Our manuscript on the “Seasonal fluxes of carbonyl sulfide in a midlatitude forest” was just recently published in PNAS (document online). Lead author Róisín Commane and I met at Harvard Forest where she installed an Aerodyne Research Inc., laser spectrometer to study the seasonal behavior of carbonyl sulfide (interchangeably called OCS and COS by different groups). Of particular interest are the common pathways to both CO2 and OCS, for example both trace gases react with carbonic anhydrase enzymes in leaves. This commonality may provide a quantitative, independent measure of the photosynthetic pathway for carbon assimilation. In this study, we find that vegetative uptake accounted for 72% of annual uptake of OCS, and nighttime uptake through stomata and…