Jennifer A. O'Keefe Suttles Meagan J. Eagle Shannon Valley 2026 1.0 comma-separated values text file (*.csv). data release DOI:10.5066/P1XVJEZG Woods Hole Coastal and Marine Science Center, Woods Hole, MA U.S. Geological Survey, Coastal and Marine Hazards and Resources Program Suggested citation: O'Keefe Suttles, J.A., Eagle, M.J., and Valley, S., 2026, Collection, analysis, and age-dating of sediment cores from coastal wetlands in Oyster Bay, Alabama, 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P1XVJEZG. https://doi.org/10.5066/P1XVJEZG To assess historical environment changes associated with changes in hydrologic connection to the Gulf Intracoastal Waterway (GIW) and Mobile Bay, six sediment cores (50-80 cm in length) were collected in 2021 from two coastal wetland sites. These two sites in Gulf Shores, Alabama were: Oyster Bay Nature Preserve ("OB", a brackish marsh with natural hydrology) and the Emmet O. and Vina Wenzel Wetland Preserve ("WW", an impounded coastal wetland). The OB control site is a 1.5 square kilometer wetland with unobstructed natural oscillations in water levels and continuous connection to the GIW and Mobile Bay. The WW impounded study site is approximately 1.9 square kilometers; it has been cut off from saltwater exchange by three events. First, construction of the GIW in 1937 created berms of dredge spoils along the southern border. Second, culverts installed during completion of County Road 4 in the 1970s sharply reduced exchange between the wetland and the GIW. Third, Hurricane Ivan (2004) dropped a barge on the wetland; after several years, it was removed by dragging across the wetland and County Road 4 into the GIW. This sharply altered the geomorphology of the eastern section of the wetland located north of County Road 4. These three events have led to a nearly complete occlusion of the WW wetland from the GIW and Mobile Bay. As a result, the WW wetland does not experience tidal exchange and is continuously flooded due to retention of surface water from surrounding uplands. Transects were established, at both sites, starting from the tidal creek at OB and from the former tidal inlet at WW and moving toward the marsh interior. Cores were collected from three sites along each transect; core sections were age-dated using radioisotopes, and analyzed for carbon, nitrogen, and sulfur content and stable isotopes. Age-models were constructed from lead-210 in five of the six cores; the OB3 core (collected furthest from the tidal creek) was not dateable because the excess lead-210 profile was disturbed down to 20 centimeters. Accretion rates at OB were similar across the two dateable sites (OB1 and OB2) and through time with an average of 2.7 +/- 1.0 millimeters per year. Vertical accretion rates have increased with time across the WW sites, with the highest rates (6.0 +/- 1.2 millimeters per year) observed at WW2 (midway along the transect) since near total impoundment in 2008. Carbon accretion rates at OB1 and OB2 have remained similar through the past century at 65 +/- 28 grams Carbon per square meter per year. Prior to impoundment, accretion rates at WW were lower (38 +/- 24 grams Carbon per square meter per year) than OB. Since impoundment, carbon storage rates at WW have reached 132 +/- 60 grams Carbon per square meter per year. Sediment cores were collected, age-dated, and their carbon, nitrogen and sulfur content and isotopic composition were measured to calculate accretion rates. Data were collected to provide background data of differences in sediment characteristics between impounded wetlands and wetlands with natural tidal hydrology. For more information, see the following field activities: https://cmgds.marine.usgs.gov/services/activity.php?fan=2021-034-FA 20210707 Ground Condition. This is the date when the cores were collected. Complete None planned -87.72729097 -87.71778075 30.28538641 30.27500250 ISO 19115 Topic Category geoscientificInformation location elevation oceans environment inlandWaters biota USGS Thesaurus soil chemistry radiometric dating piston coring carbon isotope analysis carbon nitrogen sulfur sea-level change sedimentation wetland ecosystems plot sampling wetland functions coastal processes ecological processes National Agricultural Library Thesaurus salt marshes wetland soils wetlands ecological restoration None age model Plum age model lead-210 cesium-137 accretion rate carbon burial USGS Metadata Identifier USGS:69c14714b66b01d4f71ecb05 Geographic Names Information System (GNIS) Bon Secour Bay (114709) Oyster Bay (124364) Mobile Bay (158872) Bear Creek (113647) Gulf Shores (2403770) Portage Creek (125176)) Intracoastal Waterway (120697) State of Alabama (1779775) No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Meagan J Eagle Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER Research Physical Scientist mailing and physical

