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

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

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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.

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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

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Why Nitrogen?

 Estuarine nitrogen is commonly dissolved in water.

 Anthropogenic inputs of nitrogen include fertilizers, which enter waterways through runoff  VERY AVAILABLE (NO3

  • )

 Nitrogen makes up 78% of the atmosphere.

 Less available (N2)

 N cycling has intricate relationship with C and O

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Nitrogen’s Role in Water Quality

(Hans Paerl)

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Marshes are Marvelous!

 Disturbance protection storm and flood protection  Nursery function  Water regulation

(de Groot et al., 2002)

 Nutrient regulation  Gas Regulation

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The Millennium Ecosystem Assessment

 Assess the consequences of ecosystem change for human wellbeing  Quantify the services

(Baveye et al., 2016)

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(BILKOVIC ET AL.,2017)

Denitrification = NO3

  •  N2

Requires:

  • Nitrate
  • Anoxia
  • Labile organic carbon
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Water sampling sites

  • Beaufort Center

(BFT C)

  • Mid Town Creek

(GY)

  • Town Creek (TC)

4 Carboys = ~20L of water from each site

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18 Total cores 9 from Channel 9 From Marsh

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Flux Setup

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

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Sampling Dissolved Gasses

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

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

Nutrient (Bin Samples) Town Creek (μM) Mid Town Creek (μM) Beaufort Center (μM) NOx 0.05 1.15 30.50 NH4 0.00 7.12 26.79

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Dissolved Gas Flux from the Marsh

  • 50

50 100 150 200

Nitrogen Flux (μmol N m-2 hr-1)

N2 Flux Marsh Ambient N2 Flux Marsh Spiked

Average N2 flux at Ambient conditions

=13.05 μmol N m-2 hr-1

Average N2 flux at Spiked conditions

=112.1 μmol N m-2 hr-1 TC GY

BFT C

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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

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  • 60
  • 40
  • 20

20 40 60 80 100 120

1 2 3

Nitrogen Flux (μmol N m-2 hr-1)

N2 FLUX Ambient CH N2 Flux Spiked CH

Dissolved Gas Flux from the Channel

BFT C

GY TC

Average N2 flux at Ambient conditions

= -7.66 μmol N m-2 hr-1

Average N2 flux at Spiked conditions

=54.82 μmol N m-2 hr-1

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2 4 6 8 10 12 14 16 18

1 2 3

Organic matter (% Loss on Ignition)

Replicate Core

BFT Channel GY Channel TC Channel BFT Marsh GY Marsh TC Marsh

Sediment Organic Mater in the Marsh vs Channel?

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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

  • f denitrification
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Town Creek Hydrology

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Town Creek Nitrogen Budget

Habitat Area (M2)* Max DNF rate (μmol N m-2 hr-1) 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 O2

Annual Nitrogen Load = 731.4 kg

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

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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

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Questions?

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

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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

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  • 1500
  • 1000
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500 1000 1500 2000 2500 3000 3500 4000 1 2 3

O2 flux umol O2 m-2 hr-1 ) Core

Marsh O2 Flux

Marsh O2 Flux Ambeint Marsh O2 flux Spiked

O2 flux

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  • 1000

1000 2000 3000 4000 5000

O2 flux (umol O2 m-2 hr-1 )

Channel O2 Flux

Channel O2 Flux Ambient Channel O2 Flux Spiked

BFT C

GY TC

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Sediment Oxygen Demand

y = -0.0142x + 20.171 R² = 0.6695

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  • 30
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10 20 30 40 1000 2000 3000 4000

Channel SOD Ambient Conditions

Channel Ambient Linear (Channel Ambient) y = -0.0433x + 97.045 R² = 0.6995

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20 40 60 80 1000 2000 3000 4000

Marsh SOD Ambient Conditions

Marsh Ambient Linear (Marsh Ambient ) y = 0.0104x + 41.182 R² = 0.1674 20 40 60 80 100 120 1000 2000 3000 4000

Channel SOD Spiked conditions

Channel Spiked Linear (Channel Spiked) y = 0.0389x + 59.052 R² = 0.3297 50 100 150 200 250 300 350 1000 2000 3000 4000

Marsh SOD Spiked Conditions

Marsh Spiked Linear (Marsh Spiked)

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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

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Water sampling sites

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