NO at low concentration can enhance the formation of highly oxygenated biogenic molecules in the atmosphere

• The interaction between nitrogen monoxide (NO) and organic peroxy radicals (RO2) greatly impacts the formation of highly oxygenated organic molecules (HOM), the key precursors of secondary organic aerosols. It has been thought that HOM production can be significantly suppressed by NO even at low concentrations. Here, we perform dedicated experiments focusing on HOM formation from monoterpenes at low NO concentrations (0 – 82 pptv). We demonstrate that such low NO can enhance HOM production by modulating the RO2 loss and favoring the formation of alkoxy radicals that can continue to autoxidize through isomerization.These insights suggest that HOM yields from typical boreal forest emissions can vary between 2.5%-6.5%, and HOM formation will not be completely inhibited even at high NO concentrations. Our findings challenge the notion that NO monotonically reduces HOM yields by extending the knowledge of RO2-NO interactions to the low-NO regime. This represents a major advance towards an accurate assessment of HOM budgets, especially in low-NO environments, which prevails in the preindustrial atmosphere, pristine areas, and the upper boundary layer.

Subject headings

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Keyword

Aerosols

Atmosphere

Monoterpenes

Nitric Oxide

Oxidation-Reduction

monoterpene

nitric oxide

organic nitrate

oxygen

peroxy radical

boreal forest

concentration (composition)

hydroxyl radical

nitrous oxide

organic matter

oxygenation

radical

terpene

air pollution control

Article

atmosphere

autooxidation

boundary layer

chemical environment

circadian rhythm

comparative study

concentration (parameter)

isomerization

mass spectrometry

ozone depletion

ozonolysis

relative humidity

secondary organic aerosol

stratosphere

taiga

temperature

aerosol

oxidation reduction reaction

Publication and Content Type

ref (subject category)

art (subject category)