How damaging is acid rain? Current opinions differ widely, in part because for every proposed link between acid rain and adverse environmental effects an alternative explanation based on other phenomena can be or has been proposed, and in many cases cannot be readily dismissed. The specific areas addressed in this volume include the emissions of sulfur and nitrogen oxides, precipitation chemistry, atmospheric sulfates and visibility, surface water chemistry, sediment chemistry and abundance of diatom taxa, fish populations, and forest productivity. The book then draws conclusions about the acid deposition-phenomenon relationship, identifying phenomena which are directly acid deposition-caused and suggesting others apparently caused by human activities unrelated to acid deposition.