Sediment cores were collected from three sites within the Plum Island Ecosystems Long-Term Ecological Research (PIE-LTER) domain in Massachusetts to obtain estimates of long-term marsh decomposition and evaluate shifts in the composition and reactivity of sediment organic carbon in disturbed marsh environments. Paired sediment cores were collected from three sites on the marsh platform and from three ponds; these cores were about 100 and 50 centimeters in length, respectively. The marsh sites had similar elevations, at about 1.41 to 1.51 meters relative to the North American Vertical Datum of 1988, and similar salt marsh grass communities, dominated by Spartina patens, S. alterniflora, and Distichlis spicata. Permanently inundated ponds within each site had comparable depths (0.24–0.30 meters) but varied in size (between 643 and 7,149 square meters; Spivak et al., 2017, 2018). The U.S. Geological Survey analyzed radioisotope concentrations for lead-210, radium-226, cesium-127, and beryllium-7 from six marsh cores and three pond cores to develop an age model for each core. This data release includes calculated percent dry bulk density and raw radioisotope data for these cores. Spivak, A.C., Gosselin, K., Howard, E., Mariotti, G., Forbrich, I., Stanley, R., and Sylva, S.P., 2017, Shallow ponds are heterogeneous habitats within a temperate salt marsh ecosystem: Journal of Geophysical Research-Biogeosciences, 122(6), 1371-1384. Spivak, A. C., Gosselin, K. M., and Sylva, S.P., 2018, Shallow ponds are biogeochemically distinct habitats in salt marsh ecosystems: Limnology and Oceanography, 63(4), 1622-1642.

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 %.

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 %.

The accretion history of fringing microtidal salt marshes located on the south shore of Cape Cod, Massachusetts, was reconstructed from sediment cores collected in low and high marsh vegetation zones. The location of these marshes within protected embayments and the absence of large rivers on Cape Cod result in minimal sediment supply and a dominance of organic matter contribution to sediment peat. Age models based on 210-lead and 137-cesium were constructed to evaluate how vertical accretion and carbon burial rates have changed over the past century. The continuous rate of supply age model was used to age date 11 cores (10 low marsh and 1 high marsh) across four salt marshes. Both vertical accretion rates and carbon burial increased from 1900 to the years of collection, 2013 and 2014. Elevation of the marsh surface was measured to evaluate where the marsh falls within the current tidal frame. The historic marsh surface elevation was then reconstructed from the calculated age of each depth interval and its elevation, assuming that elevations within this shallow zone (less than 30 centimeters) have been preserved for the past century.

The accretion history of fringing microtidal salt marshes located on the south shore of Cape Cod, Massachusetts, was reconstructed from sediment cores collected in low and high marsh vegetation zones. The location of these marshes within protected embayments and the absence of large rivers on Cape Cod result in minimal sediment supply and a dominance of organic matter contribution to sediment peat. Age models based on 210-lead and 137-cesium were constructed to evaluate how vertical accretion and carbon burial rates have changed over the past century. The continuous rate of supply age model was used to age date 11 cores (10 low marsh and 1 high marsh) across four salt marshes. Both vertical accretion rates and carbon burial increased from 1900 to the years of collection, 2013 and 2014. Elevation of the marsh surface was measured to evaluate where the marsh falls within the current tidal frame. The historic marsh surface elevation was then reconstructed from the calculated age of each depth interval and its elevation, assuming that elevations within this shallow zone (less than 30 centimeters) have been preserved for the past century.

This data release is an archive of sedimentary laboratory analytical data produced by scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS SPCMSC) for sediment cores and surface samples collected from coastal marshes in Georgia (GA), Virginia (VA), and Massachusetts (MA). Collaborators from USGS Patuxent Wildlife Research Center (PWRC) and the Virginia Institute of Marine Science (VIMS) collected these samples in South Altamaha, GA, Mockhorn Island, VA, Goodwin Island, VA and Laws Point, Plum Island Estuary, MA during a period spanning 2015 to 2019. This work provides the USGS and VIMS with the necessary data needed to assess the emergence rates (chronology and sedimentation rates) of coastal marshes at these locations. This publication includes data for marsh sediment cores and surface samples collected by collaborators at the USGS PWRC and VIMS from 2015-2019. Data products include site locations, loss on ignition and radiochemical data (alpha and gamma spectrometry), and Federal Geographic Data Committee (FGDC) metadata.

This data release is an archive of sedimentary laboratory analytical data produced by scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS SPCMSC) for sediment cores and surface samples collected from coastal marshes in Georgia (GA), Virginia (VA), and Massachusetts (MA). Collaborators from USGS Patuxent Wildlife Research Center (PWRC) and the Virginia Institute of Marine Science (VIMS) collected these samples in South Altamaha, GA, Mockhorn Island, VA, Goodwin Island, VA and Laws Point, Plum Island Estuary, MA during a period spanning 2015 to 2019. This work provides the USGS and VIMS with the necessary data needed to assess the emergence rates (chronology and sedimentation rates) of coastal marshes at these locations. This publication includes data for marsh sediment cores and surface samples collected by collaborators at the USGS PWRC and VIMS from 2015-2019. Data products include site locations, loss on ignition and radiochemical data (alpha and gamma spectrometry), and Federal Geographic Data Committee (FGDC) metadata.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine Ponar grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size (for the development of a sedimentological baseline), and gamma spectroscopy (for the development of geochronologies). Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples were collected by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) to study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised with additional data. Please see the data release webpage for more details.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine Ponar grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size (for the development of a sedimentological baseline), and gamma spectroscopy (for the development of geochronologies). Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples were collected by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) to study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised with additional data. Please see the data release webpage for more details.

Sediment samples, including marsh and estuarine surface samples and marsh push and peat-auger cores, were collected from Point aux Chenes, Mississippi from October 23-26, 2018, and August 4, 2021. Marsh surface samples (top 1 centimeter (cm) of sediment; sample names appended with S), marsh push cores (core names appended with M) and peat-auger cores (core names appended with R) were collected along 50-meter (m), shore perpendicular, transects identified as sites 5, 6, 7, and 9. All samples in the dataset are referred to by alternate field activity number (FAN) 18CCT09 (FAN 2018-358-FA) and alternate FAN 21CCT02 (FAN 2021-320-FA). Estuarine PONAR grab samples (sample names appended with G), marsh surface samples, and push cores were collected and brought back for sedimentological analyses including dry bulk density, organic content, grain-size for the development of a sedimentological baseline, and gamma spectroscopy for the development of geochronologies. Peat augers were collected, described for depth to peat, and discarded in the field. Marsh and estuarine surface and core sediment samples are part of the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center's (SPCMSC) Estuarine-MaRsh Geology (EMRG) and Sea-level and Storms Impacts on Estuarine Environments and Shorelines (SSIEES) research projects which study how and where short- and long-term marsh and estuarine coastal process interact in order to identify and evaluate geologic and geomorphic variables influences on marshes and their resiliency under different storm and sea-level scenarios, determine marsh-upland boundary change rates, and sediment accumulation and erosion rates. Note: This data release was revised on August 2, 2021, and versioned on August 23, 2023. Please see the Suggested Citation section on the data release webpage for more details.