VOLATILE INORGANIC CL IN SURFACE AIR OVER EASTERN NORTH-AMERICA

Volatile inorganic Cl in surface air over eastern North America was se lectively measured using a tandem-mist-chamber technique with known co llection efficiencies for HCl, HOCl, and Cl-2. Mixing ratios of total alkaline-reactive inorganic Cl (Cl-t) and HCl (including HCl and poss ibly NOCl, ClNO2, and ClNO3) were statistically indistinguishable rang ing from <39 to approximate to 2800 pptv; most were <300 pptv. Those o f Cl (including Cl-2 and 56% HOCl) were <26 pptv Cl; anthropogenic in fluences were undetected. In addition, pre- and post-sunrise concentra tions of HCl were similar suggesting insignificant Cl photochemistry at dawn. HCl appears to be the dominant form of volatile inorganic Cl over eastern North America. Atomic chlorine is probably not an importa nt oxidant in the polluted continental boundary layer.