A fluvial mercury budget for Lake Ontario.
Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition.
Department of Civil and Environmental Engineering, 151 Link Hall, Syracuse University , Syracuse, New York 13244, United States.
Joseph S
JS
Denkenberger
Charles T
CT
Driscoll
Edward
E
Mason
Brian
B
Branfireun
Ashley
A
Warnock
D004784:Environmental Monitoring / Q000379:methods*; D060106:Lakes / Q000032:analysis / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D009864:Ontario; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
D014874:Water Pollutants, Chemical; D008628:Mercury