Water Exchange Research Articles

Development of Multiscale Force Field for Actinide (An3+) Solutions.

A multiscale force field (FF) is developed for an aqueous solution of trivalent actinide cations An3+ (An = U, Np, Pu, Am, Cm, Bk, and Cf) by using a 12-6-4 Lennard-Jones type potential considering ion-induced dipole interaction. Potential parameters are rigorously and automatically optimized by the meta-multilinear interpolation parametrization (meta-MIP) algorithm via matching the experimental properties, including ion-oxygen distance (IOD) and coordination number (CN) in the first solvation shell and hydration free energy (HFE). The water solvent models incorporate an especially developed polar coarse-grained (CG) water scheme named PW32 and three widely used all-atom (AA) level SPC/E, TIP3P, and TIP4P water schemes. Each PW32 is modeled as two bonded beads to represent three neighboring water molecules, the simulation efficiency of which is 1 to 2 orders of magnitude higher than that of AA waters. The newly developed FF shows high accuracy and transferability in reproducing the IOD, CN, and HFE of An3+. The molecular structure and water exchange dynamics of the first An3+ hydration shell and the ionic (van der Waals) radii are reinvestigated in this work. Moreover, the new FF can readily be transferred to other popular FFs, as it has practicably predicted the permeability of An3+ in a graphene oxide filter within the framework of optimized potentials for liquid simulations (OPLS)-AA FF. It holds promise for applications in exploring actinide aqueous solutions with multiscale computational overhead.

Growth, immunomodulatory, histopathological, and antibacterial effects of phytobiotic-incorporated diets on Oreochromis niloticus in unchanged water

Phytobiotics are promising diet alternatives, yet their effectiveness in high-risk aquaculture conditions remains underexplored. Therefore, a 90-day feeding trial was conducted based on dietary supplementation of Nile tilapia, Oreochromis niloticus, with herbal extracts, namely, lemon balm [Melissa officinalis (MOE)], marjoram [Origanum majorana (OME)], and chamomile [Matricaria chamomilla (MCE)] with 0% water change. The treated groups were compared to groups untreated with herbs or control groups [positive control (PC; 0% water change) and negative control (NC; 20% water exchange per day]. Fish were cultured at stocking density (20 fish m-3: 1.8kg of biomass/m3). We conducted a physicochemical analysis of the water and the clinical responses, growth, and immune responses of the fish were evaluated. Furthermore, the herbal-supplemented fish were then challenged with a pathogenic Edwardseilla tarda strain and mortality was monitored. In the 1st and 2nd months, the water parameters were within the permissible limits. After that, a fatally low dissolved oxygen concentration and the highest levels of ammonia, nitrite, nitrate, and pH were recorded during the 3rd month. Blood and immune assays were conducted in the treated groups and control groups. The herbal-treated groups appeared healthy, but during the 3rd month, lethargy and decreased appetite were evident. Generally, the herbal-treated fish showed improved growth performance parameters, survival rates, and resistance against pathogenic bacteria E. tarda, particularly in the OME and MOE-treated groups compared to the positive control group. Finally, phytobiotic supplements were shown to improve fish stress tolerance and immune activation for a certain period under stressful conditions or unchanged water, based on the stocking density, dosages of herbs used, and the extent of deterioration of the water quality.

Climatological Evaluation of Three Assimilation and Reanalysis Datasets on Soil Moisture over the Tibetan Plateau

Soil moisture is critical in the linkage between the land and atmosphere of energy and water exchange, especially over the Tibetan Plateau (TP). However, due to the lack of in situ plateau soil moisture measurements, the reanalyzed and assimilated data are the major supplements for TP climate research. Based on observations from 1992 to 2013, this study provides a comprehensive evaluation of three sets of assimilation and reanalysis products (GLDAS, ERA5-Land, and MERRA-2) on the climatic mean and variability of soil moisture over the Tibetan Plateau (TPSM). For the climatic mean, GLDAS captures the spatial distribution and annual cycle of TPSM better than other datasets in terms of lower spatial RMSE (0.07 m3×m-3) and bias (0.06 m3×m-3). In terms of the climatic variability of TPSM, the multi-data average (MDA) highlights its advantages in reducing the bias relative to any single data product. MDA describes the TPSM anomalies more stably and accurately in terms of temporal trend and variation (r = 0.94), as well as the dipole spatial pattern in EOF1. When considering both the climatic mean and spatial variability, the performance of MDA is more accurate and balanced than that of a single data product. This study overcomes the deficiency of limited time and space in previous evaluations of TPSM and indicates that multi-data averaging may be a more effective approach in the climate investigation of TPSM.

