QUANTification of dissolved Organic Matter and the metabolic balance in river networks: mechanisms and model simulations of CO2 emissions

Informations

Funding country

Norway

Acronym

-

URL

-

Start date

1/1/2021

End date

12/31/2024

Budget

1,475,508 EUR

Fundings

Abstract

Quantification of dissolved organic matter and the metabolic balance in river networks: mechanisms and model simulations of CO2 emissions We want to discover how land and rivers are connected to better understand the global carbon cycle and river food webs north of the Arctic circle. Rivers are the 'blood vessels' draining the 'body of the Earth’ and export vast amount of carbon to the sea and the atmosphere. A large fraction of this carbon is from dissolved organic matter leaching out of soils and giving the water a yellow brown colour. On its journey to the sea, bacteria on the riverbed use oxygen to transform this terrestrial carbon into CO2. The increase in bacterial activities may suppress the growth of green algae by competing for limiting nutrients, thus changing the metabolic balance between photosynthesis and respiration (increasing CO2 emissions) and the quality of the food available for consumers. We have deployed sensors throughout the river Tana network to estimate daily and annual carbon and O2 pulses of the aquatic ecosystem. We concomitantly estimated the changes in terrestrial land vegetation activity using satellite imageries at the daily time scale. We described and sampled riparian soils in four sub-catchments with varying land cover to assess soil carbon pool and transformation through the soil horizons. We carried out a laboratory experiment to explore the fate of dissolved organic carbon from mire onto the metabolic balance (photosynthesis, respiration and associated CO2 emissions) of aquatic microcosms. We are using state-of-the-art methods to identify and describe the transformation of thousands of molecules (metabolites) at the soil – water interfaces and during their journey along the river throughout the growing season. Finally, we are building a mathematical model to represent, in the most parsimonious way, our understanding of carbon processes in large northern latitude river basins with heterogeneous landscape (rocks, tundra, pine and birch forest and peat plateau with discontinuous permafrost - frozen mounts thawing rapidly with warming). We are using the River Tana (Norway) flowing north of the arctic circle as a model river basin to collect data and run scenarios of climate and land use change.