Amines in boreal forest air at SMEAR II station in Finland

We measured amines in boreal forest air in Finland both in gas and particle phase with 1-hour time resolution using an online ion chromatograph (instrument for Measuring AeRosols and Gases in Ambient Air, MARGA) connected to an electrospray ionization quadrupole mass spectrometer (MS). The measurements covered about 8 weeks between March 2015 and December 2015. With MARGA-MS we were able to separate and detect 7 different amines: monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA), propylamine (PA) and butylamine (BA). The amines were found to be an inhomogeneous group of compounds, showing different seasonal and diurnal variability. Total MMA peaked together with the sum of ammonia and ammonium ion already in March, possibly due to evaporation from melting snow and ground. In March monthly means for MMA were −3 and 6.8 ± 9.1 ng m −3 in gas and aerosol phase, respectively, and for NH 3 and NH 4 + , 52 ± 16 ng m −3 and 425 ± 371 ng m −3 , respectively. Monthly medians in March for MMA, NH 3 and NH 4 + , were −3 , 19 ng m −3 and 90 ng m −3 respectively. DMA and TMA had summer maxima indicating biogenic sources. We observed diurnal variation for DMA but not for TMA. The highest concentrations of these compounds were measured in July. In July monthly means for DMA were −3 and 8.4 ± 3.1 ng m −3 in gas and aerosol phase, respectively, and for TMA 0.4 ± 0.1 ng m −3 and 1.8 ± 0.5 ng m −3 . Monthly medians in July for DMA were −3 in gas and aerosol phase, respectively, and for TMA 0.4 ng m −3 and 1.4 ng m −3 . When relative humidity of air was > 90 %, gas phase DMA correlated well with 1.1–2 nm particle number concentration (R 2  = 0.63) suggesting that it participates in new particle formation. 0.63 EA concentrations were low all the time, July means were −3 and 0.4 ± 0.4 ng m −3 in gas and aerosol phase respectively, but they correlated well with monoterpene concentrations in July. Monthly means of PA and BA were all the time below detection limits.