Dataset: 1H NMR spectra of whole porewater DOM in California margin sediments from 2020 (Sikuliaq)

Porewater samples from gravity cores were collected as described in Komada et al. (2016) Geochim. Cosmochim. Acta, 176:259-278. Briefly, sediment cores were sectioned within hours of retrieval, then centrifuged, filtered (0.2 micron pore size). Porewater samples from multicores were extracted using Rhizon samplers (Seeberg-Elverfeldt et al., Limnol. Oceanogr. Meth., 8:361-371, 2005) to prevent contamination from squashed benthic macrofauna during centrifugation. Samples from multicores (MC) were retrieved using Rhizon samplers (5 cm, 0.15 micron pore size). Samples from BB gravity cores were collected by centrifugation, then filtered through 0.2 miron filters. Samples were immediately poisoned with HgCl2 and flame-sealed under a stream of high-purity nitrogen gas and refrigerated until analysis. 

Blank samples: MQ_blank samples = UV-irradiated MQ water collected on the ship in parallel with porewater samples; Rhizon_blank samples = UV-irradiated MQ water collected on in the laboratory after passing it through a Rhizon sampler.

1H NMR spectra were acquired in 5-mm O.D. thin-wall precision NMR tube (Bel-Art Wilmad part #528-PP-7-5) in 5% D2O (Sigma Aldrich part #151882) using a Bruker Avance NEO 500 MHz instrument with Prodigy cryoprobe using W5-WATERGATE solvent suppression method (Lam and Simpson, Analyst, 133:263-269, 2008).