived from discarded natural rubber (NR) soles was effectively employed to remove anionic and cationic dyes from a model tannery dye solution, aligning with mass balance approaches in the leather sector. Discarded rubber charcoal (DRC) was prepared at 350°C using a self‐fabricated pyrolytic cell. The resulting charcoal was then dried, ground, and separated through 40‐mesh size lab‐scale sieves, and it was subsequently employed for the removal of dyes from tannery wastewater. The dye removal performance was optimized by adjusting parameters such as dosage, pH, contact time, and concentration. The maximum adsorption capacity and removal efficiency of the anionic acid dye (AD) were found to be 158.22 mg/g and 88.39% at pH 1, respectively, while those of the cationic methylene blue dye were 166.18 mg/g and 85.53% at pH 12, respectively, between 15 and 30 min, depending on the DRC conditions. Fresh charcoal and dye‐loaded charcoal were characterized through Fourier transform infrared spectroscopy, x‐ray diffraction, Brunauer–Emmett–Teller, scanning electron microscope (SEM), and transmission electron microscope with Energy‐Dispersive X‐ray (EDX) Spectroscopy for respective functional groups and morphology studies, and zeta potential measurements were employed to characterize the charcoal surface charge. The SEM image revealed that the shape of the DRC particles resembles a honeycomb structure, with an average size of 573.56 µm. The adsorption kinetic study indicates that the Freundlich isotherm model and pseudo‐second‐order kinetics were well‐fitted for dye removal in this study. The charcoal exhibited robust stability, retaining its capacity of 57.42 mg/g of AD and 44.94 mg/g of MB dye after four reuse cycles. This resilience was observed in treatment with various desorption agents, including HCl, CH3COOH, NaOH, and C2H5OH. The findings of this study suggest that NR‐derived charcoal could be used as a successful substitute for commercial activated carbon in wastewater treatment to get rid of the acid and basic dyes of the leather industry. Based on the observed results, a plausible mechanism was also proposed.

New modified chloride mass balance for hydrogeological applications

New modified chloride mass balance for hydrogeological applications

Mass Balance of Maritime Glaciers in the Southeastern Tibetan Plateau during Recent Decades

Maritime glaciers in the southeastern Tibetan Plateau (SETP) are particularly sensitive to changes in climate, and their changes directly and severely affect regional water security and glacier-related hazards. Given their large societal importance, a better understanding of the mass balance of maritime glaciers in the SETP, a key variable for characterizing the state of glacier health, is of great scientific interest. In this review, we synthesize in situ, satellite-based observations and simulations that present an overall accelerating negative mass balance of maritime glaciers in the SETP in recent decades. We hereby highlight a significant spatiotemporal difference in the mass balance of maritime glaciers across the SETP and investigate the drivers of the accelerated mass loss of these glaciers in recent years. We find that accelerated glacier mass loss agrees with the variabilities in temperatures rising and precipitation decreasing at regional scales, as well as the spatial patterns of widespread melt hotspots (e.g., thin debris, ice cliffs, supraglacial ponds, and surface streams), the expansion of glacial lakes, enlarged ice crevasses, and frequent ice avalanches. Finally, the challenges of the mass balance study of maritime glaciers and future perspectives are proposed. Our review confirms the urgent need to improve the existing glacier inventory and establish comprehensive monitoring networks in data-scarce glacierized catchments, and it suggests paying particular attention to the development of glacier mass-balance models that coupe multiple physical processes at different interfaces to predict the status of maritime glaciers and their responses to climate change. This study can inform the sustainable management of water resources and the assessment of socio-economic vulnerability due to glacier-related hazards in the SETP and its surroundings in the context of marked atmospheric warming.

