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Department of Chemistry SeminarCampus Calendar

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Thursday, March 11, 2021
11:00 am - 12:00 pm

Location: Virtual

Event Description: Dr. Daniel Obrist
Environmental, Earth & Atmospheric Science
University of Massachusetts-Lowell

Dry Deposition of Atmospheric Mercury Across Forests and Ecosystems: an Underestimated Global Atmospheric Mercury Sink

Abstract: Assimilation of Hg by vegetation is one of the largest global Hg flux, assimilating between 2,145 to 3,059 Mg yr−1 of atmospheric mercury each year. Most vegetation Hg originates from uptake of atmospheric gaseous elemental mercury (GEM), but direct measurements of this important atmosphere sink are largely lacking. We present a year-long direct ecosystem-atmospheric GEM exchange record using tower-based micrometeorological methods in a remote hardwood forest in Massachusetts. Cumulative GEM exchange showed a net GEM deposition of 35.1 µg m-2 over 470 days of measurements and an annual GEM deposition of 26.8 µg m-2, which exceeded atmospheric wet mercury deposition five-fold and litterfall mercury deposition, which has been used as a proxy measure for GEM deposition, three-fold. Seasonal dynamics showed the forest GEM sink to be largest during active vegetation growing periods and during midday, analogous to photosynthetic CO2 assimilation and in support of plant GEM uptake as a driver for ecosystem GEM deposition. Forest floors constituted additional GEM sinks throughout the year. Our data suggests that mercury loadings to forests are currently underestimated and, if confirmed across other forests, will constitute much larger global GEM sinks than currently proposed.

Date: Thursday, March 11, 2021
Time: 11 AM

Virtual Presentation on Zoom:
https://syracuseuniversity.zoom.us/j/94819870105?pwd=TXd0djFuRUZ2amJpOGRvSUpMR1RkUT09 Meeting ID: 948 1987 0105
Phone: +1 646 876 9923 US (New York)


Faith A. Ashmore

Sponsor: Department of Chemistry

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