NADP Mercury Deposition Network: Opportunity to Measure Potential Trends in Hg Deposition Related to the Mercury Air Toxics Standard and Minimatta Protocol

Oral Presentation

Prepared by R. Brunette1, R. Nelson2, D. Disney2, P. Garcia-Strickland2, M. Flournoy2, D. Gay3, R. Tordon4, R. Tanabe5
1 - Eurofins Frontier Global Sciences, 11720 North Creek Parkway North, suite 400, Bothell, WA, 98011, United States
2 - Eurofins Frontier Geosciences/Global Sciences – National Atmospheric Deposition Program – Mercury Deposition Network, Mercury Analytical Laboratory And Site Liaison Support, , , United States
3 - University Of Illinois, National Atmospheric Deposition Program, , , United States
4 - Environement Canada, Meteorological Service of Canada | Service météorologique du Canada, , , Canada
5 - Environment Canada, Climate Change, Science and Technology Branch, , , Canada

Contact Information:; 425-686-3560


As part of the National Atmospheric Deposition Program (NADP ( the Mercury Deposition Network (MDN) provides an ongoing, long-term (20 year) monitoring record of mercury in wet deposition (precipitation) that today includes more than 100 active monitoring stations across the United States and Canada.

Due to recent National and International initiatives aimed at reducing mercury emissions, including the Mercury Air Toxics Standard (MATS) and Minamata protocol, the MDN is poised to potentially offer an important tool in measuring the effect of these mercury regulations.

Although MATS requires monitoring Hg at the point of the emission source, because mercury can be both regionally and globally transported, it is equally important to measure mercury entering the environment directly from the atmosphere. Some research suggests that wet deposition of mercury could contribute as much as 50-90% of the mercury loading to many inland water bodies.

The MDN is likely the longest running, standardized, peer-reviewed and quality assured Hg deposition monitoring network in North America. The MDN therefore offers the policy makers, scientists, and researchers almost 20 years of baseline Hg deposition data (prior to MATS) and the potential to measure increases/decreases of mercury deposition (trends) looking forward. There are many factors that can affect trends in mercury deposition and changes could happen very quickly or slowly over time and underlines the need for long term monitoring.

MDN Hg Deposition data is used around the world and the data is available to anyone online. The MDN currently has a need for better monitoring coverage and sponsorship of monitoring sites is open to anyone. This presentation offers information on how the MDN monitoring works, a look at Hg deposition data from the past 20 years, uses of the MDN data, and how data can potentially be used to measure long term increasing or decreasing Hg deposition trends.