In the spring of 1986 and 1989, particle nitrite was measured at Barrow, Alaska, by filter sampling and by ion chromatographic analysis. Particle nitrite concentrations averaged 2.9 +/- 3.4 and 2.6 +/- 2.0 ppt (molar ratio) in 1986 and 1989, respectively. Both seasons showed diurnal variations with higher concentrations during the day which might have been caused by daytime down mixing. In 1989, nitrite was determined in several snow samples with concentrations between 0 and 0.18 mu mol l(-1). Particle nitrite was probably in disequilibrium with gas phase, suggesting a heterogeneous source for gaseous HONO. A relationship between particle nitrite and sodium ions suggests that sea salt could be involved in nitrite formation, perhaps through hydrolysis of nitryl halides.
Measurements in the Arctic troposphere over several years show that MSA concentrations in the atmospheric boundary layer, 0.08-6.1 parts per trillion (ppt, molar mixing ratio), are lower than those over mid-latitude oceans. The seasonal cycle of MSA at Alert, Canada (82.5 degrees N, 62.3 degrees W), has two peaks of 6 ppt in March-April and July-August and minima of 0.3 ppt for the rest of the year. At Dye 3 (65 degrees N, 44 degrees W) on the Greenland Ice Sheet, a similar seasonal MSA cycle is observed although the concentrations are much lower with a maximum of 1 ppt. Around Barrow, Alaska (71.3 degrees N, 156.8 degrees W), MSA is between 1.0 and 25 ppt in July, higher than 1.5+/-1.0 ppt in March-April. The mid-tropospheric MSA level of 0.6-1 ppt in the summer Arctic is much lower than about 6 ppt in the boundary layer. Al Alert, the ratio of MSA to non-sea-salt (nss) SO42- ranges from 0.02 to 1.13 and is about 10 times higher in summer than in spring. The summer ratios are higher than found over mid-latitude regions and, when combined with reported sulfur isotope compositions from the Arctic, suggest that on average a significant fraction (about 16-23%) of Arctic summer boundary layer sulfur is marine biogenic. The measurements show that the summer Arctic boundary layer has a significantly higher MSA/nss-SO42- ratio than aloft.