I. Data Set Descriptors A. Title: Amanda C. Spivak. 2022. Experimental soil metabolism responses to oxygen availability and carbon pulses. Georgia Coastal Ecosystems LTER Data Catalog (data set ORG-GCEL-2212; /data/ORG-GCEL-2212) B. Accession Number: ORG-GCEL-2212 C. Description 1. Originator(s): Name: Amanda C. Spivak Address: Marine Science Rm. 164 Marine Sciences Athens, Georgia 30602-3636 Country: USA Email: aspivak@uga.edu 2. Abstract: Soil metabolism rates were measured in experimental flow-through reactors (FTRs) in order to assess responses to oxygen availability (i.e., redox conditions) and pulsed inputs of bioavailable carbon. The oxygen and carbon manipulations were meant to simulate patchy conditions in the rhizosphere of Spartina alterniflora marshes. The experiment was conducted over 97 days. During the first 84 days, pulses were applied weekly and metabolic responses were measured 1 and 5 days later. After the final carbon pulse, metabolism responses were followed for another 13 days in order to assess starvation responses. We used soils from Airport marsh on Sapelo Island. 3. Study Type: Leveraged Study 4. Study Themes: Organic Matter/Decomposition, Marsh Ecology 5. LTER Core Areas: Organic Matter 6. Georeferences: none 7. Submission Date: Dec 17, 2022 D. Keywords: carbon cycling, carbon fluxes, decomposition, GCE, Georgia, Georgia Coastal Ecosystems, LTER, Marsh Landing, marshes, Organic Matter, respiration rates, root decomposition, Sapelo Island, Spartina alterniflora, USA II. Research Origin Descriptors A. Overall Project Description 1. Project Title: Georgia Coastal Ecosystems LTER - IV 2. Principal Investigators: Name: Merryl Alber Address: Dept. of Marine Sciences University of Georgia Athens, Georgia 30602-3636 Country: USA Email: malber@uga.edu 3. Funding Period: Feb 01, 2019 to Jan 31, 2025 4. Objectives: The GCE-LTER project has four goals. 1) Track environmental and human drivers that can cause perturbations in our focal ecosystems. This will be accomplished this through continuing long-term measurements of climate, water chemistry, oceanic exchange, and human activities on the landscape. 2) Describe temporal and spatial variability in physical, chemical, geological and biological characteristics of the study system (coastal wetland complexes) and how they respond to external drivers. This will be accomplished through field monitoring in combination with remote sensing and modeling. 3) Characterize the ecological responses of intertidal marshes to disturbance. This will be accomplished by ongoing monitoring and experimental work to evaluate system responses to major perturbations in three key marsh habitats (changes in inundation and predator exclusion in Spartina-dominated salt marshes; increases in salinity in fresh marshes; changes in runoff in high marshes), by implementing standardized experimental disturbances along salinity and elevation gradients, and by tracking responses to natural disturbances. 4) Evaluate ecosystem properties at the landscape level (habitat distribution, net and gross primary production, C budgets) and assess the cumulative effects of disturbance on these properties. The project will also develop relationships between drivers and response variables, which can be used to predict the effects of future changes. This will be accomplished through a combination of data synthesis, remote sensing and modeling. 5. Abstract: The Georgia Coastal Ecosystems (GCE) Long Term Ecological Research (LTER) program, based at the University of Georgia Marine Institute on Sapelo Island, Georgia, was established in 2000 to study long-term change in coastal ecosystems. Estuaries (places where salt water from the ocean mixes with fresh water from the land) and their adjacent marshes provide food and refuge for fish, shellfish and birds; protect the shoreline from storms; help to keep the water clean; and store carbon. The GCE LTER researchers study marshes and estuaries to understand how these ecosystems function, to track how they change over time, and to predict how they might be affected by future changes in climate and human activities. They accomplish this by tracking the major factors that can cause long-term change in coastal areas (e.g. sea level, rainfall, upstream development), and measuring the effects of these factors on the study site. They also conduct focused studies to assess how key marsh habitats will respond to major changes expected in the future, including large-scale experiments to evaluate the effects of a) increases in the salinity of the water that floods freshwater marshes (mimicking drought and/or sea level rise), b) changes in water runoff from land into the upland marsh border (mimicking drought or upland development), and c) exclusion of larger organisms in the salt marsh (mimicking long-term declines in predators). During this award they will initiate additional studies to systematically evaluate how coastal wetlands respond to disturbances. Disturbances, or disruptions in the environment, are particularly important to understand in the context of long-term background changes such as increasing sea level, and GCE researchers are working to assess the cumulative effects of multiple disturbances on the landscape. The GCE education and outreach program works to share an understanding of coastal ecosystems with teachers and students, coastal managers, citizen scientist and the general public. 