Stable carbon and nitrogen isotopic composition of bulk aerosol particles in a C4 plant landscape of southeast Brazil

The carbon and nitrogen isotopic compositions of aerosol particles collected in the Piracicaba region, where C4 plants like sugarcane and pasture dominate the land cover, were measured. For comparison, aerosol particles were also analyzed from the Santarém region, Amazon basin, where the main land cover is primary forest. The average δ13C value of samples collected in Piracicaba was equal to −20.9±0.8‰. The average δ13C of samples collected in Santarém was almost 5‰ smaller than in Piracicaba (−25.8±0.5‰). This difference between the two sites was attributed to the presence of C4 material in Piracicaba aerosol particles. On the other hand, there was no statistical difference between the average δ15N values observed in Piracicaba (10.6±2.8‰) and Santarém (11.5±2.1‰). The δ13C and δ15N values of aerosol particles collected in Santarém were higher than vegetation tissues and soil organic matter, which are the potential sources of organic matter to aerosol particles.