Freshwater Shortage Research Articles

Using Marker-Assisted Selection to Develop a Drought-Tolerant Rice Line with Enhanced Resistance to Blast and Brown Planthopper

Rice is a major global staple crop, but rising temperatures and freshwater shortages have made drought one of the most severe abiotic stresses affecting agriculture. Additionally, rice blast disease and brown planthopper infestations significantly impact yields. Therefore, developing water-saving, drought-resistant, high-yielding, and disease-resistant rice varieties is critical for sustainable rice production. The new water-saving and drought-resistant (WDR) rice ‘Huhan 1516’, bred using marker-assisted selection (MAS) and marker-assisted backcrossing (MABC) techniques, addresses these challenges. This variety is highly adaptable to drought-prone and water-scarce regions such as the Yangtze and Huai River basins. With its high yield, drought tolerance, and broad-spectrum resistance to rice blast (conferred by the Pi2 gene) and brown planthopper (BPH), ‘Huhan 1516’ is suitable for various farming systems and environments. Field trials show that this variety outperforms control varieties by 2.2% in yield and exhibits moderate resistance to both rice blast and brown planthopper. ‘Huhan 1516’ has been recognized as a new water-saving and drought-resistant rice variety by the state, and as a released cultivar, it has great potential for market promotion and application.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

Slightly Saline Water Improved Physiology, Growth, and Yield of Tomato Plants in Yellow Sand Substrate

Efficient utilization of saline water and yellow sand resources can enhance water and soil resource management while boosting crop yields in Xinjiang. This study conducted a two-season field experiment in Alar City, Xinjiang, from March to July 2023 and August 2023 to January 2024. The objective was to examine the effects of different irrigation water salinities (2, 3, 4, 5, and 6 g·L−1) on the physiology, growth, and yield of sand-cultured tomatoes grown in yellow sand slag. Groundwater irrigation with salinity levels of 0.8–1 g·L−1 was used as the control (CK). The results showed that the salinity of the substrate gradually increased with the salinity of irrigation water in each treatment. The salt accumulation increased by 59.5%, 82.5%, and 99.5% at the end of the experiment for T3 (4 g·L−1), T4 (5 g·L−1), and T5 (6 g·L−1), respectively, compared to CK. As the salinity of irrigation water increased, plant height, stem thickness, chlorophyll content, net photosynthesis rate, stomatal conductance, transpiration rate, and total yield of tomato showed an increasing and then decreasing trend, in which the total tomato yield of the T2 (3 g·L−1) treatment was significantly increased by 35.2% compared with that of CK between the two seasons. In contrast, as the salinity of irrigation water increased, the inter-cellular CO2 concentration of tomato leaves showed a decreasing and then increasing trend, with the T2 treatment having the lowest inter-cellular CO2 concentration. Pathway analysis revealed that appropriate salinity levels increased tomato yield by regulating inter-cellular CO2 concentration. Based on these findings, a 3 g·L−1 salinity level is recommended for irrigating sand-cultured tomatoes to maximize yellow sand resource use, address freshwater shortages, and optimize water and soil management in the Xinjiang region.

All-day freshwater harvesting enabled by designing benzoxazine molecule with intrinsic photothermal conversion and radiation cooling ability

The importance of clean water resources for human health and economic development cannot be overlooked. Providing a way for fully passive all-day freshwater harvesting presents a significant challenge. Herein, we propose a strategy for all-day freshwater harvesting passively through a freestanding Janus film which combining solar-driven interfacial desalination during day time and dew water generation driven by passive radiative cooling at night. Specifically, the core of the strategy was a new bio-based benzoxazine which containing high-infrared emittance in the atmospheric window and the resultant cured black freestanding film owns a steady high light absorbance in the whole range of the solar irradiation wavelength. The home-made device made by the Janus film achieved a drinkable freshwater collection efficiency of 90.9 % when desalinating seawater under 1 sun illumination and achieved a dew water collection rate of 68.36 g m−2 day−1 at night. Moreover, the film has an excellent antibacterial effect, which ensures the quality of water collection and enhances the service life. Combining the advantages of bio-based raw materials, a simple fabrication process and scalability of the film, the all-day freshwater collection system makes a promising solution to alleviate freshwater shortage in many arid regions, islands and even boats sailing on the sea.

