Johann Holdt

I am currently a PhD candidate with focus on environmental geosciences. In the frame of an interuniversity collaboration research project (see below and here), I am investigating the sedimentology and organic geochemistry of floodplain aquifers to predict nitrate reduction potentials. In addition, my work focuses on the biogeochemical cycling of nutrients in lakes, with particular emphasis on sedimentary phosphorus release and its role in freshwater ecosystems.
My research addresses key challenges related to nitrate groundwater pollution, eutrophication, and the development of effective environmental management strategies.

Short curriculum
Since 2023:
PhD candidate University of Göttingen / University of Tübingen, Germany
Topic: Linking Redox-Cycling to Hydrogeology: Sedimentological Controls on the Capacity of Aquifers to Reduce Nitrate and other Dissolved Electron Acceptors.
(collaboration between the Universities of Göttingen, Kassel, Tübingen and Vienna)

2020–2022:
Graduate student (M.Sc.), Geosciences, University of Göttingen, Germany
MSc Thesis: “Seasonal and spatial dynamics of hydrogeochemical parameters of Lake Stechlin (Brandenburg) under the influence of increasing eutrophication”
(collaboration with the Leibniz Institute of Freshwater Ecology and Inland Fisheries Berlin)

2016–2020:
Undergraduate student (B.Sc.), Geosciences, University of Göttingen, Germany
BSc Thesis: “Assessing fingerprints of early Archean life in barite and chert of the ca. 3.5 Ga Dresser Formation, Western Australia – a geobiological approach”

Current teaching
• B.Geo.111, LV 3: Introduction to the Chemical Analysis of Solids & Fluids (summer term 2025)
• M.EES.211: Case Studies in Environmental Geosciences (summer term 2025)

Analytical skills
• Elemental (carbon, nitrogen, hydrogen, sulfur) analyses (Elementar Vario Cube, Elementar Analysesysteme)
• Organic / inorganic carbon quantification in soils & sediments (Elementar SoliTOC Cube, Elementar Analysegeräte; RC612 multi-phase carbon analyzer, LECO)
• Ion analyses of water samples via ion chromatography (IC 820, Metrohm)
• Elemental analyses of thin sections via micro-XRF (Tornado M4, Bruker)

Community Services
• Social Media Management of the Department of Geobiology
• Supervision of bachelor- and master students

Publications