DOI: 10.5061/dryad.pk0p2ngt6
title: Data from: Chemically distinct particle phase emissions from highly controlled pyrolysis of three wood types

description: Wood pyrolysis is a distinct process that precedes combustion and
 contributes to biomass and biofuel burning gas phase and particle phase
 emissions. Pyrolysis is defined as the thermochemical degradation of wood,
 the products of which can be released directly or undergo further reaction
 during gas-phase combustion. To isolate and study the processes and
 emissions of pyrolysis, a custom-made reactor was used to uniformly heat
 small blocks of wood in a nitrogen atmosphere. Pieces of maple, Douglas
 fir and oak wood (maximum 155 cm3) were pyrolyzed in a
 temperature-controlled chamber set to 400, 500, or 600°C. Real time
 particle phase emissions were measured with a Soot Particle Aerosol Mass
 Spectrometer (SP-AMS) and correlated with simultaneous gas phase emission
 measurements of CO. Particle and gas emissions increased rapidly after
 inserting a wood sample, remained high for tens of minutes, and then
 dropped rapidly leaving behind char. The particulate mass loading profiles
 varied with elapsed experiment time, wood type and size, and pyrolysis
 chamber temperature. The chemical composition of the emitted particles was
 organic (C, H, O), with negligible black carbon or nitrogen. The emitted
 particles displayed chemical signatures unique to pyrolysis and notably
 different from flaming or smoldering wood combustion. The most abundant
 fragment ions in the mass spectrum were CO+ and CHO+, which together made
 up 23 % of the total aerosol mass on average, whereas CO2+ accounted for
 less than 4 %, in sharp contrast with ambient aerosol where CO2+ is often
 a dominant contributor. The mass spectra also showed signatures of
 levoglucosan and other anhydrous sugars. The fractional contribution of
 m/z 60, traditionally a tracer for anhydrous sugars including
 levoglucosan, to total loading (f60) was observed to be between 0.002 and
 0.039, similar to previous observations from wild and controlled wood
 fires. Atomic ratios of oxygen and hydrogen to carbon, O : C and H : C as
 calculated from AMS mass spectra, varied between 0.41–0.81 and 1.06–1.57,
 respectively, with individual conditions lying within a continuum of O : C
 and H : C for wood’s primary constituents: cellulose, hemicellulose, and
 lignin. This work identifies the mass spectral signatures of particle
 emissions directly from pyrolysis, including f60 and CO+/CO2+ ratio,
 through controlled laboratory experiments in order to help understand the
 importance of pyrolysis emissions in the broader context of wild and
 controlled wood fires.
description: In each experiment, individual pieces of wood were heated under
 N<sub>2</sub> so as to measure the pyrolysis products
 primarily with an Aerosol Mass Spectrometer (AMS). The emissions from
 pyrolysis were entirely organic and further analyzed by individual ion
 fragments and bulk properties including O/C, H/C, and oxidation
 state.  This dataset includes the total organic,
 individual ion, and O/C and H/C ratio data obtained with the AMS, along
 with the mass loss and gas phase measurements that comprise the figures in
 this paper.  This data was processed into its current
 form from raw data using the openly accessible Squirrel and Pika software
 for AMS data, including calculation of O/C and H/C ratios from
 individually fit ion fragments. The software can be found at:
 https://cires1.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware/
description: Data from each figure are provided as csv files.