Interaction between nitrogen and sulfur cycles in the polluted marine boundary layer

Simultaneous measurements are reported of the nitrate radical (NO 3 ), nitrogen dioxide (NO 2 ), ozone (O 3 ), and dimethylsulfide (DMS) in the nighttime marine boundary layer over Biscayne Bay in South Florida. These field observations are analyzed and used to initialize a boundary layer box model which examines the relative importance of the various sinks for NO x in the marine boundary layer. The results show that the observed lifetime of NO 3 (≤6 min.) is probably controlled both by the loss of nitrogen pentoxide (N 2 O 5 ) to reaction with water vapor and aerosols and by the reaction between NO 3 and DMS. The model is then extended to investigate the loss of nitrogen oxides from an air parcel that remains in the boundary layer with a constant sea‐to‐air DMS flux for several days. The principal conclusions are (1) that DMS is a much more important sink for NO 3 at lower NO 2 levels and (2) that the reaction between NO 3 and DMS is an important sink for DMS in the marine boundary layer and could exceed that of the daytime removal by OH.