[This corrects the article DOI: 10.1093/nsr/nwad244.].
[This corrects the article DOI: 10.1093/nsr/nwad244.].
Persistent 4%-22% gaps in nitrogen (N) mass balances have hindered sustainable N management in paddy agriculture. Periphyton are known N sinks, yet their role in paddies remains unclear. We used 15N tracing in 840 paddies across China to quantify periphyton-associated N pools and their fate. Periphyton captured 6%-24% (mean: 12%) of the applied N fertilizer (i.e. ∼0.8 Tg N yr-1 nationwide), effectively accounting for the missing N in previous budgets. Most of the sequestered N was stored as bioavailable ammonium. Partitioning analysis revealed that periphyton-mediated N was subsequently released into residual soil N (512-640 kt), denitrification (56-128 kt) and ammonia volatilization (64-232 kt). Thus, periphyton act as transient N reservoirs, immobilizing N fertilizer early in the growing season and gradually releasing it through biomass decay. This overlooked pathway closes a critical gap in agroecosystem N cycling and supports more precise N management in rice systems.
Over the past decade, China has achieved remarkable progress in mitigating aerosol pollution. However, ozone (O3) pollution still shows a worsening trend, implying that China's control measures may have been less effective in tackling O3 pollution. Herein, we conduct synchronized observations of O3 and its precursors across 37 cities in the heavily polluted North China Plain (NCP) during the summer of 2021 and apply a unified observation-based model to diagnose O3 formation mechanisms. Our results reveal a significant transition in the urban O3 formation regime, shifting from being primarily volatile organic compound (VOC) limited to VOC-nitrogen oxides (NOx) co-limited across the NCP between the 2010s and the 2020s. Notably, the primary VOC species, their respective sources, and the optimal VOCs/NOx reduction ratios exhibit remarkable regional consistency. Modeling analyses further indicate that a long-term national 'carbon neutrality' strategy could effectively alleviate O3 pollution, with targeted VOC emission reductions from major anthropogenic sources offering the greatest mitigation potential. These findings underscore the efficacy of China's endeavors in mitigating O3 pollution, although the effects are not immediately evident from ambient O3 concentrations. O3 pollution control in Chinese cities has reached a critical inflection point, offering considerable flexibility and feasibility in formulating future control policies.
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