Air pollutants effect on monoterpenes composition and foliar chemical parameters in Schinus areira L.

Monoterpenes, pigments, lipid peroxidation products, sulfur and water content expressed as dry weight/fresh weight ratio were measured in leaves of Schinus areira L. collected in Mendoza, Argentina. The sampling sites showed different SO2, NO2 and PM10 levels, which allowed setting out zones by mapping. Foliar chemical parameters in S. areira were analysed in relation to these zones. High hydroperoxy conjugated dienes (HPCD) and α-phellandrene content in foliar samples coming from areas with high SO2 levels were measured. Principal component analysis (PCA) showed a positive association among SO2, HPCD, malondialdehyde, sabinene and β-pinene. In relation to NO2 levels high values of chlorophyll (Chl)-b and Chl-b/Chl-a ratio were found. PCA showed for NO2, an association with Chl-b/Chl-a, phaeophytin-a/Chl-a ratios and α-phellandrene. As regard PM10, no significant differences were found in the chemical parameters indicating foliar damage, whereas the contents of tricyclene, α-pinene and β-pinene showed low values in the area with high levels of this pollutant. From the results, it can be inferred that the more noticeable changes in the foliar chemistry of S. areira were detected in relation to the different SO2 levels. This response was associated to an increase in the foliar oxidation processes accompanied by modifications in the levels of terpenes. This is important, as SO2 was the only pollutant whose values in the annual arithmetic mean were over the standard value of 30 ppb.