A sealed-tube method for offline δ C analysis of CO via a Gas Bench II continuous-flow isotope ratio mass spectrometer.

Rationale: The isotopic measurement of environmental sample CO via isotope ratio mass spectrometry (IRMS) can present many analytical challenges. In many offline applications, exceedingly few samples can be prepared per day. In such applications, long-term storage (months) of sample CO is desirable, in order to accumulate enough samples to warrant a day of isotopic measurements.

The radiocarbon signature of microorganisms in the mesopelagic ocean.

Several lines of evidence indicate that microorganisms in the meso- and bathypelagic ocean are metabolically active and respiring carbon. In addition, growing evidence suggests that archaea are fixing inorganic carbon in this environment. However, direct quantification of the contribution from deep ocean carbon sources to community production in the dark ocean remains a challenge.