This week (19th Oct–24th October) is Real Time Chem Week (if that means nothing to you,check out their FAQ page here!). As part of it, we’re featuring the RTC Week competition-winning entries of five different chemists here on Compound Interest, with a different feature every day this week. Today’s feature takes a look at how what happens to the nitrogen-containing compounds released into the atmosphere by both natural and industrial processes, and considers some of the health effects they can cause.

NadineBorduas

RTCW3 – Atmospheric Organic Nitrogen

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Dr. Nadine Borduas carried out her PhD research on how various nitrogen-containing amine compounds react when they are released into the atmosphere, research which has implications for both our climate and our health. Here, she explains what her research entailed.

Organic nitrogen compounds are present in our atmosphere from natural and industrial sources and have impacts on air quality and climate. Due to recent advances in instruments, these  compounds are being detected in gases and aerosols, raising questions as to their source, processing and sinks in the environment.

Nitrogen compounds have been recently identified as contributors to aerosol (small particle) formation and growth. Their novel large-scale use as solvents in carbon capture and storage (CCS) technology and their emissions from cigarette smoke mean is now important to address the gaps in our understanding of the fate of organic nitrogen. During my PhD, I studied experimentally and theoretically the chemical atmospheric fate of specific organic nitrogen compounds in the amine, amide and isocyanate families, giving us information that can be used in chemical transport models to assess the fate of this emerging class of atmospheric pollutants.

In a big plastic bag, surrounded by lamps simulating sunlight and connected to online mass spectrometers, I measured the kinetics of the reactions of amine and amide compounds with important atmospheric oxidants like OH radicals and ozone. These rates tell us how quickly these compounds decompose in our atmosphere. I showed both experimentally and theoretically that amines are oxidized to amides which are themselves oxidized to isocyanates (but ten times slower).

I also studied the fate of isocyanic acid (a member of the isocyanate family) in the aqueous phase, which ultimately hydrolyses to ammonia. Consequently, the fate of gas phase amines leads in part to ammonia via the amide and isocyanate intermediates. This is significant, because ammonia react with other chemicals present in the air and can contribute to smog and impact the climate, as well as causing potential health issues.

I have investigated how to incorporate this knowledge into structure-activity relationship (SAR) models and show new factors governing the fate of organic nitrogen in the atmosphere. This should allow for improved model predictions regarding the identities, amounts, and fates of the compounds produced.”

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