Extreme Storm Events Causes Distinctive Nitrogen Loads Transported through a Southeastern USA Coastal Plain In-Stream Wetland.

Nitrogen (N) is a major non-point source contributor to the eutrophication of Coastal water bodies by causing nutrient enrichment and a rise in plant production.  Fortunately, wetlands can remove N loads from water by biological uptake and/or through storage processes in sediments.  The N stored in wetlands can, however, be transitory, because precipitation from storm events can create internal hydrological disturbances resulting in accelerated N export.  The objective of this research was to determine the effects of storm events on N loads delivered during base flow and storm flow events from an in-stream wetland.  The wetland is located in the Southeastern USA Coastal Plain region; it occurs in a watershed with high livestock production.  From 1991 to 1999, daily precipitation, wetland outflow measurements and composite water sampled were collected.  A digital hydrological model was used to separate wetland out flow into base and storm flow events.  In addition, sediment pore water N concentrations during 1997 to 1999 along with sediment N concentrations were also measured to corroborate shifts in N storage pools.  Cumulative N loss (as NH₄-N and NO₃-N) varied substantially over the study period with highest N loss occurring in 1999 (after three successive hurricanes).  Assessment of annual N loads transported during storm and base flow events along with shifts in sediment pore water N concentrations will be addressed.