Freshwater Supply Research Articles

Facile construction of robust superhydrophobic ZIF‐8@pulp/cellulose nanofiber (CNF) membrane for multifunctional applications

Given the increasing contamination of freshwater supplies, it is essential to effectively treat industrial wastewater. However, treating industrial wastewater using a single method is challenging due to the presence of complex contaminants like petroleum, organic dyes, bacteria, and other complex contaminants. In this study, we present a straightforward and scalable approach to prepare multifunctional nanocellulose-based membranes (NM) that exhibit superhydrophobicity, self-cleaning, oil/water separation, photocatalysis, and anti-bioadhesion properties. To begin with, we created NM by extruding fiber slurry onto a stencil and drying it. Next, we built a polyurethane (PU)/ZIF‐8/1H, 1H, 2H, 2H‐perfluorooctyltriethoxysilane (POTS)-based superhydrophobic layer by spraying it over the NM's surface. By employing the aforementioned processes, we successfully integrated multiple functions into a single superhydrophobic NM. Our results demonstrate that the NM-PU/ZIF-8/POTS membrane exhibits superior hydrophobicity performance, with a high-water contact angle (166.8 ± 0.8°) and a low rolling angle (5 ± 0.3°). Moreover, these samples retain high-water contact angles and low rolling angles even in harsh environments such as acid and alkali solutions, high temperatures, abrasion resistance, UV aging resistance, bending and folding, tape peeling, and self-cleaning. The NM-PU/ZIF-8/POTS membrane also exhibits high and stable oil-water separation performance, with a separation efficiency of 94.6% and a relatively high separation flux (133.2 L·m−2·h−1). At the same time, the NM-PU/ZIF-8/POTS membrane exhibits water-in-oil emulsion separation ability. The membrane’s stability, effectiveness, and reusability were demonstrated through ten repetitions of degradation experiments using aqueous methylene blue solution, with the NM-PU/ZIF-8/POTS membrane exhibiting an excellent degradation rate (>94%). Finally, the bioadhesion resistance test indicated a reduction of 69.1% in the adhesion rate of the NM-PU/ZIF-8/POTS membrane. Overall, the creation of the NM-PU/ZIF-8/POTS membrane serves as a useful inspiration for the practical application of superhydrophobic NM in multifunctional integration, while also broadening the scope of membrane applications.

Machine learning assisted water management strategy on a self-sustaining seawater desalination and vegetable cultivation platform

To enable vegetable cultivation in conditions lacking freshwater and soil, such as islands and offshore platforms, this study proposes to combine interfacial solar evaporation with hydroponic techniques to set up an electricity-free self-sustaining desalination and cultivation platform. To maintain a dynamic balance between freshwater supply and demand on the platform, we investigate the relationship between water consumption in hydroponic lettuce cultivation and meteorological conditions such as temperature, humidity, and solar radiation. The limitations of traditional evapotranspiration models like the FAO-PM model in practical hydroponic cultivation is highlighted and four machine learning algorithms, including Random Forest, Backpropagation Neural Network, Support Vector Regression, and N-BEATS, are developed to predict water consumption specifically for hydroponic cultivation. The Random Forest model, selected based on performance comparison, achieves MAPE and R2 values of 10.05% and 0.974 respectively on the test set. Using meteorological data from Shanghai in 2022, the feasibility of the platform is assessed, demonstrating a theoretical lettuce yield of 260 plants/m2/year for solar stills on a unit area without water shortages throughout the year. This study verifies the feasibility and stability of the hydroponic cultivation platform, and is promising for the development of sustainable agriculture in offshore scenarios with limited freshwater and soil resources.

