Use of Membranes and Detailed HYSPLIT Analyses to Understand Atmospheric Particulate, Gaseous Oxidized, and Reactive Mercury Chemistry

Document Type

Article

Journal/Book Title

Environmental Science & Technology

Publication Date

1-6-2021

Publisher

American Chemical Society

Award Number

NSF, Division of Atmospheric and Geospace Sciences (AGS) 1951513

Funder

NSF, Division of Atmospheric and Geospace Sciences (AGS)

Volume

55

Issue

2

First Page

893

Last Page

901

Abstract

The atmosphere is the primary pathway by which mercury enters ecosystems. Despite the importance of atmospheric deposition, concentrations and chemistry of gaseous oxidized (GOM) and particulate-bound (PBM) mercury are poorly characterized. Here, three membranes (cation exchange (CEM), nylon, and poly(tetrafluoroethylene) (PTFE) membranes) were used as a means for quantification of concentrations and identification of the chemistry of GOM and PBM. Detailed HYSPLIT analyses were used to determine sources of oxidants forming reactive mercury (RM = PBM + GOM). Despite the coarse sampling resolution (1–2 weeks), a gradient in chemistry was observed, with halogenated compounds dominating over the Pacific Ocean, and continued influence from the marine boundary layer in Nevada and Utah with a periodic occurrence in Maryland. Oxide-based RM compounds arrived at continental locations via long-range transport. Nitrogen, sulfur, and organic RM compounds correlated with regional and local air masses. RM concentrations were highest over the ocean and decreased moving from west to east across the United States. Comparison of membrane concentrations demonstrated that the CEM provided a quantitative measure of RM concentrations and PTFE membranes were useful for collecting PBM. Nylon membranes do not retain all compounds with equal efficiency in ambient air, and an alternate desorption surface is needed.

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