The Controls on Cross-Shelf Transport of Terrestrially-Derived Material in River Plumes

Jonathan Izett1, Katja Fennel2, Emma Shouldice1 and Jonathan Sharples3, (1)Dalhousie University, Halifax, NS, Canada, (2)Dalhousie University, Department of Oceanography, Halifax, NS, Canada, (3)University of Liverpool, Earth, Oceans and Ecosystem Sciences, Liverpool, L69, United Kingdom
Rivers connect land and sea, delivering large amounts of terrestrially-derived materials (such as nutrients, sediments, and pollutants) to the coastal ocean. Understanding the fate of this delivery is critical: nutrients can accumulate on shelves, driving high levels of production which can ultimately lead to negative ecological impacts such as hypoxia, or they can be exported rapidly across the shelf to the deep ocean where their impact is minimized. Many previous studies into river plume transport have explored the influences on alongshore coastal transport within river plumes; however, little attention has been paid to the controls on cross-shelf transport. The presented work will show the results of an idealized river plume model developed using the Regional Ocean Modelling System (ROMS), examining the impact of latitude, river discharge, and the influence of winds on cross-shelf transport. Nutrient budgets for the adjacent shelf seas will also be presented, describing the fate of terrestrial nutrients within river plumes and determining the degree to which river plumes are able to successfully export material to the deep ocean.