Evaluation of Differences in Solubility in Organic Solvents of Softwood/Hardwood-Based Industrial Kraft Lignins Using Hansen Parameters and FTIR

Abstract: Lignin is part of the lignocellulosic biomass found in hardwoods, softwoods, and herbaceous plants. It is isolated by fractionation and pulping processes, where it is considered a waste product and is mainly burned to generate electricity and heat. However, lignin is a biopolymer that can be a source of many chemicals of significant value after treatments of functionalisation or depolymerisation. The main processes for its valorisation require solubilisation in organic solvents, which may affect the process’s mass balance and the biopolymer’s chemical structure, as lignins are rarely completely soluble in organic solvents. In this research, two industrial Kraft lignins derived from softwood and hardwood were treated using different green organic solvents (2-methyl tetrahydrofuran, tetrahydrofuran, 1-methoxy-2-propanol, and acetone), measuring the soluble and insoluble content to determine the mass balance, and the solubility was evaluated using Hansen parameters and FTIR. The results showed that both lignins were more soluble in tetrahydrofuran and 1-methoxy-2-propanol. Also, tetrahydrofuran performed better than the 2-methyl tetrahydrofuran, which is considered the green alternative. The reason can be explained using the Hansen solubility parameters. Moreover, the solubilised fractions showed similar FTIR spectra. The same is the case for the insoluble parts. In conclusion, the two lignins studied showed different solubilities in absolute values in organic solvents, but the trends were similar.

Exergy Analysis of Integrated Methanol and Dimethyl-Ether Co-production Towards Net Zero Waste Emission

AbstractThe energy sector, currently dominated by fossil fuels, significantly contributes to carbon emissions and climate impacts. This study addresses the urgent need for renewable energy resources and promotes the utilization of waste from Malaysia’s palm oil industry. It proposes upgrading conventional palm oil mills to integrated mills to produce valuable biofuels such as methanol (MET) or dimethyl ether (DME). Using Aspen Plus V11 for simulation, mass and energy balances were provided for feasibility analysis, including techno-economic, exergy, and carbon analysis. The integrated process demonstrated 10 to 15% higher exergetic efficiency than conventional mills, enhancing the renewability index by 40% and reducing carbon emissions to 0.50 tonne CO2 per tonne of palm oil. The integrated mills, operating at 61–64% exergetic efficiency, achieve a 28% reduction in exergy destruction when palm wastes are recovered and transformed into biofuels. Despite an 87% increase in non-renewable exergy consumption due to additional operating requirements, the overall renewability index remains high (around 0.9), demonstrating the commercial viability and environmental benefits of this approach. Overall, this study lays the foundation for integrated palm oil mill operation by utilizing palm waste to achieve net zero waste emissions, which is a positive outlook.

Life Cycle Assessment of Cobalt Catalyst Production and Recycling

Catalysts with an active phase of cobalt are crucial for Fischer–Tropsch synthesis (FTS), yet the environmental impacts of the catalyst production and the recycling of the spent catalyst remain largely unknown. The goal of this study was to evaluate the impacts of both catalyst production as well as the recycling of spent catalyst as cobalt hydroxide, cobalt sulfate, or cobalt carbonate. Life cycle assessment (LCA) was used to quantify the environmental impacts of the studied processes. The life cycle inventory (LCI) was gathered based on the mass and energy balances of process simulations built on information available in the literature. The results show that compared to primary production of equivalent products, all studied recycling processes for spent catalyst decrease the environmental impacts by more than 50% in all investigated impact categories. For example, the global warming potential (GWP) of cobalt recovery from spent FTS catalyst as cobalt sulfate was 1.7 kg CO2-eq./kg CoSO4whereas the corresponding GWP for primary production was 4 kg CO2-eq./kg CoSO4. The process hotspots of recycling were found to be the production of the chemicals consumed, particularly sodium hydroxide and sulfuric acid, which together contributed between 64 and 95% of the total environmental impacts. LCAs on FTS have included the consumption of cobalt catalyst in the LCI using various approximations. The impacts calculated for the production of cobalt catalyst in this study were found to be markedly higher. The largest contributors included the production of materials for the precursor and support, as well as NOx emissions and consumption of nitric acid.Graphical

Evidence for littoral convergence and sediment delivery to Mattole submarine canyon, Northern California

