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 Herring River estuary in Wellfleet, Cape Cod, Massachusetts, has been tidally restricted for more than a century by a dike constructed near the mouth of the river. Upstream from the dike, the tidal restriction has caused the conversion of salt marsh wetlands to various other ecosystems including impounded freshwater marshes, flooded shrub land, drained forested upland, and brackish wetlands dominated by Phragmites australis. This estuary is now managed by the National Park Service, which plans to replace the aging dike and restore tidal flow to the estuary. To assist National Park Service land managers with restoration planning, the U.S. Geological Survey collected fourteen sediment cores from different ecosystems within the tidally restricted Herring River estuary (four sites) and an estuary in Wellfleet Harbor near the Herring River dike (three sites) between 2015 and 2017. Collected cores were up to 70 cm in length with dry bulk density ranges from 0.03 to 2.39 grams per cubic centimeter and carbon content 0.23% to 46.25%. Land surface elevation was measured at each site (ranging from -0.149 meters to 1.494 meters relative to NAVD88) to determine the boundaries for each site within current tidal conditions. 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. This dataset can help evaluate differences among the varied ecosystems and vegetation types to make predictions about potential changes as tidal restoration commences in the Herring River estuary.

The San Juan Bay Estuary, Puerto Rico, contains mangrove forests that store significant amounts of organic carbon in soils and biomass. There is a strong urbanization gradient across the estuary, from the highly urbanized and clogged Caño Martin Peña in the western part of the estuary, a series of lagoons in the center of the estuary, and a tropical forest reserve (Piñones) in the easternmost part with limited urbanization. We collected sediment cores to determine carbon burial rates and vertical sediment accretion from five sites in the San Juan Bay Estuary. Cores were radiometrically-dated using lead-210 and the Plum age model. Sites had soil C burial rates ranging from 50 grams per meter squared per year (g m-2 y-1) in the San José lagoon to 632 g m-2 y-1 in the Caño Martin Peña in recent decades. Soil accretion and carbon burial rates were greater in recent decades (1970-2016) compared to historic decades (1930-1970) at some of the forest mangrove sites (i.e. Caño Martin Peña). Apparently, not only urbanization, but site-specific flushing patterns, landscape setting, and soil characteristics affected soil C burial rates. This dataset can help evaluate how differences in urbanization (low in the forest preserve to high in the clogged canal), flushing, and landscape setting influence soil accretion and carbon burial in urban, tropical mangrove forests.

Salt marshes are environmental ecosystems that contribute to coastal landscape resiliency to storms and rising sea level. Ninety percent of mid-Atlantic and New England salt marshes have been impacted by parallel grid ditching that began in the 1920s–40s to control mosquito populations and to provide employment opportunities during the Great Depression (James-Pirri and others, 2009; Kennish, 2001). Continued alteration of salt marsh hydrology has had unintended consequences for salt marsh sustainability and ecosystem services. Great Barnstable Marsh (Barnstable, Cape Cod, Massachusetts) has areas of salt marsh that were ditched as well as natural areas. The U.S. Geological Survey (USGS) measured parameters for groundwater wells (water elevation, water depth below land surface, salinity, and water temperature), soil and air temperature, and other meteorological parameters. All these parameters affect plant productivity and are key components of salt marsh carbon cycling, carbon storage, and its ability to maintain elevation in response to changing sea level. These USGS datasets can be used to evaluate changes in water levels across ditched and natural salt marsh regions and provide information for any future studies of salt marsh productivity and geomorphic models in Great Barnstable Marsh. James-Pirri, M.-J.,Ginsberg, H.S., Erwin,R.m., and Taylor, J., 2009, Effects of open marsh water management on numbers of larval salt marsh mosquitoes: Journal of Medical Entomology, 46(6), 1392-1399, doi:10.1603/033.046.0620. Kennish, M. J., 2001, Coastal salt marsh systems in the U.S.-A Review of Anthropogenic Impacts: Journal of Coastal Research, 17(3), 731-748, https://www.jstor.org/stable/4300224.

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.

