Deposition of Mercury at the Earth’s Surface

Viernes 25 de marzo de 2022 – 12:00 PM

IMPARTE: Dr. David A. Gay┃Coordinador del «National Atmospheric Deposition Program» (NADP) de los Estados Unidos

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RESUMEN

One of the most critical measurements needed to understand the biogeochemical cycle of mercury, and to verify emission source attribution models, is the rate of atmospheric deposition of atmospheric mercury. Mercury from the atmosphere is thought to be the largest source of mercury to most rivers and lakes across the globe. Once deposited to waterbodies, mercury is converted into an organic form (“methyl mercury”), which can bioaccumulate and biomagnify up the food chain. Mercury can reach concentration in fish, and when eaten can have profound impacts upon human health, particularly in children. This methyl mercury can also similarly adversely affect many different organisms in the ecosystem. 

Therefore, the monitoring of mercury deposition provides a method for beginning to understand the mercury problem at many locations around the globe, and for determining if the input of mercury is decreasing as we try to decrease mercury emissions from global anthropogenic sources. The goal of the Minamata Convention is to reduce mercury and mercury deposition around the world and to monitor this progress with measurements. There are few measurements of mercury and mercury deposition in Mexico. 

The National Atmospheric Deposition Program (NADP) operates two mercury deposition networks: the Mercury Deposition Network (MDN) and the Atmospheric Mercury Network (AMNet). These networks operate sites across North America and in Taiwan to monitor mercury in wet deposition (in the MDN) and to estimate dry deposition (in the AMNet). Together, these observations are used to estimate the total deposition of mercury to the Earth’s surface in North America. We are planning to work with UNAM Scientists to establish several AMNet sites in Mexico City, and the surrounding area. With gaseous mercury measurements, we can obtain 5 minute observations of gaseous elemental mercury. And with these measurements, we can provide longterm averages of mercury in the atmosphere (nanograms/m3), estimates of dry deposition to the surface (nanograms/square meter day), and opportunities to determine of the sources of this mercury. In this talk we will discuss the global mercury problem, and results from both observational networks in the US. Additionally, we will show some of the advantages that these measurements for Mexico, with its own monitoring sites and research.

Dr. David A. Gay

Education

Ph.D. Environmental Sciences (concentration in Climatology), University of Virginia, Charlottesville, 1996.  Dissertation:  Variation of Rural, Western U.S. Visibility and Aerosol Characteristics under Different Synoptic Conditions (Dr. Robert E. Davis, advisor).

M.S. Environmental Sciences (concentration in Atmospheric Sciences), Washington State University, Pullman, 1987. Thesis:  A National Inventory of Biogenic Hydrocarbon Emissions Based upon a Simple Forest Canopy Model (Dr. Brian Lamb, advisor).

B.S. Environmental Sciences (concentration in Water Quality, Chemistry, Statistics), McNeese State University, Lake Charles, LA, 1985.

Professional Experience

Research Scientist and Coordinator, National Atmospheric Deposition Program, Illinois State Water Survey. Primary duties include project management of a five-network system (380 sites), including budgeting and expenses, and supervision of two laboratories and thirty employees, Principal investigator of the grant. January 2008 to present (except March 2018-Mar 2020). Website: http://nadp.slh.wisc.edu/.

Managing Editor, Atmospheric Environment, Elsevier, Inc. Responsible for data to day management of Atmospheric Environment submissions. December, 2019 to present.

Research Scientist, National Atmospheric Deposition Program, Wisconsin State Laboratory for Hygiene, University of Wisconsin. Primary duties include transition of the NADP project from the University of Illinois to the University of Wisconsin, include project management of a five-network system (380 sites), including budgeting and expenses. March 2018 to present.

Adjunct Faculty, Parkland College, Champaign IL, Fall 2018, Spring 2019, Fall 2019.  Introduction to the Atmosphere and Weather, and Laboratory (freshman level). Fall and Spring Semesters 2018/2019. Adjunct Faculty, Eureka College, Eureka IL. Earth Science and Laboratory (freshman level). Spring 2019.

Associate Research Scientist, Center for Atmospheric Science, Illinois State Water Survey. Primary duties included research project administration, data quality assurance and analysis, and statistics. Group research function is atmospheric monitoring of air pollutants and climate, atmospheric chemistry, etc. National Atmospheric Deposition Network’s Assistant Coordinator. Responsible for the Mercury Deposition Network. Primary duties included management of network and employees, day-to-day operation of network.  May, 2003 to May, 2007.

 Self-Employed Business Owner Owned and operated the Mountain Handcrafts Co. Primary duties included day-to-day operations, budgets, bookkeeping, management, and purchasing. April 1996 to May 2003.

Assistant Lecturer, University of North Carolina, Charlotte.  Two one-year contracts.  Introductory Atmospheric Interactions (Physical Geography, freshman level, four sections); Soil Science and Laboratory (junior level, four sections); Synoptic Meteorology and Laboratory (junior level, two sections); Senior Synoptic Meteorology Independent Study (two sections). August 1994 to June 1996.

Environmental Scientist CH2M Hill, Inc. (Engineering), Portland, OR, July 1987 to June 1990; part time from June 1990 to June 1992.  Responsible for numerical modeling (UNIMAP); emission rate estimates; meteorological monitoring and analyses; air sampling for criteria pollutants; hazardous waste ambient air sampling (evacuated canisters, absorbent traps); proposal and report writing; data gathering, accuracy checks and presentation; quality assurance plans.  Hazardous waste trained and experienced. Clients included both industry and government.