Chemical characterization of fine particulate matter emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

Thilina Jayarathne, Chelsea E. Stockwell, Ashley A. Gilbert, Kaitlyn Daugherty, Mark A. Cochrane, Kevin C. Ryan, Erianto I. Putra, Bambang H. Saharjo, Ati D. Nurhayati, Israr Albar, Robert J. Yokelson, Elizabeth A. Stone

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Fine particulate matter (PM2:5) was collected in situ from peat smoke during the 2015 El Niño peat fire episode in Central Kalimantan, Indonesia. Twenty-one PM samples were collected from 18 peat fire plumes that were primarily smoldering with modified combustion efficiency (MCE) values of 0.725-0.833. PM emissions were determined and chemically characterized for elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble ions, metals, and organic species. Fuel-based PM2:5 mass emission factors (EFs) ranged from 6.0 to 29.6 g kg1 with an average of 17:36:0 g kg1. EC was detected only in 15 plumes and comprised 1% of PM mass. Together, OC (72 %), EC (1 %), water-soluble ions (1 %), and metal oxides (0.1 %) comprised 7411% of gravimetrically measured PM mass. Assuming that the remaining mass is due to elements that form organic matter (OM; i.e., elements O, H, N) an OM-to-OC conversion factor of 1.26 was estimated by linear regression. Overall, chemical speciation revealed the following characteristics of peat-burning emissions: high OC mass fractions (72%), primarily water-insoluble OC (8411 %C), low EC mass fractions (1 %), vanillic to syringic acid ratios of 1.9, and relatively high n-alkane contributions to OC (6.2 %C) with a carbon preference index of 1.2-1.6. Comparison to laboratory studies of peat combustion revealed similarities in the relative composition of PM but greater differences in the absolute EF values. The EFs developed herein, combined with estimates of the mass of peat burned, are used to estimate that 3.2-11 Tg of PM2:5 was emitted to atmosphere during the 2015 El Niño peatland fire event in Indonesia. Combined with gas-phase measurements of CO2, CO, CH4, and volatile organic carbon from Stockwell et al. (2016), it is determined that OC and EC accounted for 2.1 and 0.04% of total carbon emissions, respectively. These in situ EFs can be used to improve the accuracy of the representation of Indonesian peat burning in emission inventories and receptor-based models.

Original languageEnglish
Pages (from-to)2585-2600
Number of pages16
JournalAtmospheric Chemistry and Physics
Volume18
Issue number4
DOIs
StatePublished - Feb 21 2018

Funding

This research was primarily supported by NASA grant NNX13AP46G to SDSU and UM. The research was also supported by NASA grant NNX14AP45G to UM. We also acknowledge the T. Anne Cleary International Dissertation Research Fellowship awarded by the Graduate College, University of Iowa, and Center for Global and Reginal Environmental Research (CGRER) graduate student travel award for field research. We also thank David Peate, Iowa Trace Element Analysis Laboratory, for the assistance given during metal analysis. We are also grateful to Laura Graham, Grahame Applegate, and the BOS field team for their excellent support during the sample collection.

FundersFunder number
National Aeronautics and Space AdministrationNNX14AP45G, NNX13AP46G

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