Determining Ideal Nitrogen Loads for Rerouted Agricultural Drainage Water into Restored Forested Wetlands: A Experimental and Modeling Approach

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1 Determining Ideal Nitrogen Loads for Rerouted Agricultural Drainage Water into Restored Forested Wetlands: A Experimental and Modeling Approach Tiffany L. Messer, Dr. Michael R. Burchell, II, and Dr. François Birgand, 2014 WRRI Annual Conference March 20 th, 2014

2 Background

3 Hyde County Wetland Restoration Project overview Swan Lake Alligator River National Wildlife Refuge Restored Wetlands Existing Farmland Current Pumped Drainage Pamlico Sound Proposed Rerouted Drainage

Stakeholder Goals and Concerns v Hydrologic improvements to the restoration and surrounding refuge lands v Reduce pumping to Pamlico Sound v Improve wetland ecosystem structure v Reverse

4 Stakeholder Goals and Concerns v Hydrologic improvements to the restoration and surrounding refuge lands v Reduce pumping to Pamlico Sound v Improve wetland ecosystem structure v Reverse subsidence v Reduce threat of fire v Combat SLR/salt water intrusion v Concern: Water quality of diverting drainage water through wetlands towards nitrogen-limited receiving waters (Swan Lake)

5 Forested Wetland Studies v Previous studies in the Albemarle-Pamlico peninsula have reported wetlands that received agricultural drainage water effectively store water and reduce nutrients up to 97% (Ardόn et al., 2010; Bruland et al., 2006; Chescheir et al., 1991). v Available studies have evaluated wetland performance at the field scale after pumping to those areas began, with little control of how the areas were loaded with drainage water (Bruland et al., 2006; Chescheir et al., 1991). v Studies are necessary to allow for a mass balance approach to accurately predict N transformations and appropriate hydraulic loads within wetland systems (Kovacic et al., 2000).

6 Research Objectives

7 Research Objectives 1. Utilize mesocosm-scale wetlands with restoration site soils to determine the fate and assimilation potential of nitrate. 2. Improve our understanding of the fate of applied nitrate in these systems with advanced analytical techniques Continuous WQ probes 3. Determine ideal volumes of water and associated nutrient loads that can be diverted away from the Pamlico Sound and into the restored wetland.

8 Focus: NO 3 N Reduction: Denitrification or Plant Uptake? Microbial denitrification allows for complete removal of NO 3- -N from the system Denitrification requires: Anoxic conditions Nitrate source Suitable ph conditions Carbon source Suitable temperature N 2 Deposition OrgN Mineralization Immobilization NH 4 + Nitrification NH 3 NO - 3 NO - 2 DNRA Denitrification NO N 2 O Denitrification NO 3 -

9 Materials and Methods

Wetland Nitrogen Fate Investigated Criteria Denitrification Plant Uptake/ Soil Retention Soil redox & Antecedent Conditions Plant Establishment

10 Wetland Nitrogen Fate Investigated Criteria Denitrification Plant Uptake/ Soil Retention Soil redox & Antecedent Conditions Plant Establishment Year Carbon Availability Luxury Uptake Temperature Above and Below Ground Biomass ph Beginning and End of Growing Season Soil Sampling Nitrogen Load

11 Mesocosm Experimental Setup Drainage Water Mixing Tank Recirculation System Organic Rep 1 Control 1 Mineral Rep 1 Spectro:lyser probe multiplexor system Greenhouse Perimeter Mineral Rep 2 Organic Rep 2 Mineral Rep 3 Organic Rep 3 Control 3 Control 2

12 Batch Run Plan v Various hydraulic and nutrient loading rates v NO 3 -N concentrations mg L -1 v Base load (1X) has 2.5 mg L -1 of NO 3 -N at depth of 18 cm v Runs last 7-10 days with depths of 18 and 30 cm Run Types Load 1X 2X 2X 4X 4X 8X NO 3 - N (mg L - 1 ) Water Depth (cm) Antecedent Condition (cm) Seasons Completed Winter Spring Fall Fall Summer Fall Winter Seasons Plan to Complete Summer Spring Summer Fall Summer Fall Spring Summer Fall Summer Spring

