都市緑地からの一酸化二窒素排出はその炭素隔離便益を大幅に相殺する
Nitrous Oxide Emissions from Urban Green Spaces Substantially Offset Their Carbon Sequestration Benefits (原題)
叶四清, Zimeng Zhang, Jinya Yang, Loreena Avery, Jiahao Liu, Linlin Wang, Xiaoyan Wu, Chengxin Zhang, Xuguang Chi, Tengyu Liu, Yongmei Huang, Lei Zhang, Qian Yu, Jan Mulder, Lei Duan, Yu Zhao
🤖 gxceed AI 要約
日本語
中国の都市緑地（UGS）を高頻度連続観測と機械学習で全国推計し、平均12.5 kg·N·ha⁻¹·yr⁻¹のN2O排出を明らかにした。施肥なしでも、窒素富化・灌漑・ヒートアイランドの相乗効果で脱窒のホットモーメントが発生する。CO2換算でN2O排出は緑地植生の炭素隔離便益の68%を相殺し、純気候便益の過大評価を示す。都市計画は緑被率最大化から精密な窒素・水管理へ転換すべきと提言する。
English
A national-scale assessment of N2O fluxes from China's urban green spaces (UGS), using high-frequency monitoring and machine-learning extrapolation, finds mean emission intensity of 12.5 kg N/ha/yr even without fertilizer. Urban nitrogen enrichment, irrigation pulses, and heat-island effects trigger denitrification hot moments. Converted to CO2e, these emissions offset 68% of UGS carbon sequestration, showing net climate benefits are overestimated; planning should shift to precision nitrogen-water management.
Unofficial AI-generated summary based on the public title and abstract. Not an official translation.
📝 gxceed 編集解説 — Why this matters
日本のGX文脈において
日本でも都市緑化・NbSは気候中立戦略の柱だが、SSBJや有報の開示では緑地の炭素隔離便益のみが語られがち。本論文はN2Oという非CO2温室ガスの見落としを定量的に示し、自治体の気候行動計画やTCFDシナリオ分析における『純便益』評価の再考を促す。
In the global GX context
As cities worldwide adopt NbS and urban greening for climate neutrality, this study challenges the assumption that green cover is a net climate win. It adds non-CO2 GHG accounting (N2O) to the urban carbon narrative, relevant to ISSB/CSRD disclosures that increasingly require full GHG inventories and to transition planning that must avoid carbon-offset overstatement.
👥 読者別の含意
🔬研究者:都市炭素収支にN2Oを含める重要性と、機械学習によるフラックス外挿手法の応用例を提供する。
🏢実務担当者:都市緑化・NbSプロジェクトの炭素クレジット算定時にN2O排出を考慮し、過大なオフセット主張を避ける必要がある。
🏛政策担当者:気候中立計画や緑地政策において、緑被率目標だけでなく窒素・水管理を組み込むべき根拠を提供する。
📄 Abstract（原文）
Abstract Urban green spaces (UGS) are a cornerstone of global climate adaptation strategies, widely regarded as Nature-based solutions (NbS) for their ability to sequester carbon and mitigate heat islands. However, their net climate benefit remains uncertain due to the poorly quantified release of nitrous oxide (N2O), a potent greenhouse gas and ozone-depleting substance. Here, we present the national-scale assessment of N2O fluxes from China’s rapidly expanding UGS, based on high-frequency continuous monitoring and machine-learning extrapolation. We reveal that UGS function as intensive N2O sources, with a mean emission intensity of 12.5 kg·N·ha–1·yr–1, even though most monitored plots received no direct fertilizer application. These emissions are driven by a unique urban synergy where anthropogenic nitrogen enrichment interacts with irrigation pulses and the urban heat island effect to trigger explosive hot moments of denitrification. Crucially, when converted to CO2 equivalents, these N2O emissions offset 68% of the reported carbon sequestration benefits provided by China’s UGS vegetation. Our findings demonstrate that ignoring N2O emissions leads to a significant overestimation of the net climate benefit of urban greening. To ensure cities contribute effectively to climate neutrality, urban planning must pivot from simply maximizing green cover to implementing precision nitrogen-water management.
🔗 Provenance — このレコードを発見したソース
- openalex https://doi.org/10.1021/acs.est.6c07990first seen 2026-09-27 04:42:25
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