At geologic timescales, a significant proportion of the sediment eroded from continents is transferred from rivers to littoral cells, then through submarine canyons to deep ocean basins. Accumulation and occasional discharge of sediment from canyon headwall regions is a likely driver for the sediment gravity flows believed to be responsible for much of this mass transport, but the responsible mechanisms and event timescales in canyon heads are imprecisely defined, largely due to the drowning of canyon heads since the last glaciation and the resulting dearth of modern depositional environments to observe. We investigated a littoral cell adjacent to Mattole submarine canyon in Northern California to better understand the influence of bathymetry and coast shape on sediment trajectories and hypothesize that canyon heads promote littoral sediment accumulation due to bathymetric sheltering of the adjacent coast from waves and convergence of littoral cells exposed to varying wave direction. The uppermost gullies of Mattole Canyon extend to the littoral cell, and a train of sediment waves within the uppermost thalweg of Mattole Canyon suggests that gravity-driven flows of shore-derived sediment may have recently occurred. Mattole Canyon and nearby Mendocino Canyon flow into the deep Mendocino Channel, which has the highest observed Late Holocene sediment accumulation rates in Northern California. We documented the beach slope, grain size, and sediment provenance along 15 km of coast adjacent to Mattole Canyon and conducted numerical wave modeling to infer the dominant direction and magnitude of sediment transport, relative wave sheltering by bathymetry, and estimated sediment mobility in the vicinity of the canyon head over a multi-year period. South of the canyon headwall, in the vicinity of the Mattole River outlet, coarser sediment rich in metasandstone clasts and steeper beach slopes coincide with decadal-scale beach accretion. North of the canyon head, sediments are generally finer, beaches are flatter, clast lithologies include more quartz and mudstone grains, and there is decadal-scale net erosion. Wave modeling suggests the Mattole headwall region is subject to sustained sheltering from waves due to canyon bathymetry, littoral sediment convergence above the canyon head for much of a typical year, and occasional bed entrainment of sediment in the canyon’s uppermost gullies by large waves. Larger winter waves from the northwest likely result in net southerly drift north of the canyon head, with a high likelihood of preferentially transporting fine-grained, more quartz-rich sediment towards the Mattole headwall. Smaller summer swells from the west and south likely results in net northerly transport of metasandstone clast-rich Mattole River-derived sediment towards the canyon head. The imbalance in seasonality in wave conditions, coast shape, and sediment delivery by the Mattole River and other coastal creeks is broadly consistent with the spatial patterns in grain size, mineralogy, slope, and beach width that we observe in the vicinity of the canyon, and the net delivery of sediment to the Mattole Canyon head. An approximate mass balance of sediment flux from coastal streams feeding Mattole River littoral cell suggests that sediment volumes likely accumulate in the canyon headwall region that could supply several density flow events in a typical decade. These findings highlight the importance of the connectivity of the canyon to the nearshore region for the processes and products in canyons and fans. We hypothesize that feedbacks between canyon bathymetry, sediment accumulation, and mass evacuating flows promotes the long-term persistence of canyon systems.

Interface and mixing zone between soil waters arising from upward and downward seepage - Part I: Homogeneous total density

Thin water lenses floating on top of the main groundwater body are important for many natural and agricultural systems, owing to their different properties in terms of chemical composition or density compared to the surrounding groundwater. In settings with upward seeping groundwater, lenses may form that have thicknesses ranging from tens of centimeters to a few meters, making them prone to changing conditions in the short (seasonal) or long term (climate change). Knowing their thickness, shape, movement and mixing zone width may help in managing these lenses.In a series of two papers, we present a mathematical description of the flow of water and transport of solute in a 2D cross-section between two parallel outflow faces and compare a simplified model to a complete model as described by the numerical code SUTRA. In this first paper of the series, we consider situations with a homogeneous density distribution. In the simplified model we employ the sharp interface approximation to obtain an expression for the stream function, the interface between the two types of water and the corresponding maximum lens thickness in steady state in the domain considered. This steady state description is used for travel time analyses and forms the basis for the transient analyses. For a typical example of oscillatory (e.g. seasonal) fluctuations in boundary conditions, we obtain expressions of the movement of the interface midway between two outflow faces by separating the problem into two timescales using the interface motion equation. This analysis provides insight into the importance of parameters on the vulnerability of water lenses under changing conditions, and may easily be extended to situations with abrupt or gradual changes in boundary conditions reflecting changes in land use or climate, respectively. Finally, we derive an analytical approximation of the mixing zone midway between the drains for steady state solutions, stepping away from the sharp interface approach. For a variety of examples, we validate the obtained expressions of the simplified mathematical model against the numerical model code SUTRA, which solves the fluid and solute mass balances explicitly.

