This 1991 volume presents the results of a major international and interdisciplinary study of the mechanism and consequences of surface water acidification, which is a growing environmental problem. This detailed, long-term study provides an authoritative overview of the chemical process involved in acidification and of its biological impact on freshwater life. The surface waters acidification programme (SWAP) has drawn together the many facets of this complex phenomenon. The volume includes sections on hydrochemical studies in catchments, catchment process studies, catchment manipulation experiments, chemical processes, palaeolimnological studies, biological effects on freshwater life, and modelling studies. The volume finishes with an assessment of the SWAP and its conclusions. Though the results are presented in a predominantly European context, the findings and conclusions are applicable to all those areas suffering the consequences of acidification.