Rapid Nutrient Release from Permafrost Thaw in Arctic Aquatic Ecosystems

Few studies provide experimental data to support the role of permafrost thaw on changes in arctic freshwater chemistry. We designed an incubation experiment to look at rapid nutrient release from permafrost soils and active layer soils under different warming scenarios, changes in redox environment, and microbial activity. Permafrost soil tended to immediately release more nutrients than active layer soils, especially under warmer conditions; suggesting the active layer is depleted in nutrients and the water column may be resupplied with these ions from thawing permafrost. The release of micronutrients (Ca, Fe, Mg, S, Si) from incubated permafrost soils responded strongly to increased temperature; however, temperature alone was not necessarily the primary driver of macronutrient (N, P) release from permafrost. Other physicochemical parameters influenced by temperature, such as oxidation-reduction potential (ORP), microbial activity, dissolved organic carbon (DOC), and Fe played an additional role in nutrient release from permafrost. These experiments suggest nutrient release via thaw of permafrost soils is able to contribute ample essential nutrients to arctic aquatic ecosystems, even within one day of warming. Further warming of the Arctic is likely to result in substantial changes to nutrient availability and cycling in these dominant habitats.