Acid rain in the kilauea Volcano area (Hawaii)

Abstract

Acid precipitation is present and commonplace in and around Hawaii Volcanoes National Park, where thousands of hectares of rich and diverse tropical forest flourish. The existence of a strong relationship between rain volume and pH or of a strong correlation between acidity and sulfate content below a pH of approximately 4 has not been confirmed. The discrepancy between sulfate and pH raises serious questions about SO2 from Kilauea as the major source of local acidity. The 1985–1986 samples were relatively unstable at 20°C, again casting doubt on H2SO4 as the sole or major proton donor. Model experiments down to pH 2 withUsnea, a pollution-sensitive lichen, show that the anion associated with the protons is important, but that down to and including pH 3, exposure of up to 16 hr to H2SO4 and HCl does not impair photosynthetic CO2 uptake. We do not dismiss acid rain as an ecological hazard nor do we minimize the role of SO2 as a primary source of acidity, but rather demonstrate that other interpretations and alternatives exist and require more experimentation and analysis.