GC116-0008
High Levels of Tropospheric O3 and NOx in The Andes of Central Chile: An Alert of Harmful Pollutants in a Fragile Environment

Wednesday, 16 December 2020
Poster
Maria Ruggeri1, Víctor Vidal2, Tomás Rafael Bolaño-Ortiz1, Luis Diaz-Robles3 and Francisco Cereceda-Balic2, (1)Universidad Técnica Federico Santa María, Centre for Environmental Technologies (CETAM), Valparaíso, Chile, (2)Universidad Técnica Federico Santa María, Centre for Environmental Technologies (CETAM), Valparaiso, Chile, (3)Universidad de Santiago de Chile, Department of Chemical Engineering, Santiago, Chile
Abstract:
Ozone (O3) and its precursors, among which nitrogen oxides (NOx) and Organic Volatile Compounds (VOCs) stand out, are considered tropospheric pollutants, since exposure to these causes adverse effects on the environment and human health. For this reason, they have received more attention in urban areas. However, these substances can also be present up in the mountains and cause local effects on remote ecosystems. Such is the case of Portillo (3000 masl), Chilean Central Andes, where there are some conditions that favor the formation of tropospheric O3 from NOx and VOCs: high levels of solar radiation, NOx and VOCs transported from the valley and produced in-situ by the intense local vehicle traffic (2,000 vehicles daily) from the road that connects Chile and Argentina, which passes across the study area.

In order to identify levels and temporal variations of O3 and NOx, data were measured in Portillo from January to May 2019 using an air quality monitoring station Haz-Scanner™ model HIM-6000 (Environmental Devices, USA), which measures criteria air pollutants, with 5 minutes resolution. The average daily evolution has been studied, showing that in the case of O3, very high levels occurred during summer months, with a marked tendency to decrease towards the month of May, as a response to a decrease in solar radiation. These levels resulted even higher than those registered in Santiago City by the National Air Quality Network. Hourly O3 tropospheric levels reached 119.1 ppb in February (the month of highest vehicle traffic during the summer), but in all the studied months these widely exceeded 61 ppb, pointed by Chilean legislation as health harmful threshold. Hourly NOx showed a more stable behavior during the analyzed period, with a slight tendency to decrease, mainly related to reduction in vehicular traffic. Hourly maximums of O3 were observed in the early afternoon (15-17 hs), while the daily cycle of NOx is influenced by vehicle traffic, which has a seasonal pattern.

These findings are key pieces to begin evaluating the effects that these high levels of O3 can have on the Andean Cryospheric ecosystem and organisms, considering their highly harmful oxidizing effects.

Acknowledgments: Fondecyt-ANID Postdoc. 3190513, Fondef-ANID IDeA I+D ID19I10359

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