High rates of carbon burial observed in wetland sediments have garnered attention as a potential “natural fix” to reduce the concentration of carbon dioxide (CO2) in Earth’s atmosphere. A carbon accumulation rate (CAR) can be determined through various methods that integrate a carbon stock over different time periods, ranging from decades to millennia. Our goal was to assess how CAR changed over the lifespan of a salt marsh. We applied a geochronology to a series of salt marsh cores using both 14C and 210Pb markers to calculate CARs that were integrated between 35 to 2,460 years before present. CAR was 39 g C m-2 y-1 when integrated over millennia, but was upwards of 148 g C m-2 y-1 for the past century. We present additional evidence to account for this variability by linking it to changes in relative sea-level rise (RSLR), where higher rates of RSLR were associated with higher CARs. Thus, the true CAR calculated for a wetland should integrate recent timescales that capture the influence of contemporary RSLR, but must also omit recently deposited labile organic carbon that will ultimately decompose. Therefore, caution should be exercised not to utilize a CAR calculated over inappropriate time scales as a current assessment or forecasting tool for the climate change mitigation potential of a wetland.
| Start date | End date |
|---|---|
| 2016-01-04 | 2016-01-08 |
| Rank name | Value |
|---|---|
| Species | Spartina alterniflora |
| Species | Juncus roemerianus |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| coring_method | Code indicating what type of device was used to collect soil depth profiles. | russian corer = A half cylinder coring device with the coring section sealed off by a fin attached to a rotating pivot point aluminum corer = Aluminum corer with 7 cm diameter |
| roots_flag | Code indicating whether live roots were included or excluded from carbon assessments. | roots and rhizomes included = Roots and rhizomes were included in dry bulk density and or organic matter and carbon measurements |
| sediment_sieved_flag | Code indicating whether or not sediment was sieved prior to carbon measurements. | sediment not sieved = Sediment was not sieved prior to analysis for organics. |
| compaction_flag | Code indicating how the authors qualified or quantified compaction of the core. | corer limits compaction = Authors specified that the coring device's design minimized compaction |
| dry_bulk_density_temperature | Temperature at which samples were dried to measure dry bulk density. This can include either samples that were freeze dried or oven dried. | celsius |
| dry_bulk_density_flag | Any notable codes regarding how the authors quantified dry bulk density. | to constant mass = Bulk density methodology did not specify drying temperature or length, only that samples were dried to a constant mass |
| loss_on_ignition_temperature | Temperature at which samples were combusted to estimate fraction organic matter. | celsius |
| loss_on_ignition_time | Time over which samples were combusted to estimate fraction organic matter. | hour |
| loss_on_ignition_flag | Common codes regarding loss on ignition methodology. | time approximate = Loss on ignition time recorded herein is an approximate estimate |
| carbonates_removed | Whether or not carbonates were removed prior to calculating fraction organic carbon. | TRUE = Carbonates were removed before measuring organic carbon. |
| carbonate_removal_method | The method used to remove carbonates prior to measuring fraction carbon. | direct acid treatment = Carbonates were removed using direct application of dilute acid |
| fraction_carbon_method | Code indicating the method for which fraction carbon was measured or modeled (Note: regression based models are permitted, but the use of the Bemmelen factor [0.58 gOC gOM-1] is discouraged). | EA = Each sample presented was measured using Elemental Analysis |
| fraction_carbon_type | Code indicating whether fraction_carbon refers to organic or total carbon. | organic carbon = Author specified that fraction carbon measurements were of organic carbon |
| pb210_counting_method | Code indicating the method used for determining lead 210 activity. | alpha = Alpha counting method used |
| excess_pb210_rate | Code indicating the mass or accretion rate used in the excess_pb_210_model | mass accumulation = Excess 210Pb modeled using mass accumulation rate |
| excess_pb210_model | Code indicating the model used to estimate excess lead 210. | CFCS = Constant flux constant sedimentation model used. |
| c14_counting_method | Code indicating the method used for determining radiocarbon activity. | AMS = Accelerator mass spectroscopy used |
| age_depth_model_reference | Code indicating the reference or 0 year of the age depth model. | core collection date = Year zero is set as the core's collection year. |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| site_id | Site identification code unique to each study. | |
| core_id | Core identification code unique to each site. | |
| core_date | Date of core collection. | YYYY-MM-DD |
| core_notes | Any other relevant submitter generated notes on how cores were collected. | |
| core_latitude | Positional latitude of the core in decimal degree WGS84. | degree |
| core_longitude | Positional longitude of the core in decimal degree WGS84. | degree |
| core_position_method | Code indicating how latitude and longitude were determined. | other high resolution = Any other technique resulting in positional error < 1 meter |
| core_position_notes | Any relevant submitter generated notes on how latitude and longitude were determined. | |
