| Contributors | Affiliation | Role |
|---|---|---|
| Huettel, Markus | Florida State University (FSU) | Principal Investigator |
| Mickle, Audrey | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
Study Site
The study site used in this project is an exposed carbonate sand beach located at the Public Beach in Marathon/Florida Keys (24 43.807 N, 081 00.056 W). The beach sand is composed of porous biogenic carbonate grains. Air temperature ranges from 14 to 38˚C, water temperature from 22 to 31˚C. The tidal range is 0.6 m.
Measurements
Gas (custom probe, 70 cm long, 5 mm diameter) and temperature probes (PT100) were placed at 5 cm above the sediment and at -5, -15 and -25 cm below the sediment surface. Pore gas was extracted from the sediment using a syringe pump (150 ml max. volume). After extraction of gas from the sediment, a set of stopcocks was used to switch the flow path of the syringe pump from the respective probe to a Pyroscience flow-through O2 optode installed in series with a Licor840A gas analyzer, where the CO2 concentrations were measured.
After the initial calibration, the Pyroscience FireSting-O2 meter produces O2 concentrations logged in user-selectable units.
The LI-840A CO2/H2O Gas Analyzer internally calculates CO2 and H2O gas concentrations and its output gives CO2 concentrations in µmol per mole of air (ppm), and H2O in mmol per mole of air (ppt). No further data processing is required, as the CO2 concentrations provided by the instrument correspond to the actual CO2 concentrations in the pore space of the sand.
- Imported "220606_2 O2 and CO2 profiles Marathon.xlsx" sheets 1 and 2 into the BCO-DMO system
- Joined (outer join) both sheets on "Site", "Latitude", "Longitude", "Profile", "Date", "Time", "Depth"
- Converted "Date" and "Time" to ISO 8601 Datetime format in EST/EDT, "ISO_DateTime_Local"
- Converted "Date to ISO 8601 YYYY-MM-DD format
- Converted "ISO_DateTime_Local" to "ISO_DateTime_UTC"
- Converted "Latitude" and "Longitude" to degree decimals
- Replaced spaces in parameter names with underscores, in compliance with BCO-DMO guidelines
- Exported file as "986654_v1_marathon_gas_profiles.csv"
| File |
|---|
986654_v1_marathon_gas_profiles.csv (Comma Separated Values (.csv), 204.16 KB) MD5:9efe2f42f0cda4d3b37b91d760a20445 Primary data file for dataset ID 986654, version 1 |
| Parameter | Description | Units |
| Site | Name of study site | unitless |
| Latitude | Latitude of study site, positive is North | decimal degrees |
| Longitude | Longitude of study site, negative is West | decimal degrees |
| Profile | Number of the profile | unitless |
| Date | Date of study | unitless |
| Time | Time in hour, minute, second (EST/EDT) | unitless |
| ISO_DateTime_Local | Date and time of sample collection in ISO 8601 format in Eastern Time (EST/EDT) | unitless |
| ISO_DateTime_UTC | Date and time of sample collection in ISO 8601 format in UTC | unitless |
| Depth | Sediment depth in centimeter | Centimeter (cm) |
| CO2 | Carbon dioxide concentration | Parts per million (ppm) |
| H2O | Water concentration | Parts per thousand (ppt) |
| Temperature | Temperature of gas sampled | degrees Celsius |
| Oxygen | Oxygen concentration | Percent air saturation (% air saturation) |
| Dataset-specific Instrument Name | LI-840A CO2/H2O Gas Analyzer |
| Generic Instrument Name | LI-COR LI-840A CO2/H2O gas analyser |
| Dataset-specific Description | Carbon dioxide and moisture was measured with a LI-840A CO2/H2O Gas Analyzer is an infrared (NDIR) gas analyzer based on a single path, dual wavelength, infrared detection system. The CO2 and H2O measurements are a function of the absorption of IR energy as it travels through the optical path. Concentration measurements are based on the difference ratio in the IR absorption between a reference and sample signal. The instrument uses digital signal processing techniques to determine the temperature and pressure corrected CO2 concentration. The data output provides CO2 concentrations in µmol per mole of air (ppm), and H2O in mmol per mole of air (ppt). |
| Generic Instrument Description | The LI-840A is an absolute, non-dispersive infrared gas analyser based on single path, dual wavelength and thermostatically controlled infrared detection system. Operating temperature range of -20 to +40 deg C. CO2 is measured in the range 0-20,000 ppm with an accuracy of better than 1 percent of the reading. H2O is measured in the range 0-60 ppt with an accuracy of better than 1.5 percent of reading. |
| Dataset-specific Instrument Name | Pyroscience FireSting-O2 meter |
| Generic Instrument Name | Oxygen Sensor |
| Dataset-specific Description | Pore gas oxygen concentrations were measured with a Pyroscience FireSting-O2 meter. This instrument is a PC-controlled (USB) fiber-optic oxygen meter can read optical oxygen sensors. It allows automatic temperature compensation of the oxygen measurements in samples with varying temperatures. |
| Generic Instrument Description | An electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed |
NSF Award Abstract:
Sandy beaches provide habitat for endangered species, protect the coast, and are appreciated for their high social and economic values. They are facing escalating anthropogenic pressures through coastal development, nutrient increases and global warming, which in recent years led to the development of extensive seaweed blooms that deposit massive amounts of algae on sandy beaches worldwide. This project investigates the fate of the deposited algae and their influence on the biogeochemical environment of the beach.
The decay of the algae locally depletes oxygen in the beach and produces toxic sulfides and high concentrations of ammonia that harm beach organisms, pollute nearshore waters and deter tourists. Research in this project quantifies biogeochemical and transport processes that control the algal decomposition. Generating these data is prerequisite for developing models that can predict the impact of the massive macroalgal deposition and thereby support decision making and coastal management. The project research is tightly linked to an educational component with instruction of graduate and undergraduate students in marine biogeochemical methods, and a dedicated outreach program informing the public about the seaweed issue and pathways to reduce this problem.
The project produces data on the dynamics of oxygen and carbon dioxide distribution and interfacial gas flux in the dry, supralittoral zone (between high tide line and dunes) of sandy beaches and determines how distributions and fluxes are influenced by the degradation of the macroalgae. Organic carbon and nitrogen profiling characterizes the biogeochemical sedimentary environment at the two study sites, a carbonate and a silicate beach. A set of laboratory experiments relates gas fluxes to the degradation rate of buried macroalgal layers and the effects of gas exchange, temperature and moisture. The data will allow estimates of the time frame of the algal decomposition process and provide information on the degradation capacity of sandy beaches. Since beach sedimentary O2 and CO2 dynamics and fluxes are largely undescribed, the project data contribute to the mechanistic and quantitative understanding of carbon and nutrient cycling in sandy beaches.
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 Ocean Sciences (NSF OCE) |