The streamflow into Miyun Reservoir, the only surface drinking water source for Beijing City, has declined dramatically over the past five decades. Thus, the impacts of climate variability and human activities (direct and indirect human activities) on streamflow and its components (baseflow and quickflow) needs to be quantitatively estimated for the sustainability of regional water resources management. Based on a heuristic segmentation algorithm, the chosen study period (1969–2012) was segmented into three subseries: a baseline period (1969–1979) and two impact periods I (1980–1998) and II (1999–2012). The Soil and Water Assessment Tool (SWAT) was adopted to investigate the attributions for streamflow change. Our results indicated that the baseflow accounted for almost 63.5% of the annual streamflow based on baseflow separation. The contributions of climate variability and human activities to streamflow decrease varied with different stages. During impact period I, human activities was accountable for 54.3% of the streamflow decrease. In impact period II, climate variability was responsible for 64.9%, and about 8.3 mm of baseflow was extracted from the stream on average based on the comparison of the observed streamflow and simulated baseflow. The results in this study could provide necessary information for water resources management in the watershed.

With the influence of global climate warming, the responses of regional hydroclimatic variables to climate change are of great importance for water resource planning and management. The evolution of precipitation, mean temperature, and runoff at different timescales, was investigated using the Mann–Kendall test from 1969 to 2011 in the Miyun Reservoir Basin, China. In addition, three precipitation indices and different precipitation grades were also considered. Annual precipitation had a non-significant decreasing trend, flood precipitation trend was significantly decreasing with a magnitude of 18.50 mm/10 years, and non-flood precipitation trend was significantly increasing with a magnitude of 6.91 mm/10 years. Precipitation frequency in flood season featured a significantly decreasing trend. Meanwhile, flood precipitation intensity for large rain (25 ≤ p < 50 mm/day) and non-flood precipitation amount for medium rain (10 ≤ p < 25mm/day) also showed significant increasing trends. The mean temperature exhibited significant upward trends during the year, in flood season, and in non-flood season with rates of 0.36 °C/10 years, 0.32 °C/10 years and 0.38 °C/10 years, respectively. The magnitude of the mean temperature increase in the non-flood season was greater than in the flood season. Runoff experienced continuous and significant downward trends of 1.6 × 10⁸ m³/10 years, 1.1 × 10⁸ m³/10 years and 0.40 × 10⁸ m³/10 years, respectively, during the year, in flood season, and in non-flood season. The decreased annual streamflow was more obvious after 2000 than before. The results obtained in this study could be used as references for decision-making regarding water resource management in the watershed.

Heavy metal pollution in soils, especially in mineral aggregation areas, presents significant sustainability challenges affecting ecosystem health and human well-being. This study conducted source apportionment and risk analysis of soil heavy metals in Datian County, South China, to promote sustainable land use and pollution mitigation. We collected 103 surface soil samples (0–20 cm) from a typical mineral aggregation area and analyzed the concentration distributions of heavy metals using geostatistical methods. The geoaccumulation index (I_geo) and potential ecological risk index (RI) were employed to evaluate pollution levels and ecological risks. Our findings reveal that heavy metal concentrations substantially exceeded Fujian Province’s background values, with Cd exhibiting severe pollution levels. Cd, Pb, and Cu pose moderate to high ecological risks. Major pollution sources include metal smelting enterprises, soil parent materials, mixed sources of mineral extraction and traffic pollution, atmospheric deposition, and agricultural pollution. Their contribution rates were found to be 15.66%, 17.72%, 38.32%, 8.25%, and 20.05%, respectively. Utilizing principal component analysis (PCA) and positive matrix factorization (PMF) models integrated with geostatistical methods, this study provides robust source identification and highlights sustainable practices for soil management. The results offer a scientific basis for developing strategies to mitigate heavy metal pollution and enhance environmental sustainability in the region.

Kitchen waste (KW) production has risen considerably due to the increasing affluence of populations and a booming catering sector. If not properly disposed, KW can bring serious issues for the environment. Composting is widely used as an efficient method for the resource utilization of KW. In the present paper, the effects of different ratios of ingredients (corn straw: garden waste = 4:1, based on the dry mass) on maturity and humification during KW composting were investigated. The results showed that the nitrogen retention capacity of the treatments with a ratio of ingredients to KW of 1:2.5 and 1:5.0 was higher than that of other treatments. Additionally, it was found that the number of ingredients had an effect on the germination index (GI) during composting, and the final GI values of the four treatments were in the following order: 1:7.5 > 1:5.0 > 1:10.0 > 1:2.5. Nuclear magnetic resonance (NMR) showed that the organic matter (OM) content of each treatment increased after composting, and the maturity of the 1:2.5 and 1:5.0 treatments was higher than the other two treatments. Redundancy analysis (RDA) showed that the maturity and humification were correlated with moisture content, pH and NO₃⁻-N during composting. This study concludes that the treatment with an ingredients to KW ratio of 1:5.0 was much more useful for KW composting, which is of importance to guide the disposal of KW.

Excessive nitrogen (N) inputs from human activities in the watershed have resulted in water quality deterioration and other biological hazards. It is therefore critical to fully understand the anthropogenic N inputs and their potential impacts on regional water quality. In this study, a modified net anthropogenic nitrogen input (NANI) budgeting model considering the irrigation N input was developed and applied to investigate spatial–temporal variations of anthropogenic N inputs and their relationship with riverine N flux from 2005 to 2019 in a semi-arid irrigated watershed, Ulansuhai Nur watershed (UNW), China. The results showed that the annual average anthropogenic N inputs reached 14,048.0 kg N km⁻² yr⁻¹ without a significant temporal change trend. Chemical N fertilizer was the major contributor for watershed NANI and accounted for 75.3% of total NANI. Hotspots for N inputs were located in the central part of the watershed. In this study, watershed NANI does not have a significant regression relationship with riverine N export during the study period. Riverine N export showed an obvious decreased trend, which mainly was attributed to human activities. In addition, approximately 1.92% of NANI was delivered into the water body. Additionally, the N inputs into the watershed by the irrigation water accounted for 9.9% of total NANI. This study not only expands the application range of the NANI model in irrigated watersheds, but also provides useful information for watershed N management strategies.