Mercury air surface exchange flux: A field study in the Bay Saint-Francois wetlands, Quebec, Canada

Mercury (Hg) is a highly mobile environmental pollutant that is toxic to both human and wildlife at extremely low concentration. Aquatic ecosystem and especially wetlands are important environments for Hg biochemical transformation and cycling.; An intensive two-part field study was conducted in the Bay Saint-Francois (BSF) wetlands (Quebec, Canada) from May to September 2003. The first part of the study was about atmospheric Hg exchange fluxes with water, soil and vegetation on water. Mercury air-surface exchanges with these compartments were measured using a dynamic flux chamber coupled with a Tekran RTM analyzer. Mercury flux measured over these components exhibits a consistently diurnal pattern with maximum evasion occurring during daytime and minimum fluxes at night. Daytime Hg flux is several times higher than the flux during nighttime. Measured mean Hg fluxes over soil is 1.29 ng/m 2/h, which has the highest flux rate compared with the air surface exchange with water (mean flux = 0.32 ng/m2/h) and with vegetation on water (mean flux = 0.68∼1.24 ng/m2/h at 4 sampling locations). (Abstract shortened by UMI.)...