ORGANIC RICH DEPOSITS FROM A SOUTHERN APPALACHIAN WETLAND INDICATE CARBON SEQUESTRATION POTENTIAL AND SITE STABILITY OVER THE LAST MILLENNIUM

Organic-rich sediments from wetlands in the southern Appalachian Mountains have been used to record Holocene climate variability. Wetlands make up 5-8% of terrestrial land surfaces but account for storage of 20-30% of the Earth’s carbon (Mitsch et al. 2013). This demonstrates the efficiency of wetland systems to sequester carbon and to partially offset the historical increase in carbon dioxide (CO₂) due to fossil fuel combustion. An unstudied wetland has been recently discovered within the Mills River Watershed area in North Carolina. A soil core obtained using a Dutch auger from Pilot Cove Wetland provides a multi-proxy, paleo-environmental record, and provides insight into carbon sequestration potential for the last 1,300 cal yrs BP. The core was sub-sampled at 5-cm intervals for analysis of bulk carbon, nitrogen, and stable carbon isotope-ratios. Additionally, three samples were submitted for radiocarbon age determinations. Environmental proxies were examined for trends concurrent with climate variability over the past millennium (Medieval Warming and The Little Ice Age). These proxies indicate stable conditions during these climatic events. C/N and δ¹³C showed very little fluctuation and their average values indicate a stable system for the past 1,300 cal yrs BP, the maximum age of the wetland indicated from the basal radiocarbon age determination. Carbon sequestration (SCAR) values indicate the wetland stores approximately 2.6 tons C/yr, representing a total storage capacity over 3,000 metric tons for the entire wetland. The stable proxy signal for the wetland suggests that the site may not have experienced the effects of the Medieval Warming or the Little Ice Age climatic events. Alternately, it may suggest that the wetland was buffered (e.g. beaver activity?) in some way if these climatic events did indeed affect the region. Additional cores should be collected, and organic-rich proxy indicators should be integrated with other techniques (pollen fossil or fire history studies) in order to complement the extant analyses.