Water Replenishment Research Articles

Developing a separation system to enable real-time recovery of acetone-butanol during fermentation

Methods such as gas stripping and vacuum-assisted gas stripping (VAGS) result in significant removal of water from the bioreactor, thus requiring continuous water replenishment in the bioreactor. In this study, we developed a hydrophobic stainless steel meshes capable of selectively recovering concentrated ABE stream from the bioreactor during VAGS. Three stainless steel meshes with pore sizes of 180 µm, 300 µm, and 425 µm were made hydrophobic and oleophilic with zinc oxide (ZnO) and polydimethylsiloxane (PDMS). Butanol concentrations in the model solutions range from 3 to 10 g/L which mimic concentrations typically produced during batch ABE fermentation. The meshes were integrated in a 5-L bioreactor containing 2.5 L of operational ABE model solution followed by the evaluation of selective extraction of ABE from both cell-free and Clostridium beijerinckii-rich ABE model solutions. The results show that the 180-µm ZnO/PDMS-coated mesh retained 54–64% more water in the bioreactor without C. beijerinckii cells and 61–65% more water with cells compared to the uncoated mesh. Furthermore, the butanol concentration of condensates recovered with 180-µm ZnO-PDMS-coated mesh was up to 10.8-fold greater than that of uncoated counterpart. Our data demonstrate that the developed ZnO-PDMS mesh can recover high concentrations of ABE while selectively retaining water in the bioreactor. Additionally, this technology demonstrates the potential for real-time ABE recovery during the fermentation of lignocellulosic and colloidal materials, without the concern of clogging the separation system.Key points• Hydrophobic mesh enhanced water retention in the bioreactor by up to 1.65-fold.• Butanol concentration in the collected condensate was increased by up to 10.8-fold.• Hydrophobic mesh is compatible with fermentation of lignocellulose.

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.

Determining the evaporation and evolution of surface water in a large catchment using isotopes and multiple models

The evolution and formation mechanisms of chemical components in surface water can reflect changes in the geological background of a basin and the extent of human interference. The Yangtze River basin is the largest water source area in China, yet its main ion sources and formation mechanisms are not fully understood. This study uses a combination of hydrochemistry, stable isotopes (δ18O, δD), the Craig-Gordon model, and the APCS-MLR model to quantitatively assess the water source replenishment and evaporation intensity of surface water in the Yangtze River. The study reveals the primary ion sources and controlling factors of surface water in the Yangtze River. The results show that the hydrochemical type in the upstream is mainly HCO3−-Ca2+ and Na+-K+, while in the midstream and downstream it is primarily HCO3−-Ca2+ and SO42−-Ca2+. The evolution of hydrochemical types is mainly controlled by rock weathering and human inputs. The surface water sources in the Yangtze River are directly replenished by precipitation, with the evaporation ratio in the upstream (0.66) being higher than in the midstream (0.63) and downstream (0.47). The lc-excess in the upstream (−0.32 ‰) is lower than in the midstream (1.21 ‰) and downstream (−0.27 ‰), indicating more intense evaporation in the upstream. The hydrochemical composition of the Yangtze River surface water mainly comes from geological factors (80.5 %), industrial factors (11.1 %), agricultural factors (6.4 %), and unknown factors (2.0 %). This study enhances the understanding of the chemical composition, water source replenishment, ion sources, and evolution mechanisms of the Yangtze River surface water, providing a basis for maintaining water quality and sustainable development in the Yangtze River basin.

Collaborative water-electricity operation optimization of a photovoltaic/pumped storage-based aquaculture energy system considering water evaporation effects

The increasing global population, economic development, and urbanization trends have led to a heightened demand for seafood, presenting a significant challenge to the growth trajectory of the food industry. As the most rapidly expanding segment within the food industry, aquaculture presents a sustainable solution to mitigate the overexploitation of marine resources and address the growing demand for food. Aquaculture's sufficient aquatic expanses offer considerable potential for PV deployment, thereby relieving the demand for limited land resources. However, existing research rarely addresses the collaborative operation of water and electricity in aquaculture systems. The effects of water evaporation from PV panel-covered water surfaces on the collaborative water-electricity operation are generally neglected. Hence, this work proposes a collaborative water-electricity operation of a photovoltaic (PV)-pumped storage-based aquaculture energy system considering the water evaporation effects. This optimization method accounts for the reduced water evaporation due to PV panel shading. Water surface PV and pumped storage are integrated into the system to fulfill electricity needs, with pumped storage serving as a dual-purpose device for water and electricity supply. Environmentally sustainable water-electricity generation and aquaculture energy system requirements are established. Water surface PV electricity generation is modeled based on climate and engineering conditions, while aquaculture pond electricity requirement includes oxygenation, feeding, and water replenishment. Finally, a collaborative water-electricity operation model is introduced to optimize operation strategies for various devices. A case study on a fish-light complementation project demonstrates that this optimization method can reduce reliance on the utility grid and overall system operational costs.