384 Woods Hole Road

Woods Hole MA 02543 US 508-548-8700 x2280 meagle@usgs.gov https://www.sciencebase.gov/catalog/file/get/69c14714b66b01d4f71ecb05?name=ImpoundedWetland_WestWenzel.JPG Browse graphic is a photograph of the impounded study site, Wenzel Wetland in Gulf Shores, Alabama. JPEG Radionuclide detection limits are specific to an individual sample and are a function of: 1) the detector efficiency at the energy level of the peak being measured; 2) the branching ratio (expected fraction of decay events at the energy level), 3) the background activity within the sample. Detector efficiency was determined from EPA standard pitchblende ore in the same geometry as the samples. Activities of 7Be, 137Cs, and excess 210Pb (i.e. unsupported) were decay-corrected to time of collection. Suppression of low energy peaks by self-absorption was corrected for according to Cutshall and others, 1983. Peak detection, with respect to background activity, is calculated for each radionuclide in the Genie peak integration spectroscopy software during sample analysis. Generally, measured radionuclide activity greater than or equal to 0.71 (210Pb), 0.18 (226Ra), 1.74 (7Be), and 0.06 (137Cs) dpm/g were accepted as above detection limit for this dataset. Sample carbon, nitrogen, and sulfur percentages and d13C, d15N, and d34S stable isotope ratios were measured by the Marine Biological Laboratory, Stable Isotope Laboratory (Woods Hole, MA) using a Europa 20-20 continuous-flow isotope ratio mass spectrometer interfaced with a Europa ANCA-SL elemental analyzer. All isotope ratios were related to their respective international standards and reported using per mil notation. The analytical precision based on replicate analyses of isotopically homogeneous international standards was 0.1 per mil. Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210 Pb in sediment samples—Self-absorption corrections: Nuclear Instruments and Methods in Physics Research, v. 206, issues 1–2, p. 309–312, https://doi.org/10.1016/0167-5087(83)91273-5. Dataset was queried for maximum and minimum values to be sure sample analyses were within expected ranges for the environmental conditions. Data were plotted to look for any obvious outliers that may have been indicative of analytical error. Samples with questionable results were re-analyzed. Radioisotope detection limits are defined in the attribute accuracy section of the metadata. Any measured radioisotope value below detection is given the numerical value of 0. Any samples not measured for radioisotopes are listed as NA; there are 208 samples designated with NA for radioisotope measurements. The attributes for elemental composition (wtC, wtS, wtN) and stable isotopes (d13C, d34S, d15N) list NA to indicate both an unmeasured value and any value that was measured to be below the detection limit; since zero could be a real value for a stable isotope measurement, it cannot be used as a place holder to indicate the measurement was below the detection limit of the method. All samples measured for carbon were detectable. Carbon and nitrogen were analyzed from one sub-sample, so, if carbon is reported and nitrogen is reported as NA, then nitrogen was below the detection limit. In some instances the elemental composition was detectable but the stable isotope value was below detection. Refer to the attribute definitions for further details on the number of NA designations applied to measurements below detection; 161 samples were measured for these parameters. The attributes for vertical accretion rate (VAR_LL, VAR_50, VAR_UL) and interval year (Year_LL, Year_50, Year_UL) were calculated only to the depth within each core that radioisotope measurements were within the accuracy of the method; NA is reported for any sediment section that was not dateable. The attribute reporting calculated carbon accretion rate (CAR_50) designates 298 samples as NA inclusive of samples that were not dateable or were not analyzed for carbon content. Each sample was treated in the same manner for each analysis. The OB3 core (collected