GEOL Thesis Defense - Carolyn RyanThursday, July 6, 2017 - 9:30am
Subsurface transport in a North Inlet, South Carolina salt marsh: A porewater salinity model
Subsurface transport in coastal salt marshes influences the nutrient budget of coastal environments, but is not fully understood. To expand our understanding of this transport, a simple numerical model was developed. The model simulated vertical transport of salt through the surficial muds at a North Inlet marsh on the coastal plain of South Carolina. To improve the model, a tracer study was utilized to calculate the average velocity of groundwater flow through the system. The model was compared with porewater salinity measured using tension samplers and passive diffusion samplers. Each method produced different, uncorrelated results. However, accounting for macro-pores in the surficial sediments explains the differences. Some methods, including those utilizing tension samplers, mostly measure transport occurring in the macro-pores. Passive diffusion samplers and basic single-domain transport models may more closely represent transport through the matrix of the marsh. To understand subsurface transport across the whole marsh, both pore regimes need to be considered.