Denitrification Potential of Riparian Zones Throughout Tampa, FL and Surrounding Areas.

Population growth and land use change has presented coastal areas with considerable challenges for the conservation of water resources while sustaining communities.  Urbanization and the associated increase in impervious surfaces have been established as being detrimental to water quality. The major nutrient implicated for water quality deterioration in many water bodies in coastal regions, including our study site, is nitrogen (N).  The long-term goal is to understand the fate and transport of N in urbanized watersheds within a coastal plain environment and the role vegetation plays in improving water quality in urban areas.  Riparian zones have been shown to have disproportionately greater denitrification rates relative to most areas of a landscape.  Our research objective of this study is to determine the denitrification potentials of common land-use categories in a subtropical, coastal-urban landscape.  Due to anthropogenic alteration to vegetation and hydrology, riparian zones within relatively close proximity to urbanized areas were expected to exhibit some degree of diminished denitrification potential relative to riparian zones in less disturbed rural areas.  Soil samples were collected from varying distances perpendicular to the riparian zone, and the microbial denitrification potentials of these soils were measured using the acetylene block method.   Denitrification enzyme activity (DEA) assays were analyzed through gas chromatography to measure potential rates.  Initial results suggest significant differences in based on land-use category.  Remnant forest and high residential riparian zones showed comparatively greater denitrification potential rates relative to zones within emergent forest and light residential land-use categories.