Removal of Wastewater Nitrogen and Phosphorus by an Oligohaline Marsh

Abstract

Wetlands potentially contribute to water quality improvement. The objective of this thesis was to determine the role of wastewater processing by oligohaline Council Creek marsh (0.16 km2), which receives wastewater from Easton, MD. Tidal flushing, nutrient distributions, plant uptake, and sediment burial were examined as removal mechanisms. This marsh seems to be little affected by, and has a small impact on wastewater. Wastewater flow can raise mean water levels by 3 cm in addition to seasonal changes of 30 cm induced by thermal expansion and contraction of seawater. During the ~3 d flushing time of water, nutrients passing through the marsh experienced small transformations compared with 2575% dilution of wastewater in the marsh by Choptank River water, during summer high sea level stands. During the growing season, marsh plants intercepted 3044% N and 1117% P, while sediment burial appeared to remove 27% N and 6% P, annually.