Performance comparison of laboratory scale air classifier and hydrocyclone at the same target size

The research aimed at comparing the performances of two common centrifugal type classifiers, air classifier and hydrocyclone, operated dry and wet respectively. The reason for starting the study is the possible shifting to dry processing in the future as the water has limited availability. Such comprehensive research has not been undertaken in the literature although individual assessments were completed. Within the scope, copper ore, gold ore and magnetite-calcite blends were chosen as these applications are common globally. The research commenced with the experimental tests via laboratory scale air classifier and hydrocyclone. Afterwards, size analyses and component measurements (via XRF, MLA, fire assay) were undertaken. The data was initially used in mass balancing of the experimental data to adjust the flow rates alongside with assays then Tromp curves were plotted to determine cut size, sharpness of cut, bypass parameters. Comparison of the two classifiers were completed for the same overflow target sizes. Throughout the assessments, the magnitudes of the Tromp curve parameters for the overall classification and component-based results were compared. As a result, air classifier may be alternative to hydrocyclone classification since less bypass, higher sharpness values were obtained. This study provides insights on choosing the dry or wet classification.

Carbon Dioxide Clathrate Hydrate Formation and Mass Balance Calculation: A Laboratory Experiment

Carbon Dioxide Clathrate Hydrate Formation and Mass Balance Calculation: A Laboratory Experiment

The development and evaluation of a parameter-free circuit-based model of bipolar membrane electrodialysis for process design and optimisation

Bipolar membrane electrodialysis (BPMED) is an emerging electromembrane technology which has the potential to replace existing pH manipulation process units among others and take advantage of the benefits posed by process electrification. The development of robust and flexible process models of BPMED for design and optimisation is paramount in derisking potential instillations and improving commercial viability. Herein, a circuit-based model of BPMED is presented which avoids reliance on empirical fitting parameters and training data. The resulting model is flexible enough that extension to account for added complexities may be readily adopted. The mass transfer and electrical resistance of six different domains (three membranes and three streams) were computed by applying fundamental laws such as Ohm’s law and Faraday’s first law. Acid-base reactions and their effect releasing current within the membranes were also considered. Furthermore, the stack model can be readily embedded in a broader process model. To this end, the stack model is applied to a recirculating-batch experiment using a delayed differential material balance to account for dead-time within the tubing and measurement flow-cells. Two orthogonal methods of experimental validation were conducted to assess the performance of the model over a range of concentrations and applied voltages. These involved running a recirculating-batch experiment and collecting current–voltage polarisation data, respectively, and both showed good agreement with the model predictions. Overall, a robust model of BPMED has been produced which is able to accurately predict system performance and will prove useful for the design and optimisation of industrial systems.

Bio-methanol with negative CO2 emissions from residual forestry biomass gasification: Modelling and techno-economic assessment of different process configurations

The paper presents a techno-economic comparison among five alternative process configurations for bio-methanol production from the gasification of residual forestry biomass. Process design and simulations are performed in Aspen Plus for mass and energy balance calculation, followed by preliminary sizing and economic analysis. Process schemes include a gasification island (state-of-the-art low-pressure gasification compared against a high-pressure gasifier) with syngas conditioning and compression, heat recovery, syngas composition adjustment (by CO2 capture or addition of hydrogen produced by electrolysis), methanol synthesis and purification and a heat recovery cycle for power generation. CO2 capture is performed with conventional chemical absorption in the benchmark cases, while low-temperature partial condensation of CO2 is modeled in the advanced scenario. Methanol output is 14–15 kt/y in the CO2 capture cases and 36 kt/y in the H2 addition option.Configurations with a pressurized gasifier and phase-change-based CO2 separation are the most efficient ones, with a primary energy efficiency of 50 % and a Levelized Cost of Methanol (LCOM) of 700 €/tMeOH. In comparison, LCOM increases to 730 €/tMeOH in the case with conventional capture or between 792 €/tMeOH and 831 €/tMeOH (depending on the CCS technology) if the gasification pressure is conservatively reduced to 2.5 bar. In the H2 addition scenario, LCOM increases to 821 €/tMeOH due to the significant impact of the electricity consumption for H2 production, (only partly compensated by the increased methanol production). Scenarios with CO2 capture feature negative CO2 emissions, in the range −1.64 to −1.84 tCO2eq/tMeOH, as a result of the capture and storage of biogenic CO2 (BECCS approach).

