The accretion history of fringing salt marshes in Narragansett Bay, Rhode Island, was reconstructed from sediment cores. Age models, based on excess lead-210 and cesium-137 radionuclide analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. The Constant Rate of Supply (CRS) age model was used to date six cores collected from three salt marshes. Both vertical accretion rates and carbon burial increased from 1900 to 2016, the year the data were collected. Cores were up to 90 cm in length with dry bulk density ranging from 0.07 to 3.08 grams per cubic centimeter and carbon content 0.71 % to 33.58 %.

This dataset presents radiocarbon data from 87 samples from sediment cores collected in southern Cascadia (offshore northern California) aboard the M/V Bold Horizon in September-October 2019. Sample ages were determined by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility and the W.M. Keck Carbon Cycle Accelerator Mass Spectrometry (KCCAMS) facility at the University of California, Irvine (UCI).

Nineteen sediment cores were collected from five salt marshes on the northern shore of Cape Cod where previously restricted tidal exchange was restored to part of the marshes. Cores were collected in duplicate from two locations within each marsh complex: one upstream and one downstream from the former tidal restriction (typically caused by an undersized culvert or a berm). The unaltered, natural downstream sites provide a comparison against the historically restricted upstream sites. The sampled cores represent a chronosequence of restoration occurring between 2001–10. Collected cores were up to 168 cm in length with dry bulk density ranging from 0.04 to 2.62 grams per cubic centimeter and carbon content 0.12 % to 48.91 %. Land surface elevation was measured at each site (ranging from 0.484 meters to 1.51 meters relative to NAVD88) to determine the boundaries of each site within current tidal conditions. Gamma counting results for excess lead-210 were used to construct Constant Rate of Supply age models to date individual depth intervals in the core. Additionally, gamma counting results for other radionuclides, particularly cesium-137, gave further insight to evaluate how vertical accretion and carbon burial rates have changed during the past century. Carbon isotopes were measured to evaluate organic matter source.

Coastal wetlands are major global carbon sinks; however, quantification of carbon flux can be difficult in these heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, static chamber measurements of greenhouse gas (GHG) fluxes were compared among major plant-defined zones (high marsh dominated by Distichlis spicata and a zone of invasive Phragmites australis) during 2013 and 2014 growing seasons. Two sediment cores were collected in 2015 from the Phragmites zone to support previously reported core collections from the high marsh sites (Gonneea and others 2018). Collected cores were up to 70 cm in length with dry bulk density ranges from 0.04 to 0.33 grams per cubic centimeter and carbon content 22.4 to 46.6 percent. Gamma counting results for excess lead-210 were used to construct Constant Rate of Supply (CRS) age models to age-date individual depth intervals in the cores. Additionally, gamma counting results for other radionuclides, particularly cesium-137 gave further insight to evaluate how vertical accretion and carbon burial rates have changed during the past century. Gonneea, M.E., O'Keefe Suttles, J.A., and Kroeger, K.D., 2018, Collection, analysis, and age-dating of sediment cores from salt marshes on the south shore of Cape Cod, Massachusetts, from 2013 through 2014: U.S. Geological Survey data release, https://doi.org/10.5066/F7H41QPP.

Data shows radioisotope measurements (Pb-210 and Cs-137) of sediment cores from four coastal wetlands along the Chesapeake Bay (one core from each site). Cores were sectioned every 1-2 cm depth.

The U.S. Geological Survey, Western Ecological Research Center collected sediment and accretion data at a wave-exposed tidal salt marsh in South San Francisco Bay, California. Sediment traps and feldspar marker horizons (MH) were deployed along transects of increasing distance from the sediment source, at primary, secondary and tertiary marsh channels/bay. Data were collected bi-monthly over two month periods in summer 2021 and winter 2021/2022. Included here are trap and MH plot locations, calculated sediment fluxes at each station by deployment period, annual accretion rates, and covariates associated with sediment deposition and accretion including vegetation structure and elevation. This project aimed to assess the temporal and spatial patterns in sediment deposition in order to better understand sediment delivery and marsh resilience to sea-level rise.

