MWK Project: Assessment of ground- and porewater-derived nutrient fluxes into the German North Sea – Is there a ‘Barrier Island Mass Effect (BIME)’?

Submarine groundwater discharge (SGD) is a hidden pathway of the global water cycle, which connects the land-ocean interface. Evidence is increasing that SGD plays a crucial role in the coastal ocean by (i) impacting nearshore carbon, nutrient, and trace metal budgets, (ii) fueling primary productivity, and (iii) shaping benthic communities. In BIME, we posit that the subterranean estuary (Fig. 1), the underground mixing zone of fresh groundwater and recirculating seawater, modulates SGD volumes and composition. In particular, we are interested in the very active and dynamic subterranean estuary environments underlying high-energy, mesotidal beaches, and their impacts on SGD biogeochemistry. This project involves an interdisciplinary team conducting in-depth research at our model study site on the East Frisian Spiekeroog Island bordering the German Wadden Sea. More information on the sub-projects can be found at the project website:


Niedersächsisches Ministerium für Wissenschaft und Kultur

Contributing members of the Research Group Marine Geochemistry:

Hannelore Waska
Heike Simon
Roger Carvalho
Thorsten Dittmar

Key publications:

H. Waska, J. Greskowiak, J. Ahrens, M. Beck, S. Ahmerkamp, P. Böning, H.-J. Brumsack, J. Degenhardt, C. Ehlert, B. Engelen, N. Grünenbaum, M. Holtappels, K. Pahnke, H. K. Marchant, G. Massmann, D. Meier, B. Schnetger, K. Schwalfenberg, H. Simon, V. Vandieken, O. Zielinski, T. Dittmar (2019). Spatial and temporal patterns of pore water chemistry in the inter-tidal zone of a high energy beach. Front. Mar. Sci. 6: 154

S. L. Seibert, M. E. Böttcher, F. Schubert, T. Pollmann, L. Giani, S. Tsukamoto, M. Frechen, H. Freund, H. Waska, H. Simon, T. Holt, J. Greskowiak, G. Massmann (2019). Iron sulfide formation in young and rapidly-deposited permeable sands at the land-sea transition zone. Sci. tot. environ. 649, 264-283.

S. L. Seibert, T. Holt, A. Reckhardt, J. Ahrens, M. Beck, T. Pollmann, L. Giani, H. Waska, M. E. Böttcher, J. Greskowiak, G. Massmann (2018) Hydrochemical evolution of a freshwater lens below a barrier island (Spiekeroog, Germany): The role of carbonate mineral reactions, cation exchange and redox processes. Appl. Geochem. 92, 196-208.

A. Linkhorst, T. Dittmar, H. Waska (2017) Molecular fractionation of dissolved organic matter in a shallow subterranean estuary: The role of the iron curtain. Environ. Sci. Technol. 51 (3), 1312-1320.

M. Seidel, M. Beck, J. Greskowiak, T. Riedel, H. Waska, I. G. N. Suryaputra, B. Schnetger, J. Niggemann, M. Simon, and T. Dittmar (2015) Benthic-pelagic coupling of nutrients and dissolved organic matter composition in an intertidal sandy beach. Mar. Chem. 176: 150-163.

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