This is a cross disciplinary project involving biogeochemistry and physical chemistry. Dissolved and colloidal organic matter (DOM) is the largest pool of organic matter in the water column of oceans and inland waters, and in soils and sediments it is also the major interface between dead organic matter and the microbes that mineralize it. The factors that limit the persistence of DOM currently receives large scientific interest, as they are important regulators of the global carbon cycle. Constraints on microbial degradation of DOM may include several factors, including the ability of microbes and their extracellular enzymes to reach the relevant sites in the OM, depending on steric hindrance. One cause of steric hindrance may be the aggregation of molecules, whereby enzyme sites are embedded inside organic colloids or particles. This project investigates how the ability of microbes to degrade the DOM depends on to what extent molecules are aggregated. The project is hosted by the biogeochemistry research group in the limnology research program at Uppsala university (https://www.ieg.uu.se/limnology/research/biogeochemistry/) in collaboration with the microbial ecology group at Lund University (https://portal.research.lu.se/en/organisations/microbial-ecology). Scattering experiments will be performed in collaboration with Prof. Ulf Olsson, Lund University. The project (https://kaw.wallenberg.org/en/research/unexplored-dimension-nature-gives-new-climate-insights) is a collaboration between aquatic biogeochemists, microbial ecologists, and physical and environmental chemists at both universities.
Experimental studies of the relationship between aggregation within the DOM, and microbial degradation. Important aspects of the work will be to analyze the size spectrum of DOM by e.g. light scattering and small angle X-ray scattering, and to run experiments where transformation and mineralization of DOM will be analyzed as a function of DOM colloidal size structure. We expect to perform experiments also at the Swedish national synchrotron laboratory MAX IV in Lund. The work will include development of methods to manipulate the colloidal size spectrum of DOM. Ideas how to develop the project are welcome, depending on the interests and skills of the postdoc. The position (two years, full time) is at Uppsala University, but a significant part of the work will be performed at Lund University.
Closing date: 25 October, 2022
For more information, contacts, and instruction for application, see https://www.uu.se/en/about-uu/join-us/details/?positionId=522501