A River Runs Through It: Tidal Creek Contributions to Salt Marsh - PowerPoint PPT Presentation

A River Runs Through It: Tidal Creek Contributions to Salt Marsh Denitrification Presentation by Eric von Amsberg Advised by Dr. Michael Piehler IE BOV Meeting April 3rd 2020

Why Nitrogen?  Estuarine nitrogen is commonly dissolved in water.  Anthropogenic inputs of nitrogen include fertilizers, which enter waterways through runoff  VERY AVAILABLE (NO 3 - )  Nitrogen makes up 78% of the atmosphere.  Less available (N 2 )  N cycling has intricate relationship with C and O

Nitrogen’s Role in Water Quality (Hans Paerl)

(de Groot et al., 2002) Marshes are Marvelous!  Disturbance protection storm and flood protection  Nutrient regulation  Nursery function  Gas Regulation  Water regulation

The Millennium Ecosystem Assessment  Assess the consequences of ecosystem change for human wellbeing  Quantify the services (Baveye et al., 2016)

(BILKOVIC ET AL.,2017) -  N 2 Denitrification = NO 3 Requires: • Nitrate • Anoxia • Labile organic carbon

4 Carboys = ~20L of water from each site Water sampling sites • Beaufort Center (BFT C) • Mid Town Creek (GY) • Town Creek (TC)

18 Total cores 9 from Channel 9 From Marsh

Flux Setup Each feedwater ran through 6 cores, 3 cores from the marsh and 3 cores from the channel I

Sampling Dissolved Gasses Membrane Inlet Mass Spectrometry (MIMS) measures concentrations of dissolved gasses in water

Nutrient (Bin Town Creek ( μ M) Mid Town Creek ( μ M) Beaufort Center Samples) ( μ M) NOx 0.05 1.15 30.50 NH4 0.00 7.12 26.79 Nutrient (Historic Data) Town Creek Mid Town Creek Beaufort Center ( μ M) ( μ M) ( μ M) NOx 0.40 1.13 16.88 NH4 1.53 2.64 24.06

Dissolved Gas Flux from the Marsh 200 N2 Flux Marsh Ambient 150 Nitrogen Flux ( μ mol N m -2 hr -1 ) N2 Flux Marsh Spiked 100 Average N2 flux at Ambient conditions =13.05 μ mol N m -2 hr -1 50 Average N2 flux at Spiked conditions =112.1 μ mol N m -2 hr -1 0 BFT -50 TC GY C

We know about the marsh, What about the channel?  Hot spots and Hot moments - explains that chemical cycling has areas of increased intensity across time and space.  Channel could represent hot spot for denitrification

Dissolved Gas Flux from the Channel 120 100 Nitrogen Flux ( μ mol N m -2 hr -1 ) N2 FLUX Ambient CH 80 60 N2 Flux Spiked CH 40 Average N2 flux at Ambient conditions = -7.66 μ mol N m -2 hr -1 20 0 Average N2 flux at Spiked conditions 1 2 3 =54.82 μ mol N m -2 hr -1 -20 -40 BFT GY TC C -60

Sediment Organic Mater in the Marsh vs Channel? 18 16 Organic matter (% Loss on Ignition) 14 12 10 8 6 4 2 0 1 2 3 Replicate Core BFT Channel GY Channel TC Channel BFT Marsh GY Marsh TC Marsh

Flux Result: Channel Sediments Facilitate Denitrification  Channel denitrification rates < Marsh rates  Channel cores respond to excess nutrients  At ambient conditions, feedwater with greater [NOx] had greater rates of denitrification

Town Creek Hydrology

Town Creek Nitrogen Budget Annual Nitrogen Load = 731.4 kg Max DNF rate ( μ mol N m -2 hr -1 ) Habitat Area (M 2 )* Mass of N removed (kg/yr) Removal Efficiency Marsh 78,646 149.94 361.81 51.75% Channel 12,540 84.83 65.26 9.16% Assumptions Day/Night, Tides, Area Temperature, Salinity, LOC, Dissolved O 2

