Cloud and fog deposition: Monitoring in high elevation and coastal ecosystems. The past, present, and future.

Collection methods critical load values and total nitrogen budgets for high-elevation and fog-impacted sites requires reliable cloud and fog water deposition estimates. The cost and labor intensity of cloud/fog water sample collection have made it difficult to conduct long-term studies that would provide the data needed to develop accurate estimates. Current understanding of fog formation, transport, and the role of fog and cloud deposition in hydrogeological and biogeochemical cycles is incomplete due, in part, to lack of a concerted interdisciplinary approach to the problem.

Estimates of cloud water deposition at Mountain Acid Deposition Program sites in the Appalachian Mountains.

Cloud water deposition was estimated at three high-elevation sites in the Appalachian Mountains of the eastern United States (Whiteface Mountain, NY; Whitetop Mountain, VA; and Clingman's Dome, TN) from 1994 through 1999 as part of the Mountain Acid Deposition Program (MADPro). This paper provides a summary of cloud water chemistry, cloud liquid water content, cloud frequency, estimates of cloud water deposition of sulfur and nitrogen species, and estimates of total deposition of sulfur and nitrogen at these sites. Other cloud studies in the Appalachians and their comparison to MADPro are also summarized.

Estimates of the atmospheric deposition of sulfur and nitrogen species: Clean Air Status and Trends Network 1990-2000.

The Clean Air Status and Trends Network (CASTNet) was established by the U.S. EPA in response to the requirements of the 1990 Clean Air Act Amendments.

Measurements of Rural Sulfur Dioxide and Particle Sulfate: Analysis of CASTNet Data, 1987 through 1996.

The Clean Air Status and Trends Network (CASTNet) was implemented by the U.S. Environmental Protection Agency (EPA) in 1991 in response to Title IX of the Clean Air Amendments of 1990, which mandated the deployment of a national ambient air monitoring network to track progress of the implementation of emission reduction programs in terms of deposition, air quality, and changes to affected ecosystems.