Photomineralization of the organic matter mobilized by permafrost thawing in ponds of East Canadian Arctic

This work is carried out for the PhD thesis of Flora Mazoyer. The goals are 1- to describe, quantify and compare dissolved organic matter (DOM) photodegradation efficiency in arctic thaw ponds. The factors influencing photodegradation and subsequent CO2 production, such as bacterial activity, DOM composition or water column light attenuation will be studied, 2- to evaluate the photomineralization potential of permafrost old organic matter, in the frame of the positive feedback loop hypothesis and 3- to elaborate a conceptual model of DOM photodegradation efficiency controlling factors in arctic thaw ponds. Climate warming and associated effects to come, which are likely to influence photodegradation efficiency will be taken into consideration.The project aims at providing a better understanding of current and future effects of sunlight on organic matter (OM) mineralization into CO2. The project is novel as it focuses on an abundant ecosystem in Arctic landscapes, the small and shallow thaw ponds, known to be intensive sites of greenhouse gases (GHG) production, and the north-east of Canada, a poorly studied Arctic region.