Carbon isotope values of whole porewater dissolved organic matter (DOM) samples from California margin sediments sampled in 2019 onboard the R/V Oceanus and in 2020 onboard the R/V Sikuliaq

Carbon isotopic values (radiocarbon and 13C) are reported for dissolved and particulate carbon collected from the sediments retrieved from Santa Barbara Basin (SBB), Catalina Basin (CAT), Station D (StaD), and Station K (StaK). SBB and CAT, located in the California Borderland, were sampled in June 2019 onboard the R/V Oceanus. StaD and StaK, located in the upper slope offshore central California, were sampled in Dec 2020 onboard the R/V Sikuliaq. The isotope dataset includes radiocarbon and 13C values of: porewater dissolved organic carbon (DOC), porewater dissolved inorganic carbon (DIC), sediment particulate organic carbon (POC), sediment particulate total carbon, sediment particulate total nitrogen, bottom water DOC, bottom water DIC. Sediment samples were retrieved using multi-cores and gravity cores operated by the Oregon State University Marine Rock and Sediment Sampling Group. Porewater samples were extracted from the sediment within hours of core retrieval in a refrigerated van.