Inorganic Radiocarbon in Time-Series Sediment Trap Samples: Implication of Seasonal Variation of 14 C in the Upper Ocean
In order to verify sediment trap samples as indicators of upper ocean 14 C concentrations, particulate inorganic radiocarbon (PICΔ 14 C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ 14 C measurem...
| Published in: | Radiocarbon |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1996
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0033822200030113 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822200030113 |
| Summary: | In order to verify sediment trap samples as indicators of upper ocean 14 C concentrations, particulate inorganic radiocarbon (PICΔ 14 C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ 14 C measurements were < 0‰, in contrast to GEOSECS 14 C data in the upper ocean from the northwestern North Pacific. This difference is attributed to the upwelling of deepwater that contains low Δ 14 C of dissolved inorganic carbon (DICΔ 14 C) and to the decrease over time of surface DICΔ 14 C owing to the decrease of atmospheric Δ 14 C values. In addition, PICΔ 14 C values showed significant seasonal variability: PICΔ 14 C collected in the fall was the greatest (-22‰ on average), whereas PICΔ 14 C collected in winter showed an average minimum of −48‰. It is likely that this difference was caused by changes in mixed layer thickness. Although some uncertainties remain, further study on PICΔ 14 C will enable us to estimate seasonal variability in DICΔ 14 C and air-sea CO 2 exchange rate. |
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