Submarine Groundwater Discharge in the Nice Airport Landslide Area

Natural radioactivity was measured and analyzed at the Nice Slope for over a month using radon daughters in order to trace groundwater movement from a coastal aquifer to a nearshore continental shelf. Such groundwater movement may have resulted in submarine groundwater discharge (SGD) and potentiall...

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Main Authors: Christoph Witt, Achim Kopf
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Journal of Marine Science and Engineering
Subjects:
Online Access:https://www.mdpi.com/2077-1312/13/5/909
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author Christoph Witt
Achim Kopf
author_facet Christoph Witt
Achim Kopf
author_sort Christoph Witt
collection DOAJ
description Natural radioactivity was measured and analyzed at the Nice Slope for over a month using radon daughters in order to trace groundwater movement from a coastal aquifer to a nearshore continental shelf. Such groundwater movement may have resulted in submarine groundwater discharge (SGD) and potentially sediment weakening and slope failure. The relationship among major hydrological parameters (precipitation, Var discharge, groundwater level, salinity and water origin) in the area is demonstrated in this study. Time series analyses also helped to detect tidal fluctuations in freshwater input, highlighting the crucial role SGD plays in the slope stability of the still failure-prone Nice Slope, parts of which collapsed in a tsunamigenic submarine landslide in 1979. Earlier deployments of the underwater mass spectrometer KATERINA showed that SGD is limited to the region of the 1979 landslide scar, suggesting that the spatially heterogenous lithologies do not support widespread groundwater charging. The calculated volumetric activities from groundwater tracing isotopes revealed peaks up to ca. 150 counts <sup>214</sup>Bi, which is similar to those measured at other prominent SGD sites along the Mediterranean shoreline. Therefore, this rare long-term radioisotope dataset is a valuable contribution to the collaborative research at the Nice Slope and may not remain restricted to the unconfined landslide scar but may charge permeable sub-bottom areas nearby. Hence, it has to be taken into account for further slope stability studies.
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spelling doaj-art-eb5d08f48ef64fd18b031f44aa1961622025-08-20T02:34:01ZengMDPI AGJournal of Marine Science and Engineering2077-13122025-05-0113590910.3390/jmse13050909Submarine Groundwater Discharge in the Nice Airport Landslide AreaChristoph Witt0Achim Kopf1MARUM—Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, GermanyMARUM—Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, GermanyNatural radioactivity was measured and analyzed at the Nice Slope for over a month using radon daughters in order to trace groundwater movement from a coastal aquifer to a nearshore continental shelf. Such groundwater movement may have resulted in submarine groundwater discharge (SGD) and potentially sediment weakening and slope failure. The relationship among major hydrological parameters (precipitation, Var discharge, groundwater level, salinity and water origin) in the area is demonstrated in this study. Time series analyses also helped to detect tidal fluctuations in freshwater input, highlighting the crucial role SGD plays in the slope stability of the still failure-prone Nice Slope, parts of which collapsed in a tsunamigenic submarine landslide in 1979. Earlier deployments of the underwater mass spectrometer KATERINA showed that SGD is limited to the region of the 1979 landslide scar, suggesting that the spatially heterogenous lithologies do not support widespread groundwater charging. The calculated volumetric activities from groundwater tracing isotopes revealed peaks up to ca. 150 counts <sup>214</sup>Bi, which is similar to those measured at other prominent SGD sites along the Mediterranean shoreline. Therefore, this rare long-term radioisotope dataset is a valuable contribution to the collaborative research at the Nice Slope and may not remain restricted to the unconfined landslide scar but may charge permeable sub-bottom areas nearby. Hence, it has to be taken into account for further slope stability studies.https://www.mdpi.com/2077-1312/13/5/909submarine groundwater dischargeocean observation systemsenvironmental monitoringradioactivityradioisotopescontinental shelf
spellingShingle Christoph Witt
Achim Kopf
Submarine Groundwater Discharge in the Nice Airport Landslide Area
Journal of Marine Science and Engineering
submarine groundwater discharge
ocean observation systems
environmental monitoring
radioactivity
radioisotopes
continental shelf
title Submarine Groundwater Discharge in the Nice Airport Landslide Area
title_full Submarine Groundwater Discharge in the Nice Airport Landslide Area
title_fullStr Submarine Groundwater Discharge in the Nice Airport Landslide Area
title_full_unstemmed Submarine Groundwater Discharge in the Nice Airport Landslide Area
title_short Submarine Groundwater Discharge in the Nice Airport Landslide Area
title_sort submarine groundwater discharge in the nice airport landslide area
topic submarine groundwater discharge
ocean observation systems
environmental monitoring
radioactivity
radioisotopes
continental shelf
url https://www.mdpi.com/2077-1312/13/5/909
work_keys_str_mv AT christophwitt submarinegroundwaterdischargeintheniceairportlandslidearea
AT achimkopf submarinegroundwaterdischargeintheniceairportlandslidearea