Source Apportionment of PAHs in Airborne Particulates (PM_2.5) in Southern Chile

ABSTRACT

Airborne particulate matter (PM_2.5) are known environmental cotaminants. Nevertheless, it is not only the size of particulate matter that influences human health, but also its chemical composition. The chemical composition of the PAH suite in PM_2.5 may be indicative of the source materials, typically combustion products. In this study, particulate matter (PM_2.5) was collected using portable air samplers during all of 2013 and 2014 at five locations of the Los Rios Region, Valdivia, Chile. The quantity of PM_2.5 collected was measured using gravimetric methods. Solvent extracts were analyzed for associated PAHs by means of GC-MS techniques. The concentrations of PM_2.5 for all locations ranged from 2.8 to 386 µg/m³ for the autumn/winter periods and from 1.1 to 315 µg/m³ for the spring/summer periods. The mean concentrations of PM_2.5 ranged from 11.9 to 112 µg/m³ in summer for all sites. The concentrations of PAHs for all locations ranged from 2.8 to 115 ng/m³ for the autumn/winter periods and from 0.3 to 32 ng/m³ for the spring/summer periods. To determine the possible sources of PM_2.5, cross-plots, PCA, and PVA analyses were performed. The results demonstrated that biomass burning was the dominant source of PM_2.5 at all locations during autumn/winter periods with PAHs having four to six rings; during the spring/summer periods, PAHs with two to three rings were more abundant and were related to petrogenic sources. The sources of PM_2.5 in the different studied areas were similar and were related to season rather than to geography. Analysis of meteorological data for the region demonstrated that the background summer PM_2.5 for the years studied was ∼8 µg/m³ while when temperatures decreased below 15°C, there was an exponential increase in the concentration of particles in the air.

KEY WORDS:

• PAHs
• particulate matter PM_2.5
• polytopic vector analysis
• principal component analysis
• source apportionment

Acknowledgments

The Ministry of Environment is thanked for all of their support and logistical help provided with the air samplers. We also acknowledge the tremendous support of all the people involved is this project that collaborated in the intensive and time consuming task of changing the filters. Lastly, we thank all of the local councils involved in this study (La Unión, Río Bueno, Los Lagos, Panguipulli and Valdivia).

Funding

The authors are grateful for the financial support of the Fondecyt Project 1130136.