NADP > Committees > Critical Loads of Atmospheric Deposition Committee (CLAD)> Critical Load Seminar Series

Critical Load Seminar Series


In celebration of the 50th anniversary of the Clean Air Act, we are taking a deep dive into the state of the science regarding ecosystem impacts from sulfur and nitrogen deposition. Critical loads of nitrogen and sulfur are atmospheric deposition thresholds at which ecosystem harm begins to occur. Between 1990 and 2019, annual emissions of sulfur dioxide and nitrogen dioxide emissions fell by 94% and 85%, respectively. However, deposition still harms ecosystems across the United States. Join the experts as they share how data is collected, how different ecosystem components are responding to acidic deposition, and how this information is being used in policy and land management decisions.

Seminar schedule

January 27, 2021 – Introduction to critical loads of N and S and deposition models
Speakers: Emmi Felker-Quinn (National Park Service); Mike Bell (National Park Service)

February 24, 2021 – Critical loads of N and S for epiphytic macrolichens
Speakers: Linda Geiser (U.S. Forest Service); Rob Smith (U.S. Forest Service)

March 24, 2021 – Critical loads of N and S for tree growth and survival
Speakers: Linda Pardo (U.S. Forest Service); Justin Coughlin (Environmental Protection Agency)

April 28, 2021 – Critical loads of N and S for herbaceous species and herbaceous richness
Speakers: Chris Clark (Environmental Protection Agency); Todd McDonnell (E&S Environmental Chemistry)

May 26, 2021 – Critical loads of N and S for aquatic resources
Speakers: Jason Lynch (Environmental Protection Agency, Todd McDonnell (E&S Environmental Chemistry); Leora Nanus (San Francisco State University)

June 30, 2021 – Critical loads of N and S for soil, mycorrhizae, and microbes
Speakers: Erik Lilleskov (U.S. Forest Service); Michala Phillips (U.S. Geological Survey)

July 28, 2021A synthesis of the current state of critical load science and how data are used by federal agencies
Speakers: Tara Greaver (Environmental Protection Agency); David Gay (National Atmospheric Deposition Program)

Due to a technical error, the slides from the first presentation did not show up in the recording. Slides are available here.