Analysis of graphene as a potential filtration membrane for desalination at varying operating conditions using molecular dynamics simulation and response surface methodology

ABSTRACT Water scarcity is a critical global issue exacerbated by pollution and overuse, necessitating sustainable water management solutions. Desalination using membrane technology presents a promising approach for freshwater production. This study investigated the performance of nanoporous (NPG) membranes for desalination, focusing on the influence of pressure and temperature on water flux and ion rejection. Utilizing molecular dynamics (MD) simulations with the LAMMPS package, this study evaluates NPG membranes under various conditions of pressures and temperatures. The simulations demonstrate that increasing both the pressure and temperature enhances the water flux without compromising ion rejection. The results indicate that at 300 K and 50 MPa, the water flux exceeds 2000 L/m2 h bar, significantly outperforming traditional reverse osmosis membranes, which typically achieve a capacity of approximately 1 L/m2 h bar. These findings were validated experimentally, aligning with previous research and confirming the superior performance of NPG membranes. A statistical model derived from response surface methodology revealed a linear relationship between pressure, temperature, and water flux. The study concludes that NPG membranes offer a high efficiency and scalable solution for desalination, with significant potential for energy savings and cost reduction. This study underscores the viability of NPG membranes in addressing global freshwater shortages and provides a pathway for sustainable water production.

Efficient Fog-Harvesting Origami Fan.

Fog harvesting represents a promising strategy to address the global freshwater shortage. To enhance the water collection efficiency, diverse geometric structures that can effectively drive water droplet movement are essential. Inspired by the Livistona chinensis leaf, which naturally facilitates directional droplet motion through its unique gradually varying V-groove structure, we have developed a novel origami fan structure for fog harvesting through theoretical analysis. A key feature is that we can modulate the speed of droplet transport by adjusting the opening angle of the V-shaped grooves positioned at the outer circumference. Interestingly, the water collection efficiency exhibits a linear correlation with the opening angle. The highest efficiency of the origami fan can reach 5.75 times that of the control group calculated by the projected area and 3.76 times that of the control group calculated by the real area, showcasing its significant potential for enhancing water collection from fog. The simulations demonstrate that the hollow structure enhances the condensation rate of droplets, the geometric gradient of the gradual-variation V-groove drives the condensed droplets to move rapidly on the surface, and the Janus membrane permits the aggregated droplets to transit to the fan's rear side. The synergistic action of these three components ensures a clean surface for the subsequent water-collecting cycle, contributing to the high fog-harvesting efficiency. Given its simple fabrication and superior water transfer efficiency, the origami fan holds substantial promise for widespread application in the field of droplet manipulation.

Silk-based polyelectrolyte evaporator with excellent salt resistance for high-rate and stable solar desalination

Solar-driven interfacial evaporation technology is a promising solution to solve global freshwater shortages through desalination. However, salt accumulation in the evaporator affects light absorption and reduces evaporation efficiency, thereby significantly reducing the service life and operating efficiency of the evaporator. Herein, we propose a strategy for sustainable salt resistance that enables strong salt resistance and rapid water delivery by in situ polymerization of sodium acrylate (PAAS) on the directional channel. As a result, the as-prepared SF/rGO@PAAS can achieve a high evaporation rate of up to 2.31 kg m−2 h−1 and high evaporation efficiency of up to 98% under one sun, benefiting from the inherent hydrophilicity of silk fibroin (SF), the directional channel design of water transport layer, and the efficient solar light absorption in full spectrum of reduced graphene oxide (rGO). More importantly, due to the electrostatic effect of PAAS, the evaporator showed excellent salt resistance, with no salt precipitation for 5 days of continuous evaporation in simulated seawater (3.5 wt%) while maintaining the high evaporation rate. This salt resistant evaporator provides an effective solution to the salt accumulation and addresses a key challenge in sustainable desalination.

