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1 Atmospheric Nitrogen Deposition: An increasingly Important Source of new Nitrogen Supporting Coastal Eutrophication H Paerl 1, D. Whitall 2 and R. Dennis 3 1 UNC-CH CH Institute of Marine Sciences, Morehead City, NC, 2 NOAA, Center for Coastal Management and Assessment, Silver Spring, MD, 3 USEPA/NOAA Atmospheric Modeling Division, Research Triangle Park,, NC edu/paerllab

2 Why The Concern About Atmospheric Deposition of N (AD-N) in Coastal Waters? AD-N N is a significant source of externally-supplied or new N to coastal waters N N is the nutrient most often controlling primary production & eutrophication AD-N N sources are biologically available N-sensitive waters are currently impacted by AD-N

3 How important is AD-N N as a new N source? What are the origins & chemical forms of AD-N? What are the ecological impacts on coastal ecosystems?

4 Estimated contributions of AD-N N to "new" N inputs in estuarine, coastal and open ocean waters Baltic Sea ~30 % Elmgren et al North Sea (Coastal) 20-40% GESAMP 1989 W. Mediterranean Sea 10-60% Martin et al Waquoit Bay, MA 29% Valiela et al Narragansett Bay 12% Nixon 1995 Long Island Sound 25% L. I. Sound Study 1996 New York Bight 38% Valigura et al Barnegat Bay, NJ ~40% Moser et al Chesapeake Bay 27% C. B. Program 2001 Rhode River, MD 40% Correll and Ford 1982 Neuse R., NC ~30% Whitall and Paerl 2001 Pamlico Sound, NC 20->40% Paerl and Fogel 1994 Sarasota/Tampa Bay, FL 25-30% Sarasota Bay NEP 1996 Mississippi River Plume 5 -?? % Goolsby et al. 2000

5 The Neuse R. Estuary-Pamlico Sound Excessive N loading eutrophication hypoxia WQ/habitat decline Neuse R Modeling & Monitoring Program (ModMon) Partners: UNC, ECU, Duke, NCSU, USGS, NCDENR, EPA, Collaborators: NOAA-NOS, NOS, NASA, NADP, Weyerhaeuser

6 Neuse River Estuary N Sources (at head of estuary) 54% AD-N 35% 11% Pt. Sources N Retention Values Forest 0.95 Pasture 0.90 Crop 0.70 Urban 0.70 Other 0.70 from Valigura et al Runoff Runoff (excluding AD-N)and point source values AD-N N based on yearly averages from Dodd et al from data

7 * Estimate based on previous studies and limited data from this study; wet organics comprise approx. 20% of total wet N deposition Wet NH 4 + Wet Organics * Dry NH % 2% 23% Total AD-N N for Neuse R. Estuary Based on yearly averages from data 49% *Whitall et al *Walker et al Wet NO 3-7% Dry NO 3 - Dry Organics???

8 In Eastern NC, estuarine and coastal waters are getting more ammonium-rich. Why?

9 One reason: N-Driven N Eutrophication,, Increasing Hypoxia & Sediment Ammonium Release

10 Another reason: More ammonia is being emitted locally and regionally NH 3 NH 3

11 North Carolina Atmospheric Emissions, 1996 State N Emissions (Total=325,322 Tons) Turkeys Broilers Cattle 4% 5% 8% Swine 24% 12% Area Sources Automobiles 19% 28% Point Sources Coastal N Emissions (Total=140,111 Tons) Turkeys Broilers Cattle 9% 3% 3% Swine 53% Source: NC DENR, Division of Air Quality Automobiles 12% Point 10% Sources 10% Area Sources

12 County line Neuse River Basin Number of Hogs < > prevailing wind direction (from National Climatic Data Center)

13 r 2 =0.63 r 2 = mg NH 4 + -N/m 2 /yr NH 4 +-N:NO x -N Year Year National Atmospheric Deposition Program Data Sampson Co. North Carolina (NC35)

14 National Atmospheric Deposition Program 1999 Annual Summary

15 Why the Concern About Ammonium? Not all forms of N are used equally NH 3/4+, NO 3-, Organic N

16 Nutrient Addition Bioassay Experiment, T1 Neuse River, July NO3 + P C NH4 NO3 NH4 + NO3 P NH4 + P NO3 + P H4 + NO3 + P C NH4 NO3 NH4 + NO3 P NH4 + P NO3 + P H4 + NO3 + P C NH4 NO3 NH4 + NO3 P NH4 + P Chlorophyll a (µg L -1 ) H4 + NO3 + P Ammonium is a Preferred N source Upstream CMAX Downstream

17 Looking into the green box: : phytoplankton taxonomic group responses to specific forms of N enrichments by HPLC-ChemTax ChemTax Analysis

18 (mg m -3) Concentration Bogue Sound Bioassay Chl a 12 Fucoxanthin Control Nitrate Ammonium 0 Control Nitrate Ammonium Alloxanthin 4 Zeaxanthin Diatoms 1 1 Cryptomonads 0 Control Nitrate Ammonium 0 Control Nitrate Ammonium Cyanobacteria Treatment

19 Impacts on Ecosystem Biogeochemical cycling and trophodynamics NUTRIENT INPUTS PHYTOPLANKTON COMMUNITY Linkages Between Phytoplankton Community Composition and Oxygen Depletion FORM of Limiting Nutrient (NO 3 -, NH 4 +, DON) Nutrient Ratios Grazed Phytoplankton Species Nuisance / Toxic Phytoplankton Species Dinoflagellat es Cyanobacteri a Nutrient Regeneration Decomposition of POM Water Column Carbon Recycling Carbon Deposition (POC) DECREASED O 2 Depletion Potential s INCREASED O 2 Depletion Potentials OXIC CONDITIONS PHYSICAL CONTROLS Mixing Stratification HYPOXIA ANOXIA

20 Seasonal Variability in ADN is also important NRE Sites Pooled mg N/m2/week spring summer fall winter Significantly higher than spring, fall and winter at α=.01

21 Atmospheric N inputs can bypass the estuarine N filter Estuarine N Filter

22 The Airshed Scale: Bypassing the Estuarine Filter & Influencing the Coastal Zone

23 * * Nutrient stimulation of primary production in the W. Atlantic Ocean (Gulf Stream vs. Coastal) 0.6 * 0.4 Gulf Stream C-CO 2 Fixation (DPM * 10 4 ) * Coastal Control NO3 NH4 PO4 Fe + EDTA Fe + EDTA + NO3

24 Relative Importance of AD-N N Flux to the Annual N Budget of NC Coastal Waters Direct Deposition of AD-N to Coastal Waters (903 kg N/km 2 /yr) 35% 65% Land Based N Flux to Coastal Waters (1877 kg N/km 2 /yr) Land Based DIN Flux values for Southeastern U.S. region include AD-N N deposition to land (Howarth et al. 1996), AD-N N values from UNC-IMS data (DIN+DON; where DON is estimated at 20% of DIN flux)

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26 Conclusions AD-N N is a significant source of N enrichment to coastal waters downwind of emission sources. AD-N N impacts production and composition of phytoplankton. AD-N N plays a role in eutrophication dynamics of these waters. Chemical forms of AD-N N are important and ammonium is of growing concern Impacts are both local and regional. Management of AD-N N will include local, regional, and potentially, global efforts

27 Thanks to: US EPA STAR/EaGLe Program, NC Sea Grant, National Science foundation, USDA-NRI, Environmental Defense, NC DENR/DWQ/DAQ