Potential links between Baltic Sea submarine terraces and groundwater seeping

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dc.contributor.author Jakobsson, Martin
dc.contributor.author O'Regan, Matt
dc.contributor.author Morth, Carl-Magnus
dc.contributor.author Stranne, Christian
dc.contributor.author Weidner, Elizabeth
dc.contributor.author Hansson, Jim
dc.contributor.author Gyllencreutz, Richard
dc.contributor.author Humborg, Christoph
dc.contributor.author Elfwing, Tina
dc.contributor.author Norkko, Alf
dc.contributor.author Norkko, Joanna
dc.contributor.author Nilsson, Bjorn
dc.contributor.author Sjöström, Arne
dc.date.accessioned 2020-03-25T08:02:04Z
dc.date.available 2020-03-25T08:02:04Z
dc.date.issued 2020-01-03
dc.identifier.citation Jakobsson , M , O'Regan , M , Morth , C-M , Stranne , C , Weidner , E , Hansson , J , Gyllencreutz , R , Humborg , C , Elfwing , T , Norkko , A , Norkko , J , Nilsson , B & Sjöström , A 2020 , ' Potential links between Baltic Sea submarine terraces and groundwater seeping ' , Earth surface dynamics , vol. 8 , no. 1 , pp. 1-15 . https://doi.org/10.5194/esurf-8-1-2020
dc.identifier.other PURE: 130146861
dc.identifier.other PURE UUID: fd7dd365-4900-4351-bfad-bc72a81180a4
dc.identifier.other WOS: 000505676800001
dc.identifier.other ORCID: /0000-0001-9885-8408/work/71183841
dc.identifier.uri http://hdl.handle.net/10138/313604
dc.description.abstract Submarine groundwater discharge (SGD) influences ocean chemistry, circulation, and the spreading of nutrients and pollutants; it also shapes sea floor morphology. In the Baltic Sea, SGD was linked to the development of terraces and semicircular depressions mapped in an area of the southern Stockholm archipelago, Sweden, in the 1990s. We mapped additional parts of the Stockholm archipelago, areas in Blekinge, southern Sweden, and southern Finland using high-resolution multibeam sonars and sub-bottom profilers to investigate if the sea floor morphological features discovered in the 1990s are widespread and to further address the hypothesis linking their formation to SGD. Sediment coring and sea floor photography conducted with a remotely operated vehicle (ROV) and divers add additional information to the geophysical mapping results. We find that terraces, with general bathymetric expressions of about 1 m and lateral extents of sometimes > 100 m, are widespread in the surveyed areas of the Baltic Sea and are consistently formed in glacial clay. Semicircular depressions, however, are only found in a limited part of a surveyed area east of the island of Asko, southern Stockholm archipelago. While submarine terraces can be produced by several processes, we interpret our results to be in support of the basic hypothesis of terrace formation initially proposed in the 1990s; i.e. groundwater flows through siltier, more permeable layers in glacial clay to discharge at the sea floor, leading to the formation of a sharp terrace when the clay layers above seepage zones are undermined enough to collapse. By linking the terraces to a specific geologic setting, our study further refines the formation hypothesis and thereby forms the foundation for a future assessment of SGD in the Baltic Sea that may use marine geological mapping as a starting point. We propose that SGD through the submarine sea floor terraces is plausible and could be intermittent and linked to periods of higher groundwater levels, implying that to quantify the contribution of freshwater to the Baltic Sea through this potential mechanism, more complex hydrogeological studies are required. en
dc.format.extent 15
dc.language.iso eng
dc.relation.ispartof Earth surface dynamics
dc.rights cc_by
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject ORGANIC-MATTER
dc.subject DISCHARGE
dc.subject BASIN
dc.subject DEGLACIATION
dc.subject CANYONS
dc.subject LAKE
dc.subject END
dc.subject 1172 Environmental sciences
dc.title Potential links between Baltic Sea submarine terraces and groundwater seeping en
dc.type Article
dc.contributor.organization Ecosystems and Environment Research Programme
dc.contributor.organization Biological stations
dc.contributor.organization Tvärminne Benthic Ecology Team
dc.contributor.organization Marine Ecosystems Research Group
dc.contributor.organization Tvärminne Zoological Station
dc.description.reviewstatus Peer reviewed
dc.relation.doi https://doi.org/10.5194/esurf-8-1-2020
dc.relation.issn 2196-6311
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

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