Rates of organic carbon (OC) burial in some coastal wetlands appear to be greater in recent years than they were in the past. Possible explanations include ongoing mineralization of older OC or the influence of an unaccounted-for artifact of the methods used to measure burial rates. Alternatively, the trend may represent real acceleration in OC burial. We quantified OC burial rates of mangrove and brackish marsh sites in southwest Florida through a comparison of rates derived from 210Pb, 137Cs, and surface marker horizons (MH). Age/depth profiles of lignin:OC were used to assess whether down-core remineralization had depleted the OC pool relative to lignin, and lignin phenols were used to quantify the variability of lignin degradation. OC burial rates increased in all seven cores by factors ranging from 1.4 to 6.2 over the past 120 years. We propose that these increases represent net acceleration. Change in relative sea-level rise is the most likely large-scale driver of acceleration, and sediment deposition from large storms can contribute to periodic increases. Mangrove sites had higher OC and lignin burial rates than interior marsh sites, indicating inherent differences in OC burial factors between the two habitat types. The higher OC burial rates in mangrove soils mean that their encroachment into interior, freshwater marshes has the potential to increase burial rates in those locations even more than might be expected from the acceleration trends. Regionally, these findings suggest that burial represents a substantially growing proportion of the coastal wetland carbon budget.
| Start date | End date |
|---|---|
| 2013-03-14 | 2017-05-23 |
| Rank name | Value |
|---|---|
| Species | Avicennia germinans |
| Species | Rhizophora mangle |
| Species | Laguncularia racemosa |
| Species | Conocarpus erectus |
| Species | Cladium mariscus |
| 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. | pvc and hammer = PVC pipe was driven into the sediment with a hammer to recover a core |
| 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. | no obvious compaction = Authors observed no obvious 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_time | Time over which samples were dried to measure dry bulk density. | hour |
| dry_bulk_density_1_cm_section_sample_volume | Sample volume used for dry bulk density for a 1 cm soil section | cubicCentimeter |
| dry_bulk_density_2_cm_section_sample_volume | Sample volume used for dry bulk density for a 2 cm soil section | cubicCentimeter |
| dry_bulk_density_flag | Any notable codes regarding how the authors quantified dry bulk density. | air dried to constant mass = Methodology specified that samples were air dried to a constant mass 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_1_cm_section_sample_volume | Sample volume used for loss on ignition for a 1 cm soil section | cubicCentimeter |
| loss_on_ignition_2_cm_section_sample_volume | Sample volume used for loss on ignition for a 2 cm soil section | cubicCentimeter |
| 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. | acid fumigation = Carbonates were removed by fumigating with concentrated acid |
| carbon_measured_or_modeled | Code indicating whether fraction carbon was measured or estimated as a function of organic matter. | measured = Fraction carbon was measured as opposed to modeled |
| 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 |
| cs137_counting_method | Code indicating the method used for determining radiocesium activity. | gamma = Gamma counting method used. |
| pb210_counting_method | Code indicating the method used for determining lead 210 activity. | gamma = Gamma counting method used. |
| excess_pb210_model | Code indicating the model used to estimate excess lead 210. | CRS = Constant rate of supply model 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_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. | handheld = Conventional Commercially available hand-held GPS |
| 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). | mesohaline = 5-18 ppt oligohaline = 0.5-5 ppt. |
| 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 forested = Describes wetlands dominated by woody vegetation > 5 meters in height forested to shrub = Dominated by forested to scrub/shrub biomass |
| vegetation_method | Indicate whether vegetation_class was determined using a field observation or a measurement | measurement = Vegetation measured by counts or plots. |