6. Funding Source: NSF OCE 1832178 B. Sub-project Description 1. Site Description a. Geographic Location: ML -- Marsh Landing, Sapelo Island, Georgia, USA Coordinates: ML -- NW: 081 17 50.80 W, 31 25 08.03 N NE: 081 17 40.58 W, 31 25 08.03 N SE: 081 17 40.58 W, 31 24 59.03 N SW: 081 17 50.80 W, 31 24 59.03 N b. Physiographic Region: ML -- Barrier island c. Landform Components: ML -- Intertidal salt marsh d. Hydrographic Characteristics: ML -- Site borders the Duplin River and is subject to 2-3m semi-diurnal tides e. Topographic Attributes: ML -- Flat, with elevations ranging from 0-3m above mean low tide f. Geology, Lithology and Soils: ML -- unspecified g. Vegetation Communities: ML -- Spartina alterniflora in low marsh, salt pan and salt-tolerant vegetation mixture in high marsh h. History of Land Use and Disturbance: none recorded i. Climate: Climate summary for Sapelo Island, Georgia, based on NWS data from 1980-2010: Daily-aggregated Values: Mean (sample standard deviation) mean air temperature: 20.09°C (7.28°C) minimum air temperature: 15.02°C (7.96°C) maximum air temperature: 24.82°C (6.98°C) total precipitation: 3.26mm (10.3mm) Yearly-aggregated Daily Values: Mean (sample standard deviation) total precipitation (1980-2010): 1124mm (266mm) 2. Experimental or Sampling Design a. Design Characteristics: We experimentally tested how soil microbial communities respond to pulsed inputs of bioavailable compounds under oxic and anoxic conditions. We aimed to isolate biotic from abiotic responses by applying the microbial inhibitor sodium azide (NaN3). Each of four treatments (oxic or anoxic X with or without NaN3) was replicated three times for a total of 12 experimental units. Soil cores from Spartina alterniflora marshes (9.4 cm diameter x 50 cm deep; 31.42049 °N, 81.29235 °W) and 0.2 um filtered seawater (30-34 PSU, 2 m depth; 31.319989 °N, 81.178042 °W) were collected from the Georgia Coastal Ecosystems – Long-Term Ecological Research domain during summer 2020. The FTRs were continuously supplied with filtered seawater through viton tubing (0.8 mm ID, Cole-Parmer) using Masterflex L/S peristaltic pumps. The target flow rate was 0.06 mL min-1, chosen to simulate in situ soil infiltration rates. Flow conditions were verified using the conservative tracer sodium bromide. Seawater was maintained in the dark and dissolved inorganic nitrogen (DIN) and phosphate concentrations were amended to ~100 µM and ~33 µM, respectively, to reflect field conditions, and prevent microbial nutrient limitation. Water for the anoxic treatments was bubbled with N2 while water for the oxic treatments was not bubbled to maintain ambient gas concentrations. To separate biotic and abiotic processes, water supplying half of the anoxic and oxic treatments was amended with the microbial inhibitor NaN3 at 5 mM initially, then increased to 10 mM after the first three weeks. The FTRs equilibrated under constant conditions for two weeks before experimental exudate pulses began. Weekly from Jul 30 - Oct 21, 2020, 23 mL of a 6.76 mM-C cocktail of 3.1% amino acids, 45.7% sugars, and 51.2% organic acids in seawater was pulsed into each FTR. These compounds and concentrations were chosen to mimic root exudates. b. Permanent Plots: NA c. Data Collection Duration and Frequency: Microbial metabolic responses were measured fortnightly during the pulsing phase of the experiment (days 1-83) and four times following the final pulse (days 84-97). Metabolic rates were measured 1 and 5 days following each pulse to test short-term microbial responsiveness over the ~3-month experiment. Samples were collected from the seawater reservoirs and the FTR outflows at each time point and analyzed for salinity, pH, and dissolved organic and inorganic carbon (DIC), dissolved oxygen (DO), and sulfide concentrations. Soils collected initially and at the end of the experiment were stored at -80 °C prior to analysis for elemental content and stable isotope composition, acid-hydrolysable carbon, and solid-phase iron concentrations. Beginning of Observations: May 01, 2020 End of Observations: Dec 01, 2020 3. Research Methods