Enhancing soil water stability and retention through plastic mulching under atypical climatic conditions on the Chinese loess plateau

Mulching is an agricultural practice that is extensively implemented worldwide to conserve water in soil to enhance agricultural production，and especially in the temperate continental monsoon climate regions. However, the mechanism controlling soil moisture evaporation, infiltration, and retention by mulching is unclear. We assess the impact of various mulching regimes on the soil–water equilibrium in the root zone of corn fields under atypical climate conditions(Excessive Precipitation) from 2020–2021 in five treatments: (1) ridges mulched with plastic film and furrows without mulching (RF), (2) conventional flat planting with full plastic mulching (FPM), (3) conventional flat planting with straw mulching (SM), (4) conventional flat planting with partial plastic mulching (PPM), and (5) conventional (control) flat planting with no mulching (CK). The HYDRUS-2D model was calibrated and validated using experimental data, to assess soil water content, water flux, and soil water balance within a two-dimensional soil profile. This model accurately replicated the root zone within the soil profile under all mulching scenarios, with numerical simulation outcomes closely aligning with observed measurements. Average R² values for FPM, PPM, RF, SM, and CK scenarios were 0.76, 0.75, 0.86, 0.85, and 0.77, respectively. During the 2020 and 2021 growing seasons, characterized by increased rainfall, plastic-covered treatments (FPM, PPM, RF) more efficiently reduced soil evaporation and enhanced soil-water retention. The combined soil drainage and storage changes for FPM, PPM, RF, and SM treatments exceeded those of CK by an average of 114.57, 64.93, 77.38, and 6.74 mm, respectively. FPM, PPM, and RF treatments had substantial water-retention capabilities during years of atypical climate. Notably, FPM ensured adequate water supply, facilitated deep soil water replenishment, and more effectively maintained soil water stability and retention. This underscores the pivotal regulatory function of mulching in mitigating the impacts of consecutive years of unusual climatic conditions.

Experimental Study on Water and Salt Migration and the Aggregate Insulating Effect in Coarse-Grained Saline Soil Subgrade under Freeze–Thaw Cycles

Understanding multiphase transformations and the migration of heat, water, vapor, and salt in coarse-grained saline soil under groundwater recharge and environmental freeze—thaw cycles is crucial for ensuring the stability of highway infrastructures. To clarify the water, heat, vapor, and salt migration patterns in coarse-grained saline soil, as well as the salt-insulating effect of the aggregate insulating layer, an experimental study was conducted in a soil column model under pressureless water replenishment with fluorescein-labeled liquid water under freeze—thaw cycles. The results showed that the temperature in the saline soil columns periodically changed and that hysteresis effects occurred during temperature transfer. External water replenishment and the content of liquid water inside the soil exhibited nonlinear changes with environmental temperatures. After multiple freeze—thaw cycles, two water and salt accumulation zones formed within the coarse-grained saline soil subgrade. The migration of liquid water resulted in a water and salt accumulation zone in the nonfrozen zone, whereas the migration of water vapor yielded a water and salt accumulation zone in the frozen zone. To prevent water and salt migration, a 20 cm thick gravel insulating layer could be laid at a distance of 10 cm from the bottom of the roadbed, which could provide a satisfactory salt-insulating effect. The research results provide a theoretical basis and guidance for regulating the stability of subgrades in saline soil areas.

