A study of the inorganic carbon cycling on the Scotian Shelf

Abstract

The stable carbon isotopic composition (d13CDIC) of dissolved inorganic carbon (DIC) can be used as an effective indicator of biological processes in carbon cycling, however, so far, few, if any, studies have been conducted on Scotian Shelf (NW Atlantic) waters focusing on (d13CDIC). In this study, the spatial and temporal distribution of DIC and d13CDIC in Scotian Shelf waters and their governing processes are investigated. Samples were collected on the Scotian Shelf during April and October of 2014 on the Canadian Coast Guard Ship Hudson. Throughout the research period, a combination of biological processes such as photosynthesis and respiration, and the freshwater input resulted in the changes of DIC concentration and d13CDIC values in the Scotian Shelf waters. The monthly NCP on the surface water of the study region ranges from -0.76 to 0.57 molC m-2 month-1, with an average NCP of 0.06 molC m-2 month-1. The Scotian Shelf reveals both autotrophic and heterotrophic regions in its mixed layer, with most of the offshore region presenting a heterotrophic system.