Simulation of population size and economic scale supportable by the Yellow River’s available freshwater in 2030 under multiple scenarios

The Yellow River plays a crucial role in China’s socioeconomic development and ecological security. The amount of freshwater available for allocation to the nine provinces of the Yellow River basin (YRB) is expected to be 39.485 billion m3 in 2030, for a projected population of 0.13094 billion people. This study aimed to simulate the sustainable population size and economic scale attainable with the Yellow River’s restricted freshwater supply. We forecasted population size and economic scale under various scenarios using a water resource carrying capacity (WRCC) prediction model. Further, the most likely scenarios—high, moderate, and low development—were analyzed based on historical trends. The results showed that by 2030, the available freshwater could support population sizes of 0.16, 0.152, and 0.147 billion under the high-, moderate-, and low-development scenarios, respectively, all of which are greater than 0.13094 billion. Moreover, economic scales of CNY17.5 trillion ($2.52 trillion), CNY15.01 trillion ($2.18 trillion), and CNY13.2 trillion ($1.91 trillion) could be supported under the high-, moderate-, and low-development scenarios, respectively. This study’s contributions are that (1) using population size and economic scale to characterize WRCC overcomes the limitation of measuring WRCC with a dimensionless index; (2) quantifying WRCC overcomes the flaws of single-trend measurement; and (3) the scenarios paint a clear picture of the YRB’s future water security and socioeconomic development. Our findings could help steer the direction of future water-, population-, and economy-related policymaking.

Long-term Effects of Irrigation with Treated Municipal Wastewater on Soil Chemical and Physical Responses in Commercial Vineyards in the Coastal Region of South Africa

The prolonged drought in the Western Cape province of South Africa in recent years has been particularly detrimental to the wine industry. Water restrictions imposed by authorities and the limited supply of fresh water that can be stored, have emphasisedthe need for alternative water sources for vineyard irrigation. Treated municipal wastewater has been used successfully as an alternative source of irrigation water in other countries. A long-term trial was conducted in commercial vineyards in the Coastal region of South Africa to assess the impact of treated municipal wastewater irrigation on vineyards. Cabernet Sauvignon and Sauvignon blanc grapevines were irrigated using treated municipal wastewater from the Potsdam wastewater treatment works for 11 years. Grapevines were either rainfed (RF), irrigated with treated municipal wastewater via a single dripper line (SLD), or received twice the volume of wastewater via a double dripper line (DLD). Irrigation using treated municipal wastewater increased soil pH(KCl), the electrical conductivity of the saturated extract (ECe) and Cl-. Substantial amounts of Na+ and K+ accumulated in the topsoil due to irrigation with treated municipal wastewater. These soil K+ increases could have a negative effect on wine colour stability should the levels of soil K+ be such that they are absorbed excessively by grapevines. The near-saturation hydraulic conductivity (Kns) at the surface of the soil could be related to the ECe in the topsoil. The results represent specific in-field situations in three commercial vineyards under one set of climatic conditions.

A method for robust estimation of snow seasonality metrics from Landsat and Sentinel-2 time series data over Atlas Mountains scale using Google Earth Engine

Seasonal snow cover provides the majority of freshwater supplies for human society and natural ecosystems especially in semi-arid regions. For water resource managers, precise data regarding the spatiotemporal variability of snow cover and snow phenology is of paramount importance. Owing to the great spatial and temporal heterogeneity of the snowpack and the inaccessibility of high mountainous areas, gapless satellite remote sensing presents an unprecedented opportunity to monitor snow cover effectively and affordably on a fine scale, from different aspects, and with regular revisit time. This study derives the snow seasonality metrics (first day of snowfall, last day of snow melt; and snow cover duration) over a large semi-arid region in Morocco’s Atlas Mountains. We calculate these metrics by combining over 10,000 images from Landsat 8 and Sentinel 2 satellites for four hydrological years (2016–2021) to create a harmonized product with a time interval of about 3 days using the Google Earth Engine (GEE) platform. This dense and large time series facilitates a gap-filling method to minimize and overcome the effect of cloud cover, and its assessment shows a positive correlation between the masked pixels and the interpolated ones. These methods allowed us to realize a map of the snow cover area and extract a homogeneous Normalized Difference Snow Index (NDSI) profile over the four years whereby we were able to determine the optimal threshold to separate the presence of snow from its absence. The results showed that derived snow cover metrics provide considerable variation in both time and space, where an increase in snowpack measurement values at higher elevations can be noted. Overall, the snow duration ranges between November and April depending on the characteristics of each hydrological year. The retrieved Landsat 8 and Sentinel 2 snow dates had a high level of agreement with in-situ data observations with almost a day-and-a-half delay with an overall accuracy equal to 0.96. The analysis of snow cover dynamics via GEE has offered the ability to calculate the first day of snowfall, last day of snowmelt, and snow cover duration annually at a pixel level, providing the user with the ability to track the seasonal and interannual variability in the timing of snowmelt toward a better understanding of how the hydrological cycles of higher latitude and mountainous regions are responding to climate change.

