GEOCHRONOLOGY FOR POLYCYCLIC AROMATIC HYDROCARBON CONTAMINATION IN SEDIMENTS OF THE SAGUENAY FJORD

The geochronology of polycyclic aromatic hydrocarbon (PAH) concentrations and fluxes to the sediments of the Saguenay Fjord, Quebec, and changes in the chemical assemblage are accounted for by concurrent developments in the region's aluminum industry. After a gradual increase in 1926 from the preindustrial background, PAH inputs increased dramatically in the 1940s after a major expansion in facilities and adoption of the Soderberg process. The assemblages of PAHs in the sediments indicate that their principal source until 1964 was atmospheric emissions, while direct discharges of scrubber effluents into the Saguenay River far exceeded the atmospheric inputs between 1964 and 1976, doubling the overall flux to the sediments. An input model based on a combined atmospheric/fluvial transport and deposition mechanism is derived from aluminum production data and compared with the observed fluxes. A linear relationship between the PAH and organic matter concentrations indicates that scavenging from the water column may be the dominant mechanism for the deposition of PAHs. © 1990, American Chemical Society. All rights reserved.