Issue 5, 2011

Measurements of gaseous mercury exchanges at the sediment–water, water–atmosphere and sediment–atmosphere interfaces of a tidal environment (Arcachon Bay, France)

Abstract

The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment–water, sediment–atmosphere and water–atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment–water and the sediment–atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water–atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment–water interface ranged from −5.0 to 5.1 ng m−2 h−1 and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment–atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between −78 and 40 ng m−2 h−1 and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m−2 h−1. The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in such tidal environments exhibiting background contamination level.

Graphical abstract: Measurements of gaseous mercury exchanges at the sediment–water, water–atmosphere and sediment–atmosphere interfaces of a tidal environment (Arcachon Bay, France)

Supplementary files

Article information

Article type
Paper
Submitted
14 Jul 2010
Accepted
01 Feb 2011
First published
07 Mar 2011

J. Environ. Monit., 2011,13, 1351-1359

Measurements of gaseous mercury exchanges at the sediment–water, water–atmosphere and sediment–atmosphere interfaces of a tidal environment (Arcachon Bay, France)

S. Bouchet, E. Tessier, M. Monperrus, R. Bridou, J. Clavier, G. Thouzeau and D. Amouroux, J. Environ. Monit., 2011, 13, 1351 DOI: 10.1039/C0EM00358A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements