DISSOLVED ARSENIC IN THE ST-LAWRENCE ESTUARY AND THE SAGUENAY FJORD, CANADA

Over the salinity range of 0-31‰, total dissolved arsenic increased from 6.6 nM to 18.9 nM in the St Lawrence Estuary and from 1.1 nM to 18.7 nM in its tributary Saguenay Fjord. Arsenic concentrations in the riverine end-members were similar to the lowest values found in other world rivers and reflect the geology of the respective drainage basins. In the two study areas, arsenic was nearly conservative during estuarine mixing. A close examination of the spatial distribution of arsenic in the interior basin of the Saguenay Fjord suggests, however, an enrichment of arsenic in the bottom waters by a flux from the sediments. © 1990.