The Role of Climate Change in the Proliferation of Freshwater Harmful Algal Blooms in Inland Water Bodies of the United States

Abstract Harmful algae and cyanobacteria blooms are increasing in frequency and intensity in freshwater systems due to anthropogenic impacts such as nutrient loading in watersheds and engineered alterations of natural waterways. There are multiple physical factors that affect the conditions in a freshwater system that contribute to optimal habitats for harmful algae and toxin-producing cyanobacteria. A growing body of research shows that climate change stressors also are impacting water-body conditions that favor harmful algae and cyanobacteria species over other phytoplankton. The overgrowth of these organisms, or a “bloom,” increases the opportunity for exposure to toxins by humans, companion animals, livestock, and wildlife. As waters warm and precipitation patterns change over time, exposure to these blooms is projected to increase. Hence, it is important that states and tribes develop monitoring and reporting strategies as well as align governmental policies to protect their citizens and ecosystems within their jurisdiction. Currently, the policies and approaches taken to monitor and report on harmful algae and cyanobacteria blooms vary widely among states, and it is undetermined if any tribes have specific policies on harmful algae blooms. This paper synthesizes research on algal blooms in inland freshwater systems of the United States. This review examines how climate change contributes to trends in bloom frequency or severity and outlines approaches that states and tribes may use to monitor, report, and respond to harmful algae and cyanobacteria blooms. Significance Statement Inland bodies of freshwater supply drinking water for humans and animals, water for irrigating crops, habitats for aquatic species, places of cultural significance for Indigenous peoples, and other important functions. Many of these bodies of water have been polluted with runoff from industry, including agriculture, and already support harmful algal blooms during warm conditions. Hot extremes associated with climate change are expected to increase the occurrence and duration of harmful algal blooms, and in some places, initiate blooms where none have been recorded previously. These toxic blooms are harmful to people, companion animals, livestock, and wildlife. It is important to review the interconnections among biological, climate, and water systems to monitor blooms and alert the public about their toxin production.

Mid-Late Holocene palynological development at Lake St Lucia, KwaZulu-Natal

Palynological studies were done on lacustrine core sediments in the Indian Ocean Coastal Belt Biome of KwaZulu-Natal, eastern South Africa, that were deposited during the last ∼6300 cal yrs BP in the Mkuze River delta that drains into the northern-most part of Lake St Lucia. The aim was to reconstruct the past vegetation and to infer past climate fluctuations as well as human disturbances to complement growing evidence from other disciplines about these aspects in the area. Palynological results show a dominance of Poaceae (20–50%) suggesting the consistent presence of grassy woodland. Podocarpus pollen dominated the arboreal spectra from 6300 to 2600 cal yrs BP. Thereafter Spirostachys pollen dominated the arboreal pollen spectra for the last 2600 cal yrs BP indicating a change from a forested environment to a more open woodland environment caused by a drop in moisture content (humidity). The results also show that the mid Holocene was humid and warm with high precipitation (freshwater conditions) coinciding with raised sea levels. The late Holocene was warm and dry with some marine influence with more seawater flowing into the estuary and lake due to high evaporation and low fresh water supply caused by drought. Similar pollen fluctuations were observed in records from Lakes Eteza and Sibaya, also located within the Indian Ocean Coastal Belt Biome. The presence of Pinus pollen at the top of the profiles suggests the onset of European settlement when pines were introduced for timber production.