furthest from the tidal creek) was not dateable because the excess lead-210 profile was disturbed down to 20 centimeters. All sample measurements are reported. Horizontal positions were determined with a SpectraPrecision (SP80) Real-Time Kinematic (RTK) GPS with Positional Dilution of Precision (PDOP) and Horizontal Dilution of Precision (HDOP) values less than or equal to 1.100 and 0.600 respectively. Based on the range in replicate measurements, the horizontal accuracy is estimated to be +/- 30 centimeters. No formal positional accuracy tests were conducted. Sample depth is defined as the interval within the core. The elevations of sediment sections down through the core ("elevation_min_mNAVD88") were calculated by subtracting the start of the core depth interval ("depth_min_cm") from the land surface elevation at the core collection site measured by SpectraPrecision (SP80) Real-Time Kinematic (RTK) GPS after core collection. Vertical Dilution of Precision (VDOP) for RTK GPS measurements were less than 1.000; average vertical accuracy of this method is +/- 5 centimeters. The measured land surface elevation is reported in the attribute "elevation_min_mNAVD88" for the core depth interval starting at 0-1 centimeters. Sediment cores were processed in 1 cm sections using a meter stick affixed to the core tube as a reference while cutting the split core. No formal positional accuracy tests were conducted. Study Site Selection and Core Collections: Six sediment cores (10 cm in diameter; 50-80 cm in length) were collected in 2021 from two coastal wetland sites, an impounded coastal wetland and a nearby brackish marsh with natural hydrology, in Gulf Shores, Alabama to assess historical environmental changes associated with changes in hydrologic connection to the Gulf Intracoastal Waterway (GIW) and Mobile Bay. The 1.5 square kilometer Oyster Bay (OB) Nature Preserve served as the control site; hydrologic conditions of this wetland were unobstructed with natural oscillations in water levels and continuous connection to the GIW and Mobile Bay. The impounded study site, Emmet O. and Vina Wenzel Wetland (WW) Preserve, is approximately 1.9 square kilometers; it has been cut off from saltwater exchange by three events. First, construction of the GIW in 1937 created berms of dredge spoils along the southern border. Second, culverts installed during completion of County Road 4 in the 1970s sharply reduced exchange between the wetland and the GIW. Third, Hurricane Ivan (2004) dropped a barge on the wetland; after several years, it was removed by dragging across the wetland and County Road 4 into the GIW. This sharply altered the geomorphology of the eastern section of the wetland located north of County Road 4. These three events have led to a nearly complete occlusion of the WW wetland from the GIW and Mobile Bay. As a result, the WW wetland does not experience tidal exchange and is continuously flooded due to retention of surface water from surrounding uplands. Transects were established, at both sites, starting from the tidal creek at OB and from the former tidal inlet at WW and moving toward the marsh interior. Cores were collected from three sites along each transect; all six marsh sites were established in solid (OB) or mixed (WW) Juncus roemerianus stands, to facilitate intercomparison between the unimpounded and impounded wetlands. A piston coring system was used to collect sediment cores from coastal wetlands on July 7, 2021. The PVC core liner (outer diameter 11 cm, 1 m in length) was fitted with a gasketed piston that was placed on the sediment surface. The clear, sharpened core liner was pushed down into the marsh subsurface, while the piston was maintained at the marsh surface via tension on the piston. We visually observed the sediment surface to ensure that the soil column did not compact during collection. Once the core reached the desired depth, a handled collar was tightened around the top of the core tube and the core liner and piston were pulled out of the marsh by hand. After capping the bottom of the core liner, the piston was removed, then the top of the core liner was capped. Both caps were taped to the core liner and the cores were transported to the laboratory for sectioning; as described in the next process step. 2021 Meagan J Eagle Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER Research Physical Scientist mailing and physical

384 Woods Hole Road

