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Main Title Mercury Deposition and Sources for the Upper Great Lakes Region.
Author Glass, G. E. ; Sorensen, J. A. ; Schmidt, K. W. ; Rapp, G. R. ; Yap, D. ;
CORP Author Environmental Research Lab.-Duluth, MN. ;Minnesota Univ., Duluth. Coll. of Science and Engineering. ;Ontario Ministry of the Environment, Rexdale.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-91/326;
Stock Number PB92-120500
Additional Subjects Mercury(Metal) ; Water pollution ; Deposition ; Air water interactions ; Pollution sources ; Great Lakes ; Concentration(Composition) ; Air pollution ; Precipitation(Meteorology) ; Biological effects ; Trends ; Ions ; Fishes ; Environmental transport ; Precipitation washout ; Reprints ; Northeast Region(Minnesota)
Library Call Number Additional Info Location Last
NTIS  PB92-120500 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 17p
Mercury concentrations and depositions for northeastern Minnesota were measured in precipitation to investigate depositional trends, relationships with major cations and anions, and possible source emission regions. Results for 1987-1990 showed that environmentally significant amounts of Hg are present in precipitation and air and are subsequently deposited to remote lake watersheds. Volume-weighted concentrations of total Hg in precipitation averaged about 18 ng Hg/L with calculated annual depositions near 15 micrograms Hg/sq m. Mercury concentrations in precipitation are positively correlated with the major ions, conductivity, and pH, and are negatively correlated with precipitation volume. The best predictor equation from stepwise regression has an r(sup 2) of 0.65 with Mg and chloride concentrations as predictor variables. From measurements of Hg in rain concentrations as a function of time within events, scavenging ratios for 'washable' Hg were calculated to be 140 + or - 80 (mass based at a 1 mm/hr precipitation rate). Up to about 10% of the total Hg in air is subject to washout by precipitation for a given event. Air parcel back-trajectories indicate that possible source regions within 72-hr travel time were located mostly to the south, southeast, and southwest, up to 2500 km distance away but local sources may also be important. (Copyright (c) 1991 Kluwer Academic Publishers.)