Bio-ERODS · Biogeochemistry of erosive material deposition in streams: Impact of particulate deposition upon biofilm carbon cycling

Inland waterways are an important component of the global carbon cycle, receiving an annual carbon input of ~ 4.8 Pg of carbon per year. Of this approximately 0.6 Pg is buried, entering the lithosphere, whilst 3.3 Pg is recycled through aquatic food webs. These numbers highlight the global importance of streams, rivers lakes and other inland waters but provide little detail regarding the dynamics of organic matter burial and remineralisation. A poorly defined aspect is the relationship between organic matter burial and remineralisation of organo-mineral complexes. Organo-mineral particles form by adsorption of dissolved organic matter to freshly-eroded mineral surfaces, and are thought to greatly control the fluxes of particulate organic carbon at the watershed scale. The unique physico-chemical properties of these particles may enhance their deposition onto and subsequent burial into the sediments of inland waters. However, the metabolic fate of these particles at the water-streambed interface remains poorly studied. Particle deposition at the streambed is enhanced by benthic microbial biofilms. As such, understanding the potential role of organo-mineral complexes in the preservation and burial of organic matter, requires investigation of the interactions with biofilms. Bio-ERODS aims to experimentally investigate biophysical mechanisms driving biofilm-particle interactions and mechanisms that potentially alter the organo-mineral complexation and thus contributing to stream biogeochemistry. Bio-ERODS will thus elucidate, at the fine scale, fundamental mechanisms of the controls on carbon fluxes in streams and rivers.