Atmospheric pollution in a tropical rain forest: effects of deposition upon biosphere and hydrosphere II. Fluxes of chemicals and element budgets.

Abstract

Three rain forest ecosystems in the Serra do Mar, theatlantic coastal mountain range of Brazil, have beeninvestigated in the frame of an interdisciplinaryGerman-Brazilian research project on dispersion,transformation and deposition of air pollutants in andaround the industrial area of Cubatao. Part I ofthis paper gives a description of the overall goals ofthe project, the area of investigation, and thematerials and methods used. It reports on the resultsof the field measurements conducted from 1991 to 1995,covering concentrations of chemicals in precipitation,soil water, surface water and litter fluxes. In thepresent paper, part II, the element fluxes arepresented with calculated concentrations in thetransport media (precipitation, seepage water,litterfall) and their respective flow rates. Elementbudgets for the ecosystem and for the soil compartmentare interpreted with respect to turnover of chemicals,including nutrients, in forest vegetation, and toprocesses of soil acidification.The forests under investigation are characterized bya very high input from the atmosphere. Between 100 and200 kg S ha-1 are annually carried into soil byprecipitation in the form of sulfate, 20 to 70 kg ofnitrogen mainly in the form of ammonium, 3 to 24 kg offluoride. Input of ammonium and organic bound nitrogenis followed by nitrification in the top soil. At themost polluted site, nitrate output with seepageamounts to 300 kg N ha-1 yr-1, sulfate output tomore than 400 kg S. Soil acidification associated withturnover of sulfur and nitrogen is followed by therelease of aluminum from soil minerals, and leachingof ionic forms of Al (up to 280 kg Al ha-1annually). Transfer of aluminum ions to groundwaterand surface water can have serious ecologicaleffects. Alkalinity is consumed, and the water issubject to acidification.