摘要：In a boreal forest environment at Hyytiälä (SMEAR II station), Finland, from 21 June 2010 to 31 April 2011, concentrations of gases (HCl, HNO3, HONO, NH3, SO2) and inorganic ions (Cl–, NO3 –, SO4 2–, NH4 +, Na+, K+, Mg2+, Ca2+) in PM10 and PM2.5 particles were measured with an on-line ion chromatograph MARGA 2S. The MARGA data were compared with those of the filter samples and the Aerosol Mass Spectrometer. The linear-regression slopes derived from MARGA against the filter data were 0.98, 1.08, 0.50 and 1.31 for SO2, SO4 2–, HNO3 and NO3 –, respectively. The respective coefficients of determination (r2) were 0.89, 0.90, 0.70 and 0.93. After installing a concentration column, improved values of cation slopes of 1.00, 1.19, 0.88, 1.00, 0.73 and 0.89 for NH3, NH4 +, Na+, K+, Mg2+, and Ca2+, respectively, were obtained. The corresponding coefficients of determination (r2) were: 0.79, 0.83, 0.95, 0.90, 0.85 and 0.62. According to these results, traditional filter collection can be replaced with the MARGA instrument at background sites, if a concentration column is used at least for the cations. This would improve the temporal resolution of the observations. The average concentrations of nitrogen-containing gases were highest in the summer (NH3: 0.47 ppb, HNO3: 0.10 ppb and HONO: 0.11 ppb), which can be explained by the higher temperatures and increased amounts of sunlight followed by stronger agricultural and soil-related sources. In the summer, clear diurnal cycles were found in all N-containing gases, but in the winter the concentrations remained low most of the time and no diurnal cycles were observed. The concentration of ammonia was found to depend exponentially on the prevailing temperature, the increase with temperature being strongest in dry conditions.
