Stockholm university

Research project Anthropogenic carbon accumulation in coastal sediments - A significant but overlooked methane source

This project aims to use the Baltic Sea to test the hypothesis whether the sediment methane legacy pool, especially derived from the organic carbon legacy pool with large proportion of terrestrial organic carbon, will be a long-lasting source of methane (CH4) to the atmosphere from years to centuries.

Anthropogenic activities have drastically perturbated carbon distribution and transformation in global coastal systems mostly by eutrophication, industrial effluents and climate change. They have led to acceleration of anthropogenic organic carbon  deposition onto coastal sediments and subsequently a shoaling of sediment biogeochemical zonation, which in turn results in a formation of methane (CH4) legacy pools in sediments.

 

Project description

In the next three years, we will develop a unique methodological approach by combining a coupled sediment reactive-transport model and a Baltic-scale physical-biogeochemical model with biogeochemical analysis, including stable isotopes, geophysical methods and a non-invasive approach of measuring CH4 distribution continuously in the water column.

This will allow us to identify CH4 hotspots and its evolvement in response to future changes throughout the entire Baltic Sea with bearing for global coastal CH4 budgets. The findings will hold important implications on quantifying how much and how long a CH4 legacy pool will offset the carbon sequestration potential of coastal systems that have recently been often-quoted as a powerhouse of climate mitigation.

Project members

Project managers

Christoph Humborg

Professor

Stockholm University Baltic Sea Centre
humborg