Temporal and Spatial Variability of Ammonia Concentrations in the Non-Urban Troposphere

摘要

A body of data on ammonia concentrations in the non-urban boundary-layer troposphere is presented. Measurements were made using a continuous method employing liquid-phase scrubbing, chemical derivatization and fluorescence. The purpose was to explore the range of tropospheric ammonia levels observed in the NE North American continent, and to evaluate the diurnal and seasonal variations in ammonia concentrations and their relationship to temperature and other meteorological variables. Predominantly ground-level ammonia concentrations are reported, although some preliminary data from airborne sampling were obtained. Results indicate that ammonia concentrations seldom exceed 10 ppB for locations not directly impacted by industrial or urban plumes. There is also considerable spatial variability, although the fact that measurements have not been reported for all seasons at most sites makes quantitative determination of spatial variability of NH sub 3 in the non-urban troposphere not yet possible. It does appear that east coast, USA, summertime levels are usually in the 1 to 2 ppB range, with summertime levels at an inland location in Ohio somewhat higher. The anamolously low values recorded in central Massachusetts (weekly averages reported, averaging approx. 0.2 ppB from May to September 1980 and approx. 0.03 ppB from October to April) are not fully understood.