| 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 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_organic_carbon | Mass of organic carbon relative to sample dry mass. | dimensionless |
| cs137_activity | Radioactivity counts per unit dry weight for radiocesium (137Cs). | disintegrationPerMinutePerGram |
| cs137_activity_se | 1 standard error of uncertainty associated with cs137_activity. | disintegrationPerMinutePerGram |
| total_pb210_activity | Total radioactivity counts per unit dry weight for excess lead 210 (210Pb). | disintegrationPerMinutePerGram |
| total_pb210_activity_se | 1 standard error of uncertainty associated with total_pb210_activity. | disintegrationPerMinutePerGram |
| ra226_activity | Total radioactivity counts per unit dry weight for Radium 226 (226Ra) if measured as part of the 210Pb dating process. | disintegrationPerMinutePerGram |
| ra226_activity_se | 1 standard error of uncertainty associated with ra226_activity. | disintegrationPerMinutePerGram |
| ra226_mda | Minimum detectable activity for radium 226 measurements | disintegrationPerMinutePerGram |
| excess_pb210_activity | Excess radioactivity counts per unit dry weight for excess lead 210 (210Pb). | disintegrationPerMinutePerGram |
| excess_pb210_activity_se | 1 standard error of uncertainty associated with excess_pb210_activity. | disintegrationPerMinutePerGram |
| excess_pb210_mda | Minimum detectable activity for excess pb210 measurements | disintegrationPerMinutePerGram |
| age | Mean age at the bottom of the depth interval from submitter generated age depth model. Units are years prior to coring date. | nominalYear |
| age_se | Standard error of age estimate from submitter generated age depth model. | nominalYear |
| date | Date at bottom of the depth interval, calculated as coring date minus sample age. | nominalYear |
| fraction_CaCO3 | Mass of CaCO3 relative to sample dry mass. Calculated based on difference in mass loss between 550 degrees C and 990 degrees C LOI. | dimensionless |
| fraction_total_nitrogen | Mass of total nitrogen relative to sample dry mass. | dimensionless |
| fraction_total_phosphorus | Mass of total phosphorus relative to sample dry mass. | dimensionless |
| fraction_total_lignin | Mass of total lignin relative to sample dry mass | dimensionless |
| delta_13C | The isotopic signature of 13C, calculated as ((13C:12C in the sample):(13C:12C in standard)-1)x1000 | perMille |
| delta_15N | The isotopic signature of 15N, calculated as: ((15N:14N in the sample):(15N:14N in standard)-1)x1000 | perMille |
| ratio_ad_al_vanillyls | acid-to-aldehyde ratios of the vanillyl lignin phenol group | dimensionless |
| ratio_ad_al_syringyls | acid-to-aldehyde ratios of the syringyl lignin phenol group | dimensionless |
| ratio_syringyls_vanillyls | syringyl-to-vanillyl ratio of sample dry mass | dimensionless |
| ratio_p-hydroxyls_vanillyls_plus_syringyls | the ratio of p-hydroxyl phenols to the sum of vanillyls and syringyls | dimensionless |
| ratio_PON_totalP_phenols | the ratio of p-hydroxyacetophenone (PON) to total P phenols | dimensionless |
| gamma_counting_sedmass | Mass of sediment in gamma tubes used for gamma counting | gram |
| cumulative_sedmass_atdepth | cumulative mass of overlying sediment per square centimeter for each interval depth. Calculated relative to the sediment surface. | gramPerSquareCentimeter |
| excess_pb210_inventory | Cumulative inventory of excess Pb-210 for a given interval and all underlying intervals per square centimeter. | disintegrationPerMinutePerSquareCentimeter |
| excess_pb210_inventory_se | 1 standard error of uncertainty associated with excess_pb210_inventory. | disintegrationPerMinutePerSquareCentimeter |
| unit name | parent SI unit | unit type | description |
|---|---|---|---|
| perMille | amountOfSubstanceConcentration | equivalent to parts per thousand | |
| cubicCentimeter | cubicMeter | volume | cubic centimeter |
| disintegrationPerMinutePerGram | radionucleotideActivityPerMass | disintegrations per minute per gram is a measure of the activity of the source of radioactivity | |
| disintegrationPerMinutePerSquareCentimeter | radionucleotideActivityPerVolume | disintegrations per minute per square centimeter is a measure of the activity of the source of radioactivity | |
| gramPerSquareCentimeter | gramsPerSquareMeter | massPerArealMassDensity | grams per square meter per 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/