Effekter av interaktioner mellan järn och organiskt kol på biogeokemiska cykler i sjöar

The biogeochemical cycles of iron (Fe) and organic carbon (OC) in aquatic environments are tightly connected.

Fe influence key processes that regulate OC cycling, e.g. photochemical transformations, aggregation, and preservation of OC in sediments.

In light of the striking increases in Fe concentrations that are widely observed in freshwaters during the last decades, it is urgent to understand which processes respond to rising Fe, and what the consequences for the fate of OC in the aquatic compartment are.

Nevertheless, we are only beginning to understand the quantitative importance and the mechanisms by which Fe influences OC transformations and loss processes in inland waters.

The aims of the current project are to I) characterize and quantify Fe-OC interactions and their influence on the fluxes and fate of Fe and OC in lakes, and II) reveal the processes and mechanisms that control the in-lake transformations and fluxes of Fe and OC.

This will be achieved by applying a multi-method approach to characterize the Fe speciation and chemical composition of organic material in situ, and by controlled laboratory studies that investigate Fe-OC transformations that are triggered by light, pH gradients, microbial activity and increasing Fe.

Integrating observational and experimental efforts will bring us beyond the identification of potential mechanisms, and reveal the significance and relative importance of individual processes related to Fe-OC biogeochemistry in lakes.