This book presents the latest scientific information and analysis concerning the costs, benefits, and environmental effectiveness of the Acid Rain Program (ARP), a bipartisan mandate under Title IV of the 1990 Clean Air Act Amendments signed into law by President George H W Bush to reduce sulphur dioxide (SO2) and nitrogen oxides (NOx) emissions from electric generating sources. Notably, the SO2 program includes the use of a creative emissions cap-and-trade program that combines the best of American science, government, and market-driven innovation. This book focuses on emission reductions from power plants, summarises changes in deposition rates and environmental impacts, and evaluates the ecological effects expected to accompany future reduction in SO2 and NOx emissions.

When we originally published Biogeochemistry of a Forested Ecosystem in 1977, the Hubbard Brook Ecosystem Study (HBES) had been in existence for 14 years, and we included data through 1974, or a biogeo chemical record of 11 years. Now our continuous, long-term biogeo chemical records cover more than 31 years, and there have been many changes. The most notable change, however, is that three of our coauthors on the original volume are now deceased. They are deeply missed in so many ways. In spite of the longer records, different trends, and new insights, we believe that the basic concepts and approaches we presented in 1977 represent the most valuable contribution of the original edition. They are still valid and useful, particularly for an introductory study of, or course in, biogeochemistry. Our goal in this revision is to preserve these fea tures, correct errors, and revise or eliminate misleading or ambiguous short-term data (11 years!), while maintaining approximately the original length and the modest cost.

A summary of the twenty-seven State-of-Science and State-of-Technology (SOS/T) Reports published in 1990 by the National Acid Precipitation Assessment Program. Cf. Pref.; p. 3.

'Acid rain' is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry. Wet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depends on many factors, including how acidic the water is, the chemistry and buffering capacity of the soils involved, and the types of fish, trees, and other living things that rely on the water. Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. When that happens, the runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone. Prevailing winds blow the compounds that cause both wet and dry acid deposition across state and national borders, and sometimes over hundreds of miles. This new book combines an excellent background article with over 900 abstracts and book citations. Easy access is provided by title, author, and subject indexes.