Analysis of PM2.5 in Córdoba, Argentina under the effects of the El Niño Southern Oscillation

- Córdoba has PM2.5 levels well above WHO standards for the (2014-2016) period.
- Heavy levels of toxic metal concentrations are found in the City.
- Combustion and traffic-related emission processes are the major sources of PM2.5.
- The effect of ENSO on PM2.5 speciation data was analyzed.

In this work, PM2.5 samples were collected in the winter-spring months of 2014-2016 at an urban site in Córdoba. Córdoba is the second largest city in Argentina and is an important industrial and touristic center. The collected samples were individually analyzed for chemical composition using different techniques. The soluble inorganic ions and carbonaceous particles were determined from bulk aerosol samples for the first time in the city. The mass concentrations of PM2.5, organic carbon, elemental carbon, inorganic ions and metals were determined according to the mass balance. The dominant mass components were organic matter and elemental carbon (54.8%), mineral dust (6.1%), secondary inorganic aerosols (3.0%), and salt (1.2%). A principal component analysis was applied to the samples and resulted in five major factors that explained 79% of the variance in PM2.5. These factors represented combustion, industrial sources, soil dust, secondary inorganic aerosol, and salt, and each explained between 11% and 20% of the variance. A comparison with the results from a previous campaign (2010-2011) revealed appreciable changes in the PM2.5 chemical composition. These changes were attributed to the two extreme meteorological conditions that prevailed in the region. The years 2014-2016 were largely dominated by the warm phase of the El Niño-Southern Oscillation, which leads to humid and cold weather in the Córdoba region, while the samples from 2010 to 2011 were collected during the dry and hot years resulting from the La Niña regime.