Naturally enough, the growing literature on this subject has been led by Canadian contributions. Though the story is now familiar, it's hard to imagine a more lucid sketch of the complex transnational components than that provided by the US-born, Ontario-based Pawlick. Five succinct chapters introduce the general situation and sum up the major targets of the threat: fresh water systems from lakes to salmon rivers, forest trees both hardwood and coniferous, soil and building materials, and--obviously not least--the lungs and nervous systems of human beings. The chief source of the problem is quite clearly understood to be sulfur dioxide released, in coal-fired plants in the US and Canadian Midwest, from the new generation of superhigh smokestacks--themselves ironically built as a ""pollution abatement"" measure--that broadcast the stuff via several routes of deposition both ""gaseous"" (the original SO2) and ""wet"" (sulfuric acid formed by reaction with water vapor and other atmospheric components). In Pawlick's exposition, the greatest single danger of lowered pH in natural water systems is the increased water-solubility of toxic metals normally bound up in compounds--chiefly aluminum, omnipresent in clay soils and liberated by acid rain into lake or stream beds and the interstices of soil structures. (Among other poisonous effects, aluminum ions apparently function as part of the secondary mechanism of Alzheimer's disease.) The final three chapters rather skimpily survey the status of current cleanup efforts and the hope of a better future technological mindset. But on balance (and despite some lurid rhetoric): a clear, intelligently presented, up-to-date treatment and a next-to-ideal introduction.