08 Jul 2022
08 Jul 2022
Status: this preprint is currently under review for the journal BG.

Ideas and perspectives: Land-ocean connectivity through groundwater

Damian Leonardo Arévalo-Martínez1,2, Amir Haroon1, Hermann Werner Bange1, Ercan Erkul2, Marion Jegen1, Nils Moosdorf2,3, Jens Schneider von Deimling2, Christian Berndt1, Michael Ernst Böttcher4,5,6, Jasper Hoffmann7, Volker Liebetrau1,, Ulf Mallast8, Gudrun Massmann9, Aaron Micallef1,10, Holly A. Michael11, Hendrik Paasche8, Wolfgang Rabbel2, Isaac Santos12, Jan Scholten2, Katrin Schwalenberg13, Beata Szymczycha14, Ariel T. Thomas10, Joonas J. Virtasalo15, Hannelore Waska9, and Bradley Weymer16 Damian Leonardo Arévalo-Martínez et al.
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, 24105, Germany
  • 2Kiel University, Kiel, 24118, Germany
  • 3Leibniz Centre for Tropical Marine Research (ZMT), Bremen, 28359, Germany
  • 4Leibniz Institute for Baltic Sea Research Warnemünde (IOW), Rostock, 18119, Germany
  • 5Marine Geochemistry, University of Greifswald, Greifswald, 17489, Germany
  • 6Interdisciplinary Faculty, University of Rostock, Rostock, 18051, Germany
  • 7Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, 27515, Germany
  • 8Helmholtz Centre for Environmental Research, Leipzig, 04318, Germany
  • 9Carl von Ossietzky University of Oldenburg, Oldenburg, 26129, Germany
  • 10University of Malta, Msida, MSD 2080, Malta
  • 11University of Delaware, Newark, DE 19716, USA
  • 12Department of Marine Science, University of Gothenburg, Gothenburg, 40539, Sweden
  • 13Federal Institute for Geosciences and Natural Resources, Hannover, 30655, Germany
  • 14Institute of Gdańsk Polish Academy of Sciences, Sopot, 81-712, Poland
  • 15Marine Geology, Geological Survey of Finland (GTK), Espoo, 02150, Finland
  • 16School of Oceanography, Shanghai Jiao Tong University, China
  • deceased

Abstract. For millennia humans have gravitated towards coastlines for their resource potential and as geopolitical centres for global trade. A basic requirement ensuring water security for coastal communities relies on a delicate balance between the supply and demand of potable water. The interaction between freshwater and saltwater in coastal settings is, therefore, complicated by both natural and human-driven environmental changes at the land-sea interface. In particular, ongoing sea level rise, warming and deoxygenation might exacerbate such perturbations. In this context, an improved understanding of the nature and variability of groundwater fluxes across the land-sea continuum is timely, yet remains out of reach. The flow of terrestrial groundwater across the coastal transition zone as well as the extent of freshened groundwater below the present-day seafloor are receiving increased attention in marine and coastal sciences because they likely represent a significant, yet highly uncertain component of (bio)geochemical budgets, and because of the emerging interest in the potential use of offshore freshened groundwater as a resource. At the same time, “reverse” groundwater flux from offshore to onshore is of prevalent socio-economic interest as terrestrial groundwater resources are continuously pressured by overpumping and seawater intrusion in many coastal regions worldwide. An accurate assessment of the land-ocean connectivity through groundwater and its potential responses to future anthropogenic activities and climate change will require a multidisciplinary approach combining the expertise of geophysicists, hydrogeologists, (bio)geochemists and modellers. Such joint activities will lay the scientific basis for better understanding the role of groundwater in societal-relevant issues such as climate change, pollution and the environmental status of the coastal oceans within the framework of the United Nations Sustainable Development Goals. Here, we present our perspectives on future research directions to better understand land-ocean connectivity through groundwater, including the spatial distributions of the essential hydrogeological parameters, highlighting technical and scientific developments, and briefly discussing its societal relevance in rapidly changing coastal oceans.

Damian Leonardo Arévalo-Martínez et al.

Status: open (until 07 Sep 2022)

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Damian Leonardo Arévalo-Martínez et al.

Damian Leonardo Arévalo-Martínez et al.


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Short summary
Groundwater flows at the land-ocean transition and the extent of freshened groundwater below the seafloor are increasingly relevant in marine sciences both because they are a highly uncertain term of biogeochemical budgets, and also due to the emerging interest in the latter as a resource. Here we discuss our perspectives on future research directions to better understand land-ocean connectivity through groundwater and its potential responses to natural and human-induced environmental changes.