Air Particulate Matter, Black Carbon, and Elemental Concentrations and Source Apportionment in Calaca, Batangas

Abstract

Urbanization is among the leading causes of increased air particulate pollution in Southeast Asia. This situation puts Calaca, Batangas – a first-class rural municipality transitioning to a renowned industrial hub – at risk of the harmful effects of air particulate matter (PM). To determine the composition and possible sources of air pollution in Calaca, ambient air particulate samples were collected from December 2018 to March 2019. A total of 52 filter samples, 26 each from the PM10–2.5 and PM2.5 fractions, were collected and analyzed for PM10, PM2.5, multiwavelength black carbon (BC), and elemental concentrations. Average PM10 and PM2.5 mass concentrations were 34.01 ± 12.03 μg/m3 and 10.62 ± 4.86 μg/m3, respectively. These concentrations comply with the annual National Ambient Air Quality Guideline Values (NAAQGV) of the Philippine Clean Air Act of 1999 but exceed the prescribed guideline value of the World Health Organization (WHO). Results from energy-dispersive x-ray fluorescence (EDXRF) spectroscopy, a nuclear analytical technique, showed 14 elements present in the PM2.5 fraction – namely S, Si, K, Fe, Ca, Al, Cl, Mn, Na, Ti, Zn, Ni, Sc, and Cu arranged in decreasing average concentrations. Average biomass (BBC) and vehicular black carbon (VBC) concentrations from multiwavelength analysis were 0.7 ± 0.3 μg/m3 and 0.7 ± 0.6 μg/ m3, respectively. By reconstructing masses using these data, contributions of different sources of air PM were determined to be salt (0.54%), soil (11.31%), (NH4)2SO4 (61.15%), VBC (6.33%), and BBC (6.28%). Conditional probability function (CPF) determined that sources of PM are likely located at the 30–60° and 180° directions from the sampling site. This study provides baseline data for the chemical composition and source identification of PM in Calaca, Batangas.