Instrumentation and Sampling Daily Monitoring (Days 0, 1, 2, 3, 5, 7, and 10) v Grab samples for NO3--N,

Monitoring (0, 5, 10) v TKN, Cl-, Hourly Monitoring PLC Controller v NO3--N and DOC using the Spectro:Lyzer

Humidity Data Offload Yearly/Seasonal Monitoring (2011-2013) v Beginning and end of growing season soil

13 Instrumentation and Sampling Daily Monitoring (Days 0, 1, 2, 3, 5, 7, and 10) v Grab samples for NO3--N, NH4+-N, and PO4-3-P v Redox Potential Spectro: Lyzer Probe v ph v Dissolved Oxygen v Water Depth Daily Monitoring (0, 5, 10) v TKN, Cl-, Hourly Monitoring PLC Controller v NO3--N and DOC using the Spectro:Lyzer Probe and multiplexor system Solenoid Valve v Air Temperature Manifold v Water Temperature v Air Relative Humidity Data Offload Yearly/Seasonal Monitoring ( ) v Beginning and end of growing season soil samples v End of growing season above and below ground biomass samples 5 mm Cuvette Peristaltic Pump 12 Different Sampling Sources

14 Statistical Analysis v Multivariate statistical analyses have been used to determine differences between NO 3 -N reductions in the two wetland soil treatments and the controls over time in SAS. v Effects of treatment, season, and N loading, were assessed with Tukey honest significance tests in SAS. v All statistical tests were considered significant at α=0.05.

15 Preliminary Nitrogen Removal Modeling v Removal rate constants (k) have been calculated utilizing a widely used first order process equation (Burchell et al., 2007a; Reed et al., 2005; Kadlec and Knight, 1996) v Maximum NO 3 -N loads that can be pumped into the fullscale wetland will be determined.!!! =!!!!" C = concentrations at time t (mgl -1 ) C 0 = initial concentrations (mgl -1 ) k = rate constant (hr -1 ) t = time (hr) k

16 Preliminary Results

17 Wetland Run Summary (to date) Season (Date) Fall (9/15-10/4) Fall (10/16-10/26) Fall (11/5-11/15) Fall (9/24-10/4) Fall (10/15-10/25) Winter (1/22-2/1) Winter (2/11-2/21) Spring (5/28-6/7) Summer (7/2-7/12) Summer (8/6-8/16) Summer (8/20-8/27) Avg. Water Temp (ºC) Monitoring Time (day) Water Depth (cm) Target C i (mgl - 1 ) Actual Avg. C i (mgl - 1 ) Load Mean NO 3 - N % Removal Wetland Org Wetland Min X 65% 93% X 81% 81% X 51% 47% X 56% 70% X 95% 97% X 48% 55% X 41% 43% X 100% 100% X 97% 99% X 96% 99% X 90% 89%

18 NO 3 -N Concentration Reductions v 1X Load (2.5 mg L -1, 18 cm water depth) v NO 3 -N removal rates positively affected by temperature, as expected. v Removal curves will be used to determine NO 3 -N removal rate constants for each wetland type and adjusted for temperature. Organic Mineral * Data presented is an average of the 3 mesocosm samples.

19 UV-Spectrometer Continuous WQ data

20 Soil Redox Potentials v Redox potentials stayed below 250 mv in both the mineral and organic mesocosms in all batch runs. v The mineral mesocosms had slightly lower overall redox potentials. v The 15 cm redox potentials were consistently lower than the 5 cm redox potentials in both the mineral and organic mesocosms. Organic Mineral * Data presented is an average of the 3 mesocosm samples.

21 Carbon Availability and ph Batch Run Average Temperature (ºC) Day of Run ph DOC (mg L -1 ) Mineral Organic Winter 8.9 Spring 25 Fall 16.7 Winter 8.9 Spring 25 Fall * Data presented is an average of the 3 mesocosm samples.

