Modulation of fine aerosol ionic profiles and chemical characteristics by crop residue burning over the North-Western Indo-Gangetic Plain.

Authors

Abinash, Mohammad Asif, Sarita Bamotra, Shweta Yadav, Ambrish Kumar Mahajan, Manpreet Singh Bhatti, Ankit Tandon

Published in

Environmental monitoring and assessment. Volume 198. Issue 7. Jul 01, 2026. Epub Jul 01, 2026.

Abstract

Variations in ionic profiles and chemical characteristics viz. aerosol liquid water content (ALWC) and in situ pH of fine aerosol plausibly caused by crop residue burning (CRB) over the North-Western Indo-Gangetic Plain were studied. Ambient PM_2.5 samples were collected and criteria air pollutants were obtained for Amritsar, Punjab, from September to December, covering pre-CRB and CRB phases. These samples were analyzed for water-soluble ionic species. Further, Extended Aerosol Inorganics Model (E-AIM) model II was used to calculate ALWC and in situ pH. PM_2.5 concentrations increased significantly from 48.5 ± 22.6 μg m^-3 (pre-CRB) to 77.6 ± 24.3 μg m^-3 during CRB, showing a 60% increase during the CRB phase. Scaling analysis revealed that while gaseous pollutants (NO₂, SO₂) were primarily amplified by meteorological trapping, the surge in PM_2.5 was driven by a 2.7-fold increase, from 23 ± 36 (pre-CRB) to 63 ± 88 (CRB), in fire detection counts. Chemical characterization of water-soluble ionic species showed a doubling of the biomass burning marker K⁺ from 746 ng m^-3 to 1367 ng m^-3 and a significant rise in secondary inorganic aerosols, particularly nitrate (NO₃^-), which increased from 198 ng m^-3 to 2439 ng m^-3. Charge balance analysis revealed an alkaline aerosol nature, with neutralization pathways shifting from terrigenous dust (Ca²⁺, Mg²⁺) to anthropogenic (NH₄⁺ + K⁺) during the CRB phase. Interestingly, the median value of ALWC increased significantly (p = 0.002) from 6.18 μg m^-3 (pre-CRB) to 16.48 μg m^-3 (CRB). However, no significant variation in in situ pH was observed between pre-CRB and during CRB periods. This could be attributed to internal changes observed in the ionic profiles of fine aerosol due to CRB emissions.

PMID:
42384240
Bibliographic data and abstract were imported from PubMed on 01 Jul 2026.

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