Terrestrial carbon storage and sedimentation in the Coon Creek Watershed Wisconsin

This study examines the connections between recent terrestrial sedimentation and carbon burial and discusses the implications for the global carbon cycle. Land-use change has mobilized large quantities of sediment, causing sediment to accumulate on valley floors, altering the terrestrial sediment cycle. This accumulated sediment may be sequestering much of the “missing carbon.” Using a combination of fieldwork and laboratory work, I explored carbon storage within the well-studied Coon Creek watershed of southwestern Wisconsin. To examine the basin’s sedimentation history, soil profiles were compared to existing sedimentation data and examined for carbon and nitrogen content. Two profiles reached buried pre-settlement soil, displaying the entire post-settlement sedimentation history of the valley. Recurring intervals of relatively low carbon percentages in site profiles indicate that most sediment eroded from heavily cultivated areas. Periods of high carbon values most likely represent eroded A-horizons from agricultural fields. The total amount of carbon found to be sequestered in the basin for the period 1850-1975 is 8.056 x 10 grams. To bury this amount of carbon, these processes would have to occur over only 1.4392 x 10 m or 3.0% of global land capable of sequestering carbon. These results suggest that terrestrial sedimentation may account for the “missing carbon sink.”