Since 1981, the USGS has been the lead Federal agency for the monitoring of wet atmospheric deposition (chemical constituents deposited from the atmosphere via rain, sleet, and snow) in the United States for the interagency National Atmospheric Deposition Program (NADP).
Featured: Atmospheric Deposition of Mercury on Eastern Forests
Atmospheric mercury (Hg) deposition to forests is of concern because half of the land cover in the eastern USA is forest. Scientists learned that forests canopies record changes in atmospheric mercury over time.
The USGS supports about one-third (79 of approximately 250) of the NADP-National Trends Network sites, which measure acidity, sulfate, nutrients and other major ions in precipitation. The USGS also supports sites in the 100-site NADP-Mercury Deposition Network and the NADP-Mercury Litterfall Network. These networks provide scientists, resource managers, and policymakers with long-term, high-quality atmospheric deposition data used to support research and decision-making in the areas of air quality, water quality, agricultural effects, forest productivity, materials effects, ecosystem studies, watershed studies, and human health.
Below are highlights of FY2019 accomplishments and planned activities for FY2020.
The NWQP’s National Atmospheric Deposition Program presented results of an urban-to-rural gradient study of atmospheric nitrogen deposition in the Denver, Colorado metro area. The results suggest that establishment of more urban sites in the NADP National Trends Network, which is currently weighted towards rural areas, would provide greater accuracy in the annual national maps produced by the network.
Two papers were included in a special issue of the journal Environmental Pollution on atmospheric nitrogen deposition. The first explores the efficacy of remediation strategies designed to mitigate the deleterious effects of atmospheric nitrogen deposition on forested ecosystems, and the second predicts the trajectory of forests that are currently recovering from decreasing loads of atmospheric nitrogen deposition over the past few decades.
In FY2020, a study will be released that describes a new method for characterizing dry deposition. This approach could prove helpful in characterizing atmospheric deposition of nutrients, microplastics, and other pollutants that are transmitted through atmospheric dust deposition.
“NADP has played a key role in providing long-term monitoring data to assess policies aimed at reducing air pollution and ecological impacts of atmospheric deposition. The program includes monitoring networks for programs including acid rain, mercury, and reactive nitrogen. Policy implementation for acid rain mitigation is relatively mature and the evolution of these policies is reflective in NADP monitoring data. Programs for regulating mercury and reactive nitrogen deposition are less mature and NADP monitoring will be critical in future years to assess control program efficacy.”
James Schauer, PhD, PE, MBA, Director, Wisconsin State Laboratory of Hygiene, August 2018