Atmospheric Deposition

Over the past decade there has been considerable interest in the effects of atmospheric deposition on forest ecosystems. This volume summarizes the results of the Integrated Forest Study (IFS), one of the most comprehensive research programs conducted. It involved intensive measurements of deposition and nutrient cycling at seventeen diverse forested sites in the United States, Canada, and Norway. The IFS is unique as an applied research project in its complete, ecosystem-level evaluation of nutrient budgets, including significant inputs, outputs, and internal fluxes. It is also noteworthy as a more basic investigation of ecosystem nutrient cycling because of its incorporation of state-of-the-art methods, such as quantifying dry and cloud water deposition. Most significantly, the IFS data was used to test several general hypotheses regarding atmospheric deposition and its effects. The data sets also allow for far-reaching conclusions because all sites were monitored over the same period using comparable instruments and standardized protocols.

Atmospheric deposition is the result of air pollution gases and aerosols leaving the atmosphere as "dry" or "wet" deposition. Little is known about just how much pollution is deposited onto soils, lakes and streams. To determine the extent and trends of forest exposure to air pollution, various types of monitoring have been conducted. In this study, we evaluate data from different rural air monitoring programs to determine whether or not they may have wider applications in resource monitoring and protection. This report analyzes location-specific data collected by three national programs: The CASTNET (NDDN) Network supported by the Environmental Protection Agency, the IMPROVE (Interagency Monitoring of Protected Visual Environments) network supported by federal land managers, and the NADP/NTN program supported by many agencies.

The First International Nitrogen Conference provided an opportunity for researchers and decision-makers to exchange information on environmental pollution by nitrogen compounds on three scales: global, continental/regional and local. The main topics were air, ground water and surface water pollution; emission sources, atmospheric chemistry, deposition processes and effects; disturbance of nitrogen cycles, critical loads and levels; assessments, policy development and evaluation; target groups and abatement techniques; and new approaches leading to an integrated abatement strategy.The peer-reviewed papers from the Conference presented in this volume will provide readers with a comprehensive review of the transport, deposition and impact on ecosystems of nitrogen.

Ecosystem effects from air pollution in the Adirondacks, Catskills, and elsewhere in New York have been substantial. Efforts to characterize and quantify these impacts, and to examine more recent recovery, have focused largely on surface waters, soils, and forests. Lakes, streams, and soils have acidified. Estuaries have become more eutrophic. Nutrient cycles have been disrupted. Mercury has bioaccumulated to toxic levels. Plant species composition has changed. Some surface waters show signs of partial chemical recovery in response to emissions control programs, but available data suggest that soil chemistry may continue to deteriorate under expected future emissions and deposition. Resource managers, policymakers, and scientists now need to know the extent to which current and projected future emissions reductions will lead to ecosystem recovery.In this book, Timothy J. Sullivan provides a comprehensive synthesis of past, current, and potential future conditions regarding atmospheric sulfur, nitrogen oxides, ammonium, and mercury deposition; surface water chemistry; soil chemistry; forests; and aquatic biota in New York, providing much needed information to help set emissions reduction goals, evaluate incremental improvements, conduct cost/benefit analyses, and prioritize research needs. He draws upon a wealth of research conducted over the past thirty years that has categorized, quantified, and advanced understanding of ecosystem processes related to atmospheric deposition of strong acids, nutrients, and mercury and associated ecosystem effects. An important component of this volume is the new interest in the management and mitigation of ecosystem damage from air pollution stress, which builds on the "critical loads" approach pioneered in Europe and now gaining interest in the United States.This book will inform scientists, resource managers, and policy analysts regarding the state of scientific knowledge on these complex topics and their policy relevance and will help to guide public policy assessment work in New York, the Northeast, and nationally.