| Contributors | Affiliation | Role |
|---|---|---|
| Capece, Lena R. | University of California-Santa Barbara (UCSB) | Student |
| Rauch, Shannon | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
We collected sediment cores, biomass, and dissolved organic matter from two mangrove locations in Rookery Bay National Estuarine Research Reserve and Little Ambergris Caye during the time period of June 2022 through February 2024. Sediment cores were extruded in the field and kept at -20 degrees Celsius (°C) until analysis could be carried out back in the lab at UC Santa Barbara. We provide elemental concentrations (organic C/N/S, Fe, pyrite) and isotopic compositions (δ13C, δ34S) of important carbon, iron, and sulfur pools. Additionally, surface material (litter or microbial mat) samples were collected between 2020 and 2023 and were also analyzed for elemental (C/N/S) and isotopic compositions (δ13C, δ34S).
After measurement of samples of data on instruments, all data were wrangled and analyzed in R version 4.4.3.
XAS spectra were obtained at the Stanford Synchrotron Radiation Lightsource (SSRL) on beam line 14–3 using a spot size of 0.5 square millimeters (mm2) and a Si(111) (Φ = 90) double crystal monochromator calibrated to the thiol pre-edge peak of thiosulfate at 2472.02 eV. Spectra were averaged and normalized in the SIXPACK (Webb 2005) software package using a K-edge E0 of 2473 and pre-edge and post-edge linear normalization ranges of -20 to -7 and 35 to 70 eV, respectively. The relative abundance (%) of individual sulfur species were determined in sediments and biomass samples using least squares fitting and a set of OS standards (Capece et al. 2025).
- Imported original file "man_geochem.csv" into the BCO-DMO system.
- Marked "NA" as a missing data value (missing data are empty/blank in the final CSV file).
- Split the original "date" column into separate "year" and "month" columns.
- Corrected the spelling of "latitude".
- Changed longitude "81.7319" to "-81.7319" for the "station" site.
- Re-ordered columns so that pyrite_gc is next to pyrite_e.
- Saved the final file as "983803_v1_mangrove_geochem.csv".
| File |
|---|
983803_v1_mangrove_geochem.csv (Comma Separated Values (.csv), 26.47 KB) MD5:8898be41f5a50d9eca91f40785ed57af Primary data file for dataset ID 983803, version 1 |
| Parameter | Description | Units |
| site | sampling location with study designated with "rb" for Rookery Bay pristine (b1=basin1, b2 = basin2, f1= fringe1, f2=fringe2, o=overwash), ffc for Rookery Bay restored (t=transitional, d=deteriorated) , or basin (1-3) and fringe (1-3) for Little Ambegris Caye | unitless |
| latitude | site latitude | decimal degrees |
| longitude | site longitude | decimal degrees |
| year | year of collection | unitless |
| month | month of collection | unitless |
| habitat | type of mangrove environment (deteriorated, transitional, basin, fringe, overwash) | unitless |
| type | study location either at Rookery Bay (pristine or restored) or Little Ambergris Caye (ambergris) | unitless |
| depth | sampling interval in centimeters | centimeters (cm) |
| OC | organic carbon content as a weight percent carbon | percent |
| OC_e | standard error associated with OC | percent |
| SC | molar total sulfur to carbon ratio as a percent | percent |
| SC_e | standard error associated with SC | percent |
| CN | molar carbon to nitrogen ratio | unitless |
| CN_e | standard error associated with CN | unitless |
| d13C | total organic carbon isotope composition expressed in per mille | per mille |
| d13C_e | standard error associated with d13C | per mille |
| d34S | total sulfur isotope composition expressed in per mille | per mille |
| d34S_e | standard error associated with d34S | per mille |
| pyrite_gc | pyrite content as a weight percent sulfur | percent |
| pyrite_e | standard error associated with pyrite_gc | percent |
| CPK | protokerogen organic carbon content as a weight percent carbon | percent |
| CPK_e | standard error associated with CPK | percent |
| SPK | protokerogen organic sulfur content as a weight percent sulfur | percent |
| SPK_e | standard error associated with SPK | percent |
| SCPK | molar protokerogen organic sulfur to carbon ratio as a percent | percent |
| SCPK_e | standard error associated with SCPK | percent |
| CNPK | molar protokerogen organic carbon to nitrogen ratio as a percent | percent |
| CNPK_e | standard error associated with CNPK | percent |
| d13CPK | protokerogen organic carbon isotope composition expressed in per mille | per mille |
