High Precision C0S Monitor to Constrain the Partitioning of C02 Fluxes

Distinguishing between photosynthetic uptake and respiratory emission of CO2 from plants is a difficult problem; yet, determining the small difference between these two parameters is crucial for determining the net ecosystem exchange of CO2 between the atmosphere and the biosphere. Carbonyl sulfide (COS) is a surrogate for CO2 uptake by plants during photosynthesis, but COS is not emitted from plants during respiration. Thus, COS measurements could be used to provide unique estimates of the carbon assimilated by the biosphere, which would be independent of the influence of respiration. This project will develop a highly precise and portable instrument for absolute COS measurements based on newly available continuous wave mid-infrared quantum cascade lasers. The instrument, which will have a precision for COS of 1 part-per-trillion with a 100 s averaging time, would provide for the continuous measurement of COS, both at ground level monitoring sites and from aircraft platforms. Commercial Applications and other Benefits as described by the awardee An improved understanding of CO2 uptake by vegetation would improve our understanding of global warming and help mitigate global climate change. In addition to the worldwide market for such measurement systems in environmental and ecological research, an even larger market could exist in medicine, where COS measurements in exhaled breath could be used to diagnose cystic fibrosis, liver disease, and lung transplant rejection.