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| Titel |
Using dual carbon isotopes, 13C and 14C, to resolve the origin, mixing and alteration of major carbon pools in shallow-water CO2 vents (Kueishantao hydrothermal field, offshore Taiwan) |
| VerfasserIn |
Shing-Lin Wang, Yu-Shih Lin, George Burr, Chau-Chang Wang |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142136
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| Publikation (Nr.) |
 EGU/EGU2017-5713.pdf |
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| Zusammenfassung |
| Submarine hydrothermal vents at convergent boundaries tend to emit CO2-rich fluids due to
the subduction of marine sediment. In the shallow-water hydrothermal field, the carbon
dioxide gas bubbles can reach to the surface seawater and may alter the surface seawater
chemistry and the planktonic microbial community. We use duel carbon isotopes, 13C
and 14C, to evaluate the effect of additional CO2 input on the major carbon pools
in ambient seawater of hydrothermal vents. Radiocarbon (14C) is undetectable in
hydrothermal CO2 (Δ14C ∼-1000‰), so this “radiocarbon-dead” CO2 can be used as
an end-member to constrain the carbon sources in the hydrothermal field. Here
we report δ13C and Δ14C values of CO2(g), dissolved inorganic carbon (DIC)
and particulate organic carbon (POC) within and above two vents, yellow vent
(YV) and white vent (WV), in the Kueishantao shallow-water hydrothermal field,
northeastern offshore Taiwan. The results show that the δ13C value of vent CO2 gas is
around -6‰ within the range of mantle source. DIC was 13C-depleted (around
-9‰) than CO2 gas and POC were more 13C-depleted in YV (-25.7‰) and in WV
(-22.4‰). The Δ14C values of vent CO2 are slightly higher than -1000 ‰ with
-949.2±16.0 ‰ in YV (Temp. = 116∘C) and -890.7±7.6‰ in WV (Temp. = 58∘C). It
suggests the radiocarbon composition is more than 90% radiocarbon-dead carbon
mixed with less than 10% modern carbon. Our result clearly indicates the main
component in vent CO2 gas is the mantle-derived carbon and it is supported by helium
isotopic compositions (YV, 7.5±0.1 Ra; WV, 7.1±0.2 Ra). We expect the Δ14C
values of DIC and POC above the two vents will also reflect the mantle-derive
signal and it will also reveal how much the carbon is emitted from hydrothermal
vents and exchanged within these major carbon pools in the ambient seawater. |
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