Behavior of Tropospheric Ozone and its Relationship to Sugar Cane Burning in the São Paulo State

Abstract

The production of ethanol for use as biofuel has increased in São Paulo State. Sugar cane is reaped after its chaff is burnt off. This process releases considerable quantities of NOx and VOCs compounds known to be precursors of the formation of tropospheric ozone. The purpose of this work was to seek evidence that one of the principal sources of tropospheric ozone was the burning of the sugar cane chaff in the fields. Towards this end, samples of the ozone were taken concomitantly every fifteen days, during the period January 2008 to December 2009 from five cities which receive the effects of the sugar cane chaff burning as well as one city (the reference one) that does not and is located close to 100 km from the State Capital. The O3 concentration varied from 6 to 148.9 μg m-3 in cities 400 km from the capital which receive the effects of biomass burning and from 14.1 to 64.2 μg m-3 in the reference city. The cities with sugar cane culture have the highest concentration of O3 during the harvest when the chaff is burnt off. The highest ozone peak in the reference city was in the summer. The conclusion is that the ozone has a direct relationship to biomass burning.