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Gensel, Julia

Archived Page

This web page has not been updated since the former colleague left MARUM.

PhD student member of GLOMAR - Bremen International Graduate School for Marine Sciences

PhD project

The PhD project is embedded in the TRACES project within the SPACESII research program.

what is it about?

To study past climate, a common approach is to determine certain biomarkers, i.e., certain molecules that can be assigned to a unique origin, such as n-alkanes derived from plant waxes. Not only their concentrations, but more importantly their specific carbon and hydrogen isotope signatures (δ¹³C and δD) provide information about the conditions under which the plants that formed them grew.

There are several factors to which an ecosystem can respond with changes. These are not always readily distinguishable from one another and include the natural formation of the ecosystem itself, the response to climate-induced changes, and the response to human-induced changes.

The main objective of the work is to separate the three mentioned influences - natural formation, climatic-induced changes in the region and human influences - on the Mkhuze wetland system, an exemplary site for subtropical coastal wetlands.

subproject I is concerned with the current state of the wetland system. In orderto evaluate past changes in biomarker signals, it is important to know the current condition. Therefore, surface sediment samples describing a spatially resolved record of the catchment system and possible source plant samples were taken as a form of in situ calibration. The system was subdivided into ecological subcompartments and the characteristics of the organic matter (OM) deposited there were investigated. In addition, transport pathways of OM through the system were elaborated.

subproject II deals with the history of the system during the last 2000 years in very high resolution (decadal). The goal is to determine major evolutionary points of the system and to assess whether and, if so, how the system responds to man-made alterations and influences.

subprojectIII deals with the history of the system from its formation until today. Using the results from subproject I, I hope to be able to decipher the biomarker signals resulting from responses to natural formation processes of climatically induced changes in order to obtain reliable information about the continental climate in southern Africa.

my PhD in a nutshell

As a doctoral student, you ask yourself "What am I doing here?" much more often than you might like. And exactly this question was on my mind when I was preparing a presentation for the Mid-Term Meeting of the SPACESII research program. The requirements were actually simple: not to go into too much detail, since the participants come from a wide range of disciplines. When I thought about it, I realized that probably not even my closest friends or family know what I have been doing for the whole three years. And so I just pursued the question: "What am I actually doing for the 3 years of my doctoral studies?

PhD highlights - away from desk or lab

Mkhuze Swamps, KwaZulu Natal, South Africa

field trip to the Mkhuze Wetland System, KwaZulu Natal, South Africa in November 2018

Mkhuze River outflow into Lake St. Lucia

participation in the IMOG2019 in Gothenburg, Sweden

University of the Witwatersrand, Johannesburg

research stay at the working group of Prof. Marc Humphries (University of the Witwatersrand, Johannesburg, South Africa) in November 2019

get to feel firsthand the joy of the rainbow nation

professional background

08|2018 - present: PhD candidate at MARUM - Center for Marine Environmental Sciences, Bremen

05|2018 - 07|2018: scientific staff member at Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin

2018: M.Sc. at the Humboldt-Universität zu Berlin (Department of Chemistry)

master thesis "Formation and Transformation of Dissolved Lignin in Freshwater Ecosystems" (conducted at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin)

04|2016 - 04|2018: student research assistant at Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin

publications and presentations

Gensel, J.; Hahn, A.; Humphries, M.S.; Zabel, M. & Schefuß, E. (2019, September) Understanding the fate of plant-wax derived n-alkanes in subtropical wetland systems: The Mkhuze Swamps.
Poster session presented at the International Meeting on Organic Geochemistry (IMOG), Gothenburg, Sweden.
Reuter H.; Gensel, J.; Elvert, M. & Zak, D. (2020) Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine. Biogeosciences, 17(2), 499-514.
Reuter, H.*; Gensel, J.*; Elvert, M. & Zak, D. (2017). Direct Analysis of Lignin Phenols in Freshwater Dissolved Organic Matter. Analytical Chemistry, 89(24), 13449-13457. *equal authorship
Gensel, J.; Zak, D. & Reuter, H. (2017, September). A Decomposition Depth Profile in a Rewetted Fen Soil: A Lignin Study.
Poster session presented at the International Meeting on Organic Geochemistry (IMOG), Florence, Italy.