Effects of Nitrogen Loading on Greenhouse Gas Emissions from Salt - - PowerPoint PPT Presentation

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Effects of Nitrogen Loading on Greenhouse Gas Emissions from Salt - - PowerPoint PPT Presentation

May 17, 2023 118 likes •274 views

Effects of Nitrogen Loading on Greenhouse Gas Emissions from Salt Marshes in the US Northeast Jim Tang 1 , Kate Morkeski 1 , Jessie Gunnard 1 Kevin Kroeger 2 , Serena Moseman-Valtierra 3 , 1 Marine Biological Laboratory, Woods Hole, MA, USA 2 USGS

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Effects of Nitrogen Loading on Greenhouse Gas Emissions from Salt Marshes in the US Northeast Jim Tang1, Kate Morkeski1, Jessie Gunnard1 Kevin Kroeger2, Serena Moseman-Valtierra3,

1Marine Biological Laboratory, Woods Hole, MA, USA 2USGS Woods Hole Center, Woods Hole, MA, USA 3University of Rhode Island, RI, USA

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Atmospheric GHG concentration

CO2

N2O CH4

IPCC 2007

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IPCC emissions factor for N2O

  • 1% of fertilizer N (IPCC 2007)
  • 2.5% of fertilizer N (Davidson 2009)
  • 3-5% of fertilizer N (Crutzen et al. 2008)

Can we simply use the emissions factor to calculate N2O emissions?

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Questions

  • With N loading, how much N is released

as gases (including N2O), how much is retained, and how much is taken away by tidal water?

  • How does N loading change CO2 and CH4

fluxes and carbon sequestration in soils?

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Conceptual framework

N

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GHG and carbon sequestration

CO2 equivalent = net CO2 flux + CH4 flux * 25 + N2O flux * 298 Net ecosystem C balance (NECB) NECB = NEP – RCH4 – FL. NEP: net ecosystem production of CO2, measured with the closed transparent chamber RCH4: CH4 flux measured simultaneously with NEP. FL: net lateral flux

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Study sites

High N Mid N Low N No N

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= ¡Marsh ¡zone ¡comparison ¡(Serena) = ¡Nitrogen ¡site ¡comparison ¡(Jim ¡T.) Vertical ¡GHG ¡Flux ¡Measurement ¡Locations

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GHG flux measurement

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CO2 CH4

Gas concentration inside the chamber

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CO2 flux (µmol m-2s-1)

  • 7
  • 6
  • 5
  • 4
  • 3
  • 2
  • 1

Great Pond (Low N) Eel Pond (High N)

Measured on 9/12/2012 daytime

CO2 uptake in salt marshes

Preliminary results

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CH4 flux (nmol m-2 s-1)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

N2O flux (nmol m-2 s-1)

0.00 0.01 0.02 0.03 0.04

Great Pond (Low N) Eel Pond (High N)

CH4 and N2O emissions in salt marshes

Measured on 9/12/2012

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Preliminary conclusion

  • CO2 uptake in salt marshes may increase

with N loading, but CH4 and N2O emissions also increase with N loading.

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Acknowledgement

Funding:

  • NOAA/National Estuarine Research Reserve

System Science Collaborative

  • NSF/MRI
  • USGS

Collaborators:

  • Neil Ganju, Omar Abdul-Aziz, WBNERR staff