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DOC. Amy Elizabeth Barbera. What is DOC?. Dissolved Organic Carbon Operational definition- material that passes through filter with certain pore size (0.2-0.7 µm) Most of the DOM in the CFR is DOC. The CFR is a global riverine input to Oceans

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  1. DOC Amy Elizabeth Barbera

  2. What is DOC? • Dissolved Organic Carbon • Operational definition- material that passes through filter with certain pore size (0.2-0.7µm) • Most of the DOM in the CFR is DOC. • The CFR is a global riverine input to Oceans • Estimated overall riverine input is 0.2 x 1015 g C yr-1 • The main source of DOC in the CFR comes from terrestrial inputs and runoff from land.

  3. DOC Determination • Equipment • Shimadzu TOC-5050 Analyzer • ASI 5000 autosampler • High Temperature Combustion furnace (680°C) • Preconditioned Shimadzu catalyst Al2O3 with 0.5% platinum • Calibration method • Standards (125.0 – 416.6 μM) • Reagent grade KHP with ultra pure MQ-H2O • Samples and standards were acidified to pH=2 with 2M HCl • Sparged with CO2free carrier gas to remove inorganic C • 5 min at a flow rate of 125 mL/min

  4. DOC is combusted in the HTC-chamber • The combustion products are CO2, NO., H2O, • carried by pure CO2free air into a built in Peltier cooler at 1°C to remove water vapors. • Filtered • Shimadzu particle filter • (20mm Ǿ, sub-micron membrane) • Detected • Shimadzu NDIR detector • Measure carbon dioxide gas from the combusted carbon.

  5. Surface vs. Deep Surface DOC is higher than deep DOC for cruise 2 because of the pronounced salt wedge. This salt wedge is not apparent in cruise 1.

  6. DOC vs. Salinity Surface only

  7. Long Term Trends in CFREDOC vs. Salinity Surface only

  8. 2010 vs. 9 year Average

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