We report measurements of the uptake of peroxyacetyl nitrate (PAN) by plant leaves at mixing ratios typical of the continental lower troposphere. PAN uptake rates between 20 and 55 pmol m−2 s−1 were measured in eight plant species at an atmospheric mixing ratio of 250 pptv. Uptake rates in all species were strongly controlled by the leaf stomatal aperture. Foliar PAN uptake has important implications for balancing global and regional N cycles. From our measurements, we estimate 3% of the global annual emission of NOx to the atmosphere could be removed by foliar uptake of PAN. Regionally, the deposition rate of PAN can be as much as 20% the rate of total N deposition.