Simulation algorithm of greenhouse soil water movement based on cellular automata

Soil moisture movement reveals the hydrological environment and irrigation characteristics of plants, which is very important and basic hydrological problem. A soil moisture movement algorithm based on cellular automata suitable for greenhouse was proposed to simulate the lateral flow and vertical penetration of soil water in different soil layers. Artemisia annua was used as an experimental plant, and two numerical simulations were set up to determine the minimum water replenishment and the degree of upward soil modification. To verify the performance of the model, corn was used as an experimental plant for application simulation. The numerical simulation results show that the effect of only water for plant cells is superior to soil cells, and the disturbance behavior of the underlying soil layer should be minimized during the cultivation process. The average MAE/RMSE of all soil layers is 0.86/1.06 and in deep layer (50 cm and 60 cm) is 0.53/0.64. It shows the model has a certain prediction and simulation ability, especially in deep soil layers. The proposed algorithm can simply calculate soil flow, set the minimum water replenishment, and evaluate the water replenishment efficiency, which can provide a theoretical reference for the water replenishment and soil replacement scheme.

Determining the required amount of added solvent (H2O) to obtain a given electrolyte density

Problem. The article proposes a method for determining the required amount of water that must be added to obtain a given density of the electrolyte. Goal. The method of calculating the volume and mass of water necessary for diluting the electrolyte solution to a given density is considered. Methodology. This calculation allows, if necessary, to check the obtained results of measurements of the concentration of the electrolyte and to calculate the given density of the electrolyte taking into account the addition of the solvent (H2O). With periodic dosed replenishment of water consumed from the electrolyte, the electrolysis process occurs at a variable concentration of alkali in the electrolyte. Results. The proposed dependencies and the calculation method developed on their basis make it possible to increase the efficiency of the electrolysis process by reducing energy costs due to ensuring optimal specific conductivity of the electrolyte at a variable concentration of alkali. Originality. The resulting calculation dependence allows both during the development and operation of operating alkaline electrolyzers to calculate the current concentration and the range of changes in the concentration of alkali in the electrolyte. Practical value. The application of the obtained dependence for alkaline electrolyzers with periodic replenishment of feed water and for developed operating electrolyzers allows to analyze the nature of changes in the specific electrical conductivity of the electrolyte, i.e. evaluate the efficiency of the electrolysis process.

Water hammer protection of one-way surge tanks considering the effect of check valve

ABSTRACT One-way surge tanks are commonly employed as water hammer protection devices. However, the action process of the check valve is often disregarded in the design of protective measure. In this study, a one-way surge tank model incorporating a check valve was developed based on the method of characteristics. The check valve action process and different installation positions for one-way surge tanks were investigated based on an actual water supply project. The results show that, compared with the existing one-way surge tank mathematical model, the pipeline pressure calculated by the new model is smaller and the water replenishment is slower, which means that there is a safety risk based on the calculation results of the existing model. As the opening process of the check valve slows down, the pipeline minimum pressure is reduced. When the valve opening rate reaches 0.5 s, negative pressure appears in the pipeline. In addition, for undulated terrain with two obvious high points, when the first one-way surge tank is installed at the node behind the pump, the second one should be installed at the highest point to ensure that the pipeline pressure is greater than 0 m.

Approaches to substantiating the placement of industrial facilities within the sanitary protection zones of surface watercourses

Introduction. The article considers an approach to be used to delineate the source water protection area for the surface water bodies without putting manufacturing plants within the delineated areas out of action. The approach is based on the assessment of the disposals produced by plants on the water quality at the surface water intake point during the plant’s accident-free operation and both accidents within and beyond the design basis. Materials and methods. The article used the water protection area laws and regulations, the data observed of the disposal dispersion in the large rivers, and the original articles presented in databases and information systems: RSCI, CyberLeninka, Scopus, Web of Science. The solute transport analytical solutions for the dilution of the linear source in the flow serve as the methodological framework. Results. The article results have shown the local disposal into the river to form dispersion halo. Due to the specific dispersion processes, an area of a strip-like shape on the opposite shore can be formed where an anthropogenic influence is not present or negligible. This can be considered the background for the safe cooperative operation of the water intake and a manufacturing plant located within the water protection area. Limitations. The present article outlines the analytical approach for estimating the dilution of wastewater in river waters. The methodologies proposed are subject to several constraints, including the assumption of a constant river channel width and profile, steady discharge of contaminated wastewater, absence of water inflow losses or replenishment, lack of interaction with suspended particulate matter, uniform mixing across all segments of the river, and neglect of wind-induced effects on pollutant dispersion near the water surface. Failure to meet any of these assumptions necessitates recourse to more sophisticated numerical modelling techniques for accurate calculation. Conclusion. The use of the approach presented in the paper allows justifying the manufacturing plant’s operation within the source water protection area for the surface water bodies.

