Mineralization of organic matter in the sediments of nutrient-rich and nutrient-poor lakes
40 years of great efforts in the remediation of phosphorus loads to lakes proved very successful as phosphorus concentrations decreased significantly. In spite of the great success with respect to phosphorus however, oxygen consumption in the bottom waters of lakes remained tenaciously unchanged.
Oxygen is consumed at the sediment-water interface
i) by the freshly settled organic matter
ii) by the reduced substances diffusing from the sediment.
The former topic investigated by Robert Schwefel and Johny Wüest at EPFL.
The analysis of oxygen consuming compounds from sediment porewater will help to understand the mineralization of the deposited organic matter at the lake bottom of lakes with different trophic states. As the intensity of mineralization varies with the seasons and with lake depth, this project will produce a lake-wide overview of temporal and spatial porewater fluxes and thus mineralization rates of organic matter.