Downscaling MODIS evapotranspiration into finer resolution using machine learning approach on a small scale, Ribb watershed, Ethiopia.

By monitoring evapotranspiration (ET), the exchange of water and energy between the soil, plants, and the atmosphere can be controlled. Routine estimations of ET on a daily, monthly, and seasonal basis can give relevant information on small-scale agricultural practices, such as the Ribb watershed in Ethiopia. However, MODIS sensors have recently given high temporal resolution ET products across large areas, but their low spatial resolution limits its application on a local scale. The primary goal of the study was to downscale the MODIS ET (1km) product to a finer spatial resolution at the watershed level. The model's 12 predictor variables (NDVI, EVI, LAI, FVC, SAVI, NDMI, NDWI, Albedo, emissivity, LST, and DEM: slope and elevation) were produced using the random forest (RF) algorithm using Sentinel-2 (S-2) 20m and Landsat-8 (L-8) 30m. The RF regression model was used to assess the relationship between predicted variables and downscaled MODIS ET. The FAO-PM ET model, developed from meteorological stations, was validated by and RMSE for three seasons (rainy, post-rainy, and dry) in 2022. The results were in good agreement with MODIS ET, with an RMSE of 0.22 for S-2 and 0.28 for L-8. In the FAO-PM ET model, the downscaled result showed greater spatial details and better agreement with gage station readings ( and ). Thus, considering the effectiveness and simplicity of machine learning techniques, our study demonstrated the potential for ET downscaling. Furthermore, the study suggests integrating spatiotemporal time series data to reach higher resolution.

Snowmelt-mediated isotopic homogenization of shallow till soil

Abstract. The hydrological cycle of sub-arctic areas is dominated by the snowmelt event. An understanding of the mechanisms that control water fluxes during high-volume infiltration events in sub-arctic till soils is needed to assess how future changes in the timing and magnitude of snowmelt can affect soil water storage dynamics. We conducted a tracer experiment in which deuterated water was used to irrigate a plot on a forested hilltop in Lapland, tracked water fluxes of different mobility and monitored how the later snowmelt modifies the labelled soil water storage. We used lysimeters and destructive soil coring for soil water sampling and monitored and sampled the groundwater. Large spatiotemporal variability between the waters of different mobility was observed in the subsurface, while surface water flow during the tracer experiment was largely controlled by a fill-and-spill mechanism. Extensive soil saturation induced the flow of labelled water into the roots of nearby trees. We found that labelled water remained in deeper soil layers over the winter, but the snowmelt event gradually displaced all deuterated water and fully homogenized all water fluxes at the soil–vegetation interface. The conditions required for the full displacement of the old soil water occur only during a snowmelt with a persistently high groundwater table. We propose a conceptual model where infiltration into the soil and eventual soil water replenishment occur in three stages. First, unsaturated macropore flow is initiated via the surface microtopography and is directed towards the groundwater storage. The second stage is characterized by groundwater rise through the macropore network, subsequent pore water saturation and increased horizontal connectivity of macropores. Shallow subsurface lateral fluxes develop in more permeable shallow soil layers. In the third stage, which materializes during a long period with a high groundwater table and high hydrological connectivity within the soil, the soil water is replenished via enhanced matrix flow and pore water exchange with the macropore network.

Investigation and evaluation of risk of pathogen transfer by ballast water in Shahid Rajaee Port, Hormozgan Province, Iran.

