Hydrogels exhibit distinctive features. These properties make them suitable for applications across various fields, such as environment, energy, and medicine. In this paper, we conducted a comprehensive search on the CNKI and Web of Science databases spanning from 2000 to 2024. Using tools like CiteSpace and VosViewer, we visualized the evolution, composition, hot spots, and trends in hydrogels in the field of water treatment sustainability. The results show that from 2000 to 2024, there has been a gradual increase in the number of publications in this field. China leads in the total number of publications; although, it ranks fourth in average citation rate. Seven out of the top ten research institutions are based in China. Additionally, three journals, including the International Journal of Biological Macromolecules, Chemical Engineering Journal and Carbohydrate Polymers, stand out, with a relatively high number of publications. The identified research hotspots include a range of preparation methods, including the freezing method and cross-linking method. Additionally, other preparation methods and the examination of water retention rate and adsorption isotherm are part of the research focus. The primary emphasis is on studying the adsorption of heavy metals, microplastics, and organic pollutants in dye wastewater. The main adsorption mechanisms investigated are chelation, electrostatic attraction, and functional group interaction. These findings have potential applications in water purification, seawater desalination, and atmospheric condensation. For the authorized patents in hydrogel-related fields, with the continuous improvement in innovation ability and the continuous enhancement of intellectual property protection awareness, the number of authorized patents continues to rise. China has seven of the top ten institutions in the number of patents granted, and the total number of patents granted in China ranks first in the world. Future work should focus on methods for synthesizing new pollutants and other target pollutants and on improving adsorption efficiency. Additionally, the development of cost-effective hydrogel materials with improved treatment efficacy is essential to advance sustainable practices in water treatment.

To ensure water source security and sustainability of the national major strategic project “South-to-North Water Diversion”, this study aims to evaluate the spatio-temporal evolution characteristics of the ecosystem service value (ESV) in its water source area from 2002 to 2022. This study reveals its changing trends and main influencing factors, and thereby provides scientific support for the ecological protection and management of the water source area. Quantitative assessment of the ESV of the region was carried out using the Equivalence Factor Method (EFM), aiming to provide scientific support for ecological protection and resource management decision-making. In the past 20 years, the ESV has shown an upward trend year by year, increasing by 96%. The regions with the highest ESV were Garzê Prefecture and Aba Prefecture, which increased by 130.3% and 60.6%, respectively. The ESV of Xinlong county, Danba county, Rangtang county, and Daofu county increased 4.8 times, 1.5 times, 12.5 times, and 8.9 times, respectively. In the last two decades, arable land has decreased by 91%, while the proportions of bare land and water have decreased by 84% and 91%, respectively. Grassland had the largest proportion. Forests and grasslands, vital for climate regulation, water cycle management, and biodiversity conservation, have expanded by 74% and 43%, respectively. It can be seen from Moran’s I index values that the dataset as a whole showed a slight positive spatial autocorrelation, which increased from −0.041396 to 0.046377. This study reveals the changing trends in ESV and the main influencing factors, and thereby provides scientific support for the ecological protection and management of the water source area.