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Submicron particles in Chile originate from the sea and human activities

Submicron particles in Chile originate from the sea and human activities

Half of the submicron particles in the Chilean coastal area originates from the sea, half are caused by human activities.

Finnish Meteorological Institute together with Centro Mario Molina Chile studied the chemical composition and origin of submicron particles (<1 μm in diameter) in Valle Alegre, the coastal area of Central Chile. It was found that the submicron particles were dominated by organic matter (42% of mass) and sulfate (39% of mass) while the mass fractions of ammonium, nitrate and black carbon were considerably smaller (13, 2 and 4% of mass, respectively).

Organic matter consisted of five different types of organic species; hydrocarbon-like organics, biomass burning organics, low-volatility oxygenated organics, semi-volatile organics and oxygenated organics formed in marine environment. Sulfate had two sources in Valle Alegre; the majority (∼70%) of sulfate was related to anthropogenic sources through the oxidation of gas phase SO2 while ∼24% of sulfate originated from the oxidation of dimethyl sulfide in the marine environment. Overall, anthropogenic sources emitted at least half of the submicron particle mass measured in Valle Alegre.

During this study, the average concentration of fine particles was relatively small (9.5 μg m-3). This could be due to the location of the measurement site that was quite far from the major emission sources. However, the concentration of sulfate was much higher than in Finland probably due to industrial sulfur emissions in Chile.

Industry is one of the major air pollution source in Chile

Chile is one of the most prosperous nations in South America and its economy is based on the mining industry. Industrial plants emit large quantities of particulates and gases causing serious air quality problems to neighboring areas. Measurements of this study were made in Valle Alegre, Valparaiso Region of Chile. Valle Alegre is a rural valley with agricultural activity but there is also a large industrial area with e.g. smelters, power plants, oil refineries and cement factories nearby, and one of the largest ports in the area.

Valle Alegre has been officially recognized as "Saturated Area" which means that mass concentrations exceed the national air quality standards for PM2.5. Today there is also a discussion to include an air quality standard of SO2. In this hypothetical scenario, is estimated that the zone could be also saturated by SO2. This paper comes as a good opportunity in order to improve significantly the air quality information available at the zone. 

Further information:

Sanna Saarikoski, Senior Research Scientist, Finnish Meteorological Institute, tel. +358 50 590 6091,

Saarikoski, S., Reyes, F., Vázquez, Y., Tagle, M., Timonen, H., Aurela, M., Carbone, S., Worsnop, D. R., Hillamo, R., Oyola, P. Characterization of submicron aerosol chemical composition and sources in the coastal area of Central Chile. Atmospheric Environment, 199, 391-401, 2019.

The research was funded by the Academy of Finland, Business Finland and the Chilean Ministry of the Environment.

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