Photochemical Alteration of Dissolved Organic Nitrogen in the Surface Ocean of the North Atlantic

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Photochemical Alteration of Dissolved Organic Nitrogen in the Surface Ocean of the North Atlantic. Max Jacobson Daniel Sigman Katye Altieri Sarah Fawcett. Background: A Discrepancy. Sargasso sea water has

Transcript of Photochemical Alteration of Dissolved Organic Nitrogen in the Surface Ocean of the North Atlantic

  • Max JacobsonDaniel SigmanKatye AltieriSarah Fawcett

  • Background: A DiscrepancySargasso sea water has
  • DONNH4+NH3(g)Rain [NH4+ ] = 3.5 MNH4+ in the Nitrogen cycle4 M
  • Project goalTo test the hypothesis that the photo-oxidation of the high concentration surface DON pool contributes to ammonia efflux from the subtropical surface ocean

  • Testing the hypothesisDesign an apparatus and/or system to demonstrate the conversion of dissolved organic nitrogen (DON) into ammonium.

    Test the closed system at Princeton and test the open system at the Bermuda Institute of Ocean Sciences.

  • MethodsAcidified filters to capture NH3 efflux: Filter impregnation (Quinn 1990)Extracted captured NH4+ from filters sonicationCollected and filtered Sargasso seawater using 8L Niskin bottlesOrthophthalaldehde (OPA) fluorescence techniques for measuring nanomolar concentrations of NH4+ (Holmes et al 1999)Irradiated systems in ambient sunlight with dark control

  • OPA FluorescenceMeasures nM concentrations of ammoniumVery accurateExample: Standard curve with concentrations 0, 10, 25, 100, 250, and 1000 nM

    Chart2

    10291.975

    12116.5455

    15089.51

    18104.565

    29420.235

    58093.725

    211848.69

    Concentration (nM)

    Raw fluorescence units (RFU)

    6/7/11 Standard Curve

    Sheet1

    Standard curveFluor-1Fluor-2AverageconcentrationBlank

    110411.610172.3510291.97505.01125680365568.36

    212346.8811886.21112116.54551014.0393146957

    314672.021550715089.512528.749678377

    418019.3218189.8118104.5655043.6683077684

    530047.7828792.6929420.23510099.6587580406

    658511.957675.5558093.725250241.5364918357

    7212771.43210925.95211848.6910001002.3230578921

    SargassoFluor-1Fluor-2AverageConcentrationRange-1Range-2

    114145.9720608.4617377.21540.0724.0856.06

    213502.071214812825.03517.5420.8914.19

    415801.0810786.5713293.82519.8632.277.46

    59750.0910533.5810141.8354.272.336.21

    69854.1113674.2411764.17512.302.8421.75

    720493.3115288.0617890.68542.6155.4929.73

    939839.217569.3628704.2896.12151.2141.02

    1013206.7812459.3612833.0717.5819.4315.74

    1110255.59733.59994.53.544.832.25

    1212984.6911304.4712144.5814.1818.3310.02

    1410854.810390.110622.456.657.805.50

    Sheet1

    concenctration (nM)

    Raw fluorescence units (RFU)

    6/7/11 Standard Curve

    Sheet2

    Raw fluorescence values

    concenctration (nM)

    6/7/11 Fluorescence

    Sheet3

  • The Closed System

  • Testing the Closed SystemFilters were exposed to air on a lab bench for 10, 20, 30, and 40 minutes to investigate contaminationFilters exposed to air for 10 minutes were stored in Ziploc bags for 10, 20, 30, and 40 minutes, 24 and 48 hours to assess contamination associated with storageOne filter was left in the closed system and another filter was left in a fume hood overnight to confirm that the system was air tightThe experiment was run with two bottles: one filled with 10mM NH4+ and the other with HPW

  • ResultsAir exposure contaminated filtersStoring in ziploc did not contaminate filtersThe closed system is definitely airtight: The filter left in the fume hood had several orders of magnitude more NH4+ than that stored in the closed system

    Time(minutes)Time(minutes)[NH4+][NH4+]ExposureZiploc

    Chart1

    80.4058595433406.11832674

    162.1793114253

    273.1444126748

    Times

    10min

    Time (minutes)

    [NH4+] (nM)

    Exposure

    Sheet1

    Standard

    concentration (nM)Fluorescence[NH4+]