| d13CPK_e | standard error associated with d13CPK | per mille |
| d34SPK | protokerogen organic sulfur isotope composition expressed in per mille | per mille |
| d34SPK_e | standard error associated with d34SPK | per mille |
| d34Spy | pyrite sulfur isotope composition expressed in per mille | per mille |
| d34Spy_e | standard error associated with d34Spy | per mille |
| CSPK | inverse of SCPK, molar protokerogen organic carbon to sulfur ratio | unitless |
| depth_bin | bins below ground samples by depth in cm (0-2, 2-10, 15-25), mangrove biomass into "surface" and fine root="roots" material, and dissolved organic matter as dom | unitless |
| surfmat | dominant above ground surface material (either mat, litter, or mat/litter = mlit) | unitless |
| Dataset-specific Instrument Name | Conflo IV |
| Generic Instrument Name | Continuous Flow Interface for Mass Spectrometers |
| Dataset-specific Description | Thermo Scientific Delta V Plus Isotope Ratio Mass Spectrometer (IRMS) via Conflo IV to measure relative abundance of isotopes, in this case δ34S. |
| Generic Instrument Description | A Continuous Flow Interface connects solid and liquid sample preparation devices to instruments that measure isotopic composition. It allows the introduction of the sample and also reference and carrier gases.
Examples: Finnigan MATConFlo II, ThermoScientific ConFlo IV, and Picarro Caddy.
Note: This is NOT an analyzer |
| Dataset-specific Instrument Name | Elementar vario ISOTOPE select elemental analyzer |
| Generic Instrument Name | Elemental Analyzer |
| Dataset-specific Description | Elementar vario ISOTOPE select elemental analyzer interfaced to a Nu Horizon isotope ratio mass spectrometer to measure CNS and δ13C |
| Generic Instrument Description | Instruments that quantify carbon, nitrogen and sometimes other elements by combusting the sample at very high temperature and assaying the resulting gaseous oxides. Usually used for samples including organic material. |
| Dataset-specific Instrument Name | Metrosep A Supp 5-100/4.0 column and Metrohm 930 Compact IC Flex |
| Generic Instrument Name | Ion Chromatograph |
| Dataset-specific Description | Metrosep A Supp 5-100/4.0 column and Metrohm 930 Compact IC Flex to measure CRS |
| Generic Instrument Description | Ion chromatography is a form of liquid chromatography that measures concentrations of ionic species by separating them based on their interaction with a resin. Ionic species separate differently depending on species type and size. Ion chromatographs are able to measure concentrations of major anions, such as fluoride, chloride, nitrate, nitrite, and sulfate, as well as major cations such as lithium, sodium, ammonium, potassium, calcium, and magnesium in the parts-per-billion (ppb) range. (from http://serc.carleton.edu/microbelife/research_methods/biogeochemical/ic....) |
| Dataset-specific Instrument Name | Nu Horizon isotope ratio mass spectrometer |
| Generic Instrument Name | Isotope-ratio Mass Spectrometer |
| Dataset-specific Description | Elementar vario ISOTOPE select elemental analyzer interfaced to a Nu Horizon isotope ratio mass spectrometer to measure CNS and δ13C |
| Generic Instrument Description | The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer). |
| Dataset-specific Instrument Name | MARS-6 microwave CEM |
| Generic Instrument Name | Microwave Digestion Platform |
| Dataset-specific Description | MARS-6 microwave CEM to extract lipids from sediments |
| Generic Instrument Description | Microwave digestion is a chemical technique used to decompose sample material into a solution suitable for quantitative elemental analysis |
| Dataset-specific Instrument Name | Genesys 150 UV-Vis Spectrophotometer |
| Generic Instrument Name | Spectrophotometer |
| Dataset-specific Description | Genesys 150 UV-Vis Spectrophotometer to measure iron extracts |
| Generic Instrument Description | An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples. |
| Dataset-specific Instrument Name | Thermo Scientific Delta V Plus Isotope Ratio Mass Spectrometer (IRMS) via Conflo IV |
| Generic Instrument Name | Thermo Fisher Scientific DELTA V Plus isotope ratio mass spectrometer |
| Dataset-specific Description | Thermo Scientific Delta V Plus Isotope Ratio Mass Spectrometer (IRMS) via Conflo IV to measure relative abundance of isotopes, in this case δ34S. |