This part of the data release is a spreadsheet including radiocarbon sample information and calibrated ages of sediment cores collected in 2014 from the northern flank of Monterey Canyon, offshore California. It is one of five files in this U.S. Geological Survey data release that include data from a set of sediment cores acquired from the continental slope, north of Monterey Canyon, offshore central California. Vibracores and push cores were collected with the Monterey Bay Aquarium Research Institute’s (MBARI’s) remotely operated vehicle (ROV) Doc Ricketts in 2014 (USGS cruise ID 2014-615-FA). One spreadsheet (NorthernFlankMontereyCanyonCores_Info.xlsx) contains core name, location, and length. One spreadsheet (NorthernFlankMontereyCanyonCores_MSCLdata.xlsx) contains Multi-Sensor Core Logger P-wave velocity and gamma-ray density whole-core logs of vibracores. One zipped folder of .bmp files (NorthernFlankMontereyCanyonCores_Photos.zip) contains continuous core photographs of the archive half of each vibracore. One spreadsheet (NorthernFlankMontereyCanyonCores_Radiocarbon.xlsx) contains radiocarbon sample information, results, and calibrated ages. One .pdf file (NorthernFlankMontereyCanyonCores_Figures.pdf) contains combined displays of data for each vibracore, including graphic diagram descriptive logs. This particular metadata file describes the information contained in the file NorthernFlankMontereyCanyonCores_Radiocarbon.xlsx. All vibracores are archived by the U.S. Geological Survey Pacific Coastal and Marine Science Center. Other remaining core material, if available, is archived at MBARI.

To examine sediment transport and provenance between a marsh and estuary, surface sediments were collected along two transects in the Grand Bay National Estuarine Research Reserve, Mississippi (GNDNERR). Each shore-perpendicular transect consisted of fifteen surface samples, collected every 2.5 meters (m) from 10-m out into the estuary to 25-m into the marsh from the shoreline. Sediment samples were analyzed for their physical and radiochemical properties or signatures. Sediment samples were collected during U.S. Geological Survey (USGS) field activity number (FAN) 2017-315-FA (alternate FAN, [altFAN] 17CCT02) in April 2017. Marsh and estuarine surface samples were collected as part of the St. Petersburg Coastal and Marine Science Center (SPCMSC) Estuarine-MaRsh Geology (EMRG) research project. Please read the full metadata for details on data collection, dataset variables, and data quality.

From April 13 to 20, 2013, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS SPCMSC) collected push cores and vibracores on Dauphin Island, Alabama, along with push and auger cores in salt marshes at several locations in southwestern coastal Alabama. This work, a component of the SPCMSC’s Barrier Island Evolution Research (BIER) project, was conducted as part of USGS field activity number (FAN) 13BIM01. The objectives of the study were to evaluate processes affecting the development and evolution of certain back-barrier environments (marsh, flats, ponds, etc.) and to assist in developing geologic controls on barrier island breaching. In addition to the collection of sediment cores, marsh surface sediments were collected for micropaleontological analysis (included in this report). Ground penetrating radar (GPR) was collected on Dauphin Island and adjacent barrier-island environments. Elevation-corrected subsurface profile images of the processed GPR data, unprocessed digital GPR trace data, post-processed differential Global Positioning System (DGPS) data, and Geographic Information System (GIS) files are reported in Forde and others (2016, https://doi.org/10.3133/ds982). This data report is an archive of field-collected and laboratory analytical data for the sediment cores and surface sediments. Data products include: GPS-derived site locations and elevations; core logs and photographs; lithologic, radiochemical, elemental composition, stable isotopic composition, micropaleontological data; and Federal Geographic Data Committee (FGDC) metadata.

To parameterize accretion for SLR models, we measured historic rates of mineral and organic matter accumulation at each site by collecting deep soil cores with a Russian peat borer. At each site, we obtained cores in each of three vegetation zones: low, medium, and high marsh. Two replicate cores were sampled from each station for a total of 6 cores per site (except Coos Bay where 7 cores were taken). Coring locations were determined by RTK GPS elevation and tidal inundation data. Transects for core sampling were determined in ArcGIS, using a digitial elevation model and site-specific tidal datums to choose station locations below MHW (low), between MHW and MHHW (mid), and above MHHW (high). Sediment cores were 50 cm deep and 5 cm in diameter. In the lab, we cut cores into 1 cm sections to process for bulk density, porosity, and organic matter composition using loss on ignition in a muffle furnace at 550ºC for 8 hr. Only half of the cores collected were processed for bulk density, organic matter and Cesuim dating (one replicate). We used Cesium-137 (137Cs) isotope dating techniques to determine accumulation rates in deep soil cores. Atmospheric nuclear testing prior to 1964 resulted in the spread of 137Cs across the globe creating a reliable marker horizon in soils. We used a gamma spectrometer at the Oregon State University Radiation Center to detect 137Cs activity, measured in picocuries (pCi), in 1 cm core samples for 24 hr. We standardized the 137Cs activity of each sample to its mass. The depth of the 137Cs peak activity indicated the 1964 marker horizon, which we used to determine average soil accretion rates over the last half century. Not every processed core had a distinct peak of Cesium 137.