Explicitly defined empirical constant for phase-change simulation in a two-phase closed thermosyphon

Over several decades, the importance of energy recovery has grown because of the global shift from fossil fuels to renewable energy sources. Among various energy-recovery approaches, waste heat recovery has emerged as a prominent method owing to its ease of adoption in various fields such as power plants and commercial buildings and high amount of recovery by adopting in the heavy industry. A heat exchanger with a heat pipe offers superior waste heat recovery efficiency through its highly effective heat transfer in a two-phase closed thermosyphon (TPCT). Numerous investigations have explored the thermal hydraulic performance of TPCTs in various geometries and operation conditions, mostly relying on experimental methods owing to the challenges in accurately simulating phase change in TPCT systems. These challenges arise from using the mass-transfer intensity factor, r—an empirically selected constant in phase-change models—which lacks a robust basis in fundamental principles. This study introduces a novel approach to selecting the r value for simulating the phase-change process in TPCTs. By employing the volume-of-fluid model for multiphase interfaces along with the widely used Lee model for phase change, the proposed model establishes a correlation between evaporation and condensation mass fluxes to define the r value in condensation heat transfer within a TPCT. The utilisation of the proposed model in simulations yielded improved temperature predictions, deviating by 4–7 K from experimental results while offering a significant reduction in the number of r values to choose from, achieved by explicitly defining the r value for condensation heat transfer. The conventional approach was to set both empirical constants to re = rc = 0.1 s−1. However, this model, which provides a relationship between the two empirical constants based on mass balance, revealed that rc should be 9.8 s−1 rather than 0.1 s−1 corresponding to re = 0.1 s−1. Furthermore, the study examines the diverse thermal performance outcomes associated with varying r values for evaporation in a wide range of re (0.1–100 s−1). rc was in the range of 9.8–12.7 s−1, denoting an increase of only 30% as re increased 1000 times from 0.1 to 100 s−1. This research offers a comprehensive understanding of the computational modelling of TPCTs, providing valuable insights into their thermal characteristics based on the intricate phase-change phenomena occurring within them.

Liquid-liquid equilibrium of the 1-butyl-3-methylimidazolium-based ionic liquids + sodium citrate + water systems at 298.15 K

Liquid-liquid extraction has long been the preferred option for process engineers to develop separation processes and it is used to separate and purify various biological products, metallic ions, colorants, pharmaceutical molecules, and small organic species. Ionic liquids (ILs) are special ecological solvents that can be used as possible substitutes for traditional organic solvents used for extraction and separation processes, becoming them more sustainable and safer. In combination with salts or inorganic polymers, they can form a liquid system of two phases, advantageous due to its wide polarity and viscosity. In this scenario, liquid–liquid equilibrium (LLE) data and phase diagrams for new aqueous two-phase systems containing ionic liquid ([BMIM][OH], [BMIM][Cl], [BMIM][Br]) (1) + sodium citrate (2) + water (3) were determined experimentally at 298.15 K. The ionic liquids were synthesized and characterized in the first part of the study. COSMO-RS was used as a tool to calculate polarity graphs of study molecules. In the second part, liquid–liquid equilibrium was studied using experimental measurements of the binodal curve and tie-lines, testing the quality of experimental data by mass balance, thermodynamic modeling using the NRTL model to correlate liquid–liquid equilibrium data and to do their phase stability. The accuracy of the model data results was verified by Gibbs energy topological mixing surface analysis and σ profiles. The experimental results indicated that the studied systems had type I liquid–liquid phase behavior. It was demonstrated that the ionic liquid [BMIM][OH] demonstrated better behavior to form Aqueous Two-Phase Systems mixed with sodium citrate and water. The results obtained by the thermodynamic modeling and stability with NRTL model weren’t satisfactory, because, besides the low deviations for the liquid phases compositions, the majority of calculated tie-lines was not tangent with the Gibbs surface, showing the limitations of the model for systems with electrolytes.

Assessing ecosystem health: A preliminary investigation of the gosikhurd dam ecosystem structure and functioning, an appraisal based on ecological modelling, India.

