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Denitrification in Marine Sediments: An Unknown Environmental Feedback

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Presentation on theme: "Denitrification in Marine Sediments: An Unknown Environmental Feedback"— Presentation transcript:

1 Denitrification in Marine Sediments: An Unknown Environmental Feedback
Owen L. Coyle September 24, 2010

2 Overfertilizing with Nitrogen
1 of Gus Speth’s 8 Global Environmental Problems Known Consequences Algae Blooms Eutrophication Unknown Consequences Effects on N-Cycle Duce et al. 2008

3 Sedimentary Processes
The N Cycle Internal Cycling In & Out Sedimentary Processes courtesy Bess Ward

4 N-Transformation in Sediment
NO3- nitrite oxidation denitrification Complicated anammox ammonium oxidation NO2- dnrn NH4+ ammonification dnra Organic N new biomass

5 Mesocosms filled with Chesapeake Bay sediment and water
Project Outline Question Does supply of organic matter affect N cycling in marine sediments? Experimental Setup simulate environment with 4 mesocosms add NH4+ and NO3- (i.e. fertilizer) to all mesocosms add little OM to 2 tanks (A & C) and lots to 2 tanks (B & D) daily measurements of DIN (NH4+, NO2-, and NO3-) Mesocosms filled with Chesapeake Bay sediment and water

6 Skills Needed Sample Mesocosms w/o contamination Measure DIN species
acid-wash containers prepare samples for long term storage at -40℃ Measure DIN species prepare standards and reagents analyze using a spectrophotometer Lab Protocol keep thorough notes! clean glassware safely use hazardous chemicals

7 Practically Identical
Results-Low OM Practically Identical Key Points: NH4+ ∼ constant, then falls rapidly NO2- peak < NO3- peak Sequential: NH4+ → NO2- → NO3-

8 Practically Identical
Results-High OM Practically Identical Key Points: NH4+ initial rise NO2- peak > NO3- peak Sequential: NH4+→NO2-→NO3-

9 Summary Observed N cycling was different in high and low treatments
Data will be used to model sedimentary N processes I would like to revisit this topic in my JP

10 Thank You To: Andrew Babbin Bess Ward
Sarah, Jenna, Johanna, and all of the office mates and lab mates who made me feel at home

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