The Biogeochemical Cycle Of Barium - PowerPoint PPT Presentation

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The Biogeochemical Cycle Of Barium

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  1. The Biogeochemical Cycle Of Barium Caroline Schmidt

  2. Table Of Content  Introduction.  Behaviour Of Barium In The Deep Sea.  Barite: A Glimpse At Different Genesis.  What To Do With These Results !?  Further Literature.

  3.  Natural Occurrence As Barite (BaSO4) Ba 56 BaSO4 Ba2+ + SO42-  Barite Has A Very High Density:  4.5 137,3  Use Of Barium/Barite As A Tracer For Biological Production In the Sea

  4. How Does Barium Precipitate As Barite In The Ocean?   Ba - Precipitation Because Of Decomposition Of Organic Matter Ba - Precipitation Because Of Acantharia (SrSO4) Dissolution   Occurs In The Euphotic Zone (< 200m) Occurs Between 200 - 1200m

  5. How Is Barium Related To Organic Carbon Considering The Depth?  The Less The Corg - Flux, The Higher The Ba - Flux  Barium Decreases With Depth  Ratio Corg:Ba Is Strongly Dependent On Depth

  6. What Are The Influences?  Lateral Advection?  Sinking Rapidity?  Differences In Saturation?  Seasonal Changes?  Different Geographic Locations?

  7. Seasonal Changes !  Differences In Ba/Corg Ratios Between The Years. (Ross Sea)

  8. Different Geographical Location !  Differences Only In The Deeper Part - Difference In Dissolved Barium In The Water Column

  9. Different Barites    Hydrothermal B. Ba Enriched Hydrothermal Fluids React With Sea- water - Sulfate “Bio-Barite” Formation Within A Micro- environment Of Decaying Bio. Depris Diagenetic B. ??? In The Water Column

  10. Diagenetic Barite !  Settled “Bio-Barite” Will Be Removed By Sulfate Reduction 2 H+ + SO42- + 2 (CH2O)  2 CO2 +H2S + 2 H2O  Sulfate-Bearing Fluids From The Deeper Sediment Column Lead To Reprecipitation Of DIAGENETIC BARITE  Process Takes Place In The Sediment Column !!!

  11. How To Distinguish Barite And Barite?  Hydrothermal Barite: 34S Value Is Almost The Same Compared To Seawater  Diagenetic Barite: 34S Value Is Much Higher Compared To Seawater

  12. Conclusions  Consideration Of Different (Regional) Influences  Different Locations Cannot Be Compared  Strong Correlation Between Corg/Ba-Ratio And Depth; It Is Possible To Analyze The Biological Production With The Help Of The Barite Formation (Not Every Region)  Barium Can Be Used As A Quantitative Proxy To Determine Biological Production

  13. What To Do With That?  If We Can Measure Relative Constant Values Over A longer Periode, We Can Derive Datas For Paleoproductivity.  Paleoproductivity And Constant Datas Will Give Hints For Paleoclimate And Also For “New Production”.  We Could Include These Datas For Deriving Models Of Former And Future Climate.

  14. Literature  Dymond et al.; Barium in Deep Sea Sediment: A Geochemical Proxy For Paleoproductivity; 1992  Dymond et al.; Particulate Barium Fluxes and Their Relationships To Biological Productivity;1996  Dymond et al.; Particulate Barium Fluxes In The Ross Sea; 2002  Torres et al.; Barite Fronts In Margin Sediments: A New Look at Barium Remobilization In The Zone Of Sulfate Reduction And Formation Of Heavy Barites In Diagentic Fronts; 1995  Schwitzer, Lehrbuch der Chemie, 1999  Brockhaus In 15 Bänden, 2000