Occurrence, toxicity, and control of halogenated aliphatic and phenolic disinfection byproducts in the chlorinated and chloraminated desalinated water

Seawater desalination is widely used to overcome the freshwater shortage worldwide. However, even after three-stage reverse osmosis treatment, the desalinated water still contained 14.6 μg/L of aliphatic disinfection byproducts (DBPs), 384.2 ng/L of bromophenolic DBPs, 3.5 ng/L of iodophenolic DBPs, 1024.7 μg/L of Br-, 2.8 μg/L of I-, and 2.4 mg C/L of dissolved organic carbon (DOC). After the desalinated water was disinfected with chlor(am)ine, the concentrations of halogenated aliphatic and phenolic DBPs further increased, and bromophenolic DBPs were the toxicity forcing agents. When surface water was mixed with desalinated water and then chlorinated, the yield of aliphatic and phenolic DBPs significantly elevated. Separately chlorinating desalinated water and surface water before mixing could mitigate this adverse situation. Chloramine disinfection was more conducive to reducing the total calculated toxicity of disinfected desalinated waters and mixed waters compared to chlorine disinfection. The treatment of desalinated water with granular activated carbon could effectively remove DOC and UV254, leading to a reduction in the content of total organic halogen after chlor(am)ination. Although anion exchange resin could adsorb Br-, it also released the organic precursors of DBPs, ultimately increasing the yield of DBPs. The results of this study can provide a reference for the seawater desalination industry to improve seawater pre-treatment and desalination processes and thus minimize the DBPs.

An orientational graphene/bamboo evaporator for efficient solar-powered steam generation and desalination

Solar-powered steam generation and desalination by interfacial solar steam generation (ISSG) are promising techniques for addressing the freshwater shortage. However, the insufficient conversion efficiency and complex pollutant components confine its further extension and application. This study innovatively constructs an orientational graphene/bamboo evaporator (GBE), maintaining a solvent-accessible surface area and reducing vaporization enthalpy by selective delignification and torrefaction. The GBE device features a channel oriented from bamboo, consolidating the parallel architecture with multilayer biofilm filtration that guides efficient bulk-water pumping, steam release, and pollutant interception. The GBE demonstrates full-spectrum optical absorption at 90.5 % and 33.4 s response time while maintaining operational stability across different salt concentrations and natural water environments. The GBE achieved an evaporation rate of 1.53 kg m-2h-1as 4.34 enhancement factor under 1 kW/m−2(−|-) illumination, surpassing microplastics (99.84 %) and tetracycline (99.87 %) desalination. This work provides a high-performance and innovative approach to bamboo evaporator design, offering a viable and alternative method to address freshwater shortage.

When cellulose nanocrystals meet graphene oxide: Structurally enhanced aerogels for efficient solar steam generation and water purification

Pollution, population growth, and climate change are intensifying global freshwater shortages. Traditional methods of collecting freshwater, such as rainwater harvesting and sewage treatment, have high energy consumption, limiting their implementation in underdeveloped regions. On the other hand, solar-driven seawater evaporation offers a promising solution, purifying water using naturally abundant solar energy. Reduced graphene oxide (rGO) is considered as a strong candidate for this purpose due to its broad spectral absorption. However, its hydrophobicity hinders its direct use in solar steam generators. Here, we report the preparation of a series of cellulose nanocrystal (CNC)-rGO aerogels (CGAs) through a one-pot hydrothermal gelation process, followed by unidirectional freeze-drying. The introduction of CNCs enhances the hydrophilicity and structural stability of the resulting CGAs. The CGAs also feature uniform and unidirectional channels that promote efficient water transport, as confirmed by scanning electron microscopy (SEM) and X-ray microtomography (XMT). The CGAs have an optimized water evaporation rate of 1.80 kg m−2 h−1 under 1 sun irradiation, with 90 % solar-to-vapor energy efficiency. Moreover, durability and seawater desalination tests provide additional evidence for the practicality of CGAs in water purification. It is anticipated the implementation of CGAs will expedite the application of solar steam generators in practical scenarios.

