REACTIVE NITROGEN-COMPOUNDS AT SPITSBERGEN IN THE NORWEGIAN ARCTIC

Simultaneous independent measurements of NOy and NOx (NOx = NO + NO2) by high-sensitivity chemiluminescence systems and of PAN (peroxyacetyl nitrate) and PPN (peroxypropionyl nitrate) by GC-ECD were made at Spi tsbergen in the Norwegian Arctic during the first half year of 1994. T he average mixing ratio of the sum of PAN and PPN (denoted PANs) incre ased from around 150 pptv in early winter to a maximum of around 500 p ptv in late March, whereas episodic peak values reached 800 pptv. This occurred simultaneously with a maximum in ozone which increased to 45 -50 ppbv in March-April. The average NOx mixing ratio was 27 pptv and did not show any cycle through the period. The NOy mixing ratio showed a maximum in late March, while the difference between NOy and PAN dec reased during spring. This is an indication of the dominance of PAN in the NOy budget in the Arctic, but possible changes in the efficiency of the NOy converter could also contribute to this. Although most PAN in the Arctic is believed to be due to long range transport, the obser vations indicate local loss and formation rates of up to 1-2 pptv h(-1 ) in April-May. Measurements of carbonyl compounds suggest that acetal dehyde was the dominant, local precursor of PAN.