a. Field and Laboratory Methods: Method 1: DIC and DOC -- The DIC and DOC samples were analyzed on a Shimadzu TOC-L. Briefly, the DIC samples were analyzed by acidification with 6M phosphoric acid and integrating the CO2 emission peak measured in zero-air carrier gas bubbled through the reaction chamber. Samples were calibrated using an acidified water blank and Dickson CO2 certified reference material (Dickson et al., 2003). The DOC samples were analyzed by injecting samples onto 460 °C platinum catalyst and integrating the CO2 emission peak measured in zero-air carrier gas passed through the high-temperature reaction chamber. DIC concentration measured in each sample was subtracted from the raw uncorrected DOC measurements provided by the instrument to find true DOC sample concentration. Samples were calibrated using a 7-point DOC external standard curve, measured throughout a multi-day automated sample analysis period, approximately one randomly ordered standard after every 7 samples Method 2: Dissolved oxygen -- Dissolved oxygen was measured with an optical DO probe (YSI ProODO) Method 3: Sulfide -- Sulfide samples were stabilized with an antioxidant buffer solution and concentrations were measured with a silver/sulfide ion selective electrode (Spivak et al., 2020) Method 4: Salinity and pH -- Salinity and pH were measured with a handheld refractometer and a calibrated pH electrode, respectively Method 5: Elemental and stable isotope preparation -- Samples for elemental and isotopic analyses were dried to constant mass (60 °C), homogenized with a Retsch Mixer Mill 200, and fumed with hydrochloric (HCl) acid to remove carbonates. Analyses were conducted by the UGA Center for Applied Isotope Studies and data are reported in the conventional d-notation in units of per mil (‰) Method 6: acid-hydrolysis -- Acid-hydrolysable carbon was determined by adding 6N HCl to freeze-dried soils and heating at 105°C for 2 hours (Silveira et al., 2008). Cooled samples were centrifuged and rinsed four times with Milli Q water. Soils were dried to constant mass, homogenized, and analyzed for elemental and isotopic composition. The acid-hydrolysable fraction was calculated as the difference in carbon content between untreated and acid-treated soils. Method 7: Soil phase iron extraction -- Solid-phase iron was characterized as poorly ordered, organically bound, or crystalline via a sequential extraction of 1M HCl (poorly ordered), 0.1M sodium pyrophosphate (pH 10.4; organically bound), and 50 g L-1 sodium dithionite in 0.25 M sodium citrate buffer (pH 4.8; crystalline) (Claff et al., 2010; Koretsky et al., 2008). Soils were rinsed with Milli Q water between each step. Extracts were treated with concentrated HCl and 3 M hydroxylamine HCl and reduced on a hot plate. A 2 mL subsample was treated with 1.2 mL of 3.8 M ammonium acetate buffer, 650 µL 60.5 mM phenanthroline solution, and 6.15 mL Milli Q water. Sample color developed over 24 h prior to absorbance measurements on a Shimadzu UV-1800 spectrophotometer. Concentrations were calculated against a 0-53 µg-Fe mL-1 standard curve. b. Protocols: Method 1: none Method 2: none Method 3: none Method 4: none Method 5: none Method 6: none Method 7: none c. Instrumentation: Method 1: Shimadzu TOC-L Method 2: YSI ProODO Method 3: none Method 4: none Method 5: Retsch Mixer Mill 200 Method 6: none Method 7: Shimadzu UV-1800 spectrophotometer d. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable Method 5: not applicable Method 6: not applicable Method 7: not applicable e. Speclies List: f. Permit History: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable Method 5: not applicable Method 6: not applicable Method 7: not applicable 4. Project Personnel a. Personnel: Amanda C. Spivak b. Affiliations: University of Georgia, Athens, Georgia III. Data Set Status and Accessibility A. Status 1. Latest Update: 10-Jul-2023 2. Latest Archive Date: 10-Jul-2023 3. Latest Metadata Update: 10-Jul-2023 4. Data Verification Status: Reviewed by IM B. Accessibility 1. Storage Location and Medium: Stored at GCE-LTER Data Management Office Dept. of Marine Sciences Univ. of Georgia Athens, GA 30602-3636 USA on media: electronic data download (WWW) or compact disk 2. Contact Person: Name: Adam Sapp Address: Department of Marine Sciences University of Georgia Athens, Georgia 30602 Country: USA Email: asapp@uga.edu 3. Copyright Restrictions: not copyrighted 4. Restrictions: This information is licensed under a Creative Commons Attribution 4.0 International License (see: https://creativecommons.org/licenses/by/4.0/). The consumer of these data ("Data User" herein) has an ethical obligation to cite it appropriately in any publication that results from its use. The Data User should realize that these data