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Abating HCl and HNO3 is more effective than NH3 for mitigating high aerosol loading over the Indo-Gangetic Plain
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  • Prodip Acharja,
  • Sachin D. Ghude,
  • Bärbel Sinha,
  • Mary C Barth,
  • Rachana Kulkarni,
  • Vinayak Sinha,
  • Rajesh Kumar,
  • Kaushar Ali,
  • Gaurav Govardhan,
  • Ismail Gultepe,
  • Madhavan Nair Rajeevan
Prodip Acharja
Indian Institute of Tropical Meteorology
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Sachin D. Ghude
Indian Institute of Tropical Meteorology

Corresponding Author:[email protected]

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Bärbel Sinha
Indian Institute of Science Education and Research Mohali
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Mary C Barth
National Center for Atmospheric Research (NCAR)
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Rachana Kulkarni
Savitribai Phule Pune University
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Vinayak Sinha
Indian Institute of Science Education and Research Mohali India
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Rajesh Kumar
National Center for Atmospheric Research (UCAR)
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Kaushar Ali
Indian Institute of Tropical Meteorology, Pune
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Gaurav Govardhan
Indian Institute of Tropical Meteorology
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Ismail Gultepe
Environment and Climate Change Canada
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Madhavan Nair Rajeevan
Ministry of Earth Sciences
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Abstract

This study investigates aerosol “sensitivity regimes” to explore the effectiveness of abating gaseous precursors to mitigate aerosols over the Indo-Gangetic Plain (IGP). A new mechanistic insight is proposed by integrating ISORROPIA-II thermodynamical model with high-resolution simultaneous measurements of precursor gases (HCl, HNO3, and NH3) and inorganic constituents of PM1 and PM2.5, monitored for the first time in India using MARGA-2S instrument. The estimated aerosol acidity (pH) of PM1 and PM2.5 was 4.49±0.53 and 4.58±0.48, respectively. The sensitivity of phase-partitioning (ε) of Cl-, NO3-, and NH4+ to pH, ALWC, HCl, HNO3, and NH3 showed that fine aerosols fall in the ”HCl and HNO3 sensitive regime”, emphasizing that HCl and HNO3 reductions would be the most effective pathway to reduce aerosols in NH3-rich IGP. Since existing mitigation strategies over IGP are random and ineffective, this novel insight is the first step in providing a thermodynamically consistent “roadmap” to mitigate aerosols effectively.