| core_elevation | Surface elevation of the core relative to defined datum. | meter |
| core_elevation_datum | The datum relative to which the core elevation was measured against (For a complete list of datum names and aliases please refer to the ISO Geodedic Registry https://iso.registry.bespire.eu/register/geodetic/VerticalDatum). | NAVD88 = A gravity-based geodetic datum, North American Vertical Datum of 1988 |
| core_elevation_method | Code indicating how elevation was determined | other high resolution = Any other technique resulting in positional error < 5 cm of random error |
| core_elevation_notes | Any relevant submitter generated notes on how elevation was determined | |
| salinity_class | Code based on submitter field observation or measurement indicating average annual salinity (Note: Palustrine and freshwater should only include tidal wetlands, or wetlands that are potentially/formerly tidal but artificially freshened due to artificial tidal restrictions). | estuarine C-CAP = 5-35 parts per thousand salinity (ppt) according to the coastal change analysis program estuarine = 0.5-35 ppt according to most definitions |
| salinity_method | Indicate whether salinity_class was determined using a field observation or a measurement | measurement = Salinity observed from local instrument. |
| vegetation_class | Code based on submitter field observations or measurement indicating dominant wetland vegetation type. | emergent = Describes wetlands dominated by persistent emergent vascular plants |
| vegetation_method | Indicate whether vegetation_class was determined using a field observation or a measurement | measurement = Vegetation measured by counts or plots. |
| vegetation_notes | Any relevant submitter generated notes on how vegetation_class and dominant_species were determined. | |
| inundation_class | Code based on submitter field observation or measurement indicating how often the coring location is inundated. | mid = Study-specific definition of an elevation in the relative middle of the tidal frame, typically defined by vegetation type |
| inundation_method | Indicate whether inundation_class was determined using a field observation or a measurement | measurement = Inundation class assessed from elevation and nearby tide gauge or other similar method. |
| inundation_notes | Any relevant submitter generated notes on how inundation was determined | |
| core_length_flag | Indicated whether or not the coring team believes they recovered a full sediment profile, down to bedrock, or other non-marsh interface. | core depth limited by length of corer = The total depth of the core was limited by the length of the coring device core depth represents deposit depth = Authors report that the depth of the core represents the depth of the wetland soil deposit |
| attribute name | definition | format, unit or codes |
|---|---|---|
| study_id | Unique identifier for the study made up of the first author's family name, as well as the second author's or 'et al.' if more than three, then publication year spearated by underscores. See worksCited.bib for more detail. | |
| site_id | Site identification code unique to each study. | |
| core_id | Core identification code unique to each site. | |
| depth_min | Minimum depth of a sampling increment. | centimeter |
| depth_max | Maximum depth of a sampling increment. | centimeter |
| dry_bulk_density | Dry mass per unit volume of a soil sample. This does not include ash free bulk density. | gramsPerCubicCentimeter |
| fraction_organic_matter | Mass of organic matter relative to sample dry mass. Ash free bulk density should not be used here but should be expressed as a loss on ignition fraction. | dimensionless |
| fraction_carbon_measured | Measured mass of carbon relative to sample dry mass. | dimensionless |
| fraction_carbon_modeled | Modeled mass of carbon relative to sample dry mass. | dimensionless |
| total_pb210_activity | Total radioactivity counts per unit dry weight for excess lead 210 (210Pb). | disintegrationsPerMinutePerGram |
| total_pb210_activity_se | Standard error associated with total_pb210_activity | disintegrationsPerMinutePerGram |
| excess_pb210_activity | Excess radioactivity counts per unit dry weight for excess lead 210 (210Pb). | disintegrationsPerMinutePerGram |
| excess_pb210_activity_se | Standard error associated with excess_pb210_activity | disintegrationsPerMinutePerGram |
| c14_age | Radiocarbon age as estimated from AMS measurements. | radiocarbonYear |
| c14_age_sd | Estimated uncertainty in c14_age. | radiocarbonYear |
| c14_material | Description of the material selected for radiocarbon (14C) dating. | |
| c14_notes | Any relevant submitter generated notes on 14C dating process. | |
| delta_c13 | The isotopic signature of 13C. This is oftentimes measured along with c14_age and can be useful for analyzing carbon lability and provenance. | dimensionless |
| age | Most likely, median, or mean age of the depth interval from submitter generated age depth model. | nominalYear |
| age_se | Standard error associated with age depth model | nominalYear |
| mass_depth | Mass depth | gramsPerSquareCentimeter |
| unit name | parent SI unit | unit type | description |
|---|---|---|---|
| disintegrationsPerMinutePerGram | radionucleotideActivityPerMass | disintegrations per minute per gram is a measure of the activity of the source of radioactivity | |
| gramsPerSquareCentimeter | gramsPerSquareMeter | massPerArealMassDensity | grams per square meter per year |
| radiocarbonYear | time | one radiocarbon year |
This dataset is listed under a Creative Commons BY 4.0 and can be used with attribution. https://creativecommons.org/licenses/by/4.0/