Coastal wetlands in Tampa Bay, Florida, are important ecosystems that deliver a variety of ecosystem services. Key to ecosystem functioning is wetland response to sea-level rise through accumulation of mineral and organic sediment. The organic sediment within coastal wetlands is composed of carbon sequestered over the time scale of the wetland’s existence. This study was conducted to provide information on soil accretion and carbon storage rates across a variety of coastal ecosystems that was utilized in the Tampa Bay Blue Carbon Assessment (ESA, 2017; linkage below). Ten sediment cores were collected from six Tampa Bay wetland sites in October 2015 (maximum core length 40 centimeters). Three main vegetation types were targeted for core collection: salt marsh, dominated by Juncus and Spartina alternaflora; mangrove, including Rhizophora mangle, Laguncularia racemosa and/or Avicennia germinans; and young mangrove, where wetlands were created within the last three decades. An additional surface sediment sample was collected from a salt barren, as this site was not conducive to coring. Marsh surface elevations were measured at each site (ranging from 0.771 meters to 1.462 meters relative to NAVD88) to determine the marsh boundaries within current tidal conditions. Continuous Rate of Supply age models, based on lead-210 and cesium-137 isotope analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. Over that time, accretion rates were very similar for each ecosystem: restored marsh sites (2.5 mm per year), followed by the salt marshes (2.7 mm per year) and mature mangroves (3.2 mm per year). The resulting carbon burial rates over the past century vary as a function of vegetation type, with mature mangroves burying on average 163 grams carbon per square meter per year, compared to young (restoring) mangroves with an average of 94 grams carbon per square meter per year and the salt marsh with an average of 64 grams carbon per square meter per year . This dataset also includes dry bulk density (0.02 - 1.70 grams per cubic centimeter), percent carbon (0.32 %-39.08 %), and percent loss on ignition (0.66 % – 80.2 %) from a sub-set of core sections in order to assess possible correlative relationships among these parameters. https://estuaries.org/wp-content/uploads/2019/02/FINAL_Tampa-Bay-Blue-Carbon-Assessment-Report-updated-compressed.pdf

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.

The Herring River estuary (Wellfleet, Cape Cod, Massachusetts) has been tidally restricted for over a century by a dike constructed near the mouth of the river. Behind the dike, the tidal restriction has caused the conversion of salt marsh wetlands to various other ecosystems including impounded freshwater marshes, flooded shrub land, drained forested upland, and wetlands dominated by Phragmites australis. This estuary is now managed by the National Park Service, which has plans to replace the dike and restore tidal flow to the estuary. To assist National Park Service land managers with restoration planning, study collaborators have been investigating differences in soil properties, carbon accumulation, and greenhouse gas fluxes across differing ecosystems within the Herring River Estuary. The U.S. Geological Survey collected continuous monitoring data (including water level, soil temperature, air temperature, and meteorological parameters). These datasets can help evaluate key ecosystem drivers to make predictions about potential changes as restoration commences.

Continuous monitoring data reported are a portion of data from a larger study investigating changes in soil properties, carbon accumulation, and greenhouse gas fluxes in four recently restored salt marsh sites and nearby natural salt marshes. For several decades, local towns, conservation groups, and government organizations have worked to identify, replace, repair, and enlarge culverts to restore tidal flow upstream from historical tidal restrictions in an effort to restore salt marsh ecosystems on Cape Cod, Massachusetts. Undersized or failed culverts restrict tidal exchange between the marsh and the bays and estuaries, which leads to alterations in plant community composition and in fundamental processes controlling soil carbon accumulation, soil carbon transformations, and greenhouse gas emissions. In this study, sites were selected to compare salt marshes restored over a range of years and to compare marshes upstream and downstream from a restored tidal restriction. Salt marshes downstream from tidal restrictions represent "natural" conditions because hydrology was not substantially altered, whereas marshes upstream from repaired culverts represent "restored" conditions. At each of the four salt marsh sites, study plots were established on the natural and restored sides of the former tidal restriction. Well water-level loggers, soil and air temperature loggers, and photosynthetically active radiation (PAR) sensors were deployed over the growing season to coincide with discrete measurements of greenhouse gas fluxes made by study collaborators. Water-level loggers were also deployed in creeks near the restored tidal restriction.

