The Middle Route Project of China’s South-to-North Water Diversion Project (SNWDP) is a national-level water source protection zone and the ecological safety of its water quality and surrounding soil is of great significance. In this study, heavy metals in the surface water and topsoil in the core water source area were quantitatively analyzed using a geographic information system (GIS) and geostatistical techniques combined with environmental pollution and ecological risk assessment models to determine their environmental contamination levels, ecological risk levels, and spatial distribution patterns. Cd was identified as an essential factor responsible for the overall slight heavy metal pollution in the topsoil layer. Heavy metal contamination in surface water was primarily driven by alert-level concentrations of Hg and was consistently distributed in areas with high concentrations of Hg in the topsoil. Applying the potential ecological risk index (RI) revealed two key results. First, surface water showed no ecological risk. The concentrations of heavy metals in surface water met the goals set by relevant authorities in China. Second, overall, the topsoil was at low ecological risk, with a spatial pattern primarily influenced by Cd and Hg. Some heavy metals might have similar pollution sources and originate from human activities such as industrial activities, mining and smelting, and pesticide and chemical fertilizer applications. The study is important for improving the soil and water ecology in the reservoir area and ensuring the northward diversion of high-quality water. In addition, it provides a sound basis for making decisions about local heavy-metal remediation and treatment projects.

Under the requirements of the “double carbon” goal and the new development concept of high-quality development, the coordinated promotion of pollution, carbon reduction, and high-quality development is significant in promoting the social economy’s comprehensive green transformation. The coupling and coordination degree between pollution, carbon reduction, and high-quality development of 110 cities in the Yangtze River Economic Belt from 2010 to 2021 was measured, and the modified gravity model and social network analysis were then employed to assess the spatial network characteristics, patterns, and structure evolution. The results indicated that the coupling and coordination of urban clusters in the Yangtze River Economic Belt showed an increasing pattern, and the spatial arrangement shifted from dispersed to centralized. The spatial linkage strength and potential increased, while the spatial linkage pattern was steady. The direction of spatial connectivity remained consistent, with significant central city orientation and geographical proximity. The overall network structure was characterized by increased network density and an increased number of network links within each urban cluster, while network effectiveness fluctuated and decreased. The predominance of central or developed cities characterized individual network characteristics. This study is of great significance for exploring the coordinated development of pollution reduction, carbon reduction, and high-quality development, providing a theoretical basis for implementing ecological civilization, promoting carbon neutrality, promoting regional coordinated development, and achieving green, low-carbon, and sustainable development.