ӨЗБЕКІСТАН ТАУ МҰЗДЫҚТАРЫ КӘЗІРГІ УАҚЫТТАҒЫ ЖАҒДАЙЫ

The condition of glaciers in the mountainous regions of Uzbekistan, in the upper reaches of the Piskem, Kashkadarya and Surkandarya rivers, is considered. As well as a reduction in fresh water supplies due to global warming. The results of studies of glaciers in recent years are presented.

Pericopes in the Present: Gender, Water, and Flows of Blood in and Beyond Mark 5

This essay considers polyvalent meanings of fresh water and the gendered dynamics of menstrual blood and porous, gendered bodies in the history of interpretation of Mark 5:24–35. Drawing upon a hydrosocial, anti-colonial, intersectional feminist hermeneutic, this essay articulates intersections among the uneven contemporary menstrual burdens associated with insufficient fresh water supply, indicates how gendered and racialized medicine and public health figure into these dynamics, and offers a robust alternative to the dominant history of biblical interpretation usually applied to the Mark 5 pericope of the hemorrhaging woman.

The dam that fly ash built.

When the first concrete was poured in 1949 for the Hungry Horse Dam (Montana, USA), pozzolan cements had already been used in several major North American dams, including Grand Coulee on the Columbia River (diatomaceous earth explored but ultimately not used), Friant on the San Joaquin River and Altus on the North Fork Red River (pumicite) and Bonneville on the Columbia River and Davis on the Colorado River (calcined clay). But Hungry Horse Dam stands out as the first dam constructed using coal combustion fly ash. Utilising 2.4 million cubic metres of concrete, the dam is located on the South Fork Flathead River, one of the tributaries feeding one of the nation's major waterways, the Columbia River, and closely related to the adjacent Glacier National Park. In this respect, Hungry Horse is directly connected to two momentous periods in modern history - the massive adoption in the 1950s of coal as fuel for power plants, and the ongoing threats to fresh water supply and the rapid retreat of alpine glaciers due to global warming. Two concrete cores from this dam, one with fly ash and one without fly ash, are examined microscopically to explore the long-term suppression of alkali-aggregate reaction by fly ash. The core without fly ash exhibits clear evidence of alkali-aggregate reaction, manifested by sandstone coarse aggregate particles with darkened reaction rims. Sandstone coarse aggregate particles of the same lithology in the core with fly ash are without signs of alkali-aggregate reaction. A detailed examination of the darkened rims indicates that alkali-silica reaction products fill the narrow gaps between adjacent sand grains in the sandstone. This alkali-silica gel infilling allows for optical continuity between adjacent sand grains and is responsible for the classic darkened rim associated with the alkali-aggregate reaction.

Relation of Hydrogeology and Contaminant Sources to Drinking Water Quality in Southern Kazakhstan

Southern Kazakhstan is one of the fastest-growing regions of this country and continued development depends on a sustainable supply of freshwater for multiple purposes. Groundwater in Southern Kazakhstan occurs in a wide variety of hydrogeological conditions with varying levels of quality and vulnerability to contamination. The aim of this paper is to investigate the present groundwater quality through sampling and laboratory analysis of source water from public supply wells, compare results to hydrogeology and known contaminant sources, and indicate where future protections may be needed. Protection from surface-borne contaminants is mainly determined by the thickness of the vadose zone, depth of the groundwater level, presence, thickness and composition of aquifers, and mobility of pollutants. Forty-five wells were sampled, yielding 106 samples of groundwater presently used for drinking water, which were evaluated to investigate the occurrence of potential pollutants and hydrogeology of the region. Of the samples collected, 46 samples were used for analysis of inorganic water chemistry, 30 for individual indicators including metals, and 31 samples for determination of petroleum products. A contaminant inventory database and geospatial database aided the interpretation of the results and allowed the prediction of future water issues. Kazakhstan’s maximum permissible concentrations (MPCs) for metals were exceeded in areas associated with industrial enterprises, while fluoride and nitrate were more closely associated with mining and agricultural sources. Groundwater quality is dependent on hydrogeology and environmental contaminants resulting from historical land uses and must be regularly monitored for drinking water safety. Petroleum hydrocarbons were not detected in any of the drinking water sources.

