Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM103	12.09.2021 - 15.11.2021		Gulf of St. Lawrence North Atlantic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Holz Sebastian	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Emden	Emden

Ziel der Reise / Objectives of Cruise:

Our overarching hypothesis is that ice sheet dynamics and landscape evolution during the last glacial – interglacial cycle(s) significantly altered the recharge of freshwater offshore aquifers (FOAs) hosted in fractured consolidated clastic sediments. If this is the case, we should observe groundwater distribution aligned with the main ice sheet distribution, e.g. the St. Lawrence Channel. If this is not the case, we will observe a distribution that is controlled by distance from the coast and water depth. At any rate, the distance of resistivity anomalies from onshore aquifers and their patchiness will reveal the influence of sea level change. Our project will provide answers to the following fundamental questions directly from the results of the cruise: ? How are FOAs distributed and what are their geometrical, physical, and lithological characteristics? ? What are the roles of both fractured sandstone and unconsolidated Quaternary sediments of glacial origin in hosting fresh groundwater reserves on the continental shelf, in controlling spatial variation in salinity distributions, and in driving fresh groundwater discharge? ? When and how was the groundwater emplaced? ? Which FOAs are hydraulically linked to onshore/coastal groundwater aquifers and what are the consequences of such links? Furthermore, we will address the following questions within the SOURCE project based on data from this cruise and additional data to be collected by the Canadian colleagues: ? What is the distribution of modern groundwater seeps at the seafloor and what is their effect on the hydrogeological cycle and benthic ecosystems? ? How will climate change or pumping affect the quality and quantity of linked offshore-onshore groundwater aquifers? ? Can coastal cities sustainably extract groundwater from offshore aquifers to meet present and future freshwater needs? To answers these questions we will quantify the processes controlling the formation of FOAs hosted in fractured rocks, the recharge mechanisms, and their timing; quantitatively characterize the geometry of the offshore groundwater system; determine whether the offshore groundwater system is presently connected to a freshwater source onshore; explore the impacts of groundwater flow across the sea floor and the mixing with ambient ocean waters; define the hydrological budget of the groundwater system; determine the role played by freshened groundwater seepage on the distribution and dynamics of shallow marine benthic ecosystems; and model the evolution of the groundwater system in response to extraction, saltwater intrusion driven by relative sea-level rise, and other changes in climate such as precipitation patterns or ice extent.

Messungen / Measurements