The problem of cultivated land soil quality in the Huaihe River Basin has become increasingly prominent. How to accurately and quantitatively evaluate the soil quality of regional cultivated land and realize its efficient use has become an urgent problem. In order to explore the spatial autocorrelation and variation in soil nutrients in cultivated land in the plain of Fengtai County in the Huaihe River Basin, a total of 306 soil samples and mature wheat samples were collected in the study area to analyze soil pH, total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and slow-release potassium (SK) content and wheat biomass, and combined with geostatistical methods and GIS technology. The Kriging interpolation method and Moram‘s I index method were systematically analyzed. Principal component analysis (PCA) and Pearson correlation analysis were used to establish the minimum data set (MDS) of soil quality, which was used to calculate the soil quality index (SQI) and determine the key factors affecting soil quality. The results showed that the soil pH was in weak variation, and the other nutrient indexes were in medium variation. The spatial variability of soil-available potassium nutrients was affected by random factors such as human activities and structural factors such as soil parent materials. The spatial autocorrelation of organic matter, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, available potassium and mitigation potassium was weak, which was mainly affected by random factors such as human activities. An unequivocal positive spatial nexus was discerned across all nutrients. Cumulatively, the nutrient dispersion across the investigated territory was somewhat diffuse, manifesting in a mosaic pattern with pronounced zonal nutrient allocation disparities in the meridional, median, and septentrional segments. An explicit latitudinal dichotomy delineating zones of nutrient opulence and paucity was also observed. These insights can pave the way for tailored fertilization strategies and judicious pedological stewardship in Fengtai County.

Cadmium (Cd) pollution in soil has become a huge problem for agricultural production in China and even the world. Passivation and phytoremediation are two important remediation technologies for Cd pollution. In this study, the cadmium-contaminated and phosphorus-poor farmland soil around a mining area in Huainan was taken as the research object, and the remediation effect of biochar and phosphorus-containing materials on soil cadmium pollution was discussed. The results showed that the combined application of biochar and phosphorus-containing materials significantly reduced the pH of non-rhizosphere soil and rhizosphere soil, and increased the content of soil dissolved organic carbon (DOC). The combined application of biochar and phosphorus-containing materials significantly reduced soil pore water Cd and soil available Cd. In addition, both a single application of biochar and synergistic application of biochar and phosphorus-containing materials significantly increased the biomass of aboveground and underground parts of amaranth and soil urease and catalase activities. Phosphorus application reduced the bioavailability of Cd in soil. With the increase in phosphorus application, the content of available Cd in soil decreased significantly, and there was a certain negative correlation between Cd content and phosphorus content in plants. The abundance of beneficial microorganisms such as Ochrobactrum, Anaerolinea, Achromobacter, and Cellvibrio in soil was significantly increased after the synergistic application of biochar and phosphorus-containing materials.

Urban greening is increasingly promoted as a means to achieve sustainable and inclusive development. However, it remains unclear whether the expansion of green infrastructure reduces spatial and socioeconomic inequalities or reinforces them. This study examines the long-term dynamics of green space exposure in 287 Chinese cities from 2000 to 2020 using geospatial and statistical data. While median green coverage and exposure increased by 126% and 135%, spatial disparities also grew. Eastern cities consistently showed higher levels of exposure, and national-level improvements did not translate into proportional narrowing of interregional gaps. Granger causality tests indicate a bidirectional relationship between economic growth and green exposure at the national level. This relationship varies across regions. Cities in the east, center, and northeast exhibit strong mutual effects, while other regions show weaker or unidirectional linkages. In North China, economic development and green exposure are entirely disconnected. These differences have led to divergent patterns in exposure equity. Despite a 44% national decline in the Gini index, disparities persisted, most notably in northeastern China. The results suggest that area-based greening targets are insufficient to address inequality. Planning strategies that consider population exposure and regional conditions are needed to improve the inclusiveness of urban greening. This study offers evidence for designing more equitable greening approaches in rapidly urbanizing areas.

As a critical ecological barrier and core water conservation zone in China, the southern slope of the Qinling Mountains plays a pivotal role in safeguarding regional ecological security and ensuring a safe drinking water supply, largely mediated by groundwater quality. However, systematic investigations into nitrate contamination in this region remain limited, and the dominant sources as well as hydrogeochemical migration pathways of nitrate are still poorly constrained. To address these knowledge gaps, this study targets representative watersheds on the southern slope of the Qinling Mountains, with an emphasis on characterizing the spatial – temporal distribution patterns and identifying the primary sources of groundwater nitrate. A multi-gradient monitoring network was established along the Han River and its tributaries, supporting seasonal sampling across both dry and wet periods. Coupled with δ15N-δ18O dual-isotope tracing and comprehensive regional environmental background surveys, we quantitatively assessed the spatial heterogeneity, temporal dynamics, and source apportionment of nitrate in groundwater. Results reveal pronounced spatial variability: mean nitrate concentrations decrease downstream, and levels adjacent to the main stem are consistently lower than those in tributary zones. Furthermore, the spatial distribution of nitrate closely parallels the regional groundwater flow direction. Vertically, soil nitrate concentrations decline with depth overall, yet exhibit anomalous enrichment at a depth of ~1 m ‒ indicating that nitrate leaching has penetrated to at least this depth. Source apportionment indicates that soil nitrogen, livestock and poultry manure, and domestic sewage collectively account for the majority of nitrate inputs to groundwater. This study provides foundational observational data on groundwater nitrogen cycling in mountain – basin transitional zones, thereby strengthening the scientific basis for groundwater protection and ecosystem management in the region. It also advances theoretical understanding of nitrogen biogeochemistry in complex terrain and supports the development of targeted, evidence-based groundwater pollution mitigation strategies.