Woods Hole MA 02543 US 508-548-8700 x2280 meagle@usgs.gov Sediment cores were transported to the University of Georgia and refrigerated after collection. Within one week of collection, cores were split vertically and sectioned at 1 cm intervals. Each section was placed into a pre-weighed whirl-pak bag, wet weight was recorded, and samples were placed into a freezer until shipment to the USGS Woods Hole Coastal and Marine Science Center for further processing. Upon delivery, samples were placed into a -4 degree Celsius freezer. Frozen samples were freeze-dried to a constant weight, for at least 7 days. Dry bulk density was determined as the dry weight of a known volume of sample. Dried samples were not sieved, so samples were processed and analyzed as peat mixed with live and decomposing roots. Samples were ground in a stainless steel Waring blender to homogenize the sediment for radioisotope analysis. Following gamma analysis, sub-samples were ground to a fine powder using a Retsch Mixer Mill with stainless steel tumbler and balls; the dried, ground material was used for stable isotope (d13C,d34S,d15N) and percent C, S, and N analyses. These laboratory analyses are described in subsequent process steps. 2021 Meagan J Eagle Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER Research Physical Scientist mailing and physical

384 Woods Hole Road

Woods Hole MA 02543 US 508-548-8700 x2280 meagle@usgs.gov Gamma analysis was performed on 30 to 50 samples that spanned each sediment core. Four to seventy grams of homogenized sediment were sealed for 3 weeks and counted on a planar-type gamma counter for 24 to 48 hours to measure 137Cs, 210Pb, and 226Ra at 661.6, 46.5 and 352 KeV energies respectively (Canberra Inc. USA). Activities of 137Cs and 210Pb were decay corrected to time of collection; suppression of low energy peaks by self-absorption was corrected according to Cutshall and others, 1983. Raw data (sediment weights and radioisotope counts) were entered into Microsoft Excel spreadsheets where calculations for dry bulk density and radionuclide decays per minute per gram (dpm/g) were completed. For ease of use, in uploading the published datafile into conventional databases used by the scientific community, we have named radioisotope attributes differently from standard; instead of using the convention of isotope number then elemental abbreviation, radioisotope attributes in the datafile are named first with their elemental abbreviation then the isotope number. Within the text of this metadata document, we will describe the radioisotopes using conventional standard abbreviations. Age models were developed using Plum (Aquino-López and others, 2018; Blaauw and others, 2020) version 0.1.4 in R version 4.0.0 (R Core Team 2020). Plum is an age-depth model that utilizes 210Pb and is based on the same Bayesian chronology statistical treatment as Bacon, a widely used model with 14C ages (Blaauw and Christen 2011). Plum uses distributions of prior environmental parameters that impact the 210Pb profile, including 210Pb deposition rates, supported 210Pb (i.e., 226Ra) and accretion rates, with posterior distributions providing realistic uncertainty estimates. A major benefit of Plum over the commonly used analytical solution to the continuous rate of supply model (Appleby and Oldfield 1978) is that chronologies can be calculated even if radioisotopes have not been analyzed for the entire core. Furthermore, this model yields depth-varying accretion rate estimates, unlike the constant initial concentration model (Goldberg, 1963) which is normally used for cores with discontinuous 210Pb profiles. Total 210Pb data were input into Plum, with supported 210Pb (i.e., 226Ra) estimated within the model framework from the deepest samples. We broadened the priors from default settings within Plum. We report means (50%) and the lower (6%) and upper confidence limits (94%) for each 1 cm depth interval in each dateable sediment core. Sediment accretion rates (SAR) were obtained from each chronology using the “accrate depth” function in Plum at 1 cm depth intervals. Sample carbon, nitrogen, and sulfur percentages and d13C, d15N, and d34S stable isotope ratios were measured by the Marine Biological Laboratory, Stable Isotope Laboratory (Woods Hole, MA) using a Europa 20-20 continuous-flow isotope ratio mass spectrometer interfaced with a Europa ANCA-SL elemental analyzer. All isotope ratios were related to their respective international standards and reported using per mil notation. The analytical precision based on replicate analyses of isotopically homogeneous international standards was 0.1 per mil. Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210 Pb in sediment samples—Self-absorption corrections: Nuclear Instruments and Methods in Physics Research, v. 206, issues 1–2, p. 309–312, https://doi.org/10.1016/0167-5087(83)91273-5. Aquino-López, M.A., Blaauw, M., Christen, J.A., and Sanderson, N.K., 2018, Bayesian analysis of 210 Pb dating: Journal of Agricultural, Biological and Environmental Statistics, v. 23, p. 317–333, https://doi.org/10.1007/s13253-018-0328-7. Blaauw, M., Christen, J.A., Aquino-López, M.A., Esquivel-Vazquez, J., Gonzalez V., O.M., Belding, T., Theiler, J., Gough, B. and Karney, C., 2020, rplum: Bayesian Age-Depth Modelling of Cores Dated by Pb-210. R package version 0.1.4. https://cran.r-project.org/web/packages/rplum/index.html. Blaauw, M., and Christen, J.A., 2011. Flexible paleoclimate age-depth models using an autoregressive gamma process: Bayesian Analysis, v. 6, p. 457–474, https://doi.org/10.1214/11-BA618. Appleby, P.G., and Oldfield, F., 1978, The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sediment: Catena, v. 5, issue 1, p. 1–8, https://doi.org/10.1016/S0341-8162(78)80002-2. Goldberg, E.D., 1963, Geochronology with 210 Pb, in Miller, J.A., convener, Radioactive dating: International Atomic Energy Agency Symposium on Radioactive Dating, Athens, Greece, November 19-23, 1962, [Proceedings], p. 121-131. 2022 Meagan J Eagle Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER Research Physical Scientist mailing and physical

384 Woods Hole Road

Woods Hole MA 02543 US 508-548-8700 x2280 meagle@usgs.gov Geographic Names Information System (GNIS) placenames are included as keywords to give the general location of core collections. The entity contains attributes with specific latitude and longitude of each core collection; several attributes are also included to describe the core collection location. Refer to the entity and attribute definitions for "study_id", "site_id", and "status" for details. Point Point 406 1.0E-5 1.0E-5 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137.0 298.257222101 NAVD88 0.001 meters Attribute values local surface 1 centimeters attribute values Data_Alabama2021_Sediment.csv Comma separated text file (*csv) with soil core data collected from six coastal wetland sites connected to Mobile Bay by the Gulf Intracoastal Waterway near Gulf Shores, Alabama. The file includes latitude and longitude of core collection, calculated values of soil dry bulk density, radionuclide data from gamma spectroscopy, soil carbon, sulfur, and nitrogen content, carbon-13, nitrogen-15, and sulfur-34 data for select core sections. The dataset includes 406 records. Producer-defined study_id A text identifier for the project name as utilized by the team of researchers. Producer-defined Alabama A data point from a sediment core collected from the 2021 field collections in Gulf Shores, Alabama. Producer-defined site_id A text identifier for the general location of the study site. Note that multiple cores were collected from the same site. Refer to the reported latitude, longitude and the attribute "core_id" for specific core details. Producer-defined Oyster Bay A data point from a sediment core collected from a coastal wetland in the Oyster Bay Nature Preserve in Gulf Shores, Alabama. Producer-defined West Wenzel A data point from a sediment core collected from a coastal wetland in the Emmet O. and Vina Wenzel Wetland Preserve in Gulf Shores, Alabama. Producer-defined core_id Abbreviated alphabetical identification code of each core to indicate: 1) the study site from which it was collected using a two-letter abbreviation; and 2) a number 1, 2, or 3 to indicate the location along the transect from which the core was collected. Producer-defined OB1 Oyster Bay, core 1. Core collection location along the transect that is nearest to the tidal creek. Producer-defined OB2 Oyster Bay, core 2. Core collection location midway along the transect. Producer-defined OB3 Oyster Bay, core 3. Core collection location along the transect that is furthest from the tidal creek, moving toward the interior of the wetland. Producer-defined WW1 Wenzel Wetland, core 1. Core collection location along the transect that is nearest to the former tidal inlet. Producer-defined WW2 Wenzel Wetland, core 2. Core collection location midway along the