EVASION OF MERCURY-VAPOR FROM TEE SURFACE OF A RECENTLY LIMED ACID FOREST LAKE IN SWEDEN

Mercury is emitted from soil and water surfaces, but few actual direct flux measurements have been reported. During June, 1994 we performed the first micrometeorological measurements of Hg vapor fluxes over a b oreal forest lake. Using highly precise methods with multiple replicat e samplers, we measured concentration gradients of Hg vapor, CO2 and H 2O over the lake surface. Mercury was readily emitted from the lake su rface, and we found no evidence of Hg dry deposition to the lake. Emis sion rates over the lake averaged 8.5 ng m(-2) h(-1), and appeared to be weakly influenced by water temperature and solar radiation. These f luxes were somewhat higher than those previously measured using surfac e chambers at this site.