High-efficiency electrospun PVDF@MXene composite membrane with covalent bonding and well-dispersed internal materials for solar-driven seawater desalination

Environmentally friendly and efficient solar-driven interfacial evaporation (SDIE) has been increasingly applied to seawater desalination, and the easy-to-operate electrospinning technology has attracted more and more attention. However, photothermal materials such as MXene are often combined with polymers suitable for spinning through ordinary blending. The inherent difficult dispersion of it may lead to the instability of spinning and decrease the performance of evaporators, further hindering their production and application. To address these challenges, this work designs a covalent bonding PVDF@MXene composite as the spinning raw material. Using the electrospinning technology, the high-efficiency membrane-based evaporator with well-dispersed internal materials and strong homogeneity is successfully fabricated. The membrane performance is optimal when the MXene content is 25 %, achieving an evaporation rate of 1.88 kg·m−2·h−1 and an efficiency of 94.06 % under one sun. Besides, it exhibits remarkable salt resistance, maintaining an evaporation rate of 1.81 kg·m−2·h−1 even at the salinity of up to 20 wt%. More importantly, the membrane can be immersed in oxidative reagents for 24 h without degradation or reduced performance, demonstrating its good environmental stability. Overall, this research not only provides a rational idea for addressing the dispersion issue of MXene, but also presents a potential solution to deal with the global freshwater shortage emergency.

Hollow Hydrogels for Excellent Aerial Water Collection and Autonomous Release

Air moisture is a valuable and omnipresent resource of fresh water. However, traditional water collectors come with an enduring problem of the water‐release step, which requires special devices and additional energy to remove the water from the adsorbent, such as heat, sunlight, or both. Herein, we report the first composite conical hollow hydrogel to harvest water from aerial humidity. This hollow hydrogel device can rapidly collect water from humid air to a saturation point, whereupon it automatically and continually releases fresh water at room temperature. The entire water collection and release process doesn't require any external assistance. As an exemplary demonstration, positioning the hollow hydrogel device next to a plant turns into an individualized system for irrigation. Since the device is biodegradable, it eventually decomposes and becomes an organic fertilizer after the water supply is not required. For long‐term application, the water‐release process can be monitored in real time by an electronic device to indicate the amount of collected water. The hollow hydrogel combines the humidity‐absorbing capacity with autonomous water release that carries the potential for harvesting water from humidity to address the shortage of fresh water, especially in arid locations where other sources of water are scarce or inaccessible.

Recent Advances in Carbon-Based Interfacial Photothermal Converters for Seawater Desalination: A Review

Along with the rapid development of society, freshwater shortages have become a global concern. Although existing desalination technologies have alleviated this pressure to some extent, their long-term environmental impact and energy consumption are still questionable. Therefore, it is necessary to find a new effective way for seawater desalination with cleaner energy. Solar-driven interfacial water evaporation technology has the advantages of environmental protection, energy saving, high evaporation efficiency, low cost, and strong sustainability, and is considered one of the most effective technologies to relieve water resource stress. This review summarized the recent advances in carbon-based interfacial photothermal converters focused on the preparation methods of 2D and 3D photothermal absorbers, the potential ways to enhance the efficiency of photothermal conversion. Finally, this paper proposed the challenges and future trends of interfacial photothermal converters.

