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Estimate Submarine Groundwater Discharge (SGD)to the Atlantic Ocean. 232 Th 228 Ra. half life = 5.7 years l = 0.12 yr -1. Procedure:. 1. Measure inventory of 228 Ra in upper km of Atlantic Ocean. Flux 228 Ra = Inventory x l 2. Subtract riverine and sediment fluxes. - PowerPoint PPT Presentation
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232Th 228Ra
half life = 5.7 years = 0.12 yr-1
TTO1981-1989
Bob KeyPrinceton
1. Measure inventory of 228Ra in upper km of Atlantic Ocean.
Flux 228Ra = Inventory x
2. Subtract riverine and sediment fluxes.
3. Estimate 228Ra in SGD.
Procedure:
SGD Flux =228Ra flux (atoms)
[228Ra]SGD (at/L)
Estimate Submarine Groundwater Discharge (SGD)to the Atlantic Ocean
Distribution of 228Ra in SGD (226 samples)
Median = 6.5 x 106 at/L Mean = 17 x 106 at/L
(1.5 dpm/L) (3.9 dpm/L)
medianmean
Total 228Ra Inventory = 2.9 x 1024 atoms
Decay = 3.5 x 1023 at/yr
River flux = 0.3 x 1023 at/yr
Sed. flux = 1.3 x 1023 at/yr
SGD flux = 1.9 x 1023 at/yr
Mean 228Ra in SGD =17 x 106 at/L (3.9 dpm/L)
Median 228Ra in SGD =6.5 x 106 at/L (1.5 dpm/L)
SGD flux = 1-3 x 1016 L/yr
40-120% of the river water flux; probably >>river metal, nut, C flux
River flux = 2.4 x 1016 L/yr
TTO1981-1989