this volume contains reviewed papers from biogeomon, the third international symposium on ecosystem behavior, held at villanova university in june 1997 and attended by over 240 participants from 28 countries. earlier biogeomon meetings emphasized mostly geochemical research conducted in small watersheds. as is evident from this collection of papers, biogeomon has broadened its scope considerably to include research conducted in much larger watersheds, often assessing landscape or regional patterns and processes. major themes include acidification of soils and waters, biogeochemical implications of nitrogen and sulfur deposition, and gas fluxes from the land to the atmosphere. collectively, the papers in this volume present a variety of approaches to biogeochemical research at the ecosystem level, including monitoring, field and laboratory manipulations, stable and radioisotopic tracers, modeling, and geographic information system analyses. this book will be of interest to researchers in biogeochemistry, ecosystem ecology, global change, and anthropogenic pollution, as well as to natural resource managers and policy specialists.