Most salts raise the surface tension of water.  Interpretation of this phenomenon via 
the Gibbs adsorption equation has led to the commonly held belief that the ions are 
repelled from the air/solution interface.  Here we report results from molecular 
dynamics simulations of a series of sodium halide solution/air interfaces.  The 
simulations reproduce the experimentally measured increases in surface tension 
relative to pure water.  Analysis of the structure reveals that the small, non-polarizable 
fluoride anion is excluded from the interface, in accord with the traditional picture.   
However, all of the larger, polarizable halide anions are present at the interface, and 
bromide and iodide actually have higher concentrations in the interfacial region than 
in the bulk.  Based on the simulations we develop a molecular picture of hydrogen 
bonding in the interfacial region that might be tested by surface sensitive 
spectroscopic experiments.  The novel, microscopic view of the interfacial structure 
of aqueous salt solutions presented in this paper has implications for the reactivity of 
sea salt aerosols in the marine boundary layer, and bromine chemistry in the remote 
Arctic at polar sunrise.