Sources and Fluxes of Mercury in the St. Lawrence River

Abstract

A mass balance approach, based essentially on the reconstruction of daily fluxes and circumscribed by strict error calculations, was designed to quantify the main mercury sources for the St. Lawrence and its tributaries, which constitute a large river system. High-frequency samplings were performed over an 18-month period (1995−1996) at the main water inputs and the mouth of the river. Minor tributaries and the Montreal effluent were also sampled. This strategy allowed models to be obtained that relate mercury concentrations in solution and in particles to the hydrological regime. The calculated budget was balanced relative to the calculated errors of the estimates. Gross mercury export from the river was found to be 5.9 kmol yr-1 (73% as particulate). Tributaries and internal erosion of the river contributed equally for a total of 75% of this gross load, whereas the Upper St. Lawrence River, which is almost exclusively composed of Lake Ontario waters, accounted for less than 10%, and inventoried anthropogenic point sources accounted for about 5%. Dissolved mercury was mainly from north shore tributaries, and particulate mercury was largely from erosion of the river bed and banks. On the basis of the present results as well as estimates of atmospheric deposition from the literature it can be inferred that at least 88% of deposited mercury was retained in the watersheds.

Mercury in Abiotic Matrices of Clear Lake, California: Human Health and Ecotoxicological Implications

“…à References: 1, this study; 2, Gill and Bruland (1990);3, Gill and Bruland (1992);4, Bonzongo et al (1996);5, Henry et al (1995);6, Jacobs et al (1995);7, Bloom and Effler (1990);8, Parks et al (1989);9, Jackson (1986); 10, Cossa and Gobeil (2000); 11, Quemerais et al (1999);12, Horvat et al (2003); 13, Kotnik et al (2002);14, Watras et al (1995a);15, Watras et al (1995b);16, Watras et al (1998);17, Sullivan and Mason (1998);18, Monson and Brezonik (1998);19, Driscoll et al (1994);20, Wong et al (1997);21, Vaidya and Howell (2002); 22, Lee and Hultberg (1990). 0.486, and 0.560 mg/kg, respectively. Clear Lake sediments at sites far distant from the mine, with TotHg concentrations of ;1 mg/kg or less, exceed the TEL by ;10 times and exceed the PEL and UET toxic criteria by a factor of approximately two to three.…”

A synthesis of rates and controls on elemental mercury evasion in the Great Lakes Basin

“…The rates of Hg volatilization reported in the literature range from < 5 ng/m 2 -hr from pristine lakes and forest soils to >10 000 ng/m 2 -hr from contaminated soils (Amyot et al 2004;Gustin et al 2003). Gaseous Hg o has an atmospheric residence time of around 1 year (Fitzgerald and Mason 1997;Smith-Downey et al 2010 Quémerais et al (1999) estimated that the fluvial loss of total…”

Physical Controls on Total and Methylmercury Concentrations in Streams and Lakes of the Northeastern USA

“…Louis et al, 1996;Babiarz et al, 1998;Balogh et al, 1998;Grigal, 2002). Superimposed on these landscape controls are seasonal and event dynamics that tend to increase concentrations and fluxes of HgT and MeHg through increased water flux, sediment movement, and DOC increases (Babiarz et al, 1998;Que´merais et al, 1999;Schwesig and Matzner, 2001). In particular, hydrologic events such as snowmelt and summer storms can be very important to the flux of Hg (Bishop et al, 1995b;Scherbatskoy et al, 1998;Allan et al, 2001;.…”