Acetic and formic acid concentrations in rainwater from two tropical forest reserves in the State of São Paulo (Brazil) were measured in order to establish possible correlations with land-use change. The Brazilian Atlantic forest in the State of São Paulo is one of the most threatened ecosystems as only 1.8% of its original coverage is left. Morro do Diabo reserve is an isolated fragment of inland Atlantic tropical forest (tropical semi-deciduous mesophytic broadleaf forest) with low annual rainfall (1000-1500mm) and Intervales reserve is an important fragment of Atlantic tropical forest (ombrophilous dense forest, that shows the highest diversity in Brazil) with high annual rainfall (1700-2000mm). We collected and analyzed rainwater from both reserves during one year (2002-2003). Acetic and formic acid account for a great portion of organic acids in rainwater, showing a similar behavior to that of the Central Amazon. Acetic acid is the major constituent, followed by formic acid, contradicting results from French Guiana's and Venezuela's cloud forests. Significant correlation between DOC and acetate and DOC and H+ indicate that there is a combination of inorganic and organic sources of acidity in rainwater in reserves of the State of São Paulo. Land-use changes, direct emissions from biomass burning, agricultural practices, motor vehicle and industrial emissions could be explanations for these results.
Submetido por Vanessa P. S. Almeida em 18-MAR-2004