Vollberg, Felix (2018) Einflussnahme des submarinen Grundwasserabflusses auf die Aktivität pathogener Vibrio spp.-Bakterien im marinen Sediment. (Master thesis), University of Bremen, Bremen, 93 pp.

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Abstract

Submarine groundwater discharge (SGD), i.e. the discharge of terrestrial groundwater to the ocean,
contributes significantly to hydrological and matter cycling in coastal areas and thus directly affects
biogeochemical processes. Following the hydraulic potential, groundwater discharges out of a coastal
aquifer, which influences nutrient budgets and salinities within a coastal area, both on terrestrial and
marine compartments. According to its definition, SGD encompasses in its total a recirculated seawater
component in addition to a fresh groundwater discharge.
Brackish benthic zones of SGD have a direct effect on the living conditions of individual organisms
dwelling in coastal waters and shallow marine sediments (mud) respectively. That includes pathogenic
Vibrio bacteria whose growth is strongly dependent on water temperature, nutrient supply and
salinity. The quantity of non-halophile Vibrios (V. cholerae) should grow if the influence of fresh
groundwater increases. To what extend SGD is able to sustain favorable living conditions for Vibrio is
an open question, which is assessed in a first approach in this study.
A suite of 2D FEFLOW models will represent multiple scenarios through a relevant geological and
hydrological parameter space. Starting with a simple stationary homogeneous (sandy) landmass we
put a focus on density driven water movements in coastal areas. Increasing complexity of this setup
by implementing heterogeneity and varying geometrical shapes (e.g. coastal slope) allows to approach
natural conditions, thus creating a suitable base for further case-related investigations. We expect the
permeability and heterogeneous distribution of flow paths to be the main controlling factors of the
SGD and formation of low salinity zones in the benthic sediment. Besides building a flexible analytic
model setup, the main goal of this work is a sensitivity analysis for the relevant parameters to specify
the possible impact of SGD on Vibrio bacterial growth.
Results reveal a high vulnerability of non-halophile Vibrio cholerae growth to SGD and its primary
driving factors respectively. This dependency leads to highest growth potential at high groundwater
inflow und low hydraulic conductivities of the aquifer as well as increasing sea-side boundary slopes.
Besides its negligible effect on the extend of SGD, increasing dispersion shows as a crucial limiting
factor for V. cholerae habitats.

Document Type: Thesis supervision (Master thesis)
Thesis supervisor: Moosdorf, Nils and Hamer, Kay
Research affiliation: Biogeochemistry and Geology > Submarine Groundwater Discharge
Affiliations > Not ZMT
Projects: SGD-NUT
Date Deposited: 08 Sep 2020 16:27
Last Modified: 01 Oct 2020 13:01
URI: http://cris.leibniz-zmt.de/id/eprint/4108

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