Caribbean-Florida Water Science Center
Nitrogen transport and transformation beneath storm-water infiltration basins in karst areas, Marion County, Florida
Project Chief: Andrew M. O’Reilly
Figure 1. Study area showing locations of the South Oak and Hunter’s Trace stormwater infiltration basins and monitoring sites.
Nitrate concentrations have increased in many Upper Floridan aquifer springs since the 1950s, exceeding 1 mg/L in recent years in some springs. Stormwater runoff is one possible source of nitrogen, among others including septic tanks and land-based application of reclaimed water or fertilizer, which can contribute to elevated nitrate concentrations. Previous studies have collected water-quality data to describe the effects of various stormwater best management practices (BMPs) on groundwater quality. However, in general, little research is available to develop a process-based understanding of the effects of stormwater on groundwater from a nutrient/biogeochemical cycling perspective.
1) Identify and evaluate the natural processes (physical, chemical, and biological) that control the nitrogen cycle in soil and groundwater beneath stormwater infiltration basins
2) Develop, implement, and monitor a new stormwater infiltration BMP for nutrient (nitrogen and phosphorus) reduction
Figure 2. δ15N and δ18O of nitrate (NO3–) in precipitation, stormwater, soil water, and groundwater at the South Oak and Hunter’s Trace sites showing samples plotted relative to typical source ranges. Results indicate that denitrification is naturally occurring in the subsurface at the South Oak basin but not at the Hunter’s Trace basin.
Two stormwater infiltration basins in the karst/high recharge areas of Marion County, Florida, were monitored to identify subsurface biogeochemical processes (Figure 1). Chemical and hydrologic data were collected from 2007 to 2010, including: major elements, nutrient, organic carbon, and trace metals; dissolved gases; stable oxygen and hydrogen isotopes of water, and oxygen and nitrogen isotopes of nitrate and nitrogen gas; soil mineralogy and chemistry; nitrite reductase gene density by real-time polymerase chain reaction; and hydroclimatic data (rainfall, basin stage and groundwater level, soil moisture and temperature). Water samples were collected from ponded stormwater, suction lysimeters, and shallow wells near the water table.
O’Reilly, A.M., Chang, N.B., Wanielista, M.P., and Xuan, Zhemin, 2011. Identifying biogeochemical processes beneath stormwater infiltration ponds in support of a new best management practice for groundwater protection. In: Schirmer, M., Hoehn, E., and Vogt, T. (eds.), GQ10: Groundwater quality management in a rapidly changing world. Proceedings of the 7th International Groundwater Quality Confrence, Zurich, Switzerland. 13–18 June 2010. IAHS Publ. 342. IAHS Press, Oxfordshire, UK. p. 437–440. https://www.iahs.info/uploads/dms/abs_342_0437.pdf
O’Reilly, A.M., Wanielista, M.P., Chang, N.B., Harris, W.G., and Xuan, Zhemin, 2012. Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins: Journal of Environmental Quality, v. 41, no. 2, pp. 564–581. https://www.agronomy.org/publications/jeq/abstracts/41/2/564
O’Reilly, A.M., Chang, N.B., and Wanielista, M.P., 2012. Cyclic biogeochemical processes and nitrogen fate beneath a subtropical stormwater infiltration basin: Journal of Contaminant Hydrology 133: 53–75. https://dx.doi.org/10.1016/j.jconhyd.2012.03.005
O’Reilly, A.M., Wanielista, M.P., Chang, N.B., Xuan, Zhemin, and Harris, W.G., 2012. Nutrient removal using biosorption activated media: Preliminary biogeochemical assessment of an innovative stormwater infiltration basin: Science of the Total Environment 432: 227–242.