| Generic Instrument Description | The Thermo Scientific DELTA V Plus is an isotope ratio mass spectrometer designed to measure isotopic, elemental and molecular ratios of organic and inorganic compounds. The DELTA V Plus is an enhanced model of the DELTA V series of isotope ratio mass spectrometers, which can be upgraded from the DELTA V Advantage. The DELTA V Plus can be operated in Continuous Flow or Dual Inlet mode and can accommodate up to 10 collectors, ensuring flexibility to cover many applications. The DELTA V Plus is controlled by an automated, integrated Isodat software suite. A magnet, whose pole faces determine the free flight space for the ions, eliminates the traditional flight tube. The magnet is designed for fast mass switching which is further supported by a fast jump control between consecutive measurements of multiple gases within one run. The sample gas is introduced at ground potential, eliminating the need for insulation of the flow path, ensuring 100 percent transfer into the ion source. The amplifiers register ion beams up to 50 V. The DELTA V Plus has refined optics, enabling greater ion transmission than the DELTA V Advantage. It has a sensitivity of 800 molecules per ion (M/I) in Dual Inlet mode and 1100 M/I in Continuous Flow mode. It has a system stability of < 10 ppm and an effective magnetic detection radius of 191 nm. It has a mass range of 1 - 96 Dalton at 3 kV. |
NSF Award Abstract:
Mangrove forest sediments are important hotspots of organic carbon preservation, and they have the potential to sequester substantial amounts of atmospheric CO2. Currently, however, is it not fully understood why these environments are able to bury so much organic carbon, or how they will respond to future changes in sea level, land use, and climate. This project will investigate a mechanism that may help explain this carbon burial: organic matter sulfurization, the transformation and effective ‘pickling’ of sedimentary organic matter by sulfide. Its central aim is to understand what controls the extent of sulfurization in mangrove sediments, and to estimate the contribution of organic matter sulfurization to sediment carbon storage in different parts of the environment. By providing some of the first constraints on how, when, and where organic matter sulfurization happens in mangroves, the results of this work will guide decisionmakers managing coastal watersheds and carbon stocks in the face of land use, climate and sea level change. As part of this work, four undergraduate students and one PhD student at UC Santa Barbara will gain field and research experience. And, in collaboration with local groups associated with the field site, the team will produce a season of ‘Ocean Solutions’ podcast episodes related to conservation and human impacts of Caribbean mangroves.
The overarching goal of this project is to understand how microbial sulfur cycling affects organic matter preservation in vegetated coastal sediments, which have substantial leverage to impact the global carbon cycle on decadal to millennial timescales. It specifically investigates organic matter sulfurization, which can transform fresh, easily respired organic matter into recalcitrant, polymerized carbon stocks with long-term preservation potential. Although organic matter sulfurization is known to occur in mangrove sediments, the scale of its impact is essentially unknown. A pair of field expeditions will be conducted at a mangrove forest on the southwestern coast of Florida. In the first field season, geochemical profiles will be used to quantify organic matter sulfurization in sediments and its relationships with carbon storage, iron mineralogy, and the characteristics of sedimentary organic matter inputs. In the second field season, cyclic voltammetry will be used to target redox dynamics at the millimeter scale. Laboratory experiments will be conducted to test the susceptibility of various local organic matter sources to sulfurization and characterize their sulfurized forms. Throughout, the project applies a holistic approach to sedimentary organic matter by characterizing the dissolved, lipid, protein/carbohydrate, and proto-kerogen pools with isotopic and spectroscopic techniques. This work will yield a first quantitative, mechanistic framework for predicting the extent of organic matter sulfurization in coastal vegetated habitats and its likely response to changes in ecology, land use, or sea level.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
| Funding Source | Award |
|---|---|
| NSF Division of Earth Sciences (NSF EAR) |