The role of dissolved organic carbon in controlling the partial pressure of CO2 in boreal lakes

Par Jean-François Lapierre

Most lakes are super-saturated in CO₂ and emit greenhouse gases to the atmosphere.

The in-situ transformation of dissolved organic carbon (DOC) imported from the terrestrial landscape to dissolved inorganic carbon (DIC) constitutes a major source of CO₂ for aquatic ecosystems.

Regional specificities regarding the origin and composition of DOC generate contrasting relationships between DOC and the partial pressure of CO₂ (pCO₂), the main determinant of lakes greenhouse gases emission. This results that the observed pCO₂ may vary by more than an order of magnitude for a given concentration of DOC.

The overall objective of my thesis is to refine our understanding of the role of DOC as a substrate for the production of CO₂ in boreal lakes. More specifically, the main approach is to examine the links between catchments regional characteristics, DOC composition and origin and its biological and photo-chemical reactivity.