Water resources in Saudi Arabia: trends in rainfall, water consumption, and analysis of agricultural water footprint

Saudi Arabia is one of the most arid countries in the world. Thus, freshwater availability and consumption are of crucial importance for the fast-growing population subjected to an escalating heat stress from climate change. We provide an overarching view of water resources in Saudi Arabia, in terms of supply, demand, vulnerabilities, and the associated implications on food supply and security. To estimate the effects of climate change on natural water supply, we use ERA5 for the reliable and complete statistics of the long term-precipitation (1950-2021) trends across the Kingdom’s territory. ERA5 is the latest generation of the reanalysis of global climate from the European Centre for Medium-Range Weather Forecasts. The average annual precipitation is about 50 mm/year and does not satisfy the freshwater needs of the country. Energy-intensive desalination, driven by fossil fuels, meets two thirds of municipal freshwater requirements, while non-renewable “fossil” groundwater addresses most of agricultural consumption needs. Total freshwater use has decreased in recent years due to a significant reduction of water use by agricultural sector. Nevertheless, this sector still accounts for 67% of the total freshwater consumption and provides a third of the country’s food supply. To understand efficiency of freshwater use in the agricultural sector, we have developed a novel methodology that allowed us to estimate the country-scale water consumption associated with crop production. Results indicate that water requirements for crop cultivation in Saudi Arabia are up to three times the global average. Date and cereal production consumes almost two thirds of the total freshwater supply, while mass production is dominated by forage crops.

Availability of fresh water in cold climate regions

Challenges related to the availability of fresh water in cold climate regions are discussed with emphasis on possible degradation of the quality of drinking water. The permafrost in this region has been consistent in making sure there is little drainage in the ground. This is important, as fresh water is mainly supplied through melting water from snow and ice in the many winter months. Climate change and warmer weather plays a role in heating up the permafrost and increasing the rate of the melting snow. This has an impact on both the amount of water and potentially the drinking quality. In certain cold region areas, fresh water sources are located not far from the shore. With increased shorline erosion due to warming climate, the fresh water supply is in danger of being contaminated by salt water during large storm events. Furthermore, human activities such as road transport and sewage contamination do also have a significant impact on the water’s quality. A bowtie diagram will be used to illustrate the different risk factors and suggestions on how to maintain the quality of fresh water supplies in cold climate areas. The primary focus areas will be Isdammen, near Longyearbyen on Svalbard and Utqiagvik (formerly Barrow), Alaska.

Passive Photovoltaic Cooling: Advances Toward Low‐Temperature Operation

AbstractWith the great increase in installation, photovoltaics will develop as the main power supply source for the world shortly. However, the actual power generation and lifetime of photovoltaics are greatly compromised by the high working temperature under outdoor operation. In this review, the recent advances of four promising passive photovoltaic cooling methods are summarized with the aim to uncover their working principles, cooling performance, and application potential in photovoltaic devices. For radiative cooling, light management strategies with ultraviolet‐photon downshift and sub‐bandgap reflection are discussed in detail to reveal their great potential in reducing photovoltaic working temperature and enhancing power generation. Subsequently, the great cooling benefits of passive evaporative cooling are underlined in terms of its superior cooling power and temperature drop of photovoltaic devices. Moreover, the promising integrated cooling strategy is further highlighted due to its great potential in enhancing electricity production and fresh water supply. Most crucially, the remaining challenges and the authors'r insights are presented to advance the commercial applications of passive cooling methods in photovoltaics.

Towards a sustainable environment and carbon neutrality: Optimal sizing of standalone, green, reliable, and affordable water-power cogeneration systems

