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Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2026,6,30]]},"abstract":"<jats:p>\n                    Riverine nitrous oxide (N\n                    <jats:sub>2<\/jats:sub>\n                    O) emissions constitute a significant yet uncertain component of global greenhouse gas budgets. Integrating approximately 3,600 observations across the contiguous United States (CONUS), we present a monthly resolved, national-scale estimate of riverine N\n                    <jats:sub>2<\/jats:sub>\n                    O emissions (60.7 Gg N\n                    <jats:sub>2<\/jats:sub>\n                    O-N y\n                    <jats:sup>\u22121<\/jats:sup>\n                    ; 95% CI: 41.9 to 71.2) using a machine-learning framework. Our analysis reveals that enhanced hydrologic connectivity strongly regulates nitrogen and N\n                    <jats:sub>2<\/jats:sub>\n                    O delivery to streams, driving emission hot moments during high-flow periods, especially in nutrient-rich low-order streams. The Midwest Corn Belt is identified as a major emission hot spot, where seasonal increases in connectivity (e.g., late-winter thaws and postharvest rainfall) amplify riverine emissions relative to direct soil emissions. Our watershed-specific EF\n                    <jats:sub>5r<\/jats:sub>\n                    (0.0005 to 0.029) exceeds the IPCC default (0.0026) by more than twofold on average and up to 10-fold in intensively managed watersheds. These findings highlight the importance of incorporating hydrologic connectivity and nitrogen transport into climate models and watershed nitrogen management strategies.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2524113123","type":"journal-article","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T19:02:29Z","timestamp":1782154949000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":1,"title":["Hydrologic connectivity amplifies riverine N\n                    <sub>2<\/sub>\n                    O emission hot spots and hot moments across the contiguous United States"],"prefix":"10.1073","volume":"123","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3178-8219","authenticated-orcid":false,"given":"Minpeng","family":"Hu","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/047426m28","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Natural Resources and Environmental Sciences, 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