Obtaining polycyclic aromatic hydrocarbon concentration ratios and molecular markers for residential wood combustion: Temuco, a case study

Abstract

It is known that residential wood combustion (RWC) is an important source of fine particle emissions. The purpose of this work was to characterize the chemical composition of the particulate matter present in the Temuco urban atmosphere during winter, specifically the polycyclic aromatic hydrocarbon (PAH) profile, because PAHs are considered to be among the key compounds in particulate matter toxicity. During the 2008 winter monitoring campaign, samples of particulate matter with aerodynamic diameters of 10 (PM 10 ) and 2.5 (PM 2.5 ) mm were taken on days with contamination episodes. Sixteen U.S. Environmental Protection Agency (EPA) PAH compounds were extracted with toluene and determined by gas chromatography-mass spectrometry (GC-MS). The results show that phenantrene was the predominant compound associated with particulate matter, at a concentration range between 300 and 600 ng m À3 , 18 times higher than the second most abundant PAH compound. High-molecular-mass compounds such as dibenz [a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3,c,d]pyrene were also found, but they were minorities in the set. It was recognized from the PAH concentration ratios of the Temuco atmospheric aerosol that the main contamination source was in fact residential wood combustion; although not all the concentration ratios evaluated match the reported reference values, probably due to the kind of biomass used, the characteristics of Chilean heating appliances and climate.Implications: The study results suggest that if molecular markers (MMs) and concentration ratios (CRs) are dependent on the type of firewood and combustion processes specific to each location, among others factors, then the values of these indicators could be applicable with caution between different areas, although not necessarily they must be totally in accord. Moreover, having representative values of MM and CR of each place, it will achieve a better estimation of the source importance and concentrate the monitoring and the control strategies. Regulatory organizations in each country can have more reliable information and optimize financial and human resources, enabling it to reduce air pollution and improve the health of population.

Assessing Polycyclic Aromatic Hydrocarbons (PAHs) using passive air sampling in the atmosphere of one of the most wood-smoke-polluted cities in Chile: The case study of Temuco

“…S5). This is consistent with previous studies of PAHs in Temuco (Cereceda-Balic et al, 2012). Based on the average for the six sampling sites over the three periods, the dominant individual PAHs had the following contributions to total PAHs: phenanthrene (35-45%), fluoranthene (11-15%) and pyrene (9-12%).…”

“…Consequently, the collected PAH burdens and profiles will exhibit some variability depending on the temporal nature of PAH emissions, and on meteorological factors such as wind direction. The temporal variability of PAH emissions and concentrations in air at the LE sampling site may also explain the higher total PAH concentrations reported by Cereceda-Balic et al (2012) using active sampling, compared to the current study.…”

“…Fig. 2 shows agreement between PAH profiles in active (PM 2.5 ) (Cereceda-Balic et al, 2012) and passive samples (PUF disk) (p < 0.05; r 2 = 0.98) for both low and high molecular weight PAHs. This suggests that the PUF disk samplers are capturing both gas-phase and particle-phase PAHs with minimal bias, relative to how these phases are sampled by the active sampler.…”

“…Dominance of phenanthrene is typical for emissions from biomass combustion, particularly wood combustion (Rogge et al, 1998). Cereceda-Balic et al (2012) also reported a high phenanthrene composition of about 74% for Temuco using active sampling.…”

“…The LE station is operated under the Environmental Ministry and is located in the center of a vacant lot in a residential area, 2.7 km west of the city center. Active air sampling for PAHs (PM 2.5 ) was conducted at the LE station during the course of this study and results were reported by Cereceda-Balic et al (2012).…”