# Size-Segregated Particulate Mass and Carbonaceous Components in Roadside and Riverside Environments
## 1 Introduction  
Ambient size-classified particulate matter (PMs) down to nano-size (d\({}_{\rm p}\)\(\leq\) 0.1 \(\upmu\)m or 100 nm) range has become an important issue in the atmospheric scientific communities in the past decade [1, 2, 3]. Particulate pollution has contributed to the deterioration in air quality in many countries [2, 4, 5, 6]. The effects of ambient particles can be detrimental to the overall global climate, visibility, and public health [7, 8, 9]. Substantial evidence from medical research suggests that finer particles, especially ultrafine particles (UFPs), or PM\({}_{0.1}\), can pass into the bloodstream in the human body and then exert a variety of health effects [10, 11]. In metropolitan areas, land transportation is an important source of UFP emissions [12]. Diesel and gasoline engines are the major source of UFPs in megacities [13]. As reported by [PERSON] et al. (2013), forest fires released higher levels of PM\({}_{0.1}\) particles into the atmosphere than car engines, with sizes of approximately 120 nm a fresh aerosol plume [12]. Indonesia is one of the large contributors to atmospheric pollution due to extensive open biomass burning in the dry season in the past decade [14; 15]. The dry season in Indonesia, which commonly occurs from June to October, causes large numbers of peatland/forest fires annually in several provinces including Jambi City in Sumatra Island, Indonesia [16; 17]. As reported by the World Bank Group (2016), around 123,000 hectares of forest in Jambi had burned between June and October 2015 [18]. These fires account for 5 percent of the total area of forest fires in Indonesia. A great amount of smoke haze is emitted into the atmosphere in this area. Moreover, due to the influence of meteorological conditions, i.e., wind speed and direction, smoke haze in Jambi is not only a local problem but also contributes to transboundary haze pollution. Such pollution can be transported to neighboring provinces and neighboring countries such as Malaysia, Singapore, southern Thailand, and, of course, it has an impact on the multisector aspect of activities in those countries [14; 19; 20; 21; 22; 23]. As a result, the origin of the worst air pollution in Jambi City is not only from transportation sources but also from biomass burning. The main efforts made to understand Indonesia's air quality have focused on the status of coarse (PM\({}_{10}\), and TSP) and fine (PM\({}_{2.5}\)) particles [16; 24]. Several studies based on remote sensing, monitoring and modelling techniques have revealed that aerosol plumes during smoke-haze incidents exceeded the national standard for Indonesia, which actually has a very high value compared to the World Health Organization (WHO) standard [21; 25]. As reported by [PERSON] et al. (2019), the PM\({}_{10}\) concentration in roadsides is higher than the limit standard set by WHO for both weekdays and weekends [26]. Because of this, most studies have focused on coarse and fine particles. Studies dealing with smaller size particles as UFPs in Indonesia were still limited [27]. In the present study, therefore, in order to comprehensively understand the present status, characteristics and emission sources of PMs, including ultrafine particles in Indonesia, size-segregate airborne particles were collected in the City of Jambi as a typical provincial city in Sumatra Island. To accomplish this, air samples were collected for 12 h diurnal and nocturnal periods at two monitoring sites with different characteristics (a road side and a river side) from 2-13 August 2019, using a cascade air sampler that can collect size-segregated PMs down to the UFP range. Diurnal and nocturnal behaviors of the PM characteristics as particle mass and particle-bound carbonaceous components are discussed in relation to the influence of local sources and meteorological conditions, such as the thickness of the mixing layer. The number of the variety of vehicles observed in the roadside environment was correlated with PM mass and parameters for the carbonaceous components.