The Biogeochemical Cycle Of Barium

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.
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? 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
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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 (lt 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 CorgBa Is Strongly Dependent On Depth
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What Are The Influences?
? Lateral Advection?
? Sinking Rapidity?
? Differences In Saturation?
? Seasonal Changes?
? Different Geographic Locations?
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Seasonal Changes !
? Differences In Ba/Corg Ratios
Between The Years. (Ross Sea)
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Different Geographical Location !
? Differences Only In The Deeper Part -
Difference In Dissolved Barium In The Water
Column
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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
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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 !!!
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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
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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
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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.
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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
Productivity1996
? 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