Patterned Gold Nanoparticle Superlattice Film for Wearable Sweat Sensors.

Nanoparticle superlattices are beneficial in terms of providing strong and uniform signals in analysis owing to their closely packed uniform structures. However, nanoparticle superlattices are prone to cracking during physical activities because of stress concentrations, which hinders their detection performance and limits their analytical applications. In this work, template printing methods were used in this study to prepare a patterned gold nanoparticle (AuNP) superlattice film. By adjustment of the size of the AuNP superlattice domain below the critical size of fracture, the mechanical stability of the AuNP superlattice domain is improved. Thus, long-term sustainable high-performance signal output is achieved. The patterned AuNP superlattice film was used to construct a wearable sweat sensor based on surface-enhanced Raman scattering (SERS). The designed sensor showed promise for long-term reliable use in actual scenarios in terms of recommending water replenishment, monitoring hydration states, and tracking the intensity of activity.

IoT based Smart Aquaculture Monitoring System for Fish Tank Management

Aquaculture, the farming of aquatic organisms, plays a critical role in meeting the increasing global demand for seafood. Effective monitoring and management of aquaculture systems are essential for ensuring optimal conditions and maximizing productivity. This research presents a comprehensive aquaculture-based fish tank monitoring system designed to enhance operational efficiency and fish welfare. At the heart of the system is the Arduino Uno microcontroller, serving as the central processing unit to coordinate various functions. Key components include pH sensor for continuous monitoring of acidity levels, turbidity sensor for detecting suspended particles, and water level sensor for maintaining optical water levels within the tank. In the event of abnormal pH levels or high turbidity, the system triggers automated alerts, sending notifications to the designated owner through SMS and transmitting data to an IoT website for remote monitoring. To ensure consistent environmental conditions, two pump motors are utilized: one for automatic water replenishment in case of water level fluctuations and another for removing water in case of particle accumulation. Furthermore, the system integrates a servo motor mechanism for precise dispensing of fish feed at predetermined intervals, promoting healthy growth and nutrition. Control over pump motors and feeding schedules is facilitated through a user-friendly website interface, providing operators with seamless management capabilities.

Carbon budgets of lakes on the Tibetan Plateau: Highlighting non-negligible carbon emissions from small lakes

The release of carbon dioxide (CO2) from lakes is a critical element of carbon (C) emissions from inland waters. Within the realm of climate change, the inquiries surrounding whether lakes on the Tibetan Plateau (TP) function as C sources or sinks and the magnitude of CO2 exchange flux from these lakes have garnered significant attentions. Nevertheless, accurately assessing the lakes’ contribution to the C budgets poses challenges due to data scarcity and methodological inaccuracies. By amalgamating data from literature reviews and field measurements for different sizes of lakes during the ice-free (IF) and ice-covered (IC) periods from 2016 to 2021, this study offers a refined estimate of the CO2 exchange flux and flux rate for lakes on the TP by including lakes ranging in size from 0.01 to 1 km2 (small lakes) in the C budgets. Findings revealed that the annual CO2 exchange flux of TP lakes amounted to 7.10 Tg C yr–1, with 6.56 Tg C yr–1 and 0.54 Tg C yr–1 during the IF and IC periods, respectively. Notably, small lakes contributed 0.76 Tg C yr–1, representing 10.65 % of the total lake CO2 emissions on the TP, which indicates the significant role of small lakes in estimating CO2 emissions from TP lakes. The CO2 exchange fluxes of small lakes showed significant variability during the IF period, with the origins of lake water replenishment possibly explaining this diversity, where glacial meltwater replenishment is likely a key contributing factor. In contrast, CO2 emissions from small lakes increased during the IC period. The view of this study is that the groundwater recharge with higher CO2 concentrations and the shallow nature of small lakes may be the main reasons for the increase in CO2 emissions from small lakes during this period. The study underscores that the contribution of small lakes to the CO2 budgets of TP lakes is substantial and warrants attention, particularly in elucidating the mechanisms driving CO2 emissions from small lakes.

