NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore; Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore.
NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.
Environ Pollut. 2019 May;248:496-505. doi: 10.1016/j.envpol.2019.02.049. Epub 2019 Feb 20.
This study characterizes impacts of peat-forest (PF) smoke on an urban environment through carbonaceous profiles of >260 daily PM 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 PM 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 PM. SD PM 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 PM at the receptor site featuring large amounts of pyrolyzed organic carbon (POC) and soot-EC. Relative to the mean NSD PM 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 PM. A PFS indicator of ≥5.0 is proposed to determine dominant influence of transboundary PF smoke on receptor urban PM in the equatorial Asia with ∼90% confidence. Assessing >2900 hourly OCEC data in 2017-2018 supports the applicability of the PFS indicator to evaluate hourly impacts of PF smoke on receptor urban PM in the Maritime Continent.
本研究通过收集 2012 年、2013 年和 2015 年期间 260 多个每日 PM 样本的碳质剖面，描述了泥炭林（PF）烟雾对城市环境的影响。对 4 组样本（非烟雾主导组（NSD）、烟雾主导组（SD）、城市受体处的间歇性 PM 样本和靠近 PF 燃烧点的近源样本）中的有机碳（OC）和元素碳（EC）进行了包括 8 种碳质组分的分析。与受体处的间歇性 PM 样本特征不同，PF 烟雾引入的 OC 量比 EC 大得多，OC 占总碳（TC）的比例高达 94%，或在受体 PM 中增加了 20 倍。受体点和近源样本中的 SD PM 以 OC3 和 EC1 为主要组分。这两种样本类型还表现出 char-EC 比 soot-EC 大 1.4 倍的特征，表明以闷烧为主的 PF 烟雾，而不是受体处的间歇性 PM 特征是大量热解有机碳（POC）和 soot-EC。与受体处的平均 NSD PM 相比，跨境 PF 烟雾强度的增加使 SD 样本的 OC3 和 OC4 组分平均富集了>3 倍，使间歇性样本富集了>14 倍。代表（OC2+OC3+POC）与 soot-EC 浓度比的泥炭林烟雾（PFS）指标，与生物质燃烧的有机标志物（左旋葡聚糖）呈现出令人满意的时间趋势相关。PFS 指标系统地将 PF 烟雾的影响从源区分到城市受体，在受体处，NSD、SD 和间歇性样本的平均分别为 3.6、13.4 和 20.1，近源 PM 为 54.7。建议提出 PFS 指标≥5.0 以确定跨境 PF 烟雾对亚洲赤道地区受体城市 PM 的主导影响，置信度约为 90%。评估 2017-2018 年的>2900 个 OCEC 小时数据，支持 PFS 指标适用于评估海洋大陆受体城市 PM 中 PF 烟雾的每小时影响。
