Boreal forest fire emissions in fresh Canadian smoke plumes: C 1 -C 10 volatile organic compounds (VOCs), CO 2 , CO, NO 2 , NO, HCN and CH 3 CN

Boreal regions comprise about 17 % of the global land area, and they both affect and are influenced by cli- mate change. To better understand boreal forest fire emis- sions and plume evolution, 947 whole air samples were col- lected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous mea- surements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehen- sive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples collected in fresh Canadian smoke plumes, 57 of the 80 measured NMVOCs (including CH2O) were emitted from the fires, including 45 species that were quantified from boreal forest fires for the first time. After CO 2, CO and CH4, the largest emis- sion factors (EFs) for individual species were formalde- hyde (2.1± 0.2 g kg 1 ), followed by methanol, NO2, HCN, ethene, -pinene, -pinene, ethane, benzene, propene, ace- tone and CH3CN. Globally, we estimate that boreal forest fires release 2.4 ± 0.6 Tg C yr 1 in the form of NMVOCs, with approximately 41 % of the carbon released as C1-C2 NMVOCs and 21 % as pinenes. These are the first reported field measurements of monoterpene emissions from boreal