Breaking Rossby waves drive extreme precipitation in the world’s arid regions

More than a third of the world’s population lives in drylands and is disproportionately at risk from hydrometeorological hazards such as drought and flooding. While weather systems governing precipitation formation in humid regions have been widely explored, our understanding of the atmospheric processes generating precipitation in arid regions remains fragmented at best. Here we show, using a variety of precipitation datasets, that Rossby wave breaking is a key atmospheric driver of precipitation in arid regions worldwide. Rossby wave breaking contributes up to 90% of daily precipitation extremes and up to 80% of total precipitation amounts in arid regions equatorward and downstream of the midlatitude storm tracks. The relevance of Rossby wave breaking for precipitation increases with increasing land aridity. Contributions of wave breaking to precipitation dominate in the poleward and westward portions of arid subtropical regions during the cool season. Our findings imply that Rossby wave breaking plays a crucial role in projections and uncertainties of future precipitation changes in societally vulnerable regions that are exposed to both freshwater shortages and flood hazards.

Efficient atmospheric water harvesting enabled by hierarchically structured cellulose foam

The sorption-based atmospheric water harvesting technique is an appealing solution for addressing the challenge of freshwater shortages. In this study, a composite foam was fabricated by confining hygroscopic salt (CaCl2) into a Cr-based metal–organic framework (MIL-101), which was then integrated into a bacterial cellulose (BC) skeleton. The hierarchical structure, which contains micron- and nanoscale pores, enhances water storage, transport, and vapor evaporation throughout the whole water capture and release process. The pore confinement effect of MIL-101 and the interconnected BC network effectively restricted the leakage of the liquefied salt solution. Interestingly, the color of the CaCl2@MIL-101@BC foam changed from light green to dark green as the amount of absorbed water increased. This moisture-induced color darkening improves the light absorption ability during the water release stage under sunlight. At 30 % relative humidity, the foam can absorb up to 0.78 g g−1 of water per cycle (8 h) and desorb quickly under solar radiation. This makes foam a promising method for water production in arid areas.

Engineering of Hierarchical Porous Composite Film (ZIF-8@PVDF/PMMA) with Superhydrophobicity for Highly Efficient Water Harvesting.

Atmospheric water harvesting has attracted much attention because of its potential to escalate the global freshwater shortage. However, the water collection efficiency is hindered by the trade-off between fast droplet nucleating and rapid droplet dripping due to the opposite requirements in the chemistry and the morphology of surfaces. Herein, the hierarchical porous composite film (ZIF-8@PVDF/PMMA, HPCF) with superhydrophobicity is designed for highly efficient and stable water harvesting. It indicates that the HPCF film has a large water contact angle (WCA) of 155.50° and ultralow sliding angle (SA) of 2°, exhibiting the self-cleaning function. Significantly, it is demonstrated that the water collection efficiency of HPCF can achieve 1.13 g·cm-2·h-1, which is much higher than the value of the blank sample, as well as most of the reported values. It is attributed to the hierarchical porous structure with the ZIF-8 crystals enhancing the surface roughness and endowing the film with the hydrophilic/superhydrophobic regions. This design promotes an optimal balance between droplet nucleation and shedding, significantly enhancing the water harvesting efficiency. Consequently, this work introduces an effective approach for water collection materials suitable for fog/mist conditions and provides an effective solution for the foggy area with water scarcity, demonstrating significance for advancing research aimed at mitigating the worldwide water shortage.

Effects of long-term saline water irrigation on soil salinity and crop production of winter wheat-maize cropping system in the North China Plain: A case study