Ballast water is essential for ship operations, but can also transport harmful organisms between ports, threatening local environments. The Ballast Water Management (BWM) Convention, established by the International Maritime Organization (IMO), requires ships to implement ballast water management measures to address this issue. In this study, ballast water samples were collected from ships entering Shahid Rajaee Port in Iran before and after the Ballast Water Management Convention came into force in 2017. The sampling was conducted in coordination with Iranian authorities, following IMO guidelines. Vibrio cholerae, Escherichia coli, and Enterococci were identified in 97 ships, and physical parameters such as temperature, salinity, and pH were measured in 15 ships. To prevent sample contamination, rigorous protocols were followed, including using sterile equipment, appropriate storage, and immediate transfer to the lab. The results showed that before the BWM Convention, V. cholerae was found in 6 out of 14 ships (42%), with ballast water retention times of 2-58days. After the convention, V. cholerae was found in only 2 out of 83 ships (2.4%), with ballast water retention of 2-3days. This indicates a significant reduction in the risk of pathogen transfer through ballast water. Further analysis after the Convention showed that V. cholerae was initially detected in 4 out of 15 ships, but only 1 ship (6.6%) had levels above the standard. E. coli and Enterococci were also detected in multiple ships, but their levels were below the standard. The study investigated the relationship between the bacterial levels and the physical parameters. While some correlations were found between E. coli/Enterococci and parameters like pH, temperature, salinity, and water retention time, no significant impact of physical parameters on V. cholerae levels was observed. T-tests revealed significant relationships between the bacterial levels and the physical parameters, as well as the ballast water retention time. Ships were found to have followed the ballast water exchange guidelines of exchanging at least 200 or 50 nautical miles from shore and at depths over 200m, as mapped out for the Persian Gulf region. The results indicate that the implementation of the BWM Convention has been effective in reducing the risk of pathogen transfer through ballast water. However, the study emphasizes the importance of ongoing monitoring and enforcement to ensure continued compliance with the convention's requirements.

Intensive white shrimp (Litopenaeus vannamei) culture integrated with green mussel (Perna viridis), seaweed (Gracilariopsis bailiniae), and tilapia (Oreochromis mossambicus): impacts on water quality and growth of the shrimp

The production of Litopenaeus vannamei has significantly intensified, and integrated multi-trophic aquaculture (IMTA) has emerged as an effective farming technique to sustain the shrimp industry. Integrated aquaculture reduces pollution while increasing aquaculture production. This production system could give both ecological and economic benefits. Its contribution to the reduced amount of nutrients from intensive shrimp farming effluents and to the improvement of water quality conditions and growth of white shrimp are significant. This study aimed to evaluate the impacts on water quality and growth performance of shrimp (L. vannamei) at the same time assess the viability of rearing shrimps integrated with either green mussel, Perna viridis (GM alone), GM+seaweed (Gracilariopsis bailiniae), GM+tilapia (Oreochromis mossambicus), or GM+seaweed+tilapia. Shrimps were cultured outdoors for 60 days in a recirculating system at an average water exchange rate of 6 L hr-1. Shrimps were stocked at 400 shrimp m-3 in shrimp tank while seaweed (2kg m-2), green mussels (50 individuals per meter line), and tilapia (350 grams m-3) were cultivated separately in plastic baskets inside the biofiltration tank. Shrimp effluents were recirculated from the shrimp tank to the biofiltration tank. After 60 days of culture, results showed that shrimps without integration had the lowest average body weight (ABW), survival, weight gain, specific growth rate (SGR), biomass gain, and high feed conversion ratio (FCR) compared to shrimps with integration. This experiment confirmed that shrimp can be cultured intensively with either green mussel (GM alone), GM+ seaweed, GM+tilapia, or GM+seaweed+tilapia without adversely affecting the water quality and its growth performance and could even result in better yield than the shrimp cultured without integration. This research demonstrated the benefits of integrated aquaculture and could be further verified using large-scale culture.

Age-related decline in blood-brain barrier function is more pronounced in males than females in parietal and temporal regions.