Today, the limited sources of freshwater supply are a significant concern. Exploiting alternative sources, especially seawater, has been the focus, but purifying it is energy-intensive. Integrating desalination with renewable energy is a proposed solution, but it comes with high costs and environmental risks during construction. Hence, this study presents a framework to enhance the modeling, optimization, and evaluation of green water-power cogeneration systems to achieve the sustainability goals of cities and societies. An improved division algorithm (DA) determines the optimal component sizes based on criteria like minimal energy demand, reduced environmental and resource damage, low total life cycle cost (TLCC), and high reliability. Optimization considers varying loss of power supply probability (LPSP) levels (0 %, 2 %, 5 %, and 10 %). The environmental assessment utilizes a life cycle assessment (LCA) approach with IMPACT 2002+ and cumulative energy demand (CED) calculations. The study models the green cogeneration systems based on weather conditions, water demand, and power requirements of Al Lulu Island, Abu Dhabi, UAE. The system comprises photovoltaic panels, wind turbines, tidal generators, and backup systems (fuel cells). Results reveal that TLCC ranges from $186,263 to $486,876 for the highest LPSP. The solar-tidal-based configuration offers the lowest TLCC ($186,263) while substituting solar with wind energy increases TLCC by 160 %. The wind-tidal-based configuration has the lowest specific environmental impact (1020 mPt/yr) and cumulative energy demand (39.06 GJ/yr) for the highest LPSP. In contrast, the solar-tidal-wind-based configuration inflicts the most damage, with 62.63 GJ/yr and 1794 mPt/yr for the highest LPSP. The finding indicates that the DA is faster (100 iterations) than the genetic algorithm (1000 iterations), particle swarm optimization (400 iterations), and artificial bee swarm optimization (300 iterations). The study underscores the solar-tidal-based configuration as the optimal choice across multiple criteria, offering a promising solution for freshwater supply and environmental sustainability on Al Lulu Island.

Selective electrophilic attack towards organic micropollutants with superior Fenton-like activity by biochar-supported cobalt single-atom catalyst

The global shortage of freshwater and inadequate supply of clean water have necessitated the implementation of robust technologies for wastewater purification, and Fenton-like chemistry is a highly-promising approach. However, realizing the rapid Fenton-like chemistry for high-efficiency degradation of organic micropollutants (OMs) remains challenging. Herein, one novel system was constructed by a Co single-atom catalyst activating peroxymonosulfate (PMS), and the optimal system (SA-Co-NBC-0.2/PMS) achieved unprecedented catalytic performance towards a model OM [Iohexol (IOH)], i.e., almost 100% decay ratio in only 10 min (the observed rate constant: 0.444 min−1) with high electrophilic species 1O2 (singlet oxygen) generation. Theoretical calculations unveiled that Co-N4 sites preferred to adsorb the terminal-O of PMS (more negative adsorption energy than other O sites: –32.67 kcal/mol), promoting the oxidation of PMS to generate 1O2. Iodine (I)23 (0.1097), I24 (0.1154) and I25 (0.0898) on IOH with higher f– electrophilic values were thus identified as the main attack sites. Furthermore, 16S ribosomal RNA high-throughput sequencing and quantitative structure–activity relationship analysis illustrated the environmentally-benign property of the SA-Co-NBC-0.2 and the tapering ecological risk during IOH degradation process. Significantly, this work comprehensively checked the competence of the SA-Co-NBC-0.2/PMS system for organics abatement in practical wastewater.

Performance analysis and techno-economic assessment of a developed cooling/preheating small PVT-RO desalination plant

Middle East and North Africa (MENA) countries are experiencing rapid population growth, so water and electricity consumption plays a crucial role in the sustainable development of these countries. To overcome the water scarcity and electricity problems facing the MENA region, the developed cooling/preheating small PVT-RO desalination plants have been proposed as a practical solution. To achieve sustainable water and energy development in the MENA region, this study presents a commendable and highly efficient renewable energy project for freshwater production and electricity generation to solve the energy crisis and water scarcity in the MENA countries. Therefore, this study aims to develop a cooling/preheating small PVT-RO desalination plant to facilitate freshwater supply to remote regions and produce electricity. This was done by connecting photovoltaic/thermal (PVT) collectors with reverse osmosis (RO) desalination systems, where seawater is used as a medium to cool photovoltaic cells to increase electric power generation and at the same time recover thermal energy and use it in the initial heating of feed seawater before it is fed into the RO plants, thus increasing its productivity. The results indicate that using the photovoltaic thermal panels as preheating units will lead to a 0.135 kWh/m3 reduction in the rate of specific electricity consumption for the RO desalination plant, as well as increase the electricity generation from PVT panels by a rate of 8%. The economic feasibility presented that the proposed developed cooling/preheating small PVT-RO desalination plant represents an effective technology that reduced the freshwater cost by a rate of 49.5%.