22 Other Preliminary Results: v Significant NO 3 -N reduction in wetland mesocosms compared to the control mesocosms (α=0.05). v Differences in NO 3 -N removal between soils, season, and N load are significant (α=0.05). v Preliminary mass balance estimates indicate denitrification could account for 44-65% and 60-80% of NO 3 -N removal in the Organic and Mineral wetland systems, respectively.

23 Rate Constants (k) * Data presented is an average of the 3 mesocosm samples.

24 Preliminary Conclusions

25 Conclusions v Significant NO 3 -N reductions were observed in the wetland mesocosms with both organic and mineral soils. v Rates are greatest in the warmer seasons and limited in the winter, as expected, exhibiting the importance of temperature and season on NO 3 - N reduction. v Conditions are favorable for denitrification to occur within these systems, but we remain uncertain to the percent removal that can be contributed to denitrification.

26 Future Evaluations

27 Important Future Evaluations v More batch runs are planned for the spring and summer seasons of 2014 to fully assess seasonal variability. v Rate constants and temperature coefficients will be further developed using more complex methodology to create a more robust NO 3 -N reduction predictive model. v These models will be used to determine the seasonal NO 3 -N loads that can be applied and assimilated by the future fullscale restored wetland.

28 Acknowledgements Committee: Dr. Michael R. Burchell II, Dr. François Birgand, Dr. George Chescheir, and Dr. Steven Broome US EPA, WRRI, NC Sea Grant Assistance in Field: Maggie Rabiipour, Kathleen Bell, James Blackwell, Kris Bass, Randall Etheridge, Jacob Wiseman, Dr. Robert Lagacé, Mark Fernandez, and Yo-Jin Shiau BAE Environmental Analysis Lab: Rachel Huie and Heroshi Tajirir Soil Science Environmental & Agricultural Testing Service: Dr. Wayne Robarge, Guillermo Ramirez, and Lisa Lentz This presentation was developed under STAR Fellowship Assistance Agreement no. FP awarded by the U.S. Environmental Protection Agency (EPA). It has not been formally reviewed by EPA. The views expressed in this presentation is solely those of Tiffany L. Messer and EPA does not endorse any products or commercial services mentioned in this presentation.

29 References Ardόn, M., J. L. Morse, M.W. Doyle, and E.S. Bernhardt The water quality consequences of restoring wetland hydrology to a large agricultural watershed in the southeastern coastal plain. Ecosystems, 13: Bruland, G.L., C.J. Richardson, and S.C. Whalen Spatial variability of denitrification potential and related soil properties in created, restored, and paired natural wetland. Wetlands, 26(4): Burchell, M.R., R.W. Skaggs, C.R. Lee, S. Broome, G.M. Chescheir, and J. Osborne Substrate organic matter to improve nitrate removal in surface flow constructed wetlands. Journal of Environmental Quality, 36(1): Chescheir, G.M., J.W. Gilliam, R.W. Skaggs, and R.G. Broadhead Nutrient and sediment removal in forested wetlands receiving pumped agricultural drainage water. Wetlands, 11(1): Harrison, M.D., P.M. Groffman, P.M. Mayer and S.S. Kaushal Nitrate removal in two relict oxbow urban wetlands: a 15 N mass-balance approach. Biogeochem. 111: Kadlec, R. H. and S.D. Wallace Treatment Wetlands, 2nd ed. CRC Press, Boca Raton, FL, USA. Reed, S.C., R.W. Crites, and E.J. Middlebrooks Natural systems for waste management and treatment. McGraw-Hill, Washington, DC.

30 Questions?

Department of Biological and Agricultural Engineering. Michael R. Burchell II - Assistant Professor and Extension Specialist

Department of Biological and Agricultural Engineering Hydrologic and wetland ecosystem restoration through rerouting pumped agricultural drainage water: An innovative integrated water management system