Light rain exacerbates extreme humid heat

Humid heat waves pose significant risks to human health and the ecosystem. Intuitively, rainfall often alleviates extreme humid heat. However, here we show that light rain often accompanies extreme humid heat, exacerbating its frequency and intensity, especially over arid and semi-arid regions compared to no rain and moderate-to-heavy rain cases. This is because light rain does not dramatically reduce solar radiation but increases near-surface humidity through enhanced surface evaporation. The water replenishment from light rain as well as a shallower planetary boundary layer is crucial for consecutive extremes where there are commonly sporadic drizzle days amidst several rain-free days. These extremes last longer than rain-free extremes. Current global climate models (GCMs) overestimate light rain. After reducing this bias in a GCM, underestimations of humid heat waves in energy-limited regions and overestimations in water-limited regions are largely alleviated. These findings underscore the underappreciated impact of light rain on extreme humid heat.

A Study on the Construction and Evaluation of the Water Resource Reutilization System for Farmland Diversion and Drainage

Water is an essential resource for both rural and agricultural areas; it can be wisely distributed and used in the field to protect daily life, production, the natural environment, and the safety and stability of regional drainage and flood control systems. Our research selected a typical plains rural river network area with agriculture as the main industry to investigate the most effective method of farmland diversion and drainage. We comprehensively planned and transformed the water system flow, water conservation engineering, and the ecological environment in the irrigation area through the reutilization system. The reutilization system’s operation and scheduling design is implemented for four specific periods: the water replenishment cycle, agricultural irrigation, agricultural drainage and the rainy period of the flood season. The research period ranges from 2020 to 2023 after the completion of the system. We used monitoring, the recording of hydraulic equipment parameters and data collection to evaluate the balance of water supply and demand in the study area. At the same time, we have tracked and evaluated the four aspects of water quality enhancement, water conservation and flood control, and agricultural irrigation. The results show that the total agricultural water consumption decreased by 2.9%, and the amount of water saved increased by 9.6%. The current segment creates the rivers’ embankment standards. With a 92% irrigation guarantee rate, the current section forms and the embankment standards of the rivers satisfy the design storage volume and the flood level of one in twenty years. The water quality of all the rivers in the area has decreased by 5~10% compared to the average concentration prior to establishment. This study verifies the comprehensive effect and the suitability of the system by comparing the before and after effects, and provides a scientific basis for the method of efficient recycling and utilization of water resources in the rural plains river network area; we also propose the guidance of increasing the digital twin control and long-term operation mechanism to ensure the long-term stable operation of the technology.

Analysis of the evolution and causes of groundwater chemistry after ecological water replenishment of the Jialu River, China

Ecological water replenishment is an important measure for conserving water sources and improving the water environment. To explore the evolution and causes of groundwater chemistry after ecological water replenishment in the Jialu River, this study utilized groundwater monitoring data from 2015 to 2019 following ecological water replenishment. Various methods, including Piper’s trilinear diagram, Gibbs diagram, principal component analysis, and ion ratio analysis, were employed for research purposes. The results indicate that (1) since the implementation of ecological water replenishment in the Jialu River, there has been a general downwards trend in total dissolved solids (TDS) in groundwater. The dominant cation in groundwater is Ca2+, whereas HCO3− is the dominant anion. The concentration of cations in groundwater has generally decreased, with noticeable reductions in SO42− and Cl− concentrations in the upper reaches of the recharge river contributing to improved groundwater quality. (2) A comparison with 2015 reveals a gradual transition at sampling points from chemical types such as HCO3-Ca·Mg and HCO3·Cl–Ca·Mg to an ecological water replenishment chemical type (HCO3-Ca).

Biomimetic Ag-modified core-shell nanofibrous membrane with enhanced solar absorption and water replenishment for efficient clean water production and antibacterial activity