This study aims to comprehensively understand the Gosikhurd Dam ecosystem (GDE) ecosystem by employing the Ecopath with Ecosim software (version 6.6.5) to construct a trophic mass balancing model. This model consisted of 16 functional groups of organisms, and their interactions and trophic levels were explored. The study focuses on various performance indicators to assess the ecosystem's maturity and complexity. To achieve these objectives, monthly fish samples were collected from June 2022 to May 2023. Performance indicators such as the connectance index (CI), system omnivory index (SOI), Finn's cycling index (FCI), mean path length (FML), ascendency, overhead, and Shannon diversity index were calculated to assess ecosystem maturity and complexity. The Finn's cycling index (FCI) and the mean path length (FML) were calculated as 1.81 and 2.20, respectively, indicating the ecosystem's responsiveness to environmental changes and overall system health and stability. Ascendency and overhead values were also analysed, with ascendency being relatively higher (41.58%), reflecting a system that utilises less than half of its total capacity. The overhead value (58.42%) indicated that the ecosystem is relatively stable and capable of adapting to external perturbations. Furthermore, the Shannon diversity index was 1.67, illustrating less diversity and validating the ecosystem's immaturity. The study identifies critical species and their roles in shaping the ecosystem dynamics, highlighting the importance of zooplankton, zoobenthos, and tilapia as keystone species. These indices propound that GDE is in its developmental stage and lacks complexity compared to mature ecosystems. The findings provide valuable insights into the current state of the ecosystem and can guide future management and conservation efforts.

Convective Drying of Films of Polymer Solutions: Front Propagation Revealed by Thermal Measurements.

We report on the drying of films of polymer solutions under a controlled laminar air flow. Temperature measurements reveal that a drying front propagates in the film at constant velocity. Using thermal calibration, we are able to quantitatively determine the local drying rate of the film, and we find it agrees with conservation arguments. We further show that a simple mass balance allows us to relate the front velocity to the drying rate.

Disentangling external loadings, hydrodynamics and biogeochemical controls on the fate of nitrate in a coastal embayment

Nitrogen, as an essential nutrient, largely contributes to the coastal eutrophication. However, the accurate depiction and evaluation of how external loadings, hydrodynamics, and biogeochemical reactions mediate the occurrence, transport, and transformation of nitrate (NO3-) within coastal embayment still pose ongoing challenges to date. In this study, we took advantage of dual isotopes of NO3- to track external NO3- loadings, radium and dual isotopes of H2O to characterize the influences of hydrodynamic on NO3- transport, δ18O-NO3- and δ18O-H2O along with microbial analysis to explore major NO3- biogeochemical reactions in Tolo Harbour, Hong Kong. The multiple isotopic evidence showed that NO3- in surface harbour water was predominantly contributed by precipitation in wet season and its impact was strengthened by stratification. In dry season, NO3- in the surface harbour water became largely influenced by benthic input and biogeochemical reactions due to intensified vertical mixing. Based on NO3- mass balance model, biogeochemical reaction, especially nitrification, was found to be the major process to secure the closure of NO3- budget and increase NO3- inventory from wet to dry season. Hydrodynamics redistributed the external NO3- loadings and mediated nitrogen biogeochemical reactions, both of which further synergistically regulated the fate of NO3- in the embayment.

From satellite image to glacier scenery: A novel GlacierPix2Pix model for glacier visualization

Glacier visualization is critical for studying climate change as glaciers respond rapidly to global warming. It serves as an indicator of environmental changes and provides insights into the magnitude of climate change. Traditional on-site photography faces challenges such as safety hazards, high costs, and tight time constraints. Existing terrain generation models have limitations such as not being capable of using real satellite imagery to control generated terrain and achieving photorealistic image quality. To address these issues, this study introduces GlacierPix2Pix, a novel deep learning model that generates glacier scenery from satellite images. This study uses the Landscape HQ dataset containing 90K terrain images and the USGS Glacier Benchmark dataset containing Digital Elevation Models of 5 different glaciers over many years. This study curates a dataset of over 9K glacier images that can be used in related studies from the LHQ dataset. Glacier contours are extracted from the DEM images and glacier images. Based on the StyleGAN architecture, GlacierPix2Pix comprises a terrain generator, discriminator, and style encoder, and it supports both 2D and 3D methods. The model achieves a Frchet Inception Distance (FID) of 31.90, which surpasses the performance of other similar datadriven methods. It can successfully produce photorealistic glacier images aligned with satellite-derived contours. This research contributes to a better understanding of the urgent issues surrounding climate change, especially its effect on glaciers. Potential applications of this study include demonstrating glacier recession, helping with mapping snow cover and mass balance, and allowing detailed changes in remote locations to be observed.