Ramped Pyrolysis Oxidation (RPO) coupled radiocarbon (14C-DOC) and stable carbon (13C-DOC), high-resolution molecular composition (FT-ICR MS), and biodegradable dissolved organic carbon (BDOC) of groundwater, river water, and lagoon water in northeast Alaska, 2017

Supra-permafrost groundwater (SPGW), river water, and lagoon water were sampled near Kaktovik, AK to assess the reactivity and origin of dissolved organic matter (DOM) across interconnected hydrologic systems during late summer. Water samples were collected on August 17 th 2017 from SPGW along the beach of Jago Lagoon (Jago GW), surface water from the Jago River’s main channel above tidal influence (Jago R), and from the water column of Kaktovik Lagoon at 2–3 m depth (KA LW). Measurements were made from grab samples for river and lagoon water, and from a composite sample for SPGW gathered from 10 individual shoreline locations. Data include dissolved organic carbon concentration (DOC, mg C L -1 ), Ramped Pyrolysis Oxidation (RPO) derived fraction compositions of 13 C-DOC (δ 13 C ‰), 14 C-DOC (in fraction modern), and method/instrumental error in the 14 C and 13 C results, and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) molecular composition and summarized compound classes. Biodegradable DOC (BDOC) bottle experiments were performed using all three sample types, where DOC concentration was subsequently measured at 2, 7, 14, and 28 days. FT-ICR MS composition was subsequently measured at the 28-day timepoint to track changes in molecular formulae and compound class relative abundance following biodegradation. Data from RPO serial thermal oxidation include temperature and normalized CO 2 profiles for each background sample. Thermal-oxidation profiles of CO 2 were transformed into non-parametric activation energy (E) distributions using an inverse model. Model output includes C mass of oxidized CO 2 (µg C), T max (K), E max (kJ mol -1 ), E mean (kJ mol -1 ), E std (kJ mol -1 ), and p(0,E) max of user-defined sample fractions. FT-ICR MS results include a summary table of the relative abundance of compound classes (e.g., unsaturated phenolic, polyphenolic, aliphatic, condensed aromatics, peptide-like) and elemental groupings (e.g., CHO-type, CHON-type, CHOS-type, CHONS-type) for background (0-day) and biodegraded (28-day) samples. FT-ICR MS output is included for each sample and BDOC timepoint (0 and 28-day), including measurements of relative abundance, H:C ratio, and O:C ratio for each assigned molecular formulae.