CTD. Photo: Line Reeh.

PhD defence about dissolved organic matter in the oceans

Monday 22 Jan 18


Urban Wünsch
DTU Aqua
+45 35 88 33 47

Time & Place

Friday, 26 January 2018, 1 p.m.

Building 303A, auditorium 44
2800 Kgs. Lyngby

The thesis

A copy of the thesis “Resolving the chemical structures responsible for the UV-visible spectroscopic properties of dissolved organic matter in aquatic environments” is available for reading at DTU Aqua. Contact Rikke Hansen, rikh@aqua.dtu.dk

Dissolved organic matter in the oceans plays an essential role in the regulation of global climate, but little is known about its chemical composition. PhD Student Urban Wünsch has developed new methods to obtain this information, and on 26 January 2018 he will defend his thesis.

The ocean stores large amounts of carbon which, together with the carbon dioxide of the atmosphere, play a crucial role in the global carbon cycle and subsequent regulation of the global climate.

Scientists are using optical sensors to monitor dissolved organic matter (DOM) and evaluate its production, turnover and storage in the ocean. These sensors measure either the absorbance of light by DOM or its fluorescence in response to stimulation with ultraviolet and visible light. However, such sensors rely on measurement principles that are poorly understood. Since not all substances absorb or fluoresce, the challenge is to decipher these signals, and learn how much such sensors can tell us about all other organic substances in the water.

In his project, PhD student Urban Wünsch, DTU Aqua has developed new methods that facilitate a better chemical understanding of DOM absorbance and fluorescence. He has also developed an approach to join the data acquired from different analytical instrumentation to offer a more holistic characterisation of DOM. This will ultimately improve the use of optical sensors to monitor organic matter in aquatic environments, which is a fast evolving field not only for ocean science, but also for a suite of industrial water systems such as drinking water treatment, urban runoff and recirculated aquaculture.

About the defence

On Friday 26 January 2018, 1 p.m. PhD student Urban Wünsch, DTU Aqua will defend his PhD thesis "Resolving the chemical structures responsible for the UV-visible spectroscopic properties of dissolved organic matter in aquatic environments". The defence takes place at DTU’s campus in Lyngby, in building 303A, auditorium 44, Campus Lyngby.


  • Principal Supervisor: Associate Professor Colin Stedmon, DTU Aqua
  • Co-supervisor: Associate Professor Kathleen R. Murphy, Chalmers University of Technology, Sweden


  • Senior Researcher Sigrun Jonasdottir, DTU Aqua
  • Professor Jan Christensen, University of Copenhagen
  • Associate Professor Christopher Osburn, North Carolina State University, USA



17 JANUARY 2019