The blood-brain barrier (BBB) plays a pivotal role in protecting the central nervous system (CNS), and shielding it from potential harmful entities. A natural decline of BBB function with aging has been reported in both animal and human studies, which may contribute to cognitive decline and neurodegenerative disorders. Limited data also suggest that being female may be associated with protective effects on BBB function. Here, we investigated age and sex-dependent trajectories of perfusion and BBB water exchange rate (kw) across the lifespan in 186 cognitively normal participants spanning the ages of 8-92 years old, using a non-invasive diffusion-prepared pseudo-continuous arterial spin labeling (DP-pCASL) MRI technique. We found that the pattern of BBB kw decline with aging varies across brain regions. Moreover, results from our DP-pCASL technique revealed a remarkable decline in BBB kw beginning in the early 60 s, which was more pronounced in males. In addition, we observed sex differences in parietal and temporal regions. Our findings provide in vivo results demonstrating sex differences in the decline of BBB function with aging, which may serve as a foundation for future investigations into perfusion and BBB function in neurodegenerative and other brain disorders.

ENSO‐Modulated Variability in Winter Shelf Circulation of the Northern South China Sea

AbstractWe combined long‐term observational data from 1999 to 2021 with numerical simulations to study the seasonal changes in the currents along the continental shelf in the Northern South China Sea (NSCS) during winter and how these changes relate to the El Niño‐Southern Oscillation (ENSO). Our results indicate that during El Niño events, the eastward movement of the warm pool in the tropical Pacific Ocean not only leads to colder sea surface temperatures and a stronger Kuroshio current intrusion but also significantly affects the formation of a high‐pressure system in the subtropics over the NSCS. In El Niño years, an anomalous anticyclonic wind stress curl in the South China Sea weakens the northeast winter monsoon, which in turn weakens the cyclonic shelf circulation. The first principal component from the multivariate empirical orthogonal function decomposition, which accounts for 49.02% of the total variance, shows a significant correlation of 0.64 with the Niño 3.4 index, indicating the circulation's sensitivity to tropical climate changes. Our analysis of the winter shelf circulation, based on the along‐isobath depth‐integrated vorticity equation, reveals that the exchange of water across the isobaths over the shelf is mainly controlled by the nonlinear advection of relative vorticity, with wind stress curl and bottom stress curl playing a less significant role in regulating the structure of these exchanges. The combined effect of baroclinic forces and topography likely governs the dynamics over the slope.

Induction of multicomponent peptide assembly via solvent exchange strategy for enhanced structure and bioactivities

Multicomponent peptides, composed of numerous peptides with various binding sites and functionalities, are increasingly exploited in nanotechnology, biomedicine and functional food applications. This article reported that nucleation and growth of Zein (Z) during solvent exchange could form a confined space to drive spontaneous self-assembly of multicomponent peptides. The self-assembly process began with a concentration gradient generated by the exchange of water and ethanol driving the nucleation of Z to form small aggregates, while multicomponent peptides selectively or anisotropically adsorbed on the Z surface via electrostatic interactions and hydrophobic interactions, participating in and controlling the assembly kinetics, ultimately leading to the formation of well-defined nanoparticles (NPs). The multicomponent peptides-based assemblies could effectively encapsulate the hydrophobic functional agent quercetin (Que), presenting good biocompatibility, antioxidant activity, and preventing DSS-induced colitis. This study elucidated the self-assembly mechanism of multicomponent peptides and demonstrated their synergistic effects with hydrophobic compounds for disease prevention, offering valuable insights into the development of novel functional materials to regulate human health.