may be actively used by others for ongoing research and that coordination may be necessary to prevent duplicate publication. The Data User is urged to contact the authors of these data if any questions about methodology or results occur. Where appropriate, the Data User is encouraged to consider collaboration or co-authorship with the authors. The Data User should realize that misinterpretation of data may occur if used out of context of the original study. While substantial efforts are made to ensure the accuracy of data and associated documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is." The Data User should be aware, however, that data are updated periodically and it is the responsibility of the Data User to check for new versions of the data. The data authors and the repository where these data were obtained shall not be liable for damages resulting from any use or misinterpretation of the data. a. Release Date: Affiliates: Dec 17, 2022, Public: Dec 17, 2022 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 1832178 (data set ORG-GCEL-2212) c. Disclaimer: The user assumes all responsibility for errors in judgement based on interpretation of data and analyses presented in this data set. 5. Costs: free electronic data download via WWW, distribution on CD may be subject to nominal processing and handling fee IV. Data Structural Descriptors A. Data Set File 1. File Name: ORG-GCEL-2212_Soil_Fe_1_0.CSV 2. Size: 27 records 3. File Format: ASCII text (comma-separated value format) 3a. Delimiters: single comma 4. Header Information: 5 lines of ASCII text 5. Alphanumeric Attributes: 6. Quality Control Flag Codes: Q = questionable value, I = invalid value, E = estimated value 7. Authentication Procedures: 8. Calculations: 9. Processing History: Software version: GCE Data Toolbox Version 3.9.9b (06-Mar-2019) Data structure version: GCE Data Structure 1.1 (29-Mar-2001) Original data file processed: soil_fe.txt (27 records) Data processing history: 10-Jul-2023: new GCE Data Structure 1.1 created ('newstruct') 10-Jul-2023: 27 rows imported from ASCII data file 'soil_fe.txt' ('imp_ascii') 10-Jul-2023: 13 metadata fields in file header parsed ('parse_header') 10-Jul-2023: data structure validated ('gce_valid') 10-Jul-2023: updated 1 metadata fields in the Dataset section(s) ('addmeta') 10-Jul-2023: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 10-Jul-2023: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 10-Jul-2023: updated 1 metadata fields in the Dataset section(s) ('addmeta') 10-Jul-2023: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 10-Jul-2023: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 10-Jul-2023: updated 1 metadata fields in the Dataset section(s) ('addmeta') 10-Jul-2023: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 10-Jul-2023: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 10-Jul-2023: updated 6 metadata fields in the Data section(s) ('addmeta') 10-Jul-2023: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 10-Jul-2023: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Sample column 2. Treatment column 3. Extractant column 4. Phase column 5. Fe 2. Variable Definition: column 1. SampleID column 2. Experimental treatment - Pre= pre-experimental control, Aerobic = Oxic, Anaerobic = Anoxic column 3. Extractant solution and concentration column 4. Iron phase column 5. Micrograms of Iron per gram of dry soil 3. Units of Measurement: column 1. none column 2. none column 3. none column 4. none column 5. ug/g 4. Data Type a. Storage Type: column 1. string column 2. string column 3. string column 4. string column 5. floating-point b. Variable Codes: Sample: 0 Treatment: Pre = pre-experimental control, Aerobic = Oxic, Anaerobic = Anoxic c. Numeric Range: column 1. (none) column 2. (none) column 3. (none) column 4. (none) column 5. 30.0093 to 118.0222 d. Missing Value Code: 5. Data Format a. Column Type: column 1. text column 2. text column 3. text column 4. text column 5. numerical b. Number of Columns: 5 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 0 column 5. 7 6. Logical Variable Type: column 1. free text (none) column 2. coded value (none) column 3. free text (none) column 4. free text (none) column 5. data (continuous) 7. Flagging Criteria: column 1. none column 2. none column 3. none column 4. none column 5. none C. Data Anomalies: V. Supplemental Descriptors A. Data Acquisition 1. Data Forms: 2. Form Location: 3. Data Entry Validation: B. Quality Assurance/Quality Control Procedures: C. Supplemental Materials: D. Computer Programs: E. Archival Practices: F. Publications: not specified G. History of Data Set Usage 1. Data Request History: not specified 2. Data Set Update History: none 3. Review History: none 4. Questions and Comments from Users: none