Abstract. We present biogenic VOC, including sesquiterpenes, measurements at the SMEAR II station (Station For Measuring Forest Ecosystem-Atmosphere Relations) in Finland using an in situ gas chromatograph mass-spectrometer with 2 h time resolution. The measurements were conducted over the period October 2010-October 2011, at least one week every month. To our knowledge there are no earlier species-speciated semi-continuous BVOC data also covering dormant periods. This was also the first time sesquiterpene mixing ratios were measured in a boreal forest.During the winter months, and still in March, the mixing ratios of all biogenic compounds were very low, most of the time below detection limits. The monoterpene mixing ratios increased in April and started to show diurnal variability, with maximum mixing ratio at night and minima during the day. The diurnal variability continued until October, after which the mixing ratios decreased and then only occasional episodes took place. The diurnal variation was affected by boundary layer height. Sesquiterpene mixing ratios were very low, only a few ppt. The main sesquiterpenes were longifolene and isolongifolene. The diurnal variation of isoprene was opposite to the mono-and sesquiterpene diurnal curve due to isoprene's light dependent emissions. Due to its daytime maximum mixing ratios, isoprene also dominated hydroxyl radical reactivity in summer even though our isoprene measurements are underestimates due to a breakthrough in a cold trap.

Abstract. We present spring and summer volatile organic compound (VOC) emission rate measurements from Norway spruce (Picea abies L. Karst) growing in a boreal forest in southern Finland. The measurements were conducted using in situ gas chromatograph with 1 to 2 h time resolution to reveal quantitative and qualitative short-term and seasonal variability of the emissions. The measurements cover altogether 14 weeks in years 2011, 2014 and 2015. Monoterpene (MT) and sesquiterpene (SQT) emission rates were measured all the time, but isoprene only in 2014 and 2015 and acetone and C 4 -C 10 aldehydes only in 2015. The emission rates of all the compounds were low in spring, but MT, acetone, and C 4 -C 10 aldehyde emission rates increased as summer proceeded, reaching maximum emission rates in July. Late summer mean values (late July and August) were 29, 17, and 33 ng g(dw) −1 h −1 for MTs, acetone, and aldehydes respectively. SQT emission rates increased during the summer and highest emissions were measured in late summer (late summer mean value 84 ng g(dw) −1 h −1 ) concomitant with highest linalool emissions most likely due to stress effects. The between-tree variability of emission pattern was studied by measuring seven different trees during the same afternoon using adsorbent tubes. Especially the contributions of limonene, terpinolene, and camphene were found to vary between trees, whereas proportions of α-pinene (25 ± 5 %) and β-pinene (7 ± 3 %) were more stable. Our results show that it is important to measure emissions at canopy level due to irregular emission pattern, but reliable SQT emission data can be measured only from enclosures. SQT emissions contributed more than 90 % of the ozone reactivity most of the time, and about 70 % of the OH reactivity during late summer. The contribution of aldehydes to OH reactivity was comparable to that of MT during late summer, 10-30 % most of the time.

Abstract. We measured amines in boreal forest air in Finland both in gas and particle phases with 1 h 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 developed MARGA-MS method was able to separate and detect seven different amines: monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA), propylamine (PA), and butylamine (BA). The detection limits of the method for amines were low (0.2–3.1 ng m−3), the accuracy of IC-MS analysis was 11–37 %, and the precision 10–15 %. The proper measurements in the boreal forest covered about 8 weeks between March and December 2015. The amines were found to be an inhomogeneous group of compounds, showing different seasonal and diurnal variability. Total MMA (MMA(tot)) peaked together with the sum of ammonia and ammonium ions already in March. In March, monthly means for MMA were < 2.4 and 6.8 ± 9.1 ng m−3 in gas and aerosol phases, respectively, and for NH3 and NH4+ these were 52 ± 16 and 425 ± 371 ng m−3, respectively. Monthly medians in March for MMA(tot), NH3, and NH4+ were < 2.4, 19 and 90 ng m−3, respectively. DMA(tot) and TMA(tot) had summer maxima indicating biogenic sources. We observed diurnal variation for DMA(tot) but not for TMA(tot). The highest concentrations of these compounds were measured in July. Then, monthly means for DMA were < 3.1 and 8.4 ± 3.1 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 ± 0.1 and 1.8 ± 0.5 ng m−3. Monthly medians in July for DMA were below the detection limit (DL) and 4.9 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 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 (R2=0.63) suggesting that it participates in atmospheric clustering. EA concentrations were low all the time. Its July means were < 0.36 and 0.4 ± 0.4 ng m−3 in gas and aerosol phases, respectively, but individual concentration data correlated well with monoterpene concentrations in July. Monthly means of PA and BA were below detection limits at all times.

&lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; We present spring and summer volatile organic compound (VOC) emission rate measurements from Norway spruce (&lt;i&gt;Picea abies&lt;/i&gt; L. Karst) growing in a boreal forest in southern Finland. The measurements were conducted using in situ gas-chromatograph with 1 to 2-hour time resolution. The measurements cover altogether 14 weeks in years 2011, 2014 and 2015. Monoterpene (MT) and sesquiterpene (SQT) emission rates were measured all the time, but isoprene only in 2014 and 2015 and acetone and C&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;10&lt;/sub&gt; aldehydes only in 2015. The emission rates of all the compounds were low in spring, but MT, acetone and C&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;10&lt;/sub&gt; aldehydes emission rates increased as summer proceeded, reaching maximum emission rates in July. Late summer means were 29, 17 and 33&amp;#8201;ng&amp;#8201;g(dw)&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;&amp;#8201;h&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; for MTs, acetone and aldehydes respectively. SQT emission rates increased during the summer and highest emissions were measured late summer (late summer mean 84&amp;#8201;ng&amp;#8201;g(dw)&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;&amp;#8201;h&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;) concomitant with highest linalool emissions. The between-tree variability of emission pattern was studied by measuring seven different trees during the same afternoon using adsorbent tubes. Especially the contributions of limonene, terpinolene and camphene were found to vary between trees, whereas proportions of &amp;#945;- and &amp;#946;-pinene were more stable. SQT emissions contributed more than 90&amp;#8201;% of the ozone reactivity most of the time, and about 70&amp;#8201;% of OH reactivity during late summer. The contribution of aldehydes was comparable to the OH reactivity of MT during late summer, 10&amp;#8201;%&amp;#8211;30&amp;#8201;% most of the time.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; We measured amine and guanidine emission rates from a boreal forest floor in Finland with 1-h time resolution, using an online ion chromatograph (instrument for Measuring AeRosols and Gases in Ambient air &amp;#8211; MARGA) coupled with an electrospray ionization-quadrupole mass spectrometer (MS). MARGA-MS was connected to a closed dynamic flow-through poly(methyl methacrylate) chamber. Chamber recovery for the emission measurements was tested semi-quantitatively for monomethyl-, dimethyl- and trimethylamine (MMA, DMA and TMA), and the results were 19&amp;#8201;%, 29&amp;#8201;% and 24&amp;#8201;%, respectively. MMA, DMA and TMA showed maximum emission rates in July, but the highest emission rates for guanidine were in April, when snow was melting. The MMA, DMA and TMA emission rates also clearly varied diurnally, especially in July with maxima at afternoon. Diethylamine (DEA) also showed higher emission rates, with clear diurnal cycles in July. Other amine emission rates were mostly below the detection limits.&lt;/p&gt; &lt;p&gt;The temperature dependencies of the emissions were studied, and we noted a correlation between the emission rates and chamber temperature (T&lt;sub&gt;chamber&lt;/sub&gt;). Especially in July emission rates of DMA followed T&lt;sub&gt;chamber&lt;/sub&gt; measured two hours earlier and guanidine showed a similar pattern. On the other hand, the TMA emission rates correlated with T&lt;sub&gt;chamber&lt;/sub&gt; measured at the same time. This could be due to lower vaporizing temperature of TMA. Emission rates of DMA and TMA showed some air temperature (T&lt;sub&gt;air&lt;/sub&gt;) dependency, but for MMA dependency was not as clear.&lt;/p&gt;