    010051.59-22.2764874075

    013177.89-10.0313736242

    1022197.6525.2972856527

    1016663.283.6202263914

    2524418.533.9959265207

    2523200.7329.2261564373

    5032457.4265.4828248012

    5025647.5638.8099173554

    10041202.6799.7362813834

    10041482.08100.8306764326

    25079309.25248.9924013944

    25081825.39258.847636207

    1000269887.71995.451451177

    1000271530.651001.8865301007

    blank5473

    10

    20

    30

    40

    SamplesFluorescence 1Fluorescnece 2[NH4+] 1[NH4+] 2

    10min118149.14119422.07401.1325055814406.11832674391.9872732815

    20min35928.0536264.4279.088363166380.405859543378.6924630392

    30min56498.3257142159.6581410834162.1793114253157.0733119951

    40min84460.2885472.5269.1797422741273.1444126748263.6194177717

    Bag 1077367.3278219.76241.3979867612244.7368297364236.5924401768

    Bag 10 unfiltered77088.2278286.71240.3048059222244.9990599663235.5289590002

    Bag 2059736.8360366.7172.3427597822174.8098390192169.4133135193

    Bag 20 unfiltered92251.6493439.4299.696995809304.3492225138293.3075750648

    Bag 3089875.0590988.01290.3883514159294.7476009557284.2518289895

    Bag 30 unfiltered42323.5443718.48104.1382632878109.6019740707103.061804603

    Bag 5107841.21108721.35360.7583330069364.2056715366352.7099908551

    Bag 5 unfiltered32435.932731.865.410285535266.569268732165.3859929889

    Blank59846.4260306.1172.7720026634174.5724805139169.8308946807

    Blank/NH4+73289.1473938.6225.4245427128227.9683521993221.0529644871

    impregnated/NH4+155741.75157556.96548.3755042889555.4853315577535.2299573236

    impregnation solution6005.336028.36-38.1131565548-38.0229524891-35.3249123609

    Amy

    D311064615.121078010.874108.25709921274160.72566683643998.3962810547

    D32870369.18881522.753347.43323802443391.11961928643258.2425697302

    D33957067.75966842.623687.01480553053725.30108495553588.5983462887

    D341024780.431034629.123952.23230582433990.80772394343846.6103871361

    Sheet1

    e

    concentration (nM)

    Raw Fluorescnece Units

    Standard curve

    Sheet2

    Times

    10min

    Time (minutes)

    [NH4+] (nM)

    Exposure

    Sheet3

    Chart2

    244.7368297364

    244.9990599663

    174.8098390192

    304.3492225138

    294.7476009557

    109.6019740707

    364.2056715366

    66.5692687321

    Bags

    Time in bag

    [NH4+]

    Ziploc

    Sheet1

    Standard

    concentration (nM)Fluorescence[NH4+]

    010051.59-22.2764874075

    013177.89-10.0313736242

    1022197.6525.2972856527

    1016663.283.6202263914

    2524418.533.9959265207

    2523200.7329.2261564373

    5032457.4265.4828248012

    5025647.5638.8099173554

    10041202.6799.7362813834

    10041482.08100.8306764326

    25079309.25248.9924013944

    25081825.39258.847636207

    1000269887.71995.451451177

    1000271530.651001.8865301007

    blank5473

    10

    20

    30

    40

    SamplesFluorescence 1Fluorescnece 2[NH4+] 1[NH4+] 2

    10min118149.14119422.07401.1325055814406.11832674391.9872732815

    20min35928.0536264.4279.088363166380.405859543378.6924630392

    30min56498.3257142159.6581410834162.1793114253157.0733119951

    40min84460.2885472.5269.1797422741273.1444126748263.6194177717

    Bag 1077367.3278219.76241.3979867612244.7368297364236.592440176810

    Bag 10 unfiltered77088.2278286.71240.3048059222244.9990599663235.528959000210

    Bag 2059736.8360366.7172.3427597822174.8098390192169.413313519320

    Bag 20 unfiltered92251.6493439.4299.696995809304.3492225138293.307575064820

    Bag 3089875.0590988.01290.3883514159294.7476009557284.251828989530

    Bag 30 unfiltered42323.5443718.48104.1382632878109.6019740707103.06180460330

    Bag 5107841.21108721.35360.7583330069364.2056715366352.70999085515

    Bag 5 unfiltered32435.932731.865.410285535266.569268732165.38599298895

    Blank59846.4260306.1172.7720026634174.5724805139169.8308946807

    Blank/NH4+73289.1473938.6225.4245427128227.9683521993221.0529644871

    impregnated/NH4+155741.75157556.96548.3755042889555.4853315577535.2299573236

    impregnation solution6005.336028.36-38.1131565548-38.0229524891-35.3249123609

    Amy

    D311064615.121078010.874108.25709921274160.72566683643998.3962810547

    D32870369.18881522.753347.43323802443391.11961928643258.2425697302

    D33957067.75966842.623687.01480553053725.30108495553588.5983462887

    D341024780.431034629.123952.23230582433990.80772394343846.6103871361

    Sheet1

    e

    concentration (nM)

    Raw Fluorescnece Units

    Standard curve

    Sheet2

    Times

    10min

    Time (minutes)

    [NH4+] (nM)

    Exposure

    Sheet3

    Bags

    Time in bag

    [NH4+]

    Ziploc

  • The Open SystemVacuum pumpFilter packs (removes ammonia from air)Ring Stand and clampsReflux CondenserFilters (capture ammonium)

  • Testing the Open SystemPhysically construct the systemDevelop and test the standard operating procedure in order to optimize the performance of the open systemIncubated filtered Sargasso Sea water collected during scientific cruise under sunlight and dark conditions

  • Seawater collectionSeawater was collected aboard the R/V Stommel using Niskin bottles and transferred to 4L polycarbonate bottles. The water was filtered through a 0.2 m polycarbonate filter using vacuum filtration.Seawater was collected aboard the R/V Atlantic Explorer by inline filtration directly from the ships underway system.

  • Lessons LearnedThe temperature controlled experiments were supposed to be run on the Atlantic Explorer 2 day cruise. However, it rained continuously and irradiation experiments were not possible.Ammonium samples could not be analyzed at BIOS. The samples were frozen and brought back to Princeton.The fluorometer was stolen, and the samples could not be analyzed until it was replaced.Results from the open system were inconclusive: contamination and/or detection limit problems (see above)

  • SummaryClosed system: airtight limiting contamination from ambient air. Could be useful for concept testing if modified to increase air/water surface interaction.Open system: more representative , can control temperature, enhance air/water surface interactionFuture workContinue experimenting with open systemAmend with higher ammonium concentrationAnalyze samples same day to minimize storage and/or contamination issues

  • AcknowledgementsPrinceton Environmental InstituteBermuda Institute of Ocean SciencesAndrew PetersKaren EllisAmy GobelRosie Zhang

    *******