Comparing Right-sided Colon Adenoma and Serrated Polyp Miss Rates with Water Exchange and CO2 Insufflation: A Randomized Controlled Trial

INTRODUCTION: Postcolonoscopy colorectal cancers primarily occur in the right-sided colon because of missed adenomas and serrated polyps (SPs). Water exchange (WE) improves cleanliness and visibility of the right-sided colon. We hypothesized that WE could reduce the right-sided colon adenoma (rAMR) and SP miss rate (rSPMR) compared to standard colonoscopy. METHODS: We randomly assigned 386 colonoscopy patients to insertion with either WE or CO2 insufflation. During the first withdrawal, polypectomies were performed up to the hepatic flexure. A second endoscopist, blinded to the insertion technique, reexamined the right-sided colon. The miss rate was determined by dividing the number of additional adenomas or SPs by the total number detected in both examinations. The primary outcome was the combined rAMR and rSPMR. RESULTS: WE significantly decreased the combined rAMR and rSPMR (22.2% vs 32.2%, P < 0.001) and rSPMR alone (22.5% vs 37.1%, P = 0.002) compared to CO2 insufflation, but not rAMR (21.8% vs 29.8%, P = 0.079). Additionally, WE significantly increased the detection of SP per colonoscopy (SPPC) in the right-sided colon (0.95 ± 1.56 vs 0.50 ± 0.79, P < 0.001). Multivariate logistic regression analysis showed that ≥2 SPs in the right-sided colon was an independent predictor of rSPMR (odds ratio [OR], 3.47; 95% confidence interval [CI], 1.89─6.38), along with a higher right-sided colon Boston Bowel Preparation Scale score (OR, 0.55; 95% CI, 0.32─0.94). CONCLUSIONS: The significant reduction in rSPMR and increase in right-sided colon SPPC suggest that colonoscopy insertion using WE is a valid alternative to CO2 insufflation (Clinical trial registration number: NCT04124393).

Groundwater Geochemistry in the Karst-Fissure Aquifer System of the Qinglian River Basin, China

The Qinglian River plays a significant role in China’s national water conservation security patterns. To clarify the relationship between hydrogeochemical properties and groundwater quality in this karst-fissure aquifer system, drilling data, hydrochemical parameters, and δ2H and δ18O values of groundwater were analyzed. Multiple indications (Piper diagram, Gibbs diagram, Na+-normalized molar ratio diagram, chloro-alkaline index 1, mineral saturation index, and principal component analysis) were used to identify the primary sources of chemicals in the groundwater. Silicate weathering, oxidation of pyrite and chlorite, cation exchange reactions, and precipitation are the primary sources of dissolved chemicals in the igneous-fissure water. The most relevant parameters in the karst water are possibly from anthropogenic activities, and other chemicals are mostly derived from the dissolution of calcite and dolomite and cation exchange reactions. Notably, the chemical composition of the deep karst water from the karst basin is mainly influenced by the weathering of carbonate and cation exchange reactions and is less affected by human activities. The hydrogeochemical properties of groundwater in the karst hyporheic zone are influenced by the dissolution of carbonates and silicates, evaporation, and the promotion effect of dissolution of anorthite or Ca-containing minerals. Moreover, the smallest slope of the groundwater line from the karst hyporheic zone among all groundwater groups revealed that the mixing effects of evaporation, isotope exchange in water–rock interaction or deep groundwater recharge in the karst hyporheic zone are the strongest. The methods used in this study contribute to an improved understanding of the hydrogeochemical processes that occur in karst-fissure water systems and can be useful in zoning management and decision-making for groundwater resources.

Isotopic composition of natural waters of Kuzbass in coalbed methane production areas

