Atmospheric hydrogen cyanide (HCN): Biomass burning source, ocean sink?

The observed seasonal amplitude of atmospheric HCN concentrations implies a n atmospheric lifetime of only a few months for HCN, much shorter than is c ommonly assumed from oxidation by OH (a few years). We propose that ocean u ptake provides the missing sink, and show with a global 3-D model simulatio n that the observations of atmospheric HCN call be roughly reproduced in a scenario where biomass burning provides the main source (1.4-2.9 Tg N yr(-1 )) and ocean uptake provides the main sink (HCN atmospheric lifetime of 2-4 months). Such a budget implies that HCN is a sensitive tracer of biomass b urning on large scales! of particular value because it is readily observed from space. The ocean sink hypothesis can be tested with measurements of HC N concentrations in marine air and seawater.