Passive sampler-derived concentrations of PAHs in air and water along Brazilian mountain transects

Abstract

The atmospheric deposition of semi-volatile organic compounds represents a potential threat to pristine mountains, in particular by persistent toxic substances which have high environmental mobility, potential for bioaccumulation and display toxic effects even at relative low concentrations. Low density polyethylene passive samplers were deployed in upland surface waters and the overlying atmosphere in subtropical and tropical mountain regions in south and southeast Brazil, respectively, to determine the concentrations, transport and sources of freely dissolved and gaseous polycyclic aromatic hydrocarbons (PAHs) along altitudinal gradients. Gaseous PAH concentrations (0.70–90 ng m−3) were dominated by phenanthrene and fluorene, though methylnaphthalenes displayed high concentrations at upland sites. Fluoranthene and chrysene were the most frequently detected PAHs in shallow waters (10–110 pg L−1). Individual PAHs indicated a wood/grass combustion origin at both national parks due to current and historical man-made fires, with a minor petrogenic fingerprint, probably due to the proximity of highway traffic and touristic activities. A slightly increasing trend of 2–3 ring PAHs was observed along tropical elevation transect which may reflect long-range atmospheric transport of more volatile PAHs over tropical elevated altitudes. However, local PAH emission sources probably explain the opposite trend detected at subtropical elevation transect.