TY - JOUR

T1 - The DynaDeep observatory

T2 - a unique approach to study high-energy subterranean estuaries

AU - Massmann, Gudrun

AU - Abarike, Grace

AU - Amoako, Kojo

AU - Auer, Felix

AU - Badewien, Thomas H.

AU - Berkenbrink, Cordula

AU - Böttcher, Michael Ernst

AU - Brick, Simone

AU - Cordova, Iris Valeria Medina

AU - Cueto, Jairo

AU - Dittmar, Thorsten

AU - Engelen, Bert

AU - Freund, Holger

AU - Greskowiak, Janek

AU - Günther, Thomas

AU - Herbst, Gabriel

AU - Holtappels, Moritz

AU - Marchant, Hannah Karen

AU - Meyer, Rena

AU - Müller-Petke, Mike

AU - Niggemann, Jutta

AU - Pahnke, Katharina

AU - Pommerin, Dietmar

AU - Post, Vincent

AU - Reckhardt, Anja

AU - Roberts, Magali

AU - Schwalfenberg, Kai

AU - Seibert, Stephan L.

AU - Siebert, Christopher

AU - Skibbe, Nico

AU - Waska, Hannelore

AU - Winter, Christian

AU - Zielinski, Oliver

N1 - Funding Information: This study was conducted within the research unit FOR 5094: The Dynamic Deep subsurface of high-energy beaches (DynaDeep), funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). Acknowledgments

PY - 2023/6/22

Y1 - 2023/6/22

N2 - Subterranean estuaries are connective zones between inland aquifers and the open sea where terrestrial freshwater and circulating seawater mix and undergo major biogeochemical changes. They are biogeochemical reactors that modify groundwater chemistry prior to discharge into the sea. We propose that subterranean estuaries of high-energy beaches are particularly dynamic environments, where the effect of the dynamic boundary conditions propagates tens of meters into the subsurface, leading to strong spatio-temporal variability of geochemical conditions. We hypothesize that they form a unique habitat with an adapted microbial community unlike other typically more stable subsurface environments. So far, however, studies concerning subterranean estuaries of high-energy beaches have been rare and therefore their functioning, and their importance for coastal ecosystems, as well as for carbon, nutrient and trace element cycling, is little understood. We are addressing this knowledge gap within the interdisciplinary research project DynaDeep by studying the combined effect of surface (hydro- and morphodynamics) on subsurface processes (groundwater flow and transport, biogeochemical reactions, microbiology). A unique subterranean estuary observatory was established on the northern beach of the island of Spiekeroog facing the North Sea, serving as an exemplary high-energy research site and model system. It consists of fixed and permanent infrastructure such as a pole with measuring devices, multi-level groundwater wells and an electrode chain. This forms the base for autonomous measurements, regular repeated sampling, interdisciplinary field campaigns and experimental work, all of which are integrated via mathematical modelling to understand and quantify the functioning of the biogeochemical reactor. First results show that the DynaDeep observatory is collecting the intended spatially and temporally resolved morphological, sedimentological and biogeochemical data. Samples and data are further processed ex-situ and combined with experiments and modelling. Ultimately, DynaDeep aims at elucidating the global relevance of these common but overlooked environments.

AB - Subterranean estuaries are connective zones between inland aquifers and the open sea where terrestrial freshwater and circulating seawater mix and undergo major biogeochemical changes. They are biogeochemical reactors that modify groundwater chemistry prior to discharge into the sea. We propose that subterranean estuaries of high-energy beaches are particularly dynamic environments, where the effect of the dynamic boundary conditions propagates tens of meters into the subsurface, leading to strong spatio-temporal variability of geochemical conditions. We hypothesize that they form a unique habitat with an adapted microbial community unlike other typically more stable subsurface environments. So far, however, studies concerning subterranean estuaries of high-energy beaches have been rare and therefore their functioning, and their importance for coastal ecosystems, as well as for carbon, nutrient and trace element cycling, is little understood. We are addressing this knowledge gap within the interdisciplinary research project DynaDeep by studying the combined effect of surface (hydro- and morphodynamics) on subsurface processes (groundwater flow and transport, biogeochemical reactions, microbiology). A unique subterranean estuary observatory was established on the northern beach of the island of Spiekeroog facing the North Sea, serving as an exemplary high-energy research site and model system. It consists of fixed and permanent infrastructure such as a pole with measuring devices, multi-level groundwater wells and an electrode chain. This forms the base for autonomous measurements, regular repeated sampling, interdisciplinary field campaigns and experimental work, all of which are integrated via mathematical modelling to understand and quantify the functioning of the biogeochemical reactor. First results show that the DynaDeep observatory is collecting the intended spatially and temporally resolved morphological, sedimentological and biogeochemical data. Samples and data are further processed ex-situ and combined with experiments and modelling. Ultimately, DynaDeep aims at elucidating the global relevance of these common but overlooked environments.

KW - beach

KW - biogeochemistry

KW - groundwater

KW - infrastructure

KW - land-sea interface

KW - morphodynamics

KW - Spiekeroog

KW - submarine groundwater discharge (SGD)

UR - http://www.scopus.com/inward/record.url?scp=85164560486&partnerID=8YFLogxK

U2 - 10.3389/fmars.2023.1189281

DO - 10.3389/fmars.2023.1189281

M3 - Article

AN - SCOPUS:85164560486

VL - 10

JO - Frontiers in Marine Science

JF - Frontiers in Marine Science

SN - 2296-7745

M1 - 1189281

ER -