Sources and processes affecting the abundances of atmospheric NH x using δ 15 N over northwestern Indo-Gangetic plain.

Autor: Shaw C; Geosciences Division, Physical Research Laboratory, Ahmedabad, 380009, India; Indian Institute of Technology Gandhinagar, Gandhinagar, 382355, India., Rastogi N; Geosciences Division, Physical Research Laboratory, Ahmedabad, 380009, India. Electronic address: nrastogi@prl.res.in., Rathi A; Geosciences Division, Physical Research Laboratory, Ahmedabad, 380009, India; Indian Institute of Technology Gandhinagar, Gandhinagar, 382355, India., Kumar S; Geosciences Division, Physical Research Laboratory, Ahmedabad, 380009, India., Meena R; Geosciences Division, Physical Research Laboratory, Ahmedabad, 380009, India.
Jazyk: angličtina
Zdroj: Chemosphere [Chemosphere] 2024 Jul; Vol. 359, pp. 142356. Date of Electronic Publication: 2024 May 16.
DOI: 10.1016/j.chemosphere.2024.142356
Abstrakt: Ammonia (NH 3 ) is the major constituent among all the reactive nitrogen species present in the atmosphere, and the most essential species for secondary inorganic aerosol formation. Recent satellite-based observations have identified the Indo-Gangetic Plain (IGP) as a major hotspot of global NH 3 emission; however, the major sources and atmospheric processes affecting its abundance are poorly understood. The present study aims to understand the wintertime sources of NH 3 over a semi-urban site (Patiala, 30.3°N, 76.4°E, 249 m amsl) located in the IGP using species specific δ 15 N in PM 2.5 . A distinct diurnal variation in the stable isotopic signature of total nitrogen (δ 15 N-TN) and ammonium (δ 15 N-NH 4 + ) were observed; although, average day and night time concentrations of TN and NH 4 + were similar. Mixing model results using δ 15 N-NH 3 reveal the dominance of non-agricultural emissions (NH 3 slip: 47 ± 24%) over agricultural emissions (24 ± 11%), combustion sources (19 ± 14 %), and biomass burning (10 ± 8%) for atmospheric NH 3 . Diurnal variability in source contributions to NH 3 was insignificant. Further, significantly negative correlations of δ 15 N-NH 4 + with ambient relative humidity (RH) and daytime NO 3 - -N concentration were observed, and attributed to the possibility of NH 4 NO 3 volatilization during day-time owing to lower RH and higher temperature, resulting in isotopic enrichment of the remaining NH 4 + in aerosol phase. This study, a first of its type from India, highlights the importance of non-agricultural NH 3 emissions over the agriculture dominated IGP region, and the role of local meteorology on the isotopic fractionation of δ 15 N in aerosol NH 4 + .
Competing Interests: Declaration of competing interest Authors declare that there is no conflict of interest.
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Databáze: MEDLINE
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