Relevance. In Kuzbass, a coalbed methane production project is being implemented for the first time in Russia. Formation water extracted together with coalbed methane plays an important role, since it has been in contact with the coal-bearing rocks for a long time, therefore it contains rich geochemical information. Over the period 2002–2022, new isotopic data were accumulated both on the waters of the region coal deposits and on overlying waters, including surface waters. Aim. Based on the material accumulated on the isotopic composition (δD, δ18O, δ13C, 34S, 3H, 14C) of natural waters in coal-bearing areas, create an evolutionary scheme for the formation of waters within the framework of the developed hypothesis on the interaction of water-rock-coal-methane. Objects. River, underground waters of the zone of active water exchange, upper and lower parts of the zone of slow water exchange (extracted together with coalbed methane). Methods. Studies of the isotopic composition of waters were carried out in several laboratories: in the Multielement and Isotope Research Center of the SB RAS, the Technical Branch of the Federal State Unitary Enterprise “SNIIGGIMS”, in the radiocarbon AMS laboratory based on the Center for Collective Use “Cenozoic Geochronology” and in the Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences (POI) FEB RAS. Results and conclusions. The paper introduces the data on δD, δ18О, δ13С и δ34S for surface and groundwater in Kuzbass in coalbed methane production areas. It is shown that all the waters under consideration are infiltration based on their isotopic composition (δD and δ18О). The waters of the lower part of the slow water exchange, produced together with coalbed methane, are characterized by a positive oxygen shift and very light hydrogen. A diagram of the evolution of the isotopic composition of water-dissolved carbon in the region has been compiled according to the data obtained. It is noted that the atmospheric source of CO2 is characteristic only of river waters, and only biogenic carbon dioxide is present in groundwater. The wide range of δ13СDIC values of the latter is explained by the varying degrees of participation of light soil carbon dioxide and heavy biochemical carbon dioxide formed during methane formation in the coal seam. The heaviest values are typical for waters produced together with coalbed methane, which is associated with long-term interaction with coal and methane. The time of such interaction was determined using the radiocarbon method: 17–30 thousand years. In areas where coalbed methane is produced, an increase in δ13СDIC values for all natural waters is observed, which requires further study.

Application of Biofloc Techznology as an Environmentally Friendly Solution to Increase the Productivity of Freshwater Fish Cultivation

This study explores the application of Biofloc Technology (BFT) as an environmentally friendly solution to increase the productivity of freshwater fish cultivation. Using a qualitative research approach based on a comprehensive literature review and library research, the paper examines the effectiveness of Biofloc in improving water quality, reducing feed costs, and enhancing fish growth rates. BFT promotes the growth of beneficial microbial communities that convert organic waste into protein-rich bioflocs, which serve as a supplementary feed for fish. This technology minimizes water exchange, conserves resources, and mitigates environmental pollution in aquaculture systems. The study highlights various successful implementations of Biofloc in freshwater aquaculture, noting significant improvements in production efficiency and sustainability compared to traditional farming methods. Moreover, the paper discusses the economic and environmental benefits of adopting Biofloc Technology, including reduced dependency on high-cost commercial feed and lower environmental impact due to decreased water usage and waste output. The findings suggest that Biofloc Technology is a promising innovation for sustainable aquaculture, providing both ecological and economic advantages. This research provides insights for policymakers, fish farmers, and aquaculture industry stakeholders interested in adopting eco-friendly practices to enhance productivity while protecting aquatic ecosystems

Satellite remote sensing reveals the footprint of biodiversity on multiple ecosystem functions across the NEON eddy covariance network

Abstract Biodiversity relates to ecosystem functioning by modulating biogeochemical cycles of carbon, water, energy, and nutrients within and between multiple biotic and abiotic components of the ecosystems. However, large-scale, systematic measurements of plant biodiversity are still lacking, and the effects of biodiversity on measured biogeochemical processes are understudied. Here, we combined alpha (α) and beta (β) taxonomic measurements, spectral diversity from satellite observations, structural properties of the vegetation, and climatic drivers to assess the effect of biodiversity on ecosystem functional properties. Ecosystem functional properties were computed from eddy-covariance fluxes at 44 sites of the National Ecological Observatory Network. Based on the spectral variation hypothesis, we used the near-infrared reflectance of vegetation (NIRv) derived from Sentinel-2 satellite imagery to compute Rao’s quadratic entropy (Rao Q), a distance metric related to spatial heterogeneity. Using an automatic model averaging technique, we found that biodiversity proxies hold substantial explanatory power when predicting several ecosystem functions related to carbon and water exchange. In particular, NIRv-based Rao Q (RaoQNIRv) reflected positive biodiversity effects on productivity, as expected from the literature. In contrast, traditional taxonomic α-diversity indices were generally not selected as relevant predictors of the ecosystem functional properties. Yet, β-diversity strongly contributed to the prediction of carbon use efficiency, surface conductance, and water use efficiency. We also found that the RaoQNIRv is less affected by issues of saturation and bare soil contribution compared to RaoQNDVI. We show that spectral heterogeneity based on remotely sensed NIRv holds the potential for globally characterizing the biodiversity-ecosystem functioning relationship (BEF). While systematic measurements of taxonomic diversity co-located at biogeochemical measurement stations could reduce the uncertainty surrounding the BEF relationship at whole-ecosystem scale, remotely- sensed metrics characterizing important functional and structural diversity aspects of the landscape will be crucial for continuous spatiotemporal monitoring of biodiversity with relevant implications for ecosystem services to humankind.

