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Abstract Title: Observations of the chemistry and concentrations of reactive Hg at locations with different ambient air chemistry
Presenter Name: Mae Gustin
Company/Institution: Department of Natural Resources and Environmental Science, University of Nevada, Reno, Nevada, USA
Session: Special Session - New developments in understanding reactive mercury concentrations and chemistry
Day and Session: Thursday 28th July - Session Four
Start Time: 15:00 UTC
Co-Authors: Mae Gustin,Sarrah Dunham-Cheatham,Natalie Allen,Seth Lyman,William Johnson,Samuel Lopez,Armistead Russell,Katherine Evans

Abstract Information :

With the realization that the only automated instrument used to measure reactive Hg (RM), gaseous oxidized Hg (GOM), and particulate bound Hg (PBM) does not accurately quantify these compounds, alternate systems need to be developed. It is also important for a method to be developed that characterizes RM chemistry. The Reactive Mercury Active System (RMAS) is an alternate method for measuring RM, GOM, and PBM that uses cation exchange, nylon, and PTFE membranes to determine concentrations and chemistry. Concentrations are determined by digestion of cation exchange and PTFE membranes, and chemistry is determined by thermal desorption of nylon membranes. This system has been deployed at locations in the USA, and is currently deployed next to a highway in Atlanta, Georgia, adjacent to Great Salt Lake in Utah, adjacent to the Permian Basin at Guadalupe Mountains National Park in Texas, at Storm Peak Observatory above Steamboat Springs, Colorado, and adjacent to a highway and at a high elevation location associated with the Reno, Nevada area. RM concentrations and chemistry vary with location. Highest concentrations measured in other studies were at Mauna Loa, Hawaii (158ñ9 pg/m3), and low concentrations were measured in Maryland (11ñ2 pg/m3) . RM chemistry at the Mauna Loa site was dominated by halogen based compounds and in Maryland compounds were nitrogen, sulfur, and organic based. At the Reno and Atlanta highway locations, in the winter, roughly half of RM was PBM as oxide, sulfur, nitrogen, and organic compounds. At Great Salt Lake, RM was predominately PBM with halogenated compounds, but also oxide, S, and organic compounds. Data being developed currently, and in the past, suggest that there are multiple forms of RM that modelers must consider, and PBM is an important component of RM. This presentation will summarize concentration and chemistry data from multiple locations and discuss the implications.



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