Yongqiang Zhao

Studying carbon emission patterns and their decoupling from economic growth on the basin scale is essential for achieving harmonized regional advancement and meeting carbon neutrality targets. To this end, we utilized the Intergovernmental Panel on Climate Change (IPCC)'s carbon accounting methodology and Tapio decoupling model to quantify and evaluate the dynamics and decoupling relationship of carbon emissions within the Yellow River Basin of Henan Province (HYRB) spanning from 2010 to 2019. Key findings reveal: (1) HYRB's carbon emissions exhibited an initial rise followed by a subsequent decline from 2010 to 2019, peaking in 2013 at 13 837.5 × 10 ⁴ t. Sectorally, energy consumption dominated (73.9%), followed by cement production (17.6%, peaking at 2683.3 × 10 ⁴ t in 2014) and agricultural activities (8.5%). (2) Carbon intensity decreased by 50.4% with significant spatial heterogeneity. The Zhengzhou–Luoyang–Xinxiang urban cluster formed a high‐value agglomeration core (contributing 60.7%), resource‐based cities (e.g., Jiaozuo, Sanmenxia) exhibited prominent energy dependence, while Kaifeng and Puyang showed agricultural‐dominated emissions. (3) HYRB achieved a weak decoupling trend with the decoupling index for 2014–2019 (0.04) outperforming that for 2010–2014 (0.27), with distinct regional pathways. Five cities shifted to strong decoupling, while Puyang degraded to growth–connection (0.94) due to energy rebound effects. The study proposes differentiated strategies: core regions should enhance industrial–transport synergy, resource‐based cities accelerate energy substitution, and agricultural areas adopt low‐carbon technologies. This study provides a methodological framework for multisector carbon emission synergy analysis at the basin scale and offers scientific insights for designing carbon neutrality pathways in similar global regions.

In large river basins, the nitrogen (N) cycle is largely regulated by complicated interactions between human and natural elements. Nevertheless, the origins, fate and driving forces of reactive nitrogen (Nr) flows in the basins are still not clear. An estimation model of N flux was established for evaluating the Nr flow and its environmental effects in the Yellow River Basin of Henan Province (HYRB) by means of material flow analysis. Total N input and output of HYRB were calculated at 4090.9 and 3948.8 Gg N yr⁻¹, causing 142.0 Gg yr⁻¹ of N stored in the basin. Industry, cropland and residential activities, respectively occupied for 42.2%, 23.2% and 12.3% of the whole input, as well as 43.6%, 25.1% and 12.3% of the whole output, which were central to HYRB’s N cycle. Anthropogenic activities regulated above 95.0% of total inputs, and 49.5% of N outputs was emitted into the air and 4.5% into hydrosphere. High N input, energy intensive, imperfect sewage disposal facilities and low N utilization efficiency were the main reasons of contaminate. How to effectively regulate the input of high-strength N pollutant associated with insufficient N cycling and Nr elimination is the main issue in the Yellow River Basin. In present research also put forward corresponding control measures according to the evaluation of N flow and Nr release of HYRB. The research can supply science foundation for coordinating the human–environment relationship in large basins, and also has important reference significance for the formulation of Nr emission reduction strategies. GRAPHICAL ABSTRACT

A detailed nitrogen (N) budget has been developed for an urban ecosystem based on the method of material flow analysis. How increased human activity and urbanisation influences N cycling have also been analysed. Total N input and output in the urban ecosystem of Zhengzhou City (ZUE) was calculated at 304.8 Gg was 275.3 Gg year⁻¹, resulting in an N accumulation of 29.5 Gg year⁻¹. Industry and human life activities, which respectively accounted for 43.8% and 34.2% of total N inputs and 52.6% and 29.1% of total N outputs, were the core of N flow in the urban ecosystem. Humans activities mediated more than 98% N inputs into the ZUE, 73.2% of N was released into the atmosphere and 11.7% into hydrosphere. This very large volume of released N could contribute to regional problems. High energy consumption, insufficient wastewater treatment facility practices, and low N use efficiency are the primary causes of pollution. The major challenge ahead for the urban ecosystem is how to manage high-intensity N pollutant inputs to the urban ecosystems coupled with incomplete N cycling and removal. Based on the analysis of the N budget and loading, this study also proposes an N management strategy for the ZUE.

To assess the impact of human activity on the nitrogen (N) cycle and evaluate the sources of N in surface water, the N budget for Laoguanhe River Watershed (LRW), a typical agricultural watershed and one of the upstream tributaries of Danjiangkou Reservoir in China, was developed by using measurement data on N fluxes and literature data on other parameters. Over the whole watershed, fertilizers, human and livestock excreta, atmospheric deposition, biotic fixation, N from crop residue used as fertilizer, and imported animal feeds contributed 65.7%, 20.7%, 6.1%, 5.6%, 1.7%, and 0.3%, respectively, to total N input (40,816.6 kg N km^-2 year^-1). N transported to water bodies, denitrification, harvesting crops, and ammonia volatilization contributed 32.0%, 25.2%, 23.0%, and 19.8% of total N output (21291.2 kg N km^-2 year^-1), respectively. The N budget for the LRW suggested that more than 50% of the N input was lost to the environment, and about 17% was discharged as riverine N, which indicated that agricultural and human activities in the watershed substantially impacted water quality, and so altered the N biogeochemistry process.