Science Serving Maryland's Coasts

Stella Castro, Universidad Metropolitana

Class Year: 

Project Title: 

Geochronological Analysis of Sediments in Tidal Freshwater Marshes in the Patuxent River


Freshwater marshes are very important because of their diversity and productivity. Also, they help maintain water quality for surrounding ecosystems. Freshwater marshes have become threatened by multiple factors like anthropogenic activities and climate change. Sea-level rise is considered the strongest threat for the marshes. The rising of the water may cause degradation and even elimination of freshwater marshes and other coastal environments. In order to determine if freshwater marshes are able to keep up with the sea level rise, low and high-marsh peat cores were taken from the Patuxent River and were analyzed to determine their grain size, organic content, and 210Pb activities to determine the accumulation of sediments in this marsh. The organic content, as well as grain size, increased with distance from the river edge because the low marsh is more influenced by the river. Sand and organic content of the high marsh suggests that sediment is derived from organic decomposition of plant material. Accumulation rate of low marsh appeared to be greater and faster than the high marsh. The accumulation rates of sediment at this site were found to be greater than the sea level rise, but have been decreasing in both the high and low marsh over the past decades, without showing trends of increase or stabilization. This relationship between sea level rise and accumulation rate is crucial to understand to help maintain freshwater marshes.