Seasonal and altitudinal variations of legacy and current-use pesticides in the Brazilian tropical and subtropical mountains

Polyurethane foam (PUF) disk passive air samplers were deployed over summer (December–March) and winter (June–August) periods in 2007–2008 along altitudinal gradients in Brazilian southeastern and southern mountain regions. As part of the Global Atmospheric Passive Sampling (GAPS) Network, this work was initiated to address the lack of knowledge on the fate of legacy and current-use pesticides in South America, particularly in mountainous regions. Of the pesticides measured, concentrations in air were dominated by the current-use pesticides (CUPs) endosulfan (and its metabolite, endosulfan sulphate (EndoSO4)) and chlorpyrifos. Other pesticides that were regularly detected included α- and γ-hexachlorocyclohexanes (HCHs), dieldrin, heptachlor epoxide and p,p′-DDE. Highest air concentrations were observed for total endosulfan (Endo I + Endo II + EndoSO4) (100s–1000s pg m−3), followed by chlorpyrifos, ΣDDT (mainly o,p′-DDT + p,p′-DDE), ΣHCH (α-HCH + γ-HCH), dieldrin and heptachlor epoxide. Seasonal variations did not show any clear trends for pesticides, except for endosulfan which reached concentration values one order of magnitude higher during summer at all sites compared to levels during winter. Along the altitudinal gradients, some pesticides showed higher atmospheric concentrations at sites above 1500 m which may indicate efficient high-altitude transport from regional sources. Northerly and southerly air back trajectories appeared to be the main continental influences at the two highest-altitude sites in both mountain regions. These trajectories travelled over extended crop areas from central Brazil to Argentina. A strong, positive correlation between air concentration and altitude was observed (Spearmanʹs correlation, p < 0.05) for endosulfan, consistent with previous studies of endosulfan in mountainous regions in South America.