The Biogeochemical Cycle Of Barium

							The Biogeochemical Cycle
       Of Barium

       Caroline Schmidt
        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.
         Natural Occurrence As Barite (BaSO4)


 56            BaSO4  Ba2+ + SO42-
Ba
         Barite Has A Very High Density:  4.5
137,3

         Use Of Barium/Barite As A Tracer For
          Biological Production In the Sea
How Does Barium Precipitate As Barite In The Ocean?

                                       
  Ba - Precipitation Because   Ba - Precipitation Because
  Of Decomposition Of          Of Acantharia (SrSO4)
  Organic Matter               Dissolution

                                       
     Occurs In The                Occurs Between
     Euphotic Zone                 200 - 1200m
       (< 200m)
                       How Is Barium Related To Organic Carbon
                              Considering The Depth?

                                            The Less The Corg - Flux,
                   0        100      200
                                             The Higher The Ba - Flux
              0
                                            Barium Decreases With
            1000
                                             Depth
Depth [m]




                                                       
            2000

            3000

            4000
                                            Ratio Corg:Ba Is Strongly
                                             Dependent On Depth
            5000
                           Corg/Ba
       What Are The Influences?


 Lateral Advection?

 Sinking Rapidity?

 Differences In Saturation?
 Seasonal Changes?

 Different Geographic Locations?
                                                  Seasonal Changes !

                        Ba/Corg ratio as a function of the date
                                         1992

                3
Ba/Corg * 100




                2


                                                                                Differences In
                1

                0
                    0         2
                                  winter
                                           4     6
                                               summer
                                                        8        10
                                                            winter
                                                                          12
                                                                                 Ba/Corg Ratios
                                                                                 Between The
                Ba/Corg ratio as a function of the date                          Years.
                                 1995
                                                                                 (Ross Sea)
Ba/Corg * 100




                3

                2

                1

                0
                    0         2            4      6     8            10   12

                            winter             summer          winter
                  Different Geographical Location !

                   Comparison between the Corg/Ba ratios of
                        different traps versus depth



                       0    100         200    300      California
                   0                                    Current
                1000                                    Eq.
    Depth [m]




                2000                                    Pacific
                3000
                                                        W.
                4000                                    Atlantic
                5000
                                  Corg/Ba



 Differences Only In The Deeper Part - Difference
  In Dissolved Barium In The Water Column
                  Different Barites

                                        
Hydrothermal B.       “Bio-Barite”    Diagenetic B.

Ba Enriched           Formation          ???
Hydrothermal          Within A
Fluids React          Micro-
With Sea-             environment
water - Sulfate       Of Decaying
                      Bio. Depris
       In The Water Column
                   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 !!!
       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
                  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
             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.
                          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