Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts
Journal Article
·
· Journal of Geophysical Research. D. (Atmospheres), 119(6):3335-3351
Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1129356
- Report Number(s):
- PNNL-SA-99362; 44638
- Journal Information:
- Journal of Geophysical Research. D. (Atmospheres), 119(6):3335-3351, Journal Name: Journal of Geophysical Research. D. (Atmospheres), 119(6):3335-3351
- Country of Publication:
- United States
- Language:
- English
Similar Records
Field and Laboratory Studies of Reactions between Atmospheric Water Soluble Organic Acids and Inorganic Particles
Reactivity of liquid and semisolid secondary organic carbon with chloride and nitrate in atmospheric aerosols
Tropospheric Chemistry of Internally Mixed Sea Salt and Organic Particles: Surprising Reactivity of NaCl with Weak Organic Acids
Conference
·
Tue Jun 25 00:00:00 EDT 2013
·
OSTI ID:1092011
Reactivity of liquid and semisolid secondary organic carbon with chloride and nitrate in atmospheric aerosols
Journal Article
·
Thu May 14 00:00:00 EDT 2015
· Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
·
OSTI ID:1188902
Tropospheric Chemistry of Internally Mixed Sea Salt and Organic Particles: Surprising Reactivity of NaCl with Weak Organic Acids
Journal Article
·
Fri Aug 03 00:00:00 EDT 2012
· Journal of Geophysical Research. D. (Atmospheres)
·
OSTI ID:1049654