δ¹³C values of water column organic carbon in the Arabian Sea oxygen minimum zone

Freeze-dried punches from 0.7 µm GFF filters for suspended particulate organic matter were decalcified with 2N HCl, washed, freeze-dried, and subjected to analysis via a Flash EA 1112 Series (Thermo Scientific) analyser, coupled via a Conflo II interface to a Finnigan DELTA plus mass spectrometer as described by and Pitcher et al. (2011; doi:10.1038/ismej.2011.60). Standards for δ¹³C analysis were acetanilide and benzoic acid and samples were analysed in duplicate.