Total photoreducible mercury [Hg(II)RED] and photoreduction rates in the surface waters of four lakes in Kejimkujik National Park, Nova Scotia were measured monthly over a summer. The percent of THg that was photoreducible [%Hg(II)RED] decreased significantly in two of the four lakes from early to late summer: North Cranberry (maximum 42% to minimum 14%) and Big Dam East (maximum 51% to minimum 6%). Hg(II)RED was found to have a linear relationship with THg for all combined site data. THg and Hg(II)RED were found to have positive linear relationships with DOC concentrations (R2 = 0.97; n = 36; p < 0.01 and R2 = 0.75; n = 36; p < 0.01, respectively). A smaller proportion of THg was found to be photoreducible with increasing DOC concentration.
Keywords: Dissolved organic matter (DOM); Kejimkujik National Park; Mercury; Photoreduction; Reducible mercury.
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