Dataset: Soil carbon stocks and long-term accretion rates in tidal marshes, tidal swamps, and former tidal wetlands in eight estuaries in the Pacific Northwest, USA

We provide a dataset of 70 soil cores from estuaries in the Pacific Northwest region of the US, including from least-disturbed and restored emergent tidal marshes, forested tidal swamps, and non-tidal areas in estuarine watersheds. Data include down-core profiles of one or more soil properties: dry bulk density, organic matter content (by loss-on-ignition), carbon content (by elemental analysis), ²¹⁰Pb activity, and ¹³⁷Cs activity. Cores were typically sampled to about 50 cm depth using either a gouge auger or a PVC tube. Metadata associated with each core include geographic location, elevation of the wetland surface (by RTK-GNSS survey or laser leveling), dominant plant species (near the core or at the site level), and groundwater salinity (usually from a data logger time series at a station located <50 m from the coring location). Many of these cores are from the same sites where the Pacific Northwest Blue Carbon Working Group has collected greenhouse gas flux data (DOI: 10.25573/serc.27161883). Core collection and processing was funded by the NERRS Science Collaborative and the NCCOS-ESLR program of the National Oceanic and Atmospheric Administration. Data compilation was also supported by funding from the Pew Charitable Trusts.