Modelling Denitrification Potential in Urban Impacted Riparian Zones of Tampa, Florida.

Population growth and land use and land cover (LULC) have presented many coastal areas with considerable challenges for the conservation of water resources.  Urbanization and the associated increase in impervious surfaces have been established as being detrimental to water quality.  Our goal was to better understand how nitrate (NO₃^-) within urban impacted riparian zones may be transformed and removed from the system via low-depth soil denitrification and which environmental variables were most influential in the process.  Denitrification enzyme activity (DEA) rates were measured through gas chromatography to measure potential rates.  Results suggest high heterogeneity within the sampled LULC categories, but with high residential sites exhibiting significantly higher DEA potential and nitrogen loads relative to light residential sites at further distances from the stream.  Total nitrogen, pH, and soil organic matter were found to be the most predictive variables for DEA potential and produced an R² of 0.75 (with the inclusion of LULC and Distance) in a general linear model.  Nitrate levels tended to decrease across the riparian zone, but stream transport could not be ruled out for samples near the stream bank.