Storm surge, seawater flooding, and sea-level rise paradoxically drive fresh surface water expansion

Abstract Coastal storms and sea-level rise are expected to increase seawater flooding in low-elevation coastal zones. High sea levels and seawater flooding can drive groundwater table rise via ocean-aquifer connections. These dynamics are often overlooked but can cause groundwater flooding and salinization hazards, increasing freshwater security challenges for coastal communities and driving ecosystem transgressions. Field data and numerical modeling were used to evaluate how heavy rainfall, storm surge, and seawater flooding and infiltration during Hurricane Fiona (September 2022) and projected sea-level rise impact groundwater levels, inland surface waters, and saltwater intrusion on Sable Island National Park Reserve, Canada. During the passage of Hurricane Fiona, precipitation increased groundwater and pond levels before seawater flooded the beach. Seawater flooding and infiltration caused a sharp rise in beach groundwater levels, which in turn caused inland pond levels to rise without coincident direct inputs from precipitation or seawater. Model simulations reveal that seawater infiltration on beaches flooded the subsurface and drove the observed inland groundwater rise and freshwater pond expansion. Simulations of projected sea-level rise show that seawater flooding will only inundate a small area of land along the coast; however, inland groundwater rise and flooding, which is less well-studied, may inundate up to 30 times more land area. Further, groundwater flooding driven by rising sea levels decreases hydraulic gradients and increases saltwater intrusion via freshwater lens contraction. Findings demonstrate that seawater flooding from coastal storms and sea-level rise paradoxically cause concurrent fresh surface water expansion but freshwater lens contraction. This study provides new insights into the spatiotemporal dynamics of island freshwater resources and highlights that unseen and often overlooked groundwater-surface water exchanges are critical to consider when evaluating coastal flooding and groundwater salinization hazards and management strategies for low-elevation coastlines.

Comparison of transformer, LSTM and coupled algorithms for soil moisture prediction in shallow-groundwater-level areas with interpretability analysis

Accurate quantification of soil moisture is essential for understanding water and energy exchanges between the atmosphere and the Earth’s surface, as well as for agricultural applications. Predicting soil moisture content is vital for efficient water management, irrigation scheduling, and drought monitoring. Traditional forecasting methods, such as numerical regression models, often struggle due to various influencing factors and poor observation data quality. In contrast, deep learning algorithms, particularly recurrent and convolutional neural networks, show promise in predicting nonlinear data like soil moisture. This study focuses on shallow groundwater regions, using groundwater levels and meteorological data as features while coupling the Transformer model with other neural network structures. We investigate the potential of attention-based neural networks for soil moisture time series prediction. Our findings demonstrate that the Transformer model achieves an average R2 of 0.523 across different time lags, outperforming the LSTM model with an R2 of 0.485. The introduction of LSTM enhances the Transformer’s stability in handling temporal changes. Additionally, we verified the importance of groundwater for soil moisture prediction. This study introduces new methods for soil moisture prediction and offers new insights and recommendations for the development of artificial intelligence technology for soil moisture prediction.

Impact of tidal fluctuations on bacterial community structure in Wuyuan Bay: A comparative analysis of waters inside and outside the tidal barrage.