Fresh water shortage is a major problem for grain production in the low plain around Bohai Sea in the North China Plain. Relative abundance of shallow saline groundwater could serve as an alternative water resource for use during dry seasons. A continuous 8-year field study was conducted from 2015 to 2023 to assess the effects of salt content in irrigation water on soil salt accumulation and crop production. Fresh water (FW) with electrical conductivity (EC) at 1.6 dS/m and three levels of saline water (SW) with EC at 4.7 (SW1), 6.3 (SW2) and 7.8 dS/m (SW3) were used for irrigation. Results showed that a single irrigation event at the jointing stage of winter wheat increased grain production averagely by 18.6 %, 22.5 %, 12.9 % and 9.5 % compared with a rain-fed treatment (RF) under FW, SW1, SW2 and SW3, respectively. With an additional irrigation applied at flowering stage, both irrigations using FW increased the yield by 28.6 %, and both irrigations using SW2 increased the yield by 19.3 % compared with RF. Negative effects of salt on winter wheat overshadowed the positive effects of increased water supply under two irrigations both using SW. With an irrigation at maize sowing and the subsequent summer rainy season, the yield of maize following winter wheat was not affected by a one-time SW irrigation to the previous crop, but showed a 5.3 % yield reduction when two irrigations of SW were applied. There was no apparent salt accumulation in the top 1 m of the soil profile, but a slight increasing trend in the salt content in the 1–2 m layer of the soil profile under SW2 and SW3 irrigation. No apparent changes in soil physical properties were observed for continuous application of SW. It was suggested that SW with EC not exceeding 6.3 dS/m should be applied for a single irrigation during the winter wheat season. This practice could alleviate the fresh water shortage in this region and allow for the maintenance of a relatively stable yield of winter wheat and maize without the risk of salt accumulation in the soil.

Inclined interfacial solar evaporator using polypyrrole/polydopamine composites for efficient desalination and salinity-driven electricity generation

Water-electricity cogeneration using solar energy is an innovative technology to address global freshwater shortages and energy demands. Here, we designed an inclined evaporator based on polypyrrole/polydopamine photothermal materials for efficient water evaporation and electricity cogeneration. Due to the ingenious inclined structure of the evaporator, the water transport was highly promoted by gravity and siphon effect. This process not only improves the evaporation flux of water, but also create a salinity gradient that can be used for further electricity generation. The designed inclined PPy/PDA@MF evaporator exhibits an evaporation flux of 3.02 kg m−2 h−1 under one sun irradiance and achieves an open-circuit voltage of 56 mV during the electricity generation.

Three-Dimensional Double-Layer Multi-Stage Thermal Management Fabric for Solar Desalination.

Water scarcity is a serious threat to the survival and development of mankind. Interfacial solar steam generation (ISSG) can alleviate the global freshwater shortage by converting sustainable solar power into thermal energy for desalination. ISSG possesses many advantages such as high photothermal efficiency, robust durability, and environmental friendliness. However, conventional evaporators suffered from huge heat losses in the evaporation process due to the lack of efficient thermal management. Herein, hydrophilic Tencel yarn is applied to fabricate a three-dimensional double-layer fabric evaporator (DLE) with efficient multi-stage thermal management. DLE enables multiple solar absorptions, promotes cold evaporation, and optimizes thermal management. The airflow was utilized after structure engineering for enhanced energy evaporation efficiency. The evaporation rate can reach 2.86 kg·m-2·h-1 under 1 sun (1 kW·m-2), and 6.26 kg·m-2·h-1 at a wind speed of 3 m·s-1. After a long duration of outdoor operation, the average daily evaporation rate remains stable at over 8.9 kg·m-2, and the removal rate of metal ions in seawater reaches 99%. Overall, DLE with efficient and durable three-dimensional multi-stage thermal management exhibits excellent practicality for solar desalination.

Preparation of Aluminum-Based Superhydrophobic Surfaces for Fog Collection by Bioinspired Sarracenia Microstructures.

Freshwater shortage is a growing problem. Inspired by the Sarracenia trichome fog-trapping and ultrafast water-transport structure, a series of hierarchical textured surfaces with high-low ribs with different wettabilities was prepared based on laser processing combined with dip modification. Through fog-collection performance tests, it was found that the samples with superhydrophobicity and low adhesion had the best fog-collection effect. In addition, it was observed that the fog-collection process of different microstructured samples was significantly different, and it was analysed that the fog-collection process was composed of two aspects: directional condensation and directional transport of droplets, which were affected by the low ribs number and rib height ratio. A design parameter was given to create the Sarracenia trichome-like structure to achieve a fast water transport mode. This study provides a good reference for the development and preparation of fog-collection surfaces.