NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
This study characterizes impacts of peat-forest PF smoke on an urban environment through carbonaceous profiles of 260 daily PM2.5 samples collected during 2012, 2013 and 2015. Organic carbon OC and elemental carbon EC comprising eight carbonaceous fractions are examined for four sample groups - non-smoke-dominant NSD, smoke-dominant SD, episodic PM2.5 samples at the urban receptor, and near-source samples collected close to PF burning sites. PF smoke introduced much larger amounts of OC than EC, with OC accounting for up to 94 of total carbon TC, or increasing by up to 20 times in receptor PM2.5. SD PM2.5 at the receptor site and near-source samples have OC3 and EC1 as the dominant fractions. Both sample classes also exhibit char-EC 1.4 times of soot-EC, characterizing smoldering dominant PF smoke, unlike episodic PM2.5 at the receptor site featuring large amounts of pyrolyzed organic carbon POC and soot-EC. Relative to the mean NSD PM2.5 at the receptor, increasing strength of transboundary PF smoke enriches OC3 and OC4 fractions, on average, by factors of 3 for SD samples, and 14 for episodic samples. A peat-forest smoke PFS indicator, representing the concentration ratio of OC2 OC3 POC to soot-EC, shows a temporal trend satisfactorily correlating with an organic marker levoglucosan of biomass burning. The PFS indicator systematically differentiates influences of PF smoke from source to urban receptor sites, with a progressive mean of 3.6, 13.4 and 20.1 for NSD, SD and episodic samples respectively at the receptor site, and 54.7 for the near-source PM2.5. A PFS indicator of 5.0 is proposed to determine dominant influence of transboundary PF smoke on receptor urban PM2.5 in the equatorial Asia with similar to 90 confidence.
Journal Article - Open Access
Environmental Pollution , 248, 01 Jan 0001, 01 Jan 0001,