The tidal barrage at Wuyuan Bay effectively mitigated the odor from the tidal flat during ebb tide, however, its effect on bacterial community structure in waters are still unclear. In this study, high-throughput sequencing was used to analyze the structure of the microbial community in waters inside and outside the tidal barrage during flood and ebb tides. Results showed bacterial diversity was higher in water outside the barrage during flood tide. The dominated species at phylum and genus levels were various in waters inside and outside the tidal barrage during flood and ebb tides. The water inside during ebb tide (E1) were dominated by two cyanobacterial genera, Cyanobium_PCC-6307 (42.90%) and Synechococcus_CC9902 (12.56%). The microbial function, such as porphyrin and chlorophyll metabolism and photosynthesis, were increased in E1. Norank_f__Nitriliruptoraceae was identified as differential microorganism in waters inside the barrage. Inorganic nitrogen and nonionic ammonia were significantly high in E1, and were negatively correlated with norank_f__Nitriliruptoraceae. These results suggest tidal barrage blocks water exchange, resulting in the accumulation of nutrients in Wuyuan Bay. Consequently, the environment became favorable for the growth of cyanobacteria, leading to the dominance of algae in the water inside the barrage and posing the risk of cyanobacterial bloom. Higher Nitriliruptoraceae inside the barrage might be a cue for the change of water quality.

Characteristics of Nocturnal Boundary Layer over a Subtropical Forest: Implications for the Dispersion and Fate of Atmospheric Species.

The nocturnal boundary layer (NBL) significantly influences the dispersion and fate of atmospheric species at night. Subtropical forests are crucial in carbon and water exchange between the biosphere and the atmosphere. However, the NBL characteristics and their impact on atmospheric species over these forests remain unknown. This study conducted vertical measurements of atmospheric species such as O3 and volatile organic compounds (VOCs), along with meteorological variables, over a national forest reserve in Southern China. Results reveal that the NBL height ranged from 180 to 300 m in the summer and from 80 to 160 m in the winter. The vertical distribution of chemical species varied by time and season, with greater concentration gradients observed in the summer. Over 90% of VOCs above the NBL were anthropogenic, while biogenic VOCs were mainly found within the NBL. Higher O3 concentration and VOC product-to-reactant ratios were observed in the residual layer, suggesting enhanced oxidation levels. This unique vertical distribution of atmospheric species at night is driven by factors, such as emission, deposition, turbulence, and atmospheric chemistry, potentially affecting ecosystem functions. Results from this study highlight the importance of incorporating NBL dynamics into atmospheric models to better understand the evolution of chemical species and their ecological effects over forests.

Relationship between water quality and phytoplankton distribution of aquaculture areas in a tropical lagoon.

Aquaculture activities can affect water quality and phytoplankton composition. Our study estimated phytoplankton density and composition relating to aquaculture-impacted environmental factors. We analyzed water quality and phytoplankton at 35 sites in a tropical brackish lagoon, including inside aquaculture ponds (integrated farming of fish, shrimp, and crab), at wastewater discharge points, within 300m of these points, and farther out in the lagoon. Measurements were taken after aquaculture activities started in March and again in July. In both periods, total nitrogen (TN), total phosphorus (TP), chlorophyll-a (Chl-a), and turbidity decreased from the aquaculture ponds to the farther lagoon areas. Principal component analysis showed that nutrients, turbidity, and Chl-a were critical factors in aquaculture ponds, while salinity, temperature, pH, dissolved oxygen (DO), and water depth influenced water quality outside the ponds. Phytoplankton density was higher in July than in March due to aquaculture characteristics. Redundancy analysis indicated that phytoplankton, typical of inorganic, turbid, shallow lakes, was present throughout, whereas marine phytoplankton characterized the open water area (OWA). Marine phytoplankton caused a higher Shannon-Wiener index in July compared to March for OWA. Phytoplankton in aquaculture ponds was dominated by Oscillatoria spp., while Thalassiosira spp. dominated outside the ponds. We also identified indicator genera for two connected lagoons. Although constant water exchange prevented identifying specific indicator phytoplankton groups for aquaculture, this revealed the impact of wastewater from aquaculture ponds on the natural environment in the lagoons. Research on phytoplankton communities is necessary for the sustainable development of aquaculture and environmental management in coastal lagoons.