Microorganism contamination of evaporators can deteriorate their performance during solar-driven water evaporation. Herein, we developed a biomimetic core-shell nanofibrous membrane with enhanced solar absorption, water replenishment, and antimicrobial properties via modification of silver nanoparticles (Ag-NPs). By mimicking the core-shell structure of natural pine needles, (1) the core of polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) nanofiber, like the xylem of pine needles, can act as a support skeleton for dimensional stability; and (2) the shell of Ag-NPs-modified copper oxide (CuO) crystals (Ag@CuO), like the mesophyll of pine needles (photosynthesis for pine growth), can perform the photothermal and antimicrobial properties. The Ag@CuO nanofibrous membrane achieved increased solar absorption from 92.44 % to 95.88 % and decreased water contact angle from 36.1° to 0° after the incorporation of Ag-NPs. Furthermore, the Ag@CuO nanofibrous membrane exhibited stable evaporation rates of 1.31 kg⋅m−2⋅h−1 for 3.5 wt% saline water and 1.27 kg⋅m−2⋅h−1 for actual dye wastewater. Moreover, the nanofibrous membrane possessed excellent flexibility and robust adhesion of Ag-NPs due to the strong interfacial bonding induced by polydopamine. In addition, inhibition rates above 99.97 % against Staphylococcus aureus and Escherichia coli demonstrated the outstanding antimicrobial properties of the Ag@CuO membrane. In conclusion, the high evaporation performance, excellent flexibility, and outstanding antimicrobial properties enable the Ag@CuO nanofibrous membrane to be a good option for sustainable clean water production by treating evaporation media containing microorganisms.

Land–atmosphere feedbacks weaken the risks of precipitation extremes over Australia in a warming climate

The importance of land–atmosphere feedbacks on regional precipitation changes has been recently noted. However, how land–atmosphere feedbacks shape daily precipitation distributions, particularly the tails of precipitation distributions associated with extreme events, remains unclear on a regional scale. Herein, using the latest land–atmosphere coupling experiments, this study reveals a consistent weakening effect of land–atmosphere feedbacks on the future increase in precipitation extremes over Australia, revealing the most pronounced reduction (56.8%) for the long-term (2080–2099) projection under the low emission (SSP1-2.6) scenario. This weakening effect holds true for shifts in the extreme tail of precipitation distribution, resulting in a reduced risk of precipitation extremes in a warming climate. Land‒atmosphere feedbacks offset 28%–60% of the occurrence risk for the 99th percentile of daily precipitation, with the largest reduction of 172% when precipitation exceeds the 99.7th percentile in the long-term projection under the high emission (SSP5-8.5) scenario. Considering less water replenishment, these feedbacks may reduce the risk of flooding but potentially expedite droughts, highlighting the role of land–atmosphere feedbacks in extreme event projection and regional climate adaptation.

Electricity Harvesting from Water Evaporation on Hierarchical Pore Gradient Silica Aerogel-Based Generators.

In this study, the electric energy harvesting capability of the hierarchical pore gradient silica aerogel (HPSA) is demonstrated due to its unique porous structure and inherent hydroxyl groups on the surface. Taking advantage of the positively charged surface of unwashed HPSA credited by the preparation strategy, poly(4-styrene sulfonic acid) (PSS) can be spontaneously adsorbed onto unwashed HPSA and shows gradient distribution due to the pore-gradient structure of HPSA. By virtue of the gradient distribution and the stronger ionization of PSS, PSS-modified HPSA (PSS-HPSA) shows enhanced electricity generation performance from natural water evaporation with an average output voltage of 0.77 V on an individual device. The water evaporation-induced electricity property of PSS-HPSA can be maintained in the presence of a low concentration of salt. The desirable salt resistance capability benefits from the unique 3D hierarchical porous structure of HPSA which ensures rapid water replenishment so as to effectively avoid the salt accumulation. The HPSA-based devices with the advantages of unique porous structure, easy functionalization, good physicochemical stability, good salt resistance capability, and eco-friendliness show great potential as water evaporation-induced electricity generators.

A bacteria-based index of biotic integrity assesses aquatic ecosystems effectively in rewetted long-term dry river channel after water replenishment.

Climate-induced droughts exert a significant influence on the connectivity of river systems. It is estimated that about 25% of the world's rivers ran dry before reaching the ocean due to climate change and human activities. Ecological water replenishment is an effective measure for restoring aquatic ecosystems damaged by drought. It is urgently needed to quantitatively assess the aquatic ecosystems in rewetted dry river channels after water replenishment. This study investigated the variations in phytoplankton, zooplankton, benthic macroinvertebrates, and benthic bacterial communities in the rewetted dry river channel of Yongding River after water replenishment. In comparison with the water column communities, the benthic macroinvertebrates were identified as limiting factors for ecological restoration in rewetted dry river channels. In the absence of a certain recovery time for benthic macroinvertebrates, the benthic bacterial-based index of biological integrity, especially calculated based on their intrinsic properties, can properly assess aquatic ecosystems in rewetted dry river channels.