Comparing ecosystem gaseous elemental mercury fluxes over a deciduous and coniferous forest

Jun Zhou; Silas W Bollen; Eric M Roy; David Y Hollinger; Ting Wang; John T Lee; Daniel Obrist

doi:10.1038/s41467-023-38225-x

Comparing ecosystem gaseous elemental mercury fluxes over a deciduous and coniferous forest

Nat Commun. 2023 May 11;14(1):2722. doi: 10.1038/s41467-023-38225-x.

Authors

Jun Zhou^{1

2}, Silas W Bollen¹, Eric M Roy^{1

3}, David Y Hollinger⁴, Ting Wang¹, John T Lee⁵, Daniel Obrist^{6

7}

Affiliations

¹ Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts, Lowell, MA, USA.
² Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
³ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁴ USDA Forest Service, Northern Research Station, Durham, NH, USA.
⁵ School of Forest Resources, University of Maine, Orono, ME, USA.
⁶ Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts, Lowell, MA, USA. daniel_obrist@uml.edu.
⁷ University of California, Agriculture and Natural Resources, Davis, CA, USA. daniel_obrist@uml.edu.

Abstract

Sources of neurotoxic mercury in forests are dominated by atmospheric gaseous elemental mercury (GEM) deposition, but a dearth of direct GEM exchange measurements causes major uncertainties about processes that determine GEM sinks. Here we present three years of forest-level GEM deposition measurements in a coniferous forest and a deciduous forest in northeastern USA, along with flux partitioning into canopy and forest floor contributions. Annual GEM deposition is 13.4 ± 0.80 μg m^-2 (coniferous forest) and 25.1 ± 2.4 μg m^-2 (deciduous forest) dominating mercury inputs (62 and 76% of total deposition). GEM uptake dominates in daytime during active vegetation periods and correlates with CO₂ assimilation, attributable to plant stomatal uptake of mercury. Non-stomatal GEM deposition occurs in the coniferous canopy during nights and to the forest floor in the deciduous forest and accounts for 24 and 39% of GEM deposition, respectively. Our study shows that GEM deposition includes various pathways and is highly ecosystem-specific, which complicates global constraints of terrestrial GEM sinks.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Air Pollutants* / analysis
Ecosystem
Environmental Monitoring
Forests
Mercury* / analysis
Tracheophyta*

Substances

Mercury
Air Pollutants