{
  "abstract": "Ammonia (NH3) is the main alkaline gas in the atmosphere and a key regulator of aerosol formation, nitrogen deposition, and air quality. Yet the relationship between NH3 emissions and deposited ammonium (NH4 + ) in remote archives, remains poorly constrained. Here, we present the first ice-core record of δ 15 N(NH4 + ), covering 1000 years of European atmosphere. Ice-core δ 15 N(NH4 + ) is systematically enriched relative to inventory-based δ 15 N(NH3), consistent with atmospheric isotopic fractionation between emitted NH3 and deposited NH4 + . The 10-year seasonally resolved record shows lower δ 15 N(NH4 + ) in winter than in summer, which is consistent with NH3-NH4 + partitioning integrated during transport, although no unique pathway can be identified as other mechanisms remain insufficiently constrained. Between 1900 and 1970, lower δ 15 N(NH4 + ) broadly coincides with higher acidity and lower neutralisation factor, consistent with increasing proportion of NH4 + through NH3-NH4 + partitioning, although cloud processing and other atmospheric processes cannot be separated. After 1980, this relationship breaks down, with a divergence between ice-core NH4 + and NH3 emission inventories, the isotope-concentration relationship disappears, and a decrease in apparent isotopic fractionation. Boundary layer observations suggest that a large underestimation of NH3 emissions is unlikely. This shift therefore indicates a change in the source-to-deposition atmospheric processes, although the responsible pathway remains unresolved. Ice-core δ 15 N(NH4 + ) therefore provides a long-term view of the source-to-deposition regime shifts, a perspective increasingly needed as Europe moves toward a less acidic, more NH3-rich atmosphere.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "name": "Alexis Lamothe"
    },
    {
      "name": "Pete D Akers"
    },
    {
      "name": "Patrick Ginot"
    },
    {
      "name": "Wendell Walters"
    },
    {
      "name": "Sarah Albertin"
    },
    {
      "name": "Nicolas Caillon"
    },
    {
      "name": "Elsa Gautier"
    },
    {
      "name": "Joel Savarino"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6qmz0w534qa2t.bib",
  "cited_by": 0,
  "doi": "10.5194/egusphere-2026-5825",
  "fulltext_url": null,
  "id": "6qmz0w534qa2t",
  "issns": [],
  "landing_url": "https://hal.science/hal-05844130v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.sde"
    ],
    [
      "openalex",
      "1902|Atmospheric chemistry and aerosols"
    ]
  ],
  "openalex": "W7221664189",
  "pdf_url": "https://hal.science/hal-05844130/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6qmz0w534qa2t.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:03Z",
      "native_id": "hal-05844130",
      "source": "hal",
      "url": "https://hal.science/hal-05844130v1"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "hal:0.sde",
      "subfield": "environmental-science"
    }
  ],
  "title": "Ice core δ15N of Ammonium Reveals Changing Atmospheric Processing of NHx during European industrialisation",
  "title_text": "Ice core δ15N of Ammonium Reveals Changing Atmospheric Processing of NHx during European industrialisation",
  "type": "preprint",
  "updated_at": "2026-10-31T12:20:56Z",
  "url": "https://research.draconitic.com/paper/6qmz0w534qa2t",
  "venue": "HAL",
  "versions": []
}