Oxidized nitrogen chemistry and speciation in the Antarctic troposphere

Abstract

Understanding the NO y budget at high latitudes is important for our knowledge of present‐day clean air chemistry and essential for reliable interpretation of existing ice core nitrate data. However, measurements of NO y components at high latitudes have been limited, and no measurements have attempted to address the budget of NO y . Here we report on a campaign conducted in the austral summer of 1997 at the German Antarctic research station, Neumayer, with first Antarctic measurements for NO y in addition to light alkyl nitrates, NO, HNO 3 and p −NO 3 − . Inorganic nitrate has generally been assumed to be the dominant component of NO y in Antarctica, although this idea has not previously been tested. However, our results show that for this coastal station, methyl nitrate was present in much higher concentration than inorganic nitrate (median CH 3 ONO 2 = 38 pptv, HNO 3 = 5 pptv). It has been suggested earlier that some alkyl nitrates might have a marine source. If this suggestion is correct, the implication arises that the oceans are an important source of NO y to the Antarctic troposphere and that their role in determining nitrate concentrations in ice must be considered.