Environmental parameters affecting plant productivity and microbial respiration, such as water level, salinity, and groundwater temperature included in these datasets, are key components of wetland carbon cycling, carbon storage, and capacity to maintain elevation. Data were collected to (1) provide background data to evaluate potential differences in water level and carbon flux between wetland sites with differing elevation and tidal inundation and (2) facilitate applications of Blue Carbon projects in coastal wetlands. Associated child pages include continuous water level, salinity, and temperature from shallow wells installed in coastal wetland sites on Cape Cod, Massachusetts. These datasets are grouped by the project they support or by study site. Project study sites include salt marshes with natural tidal flow, salt marshes that were previously tidally restricted and have been restored, impounded coastal wetlands with restricted tidal flow inclusive of various vegetation types, and Phragmites dominated areas fringing natural salt marshes.

Environmental parameters affecting plant productivity and microbial respiration, such as water level, salinity, and groundwater temperature included in these datasets, are key components of wetland carbon cycling, carbon storage, and capacity to maintain elevation. Data were collected to (1) provide background data to evaluate potential differences in water level and carbon flux between wetland sites with differing elevation and tidal inundation and (2) facilitate applications of Blue Carbon projects in coastal wetlands. Associated child pages include continuous water level, salinity, and temperature from shallow wells installed in coastal wetland sites on Cape Cod, Massachusetts. These datasets are grouped by the project they support or by study site. Project study sites include salt marshes with natural tidal flow, salt marshes that were previously tidally restricted and have been restored, impounded coastal wetlands with restricted tidal flow inclusive of various vegetation types, and Phragmites dominated areas fringing natural salt marshes.

Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here we present measurements of net ecosystem exchange of carbon dioxide (CO2) and methane, along with ancillary meteorological data, collected from coastal wetlands across Cape Cod to evaluate the effect of hydrological management and salinity on carbon exchange in coastal wetlands.

Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here we present measurements of net ecosystem exchange of carbon dioxide (CO2) and methane, along with ancillary meteorological data, collected from coastal wetlands across Cape Cod to evaluate the effect of hydrological management and salinity on carbon exchange in coastal wetlands.

Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here we present measurements of net ecosystem exchange of carbon dioxide (CO2) and methane, along with ancillary meteorological data, collected from coastal wetlands across Cape Cod to evaluate the effect of hydrological management and salinity on carbon exchange in coastal wetlands.

Environmental parameters affecting plant productivity and microbial respiration, such as water level, salinity, and groundwater temperature included in these datasets, are key components of wetland carbon cycling, carbon storage, and capacity to maintain elevation. Data were collected to (1) provide background data to evaluate potential differences in water level and carbon flux between wetland sites with differing elevation and tidal inundation and (2) facilitate applications of Blue Carbon projects in coastal wetlands. Associated child pages include continuous water level, salinity, and temperature from shallow wells installed in coastal wetland sites on Cape Cod, Massachusetts. These datasets are grouped by the project they support or by study site. Project study sites include salt marshes with natural tidal flow, salt marshes that were previously tidally restricted and have been restored, impounded coastal wetlands with restricted tidal flow inclusive of various vegetation types, and Phragmites dominated areas fringing natural salt marshes.

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.

Extended time-series sensor data were collected between 2012 and 2016 in surface water of a tidal salt-marsh creek on Cape Cod, Massachusetts. The objective of this field study was to measure water chemical characteristics and flows, as part of a study to quantify lateral fluxes of dissolved carbon species between the salt marsh and estuary. Data consist of in-situ measurements including salinity, temperature, pH, dissolved oxygen, redox potential, fluorescent dissolved organic matter, turbidity, chlorophyll and dissolved carbon dioxide (pCO2). Surface water flow, water level and water elevation data were also measured. The data provided in this release represent a compiled data set consisting of multiple sensor deployments between 2012 and 2016.