Tidally induced variations of pH at the head of the Laurentian Channel

MUCCI, ALFONSO; GUSTAVO FERREYRA

CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: Otawa; Año: 2018

0706-652X

The head of the Laurentian Channel (LC) is a very dynamic region of exceptional21 biological richness. To evaluate the impact of freshwater discharge, tidal mixing, and biological22 activity on the pH of surface waters in this region, a suite of physical and chemical variables was23 measured throughout the water column over two tidal cycles. The relative contributions to the24 water column of the four source-water types that converge in this region were evaluated using an25 optimum multi-parameter algorithm (OMP). Results of the OMP analysis were used to reconstruct26 the water column properties assuming conservative mixing, and the difference between the model27 properties and field measurements served to identify factors that control the pH of the surface28 waters. These surface waters are generally undersaturated with respect to aragonite, mostly due toPage 1 of 44 Can. J. Fish. Aquat. Sci. Downloaded from www.nrcresearchpress.com by GOTEBORGS UNIV on 09/20/17 For personal use only. This Just-IN manuscript is the accepted manuscript prior to copy editing and page composition. It may differ from the final official version of record. 229 the intrusion of waters from the Upper St. Lawrence Estuary and the Saguenay Fjord. The presence30 of a cold intermediate layer impedes the upwelling of the deeper, hypoxic, lower pH and aragonite31 undersaturated waters of the Lower St. Lawrence Estuary to depths shallower than 50 meters.