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.

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.

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.

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.

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.

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 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.

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