Photochemical formation of volatile mercury in high Arctic lakes

Formation rates of dissolved gaseous mercury (DGM) were measured in three high (74 degrees N) Arctic lakes and one wetland. The rate of formation of DGM was controlled by (1) the intensity of solar radiation, particularly ultraviolet-B (280-320 nm) and ultraviolet-A (320-400 nm) wavebands and (2) the concentration of available photoreducible Hg(II) complexes. Additions of hydrogen peroxide and of fulvic acids did not enhance DGM formation rates in our experiments. This study illustrates that photoreduction of mercury occurs in a wide range of aquatic systems even in the high arctic where radiation levels are lower but continue for the entire day during the summer.