Characterization of Surficial Sediments from an Island of Wax Lake Delta, Louisiana (USA)

Abstract

Delta wetlands are an important depositional environment where rivers meet the coast. These wetlands form natural barriers to erosion and may influence the quality of river water that discharges to the ocean. This study characterizes the composition of delta wetland sediment through analysis of grab samples from Mike Island within Wax Lake Delta, Louisiana (USA). The sediment characterization is part of a broader study that assessed spatial variations in nutrient removal on the island. We collected sediment cores to an approximate depth of 20-30 cm at five sites that spanned levee and lagoon environments. Multiple grain size and organic matter characteristics were measured on the sediment samples, including loss on ignition, as a proxy for organic content, and mud fraction using hydrometer analysis. The samples have a range of mud fractions from approximately 40 to 90%. Samples from the levee are more sand-rich and have a range of organic matter contents from 0.85 to 10.81%. These results support our understanding of the relationships among delta morphology, surficial sediment characteristics, and nutrient removal rates in delta wetlands.