Economical-effective purification of brackish water through an integrated capacitive desalination & boron adsorption system

The escalating scarcity of high-quality water for potable, industrial, and agricultural use necessitates innovative methods to augment freshwater supply from unconventional sources. This study primarily aims to lower boron (B) and chloride (Cl−) levels in brackish water to meet water quality standards of B < 0.5 mg/L and Cl− < 250 mg/L. To meet this goal, an innovative adsorbent, OQAS-AC@NGO, was used for boron removal. It combines organosilicon quaternary ammonium chloride (OQAS) modified activated carbon (AC) within a self-assembled nitrogen-doped graphene oxide (NGO) structure. Before boron removal, a capacitive deionization (CDI) system was used, employing OQAS-AC as the anode and COOH-modified AC as the cathode for chloride ion electrosorption. Through this cooperation procedure, the treated water meets the required quality standards while significantly reducing chemical costs by approximately 13.5 times when compared to conventional ion exchange resin methods for adsorbent regeneration. Moreover, the OQAS-AC@NGO adsorbent sustains its efficiency through multiple cycles, outperforming non-assembled N-GO in terms of yield, performance, and water flux. This underscores the cost-effective adsorbent preparation and enhanced water productivity. Economic analysis endorses the integrated CDI & B adsorption approach, advancing both sustainable water treatment processes and practical industrial applications.

Urbanization shifts freshwater service flows in the highly urbanized watersheds of Dongjiang River, China

Freshwater ecosystem services supply and demand are important for achieving Sustainable Development Goal 6 of clean water. Urbanization has significantly impacted the supply, demand, and flow of freshwater ecosystem services due to various human activities. However, the changes in freshwater ecosystem service flow (FESF) under the influence of urbanization were still unclear. This study examines the highly urbanized Dongjiang River as an example and maps the supply-flow-demand network of freshwater services based on social-ecological network analysis. The results indicate that freshwater supply has increased by 0.21 billion m3 per year, while there is a decreasing trend of 0.17 billion m3 per year in demand. The FESF approach reveals that 42%–60% of imbalanced sub-watersheds rely on artificial water diversion projects to alleviate water deficits under dynamic flow conditions. Approximately 15.6% of the region experiences water insecurity, driven by urbanization-induced demand for water diversion. This increased demand puts stress on downstream sub-watershed water supply and elevates the risk of flow reduction in the main stream. The study highlights the need for sustainable water management strategies to ensure freshwater security in large river basins within urbanized areas worldwide and to address the challenges posed by uncertain urban expansion.

The Assessment of Freshwater Quality in the Sungai Semantan Based on the Malaysian‘s Index of Freshwater Quality

Sungai Semantan is important for fish aquaculture industry in Malaysia. Therefore, the aimed of this article is to assess the index of freshwater quality (WQI) of the Sungai Semantan, Pahang during the rainy season (February to April 2018). The Sungai Semantan WQI was monitored at three stations by assessing six freshwater quality parameters, i.e., DO, BOD, COD, NH3-N, pH, and TSS. The Semantan River’s WQI was assessed using the Malaysian Department of Environment’s WQI classification. The results showed that three freshwater quality parameters, namely DO (6.32 mg/l), COD (46.8 mg/l), and TSS (104.4 mg/l), exceeded the standard at certain stations and classified as Class IV. However, on average, all parameters showed Classes I to III for all stations, and WQI indicated the Semantan River was slightly polluted (WQI 78.2), and classified as Class II. Changes in land use in the Temerloh district for agricultural and urbanisation have exacerbated the Semantan River’s WQI. Contradict to perception that the aquaculture is the main source of freshwater pollution for the Semantan River. Consequently, the Semantan River’s WQI must be monitored regularly, as the river is critical not only for domestic freshwater supply but also for freshwater fish aquaculture and ecotourism.