transect. Producer-defined WW3 Wenzel Wetland, core 3. Core collection location along the transect that is furthest from the former tidal inlet, moving toward the interior of the wetland. Producer-defined status A text identifier indicating the general hydrologic conditions of the study site. Producer-defined Natural A text identifier indicating that the study site experiences natural tidal flow. Producer-defined Impounded A text identifier indicating the study site is continuously flooded due to altered hydrology. Producer-defined date_collected A numeric identifier of the date the core was collected in the format of month/day/year. Producer defined 07/07/2021 07/07/2021 mm/dd/yyyy latitude Latitude decimal degrees north, NAD83 Producer-defined 30.27500250 30.28538641 decimal degrees longitude Longitude decimal degrees west, NAD83. The negative value indicates a location in the western hemisphere. Producer-defined -87.72729097 -87.71778075 decimal degrees depth_min_cm A numeric identifier of the interval minimum depth below the sediment interface in centimeters. Producer-defined 0 79 centimeters depth_max_cm A numeric identifier of the interval maximum depth below the sediment interface in centimeters. Producer-defined 1.0 80.0 centimeters elevation_min_mNAVD88 A numeric identifier of the elevation of the sediment section relative to NAVD88 datum. This is calculated by subtracting the depth_min_cm of the sediment section from the RTK elevation measurement at the soil surface. Producer-defined -0.299 0.746 meters DBD_g_cm3 Dry Bulk Density: A numeric identifier of the sediment dry bulk density in grams per cubic centimeter (g/cm3). Producer-defined 0.01 2.44 grams per cubic centimeter Ra226 A numeric identifier of the sediment total radium-226 activity in decays per minute per gram (dpm/g). Measured at 352 kiloelectron volts (KeV) on a planar gamma counter. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.18 3.54 decays per minute per gram Ra226_e A numeric identifier of the measurement error in sediment total radium-226 activity in decays per minute per gram (dpm/g). Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.00 0.69 decays per minute per gram Pb210 A numeric identifier of the sediment total lead-210 activity in decays per minute per gram (dpm/g). Measured at 46.5 kiloelectron volts (KeV) on a planar gamma counter. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.71 27.22 decays per minute per gram Pb210_e A numeric identifier of the measurement error in sediment total lead-210 activity in decays per minute per gram (dpm/g). Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.04 1.77 decays per minute per gram Cs137 A numeric identifier of the sediment total cesium-137 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Measured at 662 kiloelectron volts (KeV) on a planar gamma counter. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.06 2.62 decays per minute per gram Cs137_e A numeric identifier of the measurement error in sediment total cesium-137 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection; however, after rounding, an error of 0.00 dpm/g was calculated for one sample, WW3 17-18 cm, for which the 137Cs was measured to be above the detecion limit. Producer-defined 0.00 0.27 decays per minute per gram Be7 A numeric identifier of the sediment total beryllium-7 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Measured at 477 kiloelectron volts (KeV) on a planar gamma counter. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 1.74 11.34 decays per minute per gram Be7_e A numeric identifier of the measurement error in sediment total beryllium-7 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.83 1.66 decays per minute per gram Pb210ex A numeric identifier of the sediment excess lead-210 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Calculated as the difference between total lead-210 and total radium-226 activities. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined -0.11 25.8 decays per minute per gram Pb210ex_e A numeric identifier of the propagated measurement error in sediment excess lead-210 activity in decays per minute per gram (dpm/g), decay-corrected to date of core collection. Cells with NA indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. Producer-defined 0.04 1.9 decays per minute per gram wtC Total amount of carbon by weight percent in soil. All 245 NA designations for this attribute indicate the sample was not measured. