Determination of Persian Gulf Water Transport and oxygen utilisation rates using SF 6 as a novel transient tracer

Sulphur hexafluoride (SF 6 ) has potential as a transient tracer of recently ventilated water masses, as its atmospheric burden continues to increase. Northern Arabian Sea hydrography was examined using measurements of atmospheric and dissolved SF 6 , CFC‐11, CFC‐12 and CFC‐113. Persian Gulf Water (PGW) was characterised by its SF 6 signal, and the time elapsed since its formation was evaluated by two approaches. Four ventilation age estimates were derived from SF 6 /CFC‐11, SF 6 /CFC‐12, CFC‐113/CFC‐11 and CFC‐113/CFC‐12, and their agreement at the oceanic stations confirms the validity of SF 6 as a transient tracer. A second approach, of correcting SF 6 partial pressure for PGW dilution by an optimal mixing model and referencing to the atmospheric SF 6 chronology, provided a relative tracer age. This indicated a PGW flow of 0.016 (+/−0.003) m/s across the northern Arabian Sea, with an associated oxygen consumption of 10.1 µmol/l p.a. that exceeds tracer‐derived estimates but confirms rates derived from export flux.