Translatory flow as a mechanisms for carbon and nutrient mobilization from peat lands
Alana Steinbauer (02/2014-02/2015)
Support: Ben Gilfedder, Sven Frei
Peatlands are one of the world’s largest carbon reservoirs. They are also significant carbon sources to the atmosphere, streams and rivers. While there is currently a large effort to understand and quantify atmospheric fluxes, there is still little known about mechanisms driving carbon fluxes and carbon sources to streams. The dominant carbon flux out of peatlands to streams is DOC, dissolved organic carbon, but also includes gaseous species CO2 and CH4. It is important to understand carbon fluxes out of peat lands because it can be a large source of carbon for rivers, DOC can complex many metals such as Fe, and on oxidation produces CO2. It can also be an important energy source for bacteria. One mechanism for mobilizing old water and associated solutes is translatory flow. This is where the pressure exerted by rainfall at the surface of the water table produces a pressure gradient across the aquifer causing older water to be discharged at the aquifer boundaries. This mechanism has been discussed extensively in head water catchments when trying to understand how old water is mobilized rapidly following storm events. However, little is known about how it affects peatlands, and the relevance for fluxes of biogeochemically relevant compounds such as DOC, CO2 and CH4. This project will simulate a heavy rainfall event by pumping water from a creek onto the peat surface. We will then monitor fluxes of water and biogeochemically relevant elements and molecules at the peat boundary (trench). It is hoped that this will shed light on how old water containing abundant DOC and other compounds is mobilized into creeks during heavy rainstorms.