Nutrient runoff from agricultural lands contribute to annual hypoxic zones in the Gulf of Mexico. Anoxic conditions in wetland soils allow denitrifying bacteria to remove nitrates from runoff. Through the farm bill, over two million acres of land have been enrolled in the Wetlands Reserve Program since 1990 to help restore wetlands and mitigate this problem. However, few studies have quantified ecological effects of wetland restoration and denitrification success. We are monitoring changes in nitrate concentrations during flooding events on easements ranging in restoration age from one to twelve years in western Kentucky. We are using automatic water samplers to collect discrete samples across various flood states and analyzing samples for nitrate/nitrite concentrations.
Results/Conclusions
Preliminary results from winter flood events indicate that, while in some easements nitrate concentrations remained stable, in other easements nitrate levels decreased 34-56% throughout a flood event, from 0.92 ± 0.14 mg L-1 to 0.51 ± 0.11 mg L-1 (means ± standard error). Comparing these patterns with those of adjacent river channels and with denitrification potential of wetland soils will help us understand the ability of these easements to reduce nutrient loads. Monitoring ecological processes in restored wetlands can help inform future adaptive management practices that include a variety of restoration goals for nutrient reduction.