![[Translate to English:] Ursache und Auftrieb schwefelwasserstoffhaltiger Bodenwässer](/fileadmin/_processed_/f/0/csm_%C3%9Cbersichtsbild_e97d46f69a.png)
Causes and upwelling of sulfidic bottom waters
The project Temporal and Spatial Expansion of Hypoxic and Hydrogen Sulphide Containing Bottom Water in the Bay of Kiel is part of the joint project PrimePrevention of the Third DAM Research Mission mareXtreme. The overarching goal of the PrimePrevention joint project is to develop a coordinated strategy for the coastal states to counteract the social challenges of climate change. The focus here is on the expected increase in climate-related marine natural hazards, such as harmful microorganisms and hypoxia (oxygen-depleted water).
The expansion of oxygen-depleted waters is a globally observed phenomenon that also affects eastern Schleswig-Holstein. In the Bay of Kiel, hypoxic events can be observed in late summer, during which toxic deep water containing hydrogen sufide is transported to the surface. These upwelling events cause mass mortality of fish, whose carcasses are then washed up on the region's beaches. This poses a problem for the general health of the coastal ecosystem as well as for bathing and recreational tourism and fish farms. Due to climate change, these hypoxic events are likely to occur more frequently in the future. This is where the sub-project “Development of an intelligent ocean observation system for the detection of marine biological hazards as a function of environmental conditions: Temporal and spatial extent of hypoxic and hydrogen sulphide bottom waters in the Kiel Bight” (task 2.3.2). The overall aim of the sub-project is to create a probability map of upwelling events containing hydrogen sulfide. This will identify the affected regions and provide a risk assessment of this biological hazard for stakeholders. In addition, the factors that ultimately lead to the formation and upwelling of soil water containing hydrogen sulfide will be investigated.
![[Translate to English:] Sedimentkerne](/fileadmin/_processed_/6/3/csm_Kerne_e036dde566.png)
Sediment cores from spring (A) and directly after the hypoxia phase (B). The sediments from spring reflect the good aeration of the deep water with oxygen, so that oxygen can still penetrate into the upper sediment layer. After the hypoxia phase, the sediments are oxygen-free and contain hydrogen sulfide near surface.
The sub-project will test four hypotheses:
1. The amount of organic material (OM) delivered determines the biological sulfide production (OM degradation coupled to sulphate reduction) in the sediment.
2. The occurrence of hydrogen sulfide in bottom waters is controlled by the balance of sulfide formation (by sulphate reduction) and sulfide precipitation (as iron sulfide, pyrite) in the sediment as well as sulfide consumption at the sediment-water interface (microbial oxidation with nitrate or oxygen)
3. The residence time of the bottom water determines the extent of oxygen and nitrate depletion (caused by microbial respiration) and thus the oxidation of the hydrogen sulfide produced in the sediment.
4. The water depth of the areas with sulfidic bottom water and their spatial location determine whether and when hypoxic or sulfidic bottom waters experience upwelling.
An integrated evaluation of all existing and newly collected microbial and geochemical data sets will be carried out together with WP3. This will be followed by a comprehensive synthesis with recommended action activities for society and in particular for the stakeholders identified as affected (WP1; WP4).
In the microbiological part of the WP, the interactions between the microorganisms and the environmental conditions will be investigated in more detail. Sulphate-reducing bacteria (SRB) produce hydrogen sulfide during the decomposition of organic material, which can accumulate in the sediment. This can precipitate abiotically to iron sulfide in the sediment under oxygen-free conditions. If electron acceptors such as oxygen and nitrate are available in the bottom water, hydrogen sulfide-oxidizing bacteria (SOB) can consume the biologically produced hydrogen sulfide again. However, if oxygen-free conditions prevail in the soil water, the SOB filter can no longer prevent the hydrogen sulfide from escaping into the water column and the hydrogen sulfide enters the soil water.
![[Translate to English:] SOB](/fileadmin/_processed_/1/8/csm_SOB_98bab009f3.jpg)
Transmitted light microscopy of an enrichment for hydrogen sulfide oxidizing bacteria (exemplarily marked in yellow ) ©Geomicrobiology, GEOMAR.
Hypoxia-Team
Geomicrobiology (GEOMAR)
Prof. Dr. Mirjam Perner
Matthias Thiele (doctoral candidate financed by project)
Dr. Nicole Adam-Beyer
Dr. Stefanie Böhnke-Brandt
Dr. Katja Laufer-Meiser
Biogeochemistry (University Hamburg and GEOMAR)
Prof. Dr. Florian Scholz (Universität Hamburg)
Timo Spiegel (financed by project) (Universitty Hamburg)
PD Dr. Mark Schmidt (GEOMAR)
Dr. Andrew Dale (GEOMAR)
The field data sets are collected for the water column and sediments of Kiel Bight by means of various research cruises.
Adam-Beyer, N., Scholz, F. und Perner, M. (2023) Benthic microbial communities exposed to seasonal hypoxia in the Baltic Sea. [Talk] In: FEMS2023. , 09.-13.07.2023, Hamburg, Germany
Perner, M. , Wallmann, K. , Adam-Beyer, N., Hepach, H. , Laufer-Meiser, K., Böhnke, S., Diercks, I., Bange, H. W. , Indenbirken, D., Nikeleit, V., Bryce, C., Kappler, A., Engel, A. und Scholz, F. (2022) Environmental changes affect the microbial release of hydrogen sulfide and methane from sediments at Boknis Eck (SW Baltic Sea). Frontiers in Microbiology, 13. Art.Nr. 1096062. DOI 10.3389/fmicb.2022.1096062.
ZDF Nano-Spezial 29.02.2024. Vermüllt, versauert, verschwitzt – Ökosystem Meer im Wandel
Head of the research group
"Geomicrobiology":
Prof. Dr. Mirjam Perner
GEOMAR Helmholtz Centre
for Ocean Research Kiel
Building 12
Wischhofstrasse 1-3
D-24148 Kiel
Tel.: +49 (0) 431-600-2837
Fax: +49 (0) 431-600-2941
E-mail: mperner(at)geomar.de
Team assistance / Office Management:
Marion Liebetrau
Tel.: +49 (0) 431-600-2847
Fax: +49 (0) 431-600-2941
E-Mail: mliebetrau(at)geomar.de
