The Arctic contains huge quantities of soil carbon, yet most of this carbon is unavailable for microbial degradation because it is frozen in permafrost. Permafrost is thawing with increasing temperatures, and warming in the Arctic has now been confirmed to be twice the magnitude of global warming. If this soil carbon thaws and is mineralized, the impact on the climate system could be significant. However, little is known about variability in the quality of soil organic matter (SOM) across the landscape. Variation in SOM quality is an important link between permafrost thaw, global climate change, and other important environmental quality measures. SOM is both a source and sink of CO2 and CH4, which are major greenhouses. SOM quality can also impact the mobility and fate of contaminants, as well as nutrient transport within a watershed. Finally, SOM is capable of redistributing itself during permafrost disturbances, potentially stimulating soil degradation rates in affected areas and adding sediment to streams. Julianah is examining key factors that control variability in SOM quality and microbial community structure at a range of scales and how these might influences the decomposability of SOM and subsequent impacts on water quality.