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Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange

Osterwalder, Stefan and Nerentorp, M. and Zhu, Wei and Jiskra, M. and Nilsson, E. and Nilsson, Mats and Rutgersson, A. and Soerensen, A. L. and Sommar, J. and Wallin, Marcus and Wangberg, I and Bishop, Kevin (2021). Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange. Global Biogeochemical Cycles. 35 , e2020GB006742
[Research article]

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Abstract

Air-sea exchange of gaseous elemental mercury (Hg-0) is not well constrained, even though it is a major component of the global Hg cycle. Lack of Hg-0 flux measurements to validate parameterizations of the Hg-0 transfer velocity contributes to this uncertainty. We measured the Hg-0 flux on the Baltic Sea coast using micrometeorological methods (gradient-based and relaxed eddy accumulation [REA]) and also simulated the flux with a gas exchange model. The coastal waters were typically supersaturated with Hg-0 (mean +/- 1 sigma = 13.5 +/- 3.5 ng m(-3); ca. 10% of total Hg) compared to the atmosphere (1.3 +/- 0.2 ng m(-3)). The Hg-0 flux calculated using the gas exchange model ranged from 0.1-1.3 ng m(-2) h(-1) (10th and 90th percentile) over the course of the campaign (May 10-June 20, 2017) and showed a distinct diel fluctuation. The mean coastal Hg-0 fluxes determined with the two gradient-based approaches and REA were 0.3, 0.5, and 0.6 ng m(-2) h(-1), respectively. In contrast, the mean open sea Hg-0 flux measured with REA was larger (6.3 ng m(-2) h(-1)). The open sea Hg-0 flux indicated a stronger wind speed dependence for the Hg-0 transfer velocity compared to commonly used parameterizations. Although based on a limited data set, we suggest that the wind speed dependence of the Hg-0 transfer velocity is more consistent with gases that have less water solubility than CO2 (e.g., O-2). These pioneering flux measurements using micrometeorological techniques show that more such measurements would improve our understanding of air-sea Hg exchange.

Authors/Creators:Osterwalder, Stefan and Nerentorp, M. and Zhu, Wei and Jiskra, M. and Nilsson, E. and Nilsson, Mats and Rutgersson, A. and Soerensen, A. L. and Sommar, J. and Wallin, Marcus and Wangberg, I and Bishop, Kevin
Title:Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange
Series Name/Journal:Global Biogeochemical Cycles
Year of publishing :2021
Volume:35
Article number:e2020GB006742
Number of Pages:17
Publisher:AMER GEOPHYSICAL UNION
ISSN:0886-6236
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Meteorology and Atmospheric Sciences
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Oceanography, Hydrology, Water Resources
Keywords:evasion, flux, REA, transfer velocity, uptake
URN:NBN:urn:nbn:se:slu:epsilon-p-113579
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-113579
Additional ID:
Type of IDID
DOI10.1029/2020GB006742
Web of Science (WoS)000690773700010
ID Code:25367
Faculty:S - Faculty of Forest Sciences
NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(S) > Dept. of Forest Ecology and Management
(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By: SLUpub Connector
Deposited On:16 Sep 2021 14:25
Metadata Last Modified:16 Sep 2021 14:31

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