Photoinduced reduction of divalent mercury in ice by organic matter.
Reduction of divalent mercury and subsequent emission to the atmosphere has been identified as loss process from surface snow, but its mechanism and importance are still unclear. The amount of mercury that stays in the snow pack until spring is of significance, because during snow melt it may be released to the aquatic environment and enter the food web. Better knowledge of its fate in snow might further assist the interpretation of ice core data as paleo-archive. Experiments were performed under well-controlled laboratory conditions in a coated wall flow tube at atmospheric pressure and irradiated with light between 300 nm and 420 nm. Our results show that the presence of benzophenone and of oxalic acid significantly enhances the release of mercury from the ice film during irradiation, whereas humic acid is less potent to promote the reduction. Further it was found that oxygen or chloride, and acidic conditions lowered the photolytically induced mercury release in the presence of benzophenone, while the release got larger with increasing temperatures.
Paul Scherrer Institut, Laboratory of Radiochemistry and Environmental Chemistry, 5232 Villigen PSI, Switzerland. thorsten.bartels-rausch@psi.ch
Thorsten
T
Bartels-Rausch
Gisèle
G
Krysztofiak
Andreas
A
Bernhard
Manuel
M
Schläppi
Margit
M
Schwikowski
Markus
M
Ammann
D001577:Benzophenones / Q000737:chemistry; D002413:Cations, Divalent / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D006812:Humic Substances; D007053:Ice; D008628:Mercury / Q000737:chemistry*; D055668:Photochemical Processes; D010782:Photolysis; D012914:Snow / Q000737:chemistry
D001577:Benzophenones; D002413:Cations, Divalent; D004785:Environmental Pollutants; D006812:Humic Substances; D007053:Ice; C047723:benzophenone; D008628:Mercury