Methane Emissions Above and Below a Ditch Plug, Sprague River Marsh, Phippsburg, ME

This study investigates methane emissions behind a ditch plug installation in the Sprague River Marsh, Phippsburg, Maine. Ditch plugs are common man-made tidal restrictions that inhibit tidal flow in salt marshes. Previous work has shown that higher methane emissions are associated with lower salinities. However, the effects of ditch plugs on methane emissions are previously unknown. Understanding the potential release of carbon in the form of methane on salt marshes is important for the overall carbon budget as salt marshes are one of the most effective carbon sinks. Static gas chambers were used to collect air samples above and below the ditch plug for 5 months during the summer of 2016. The samples were analyzed using a GC-FID and the data showed no statistical significant difference in methane emissions above or below the ditch plug. This concludes that the presence of the ditch plug in this particular location did not result in an increase of methane emissions on the marsh due to the high salinity levels in the area. This may not always true for ditch plugs everywhere, as these results are only considering a particular salinity regime. Vegetation and elevation were also surveyed in order to get a baseline for potential future studies