Geochemistry and Toxicity of Aluminum in the Saguenay River, Québec, Canada, in Relation to Discharges From an Aluminum Smelter

Abstract

Abstract-The transformation of bauxite to alumina, the first step in the production of metallic aluminum (Al), generates Al-rich effluents. One installation is located near Jonquière (QC, Canada), with the effluents being discharged into the Saguenay River. We undertook an integrated geochemical and ecotoxicological study to determine if these Al discharges affected the receiving water. In the spring, summer, and autumn of 1997, samples of river water were collected from stations upstream and downstream of the effluent outfalls and from a regional reference site. Samples were analyzed for Al (e.g., particulate and dissolved Al, total monomeric and organic monomeric Al, dissolved polymeric Al) and for parameters known to affect Al speciation (pH, SO 4 , fluoride, dissolved organic carbon). Parallel samples were used for ambient toxicity tests with fathead minnow and Ceriodaphnia dubia. Concentrations of total Al (231-596 g/L) and dissolved Al (112-344 g/L) at downstream stations were 1.1 to 3.7 times higher than those at the station immediately upstream. Average levels of total and dissolved Al exceeded the Québec provincial criterion of 87 g acidrecoverable Al/L, even at sites upstream of the plant. Inorganic monomeric Al at downstream stations ranged from 22 to 88 g/ L. With the exception of a single elevated value observed at one downstream site, inorganic monomeric Al levels were Ͻ75 g/ L. Other studies in soft neutral-pH waters have shown that no toxic effects occur at this concentration of inorganic monomeric Al. None of the river water samples from stations 300 m downstream from the outfalls caused significant toxicity to C. dubia or fathead minnows. We suggest that expressing guidelines as monomeric inorganic Al would offer a more useful basis for comparison with ambient Al concentrations.

Photomineralization and photomethanification of dissolved organic matter in Saguenay River surface water

“…1), extending 165 km long from Lac Saint-Jean to Tadoussac and having a mean discharge of 1194 m 3 s −1 (Bélanger, 2003), is the principal tributary of the St. Lawrence estuary. Seasonal variations in both discharge rate and water quality tend to be equalized due to regulation by hydropower dams in the upper reach of the river (Schafer et al, 1990;Roy et al, 2000). The Saguenay River intersects the St. Lawrence estuary near Tadoussac, where tides can propagate upriver to ∼ 15 km upstream of Chicoutimi.…”

Raman Spectroscopy of the Reaction of Thin Films of Solid-State Benzene with Vapor-Deposited Ag, Mg, and Al

“…The chemistry between reactive metal atoms such as Ag, Mg, and Al and organic molecules is relevant in multiple scientific contexts, including organometallic chemistry in the condensed − and gas phases, − biological systems, interstellar media, − and geochemistry. , Indeed, numerous studies on the reactions of such metals with small organic molecules have been reported in the literature. These are typically performed on matrix-isolated metal atom–organic pairs − or on gas-phase metal cation–organic pairs. − Extensive theoretical work has also been published on such reactions. − Although this previous body of work documents the ability to study reaction chemistry of these reactive metals with organics, all previous studies have been restricted to one or two metal atoms or cations reacting with a single organic molecule.…”

“…The chemistry between reactive metal atoms such as Ag, Mg, and Al and organic molecules is relevant in multiple scientific contexts, including organometallic chemistry in the condensed 1À6 and gas phases, 7À10 biological systems, 11 interstellar media, 12À14 and geochemistry. 15,16 Indeed, numerous studies on the reactions of such metals with small organic molecules have been reported in the literature. These are typically performed on matrix-isolated metal atomÀorganic pairs 17À19 or on gas-phase metal cationÀorganic pairs.…”

The effect of fluoride on the dissolution rates of natural glasses at pH 4 and 25°C

“…This is especially the case where the manufacture of phosphoric acid and phosphate fertilizers occurs (Van Craenenbroeck and Marivoet, 1987). Other potential F contamination sources include the fluoridation of drinking water supplies, the application of Fcontaining fertilizers and pesticides, and heavy industries, such as steel, glass, cement, aluminium smelters and power stations (Leece and Scheltema, 1983;Fuge and Andrews, 1988;Skjelkvåle, 1994;Camargo, 1996;Roy et al, 2000). Fig.…”