Nutrient (Historic Town Creek Mid Town Beaufort Data) ( μ M) Creek ( μ M) Center ( μ M) NOx 0.40 1.13 16.88 NH4 1.53 2.64 24.06

Implications  Large portion of nitrogen load is removed from the water, some via denitrification  Channel should be included in an overall evaluation of N budget in coastal salt marshes.  This marsh and channel provide a great service to Beaufort

Thanks to… The Piehler Posse Mike Piehler Suzanne Thompson Mollie Yacano Adam Gold Chelsea Brown Paerl Lab (Nutrients) Questions?

Sources Baveye , et al. “Soil ‘Ecosystem’ Services and Natural Capital: Critical Appraisal of Research on Uncertain  Ground.” Frontiers , Frontiers, 24 May 2016, www.frontiersin.org/articles/10.3389/fenvs.2016.00041/full. Groot, Rudolf de, et al. “Global Estimates of the Value of Ecosystems and Their Services in Monetary Units.”  Ecosystem Services , Elsevier, 23 Aug. 2012, www.sciencedirect.com/science/article/pii/S2212041612000101. Laursen, Andrew E., and Sybil P. Seitzinger. “Measurement of Denitrification in Rivers: an Integrated, Whole Reach  Approach.” SpringerLink , Kluwer Academic Publishers, Oct. 2002, link.springer.com/article/10.1023/A:1021398431995. Laursen, Andrew E., and Sybil P. Seitzinger. “Measurement of Denitrification in Rivers: an Integrated, Whole Reach  Approach.” SpringerLink , Kluwer Academic Publishers, Oct. 2002, link.springer.com/article/10.1023/A:1021398431995. Model My Watershed , modelmywatershed.org/project/.  “Overview of the Milliennium Ecosystem Assessment.” Millennium Ecosystem Assessment ,  millenniumassessment.org/en/About.html. Bilkoivc, Donna. Mitchel Molly, Toft Jason Jan. 2017  https://www.researchgate.net/publication/317003899_Living_Shorelines_The_Science_and_Management_of_Nat ure-Based_Coastal_Protection

Channel O 2 Flux 5000 O2 flux 4000 O2 flux (umol O 2 m -2 hr -1 ) 3000 Channel O2 2000 Flux Ambient Channel O2 1000 Flux Spiked 0 Marsh O 2 Flux -1000 -2000 4000 3500 3000 O 2 flux umol O 2 m -2 hr -1 ) 2500 2000 1500 Marsh O2 Flux Ambeint 1000 500 Marsh O2 flux Spiked 0 1 2 3 -500 -1000 BFT -1500 TC GY Core C

Sediment Oxygen Demand Channel SOD Ambient Conditions Marsh SOD Ambient Conditions 80 40 60 Marsh 30 Ambient 40 20 Channel Linear Ambient 20 10 (Marsh Linear (Channel Ambient ) Ambient) 0 0 y = -0.0433x + 97.045 0 1000 2000 3000 4000 0 1000 2000 3000 4000 R² = 0.6995 -10 y = -0.0142x + 20.171 -20 R² = 0.6695 -20 -40 -30 -60 -40 Marsh SOD Spiked Conditions Channel SOD Spiked conditions 350 120 300 100 Marsh Spiked Channel 250 Spiked 80 200 Linear (Marsh Spiked) 60 150 Linear (Channel 40 100 Spiked) y = 0.0389x + 59.052 y = 0.0104x + 41.182 50 20 R² = 0.3297 R² = 0.1674 0 0 0 1000 2000 3000 4000 0 1000 2000 3000 4000

DNF is hard to measure  Acetylene  Isotope studies using N15  Direct quantification of N2  Mass balance  Stoichiometric approaches  Stable isotope abundance  Molecular approaches  N2:Ar method

Water sampling sites • Beaufort Center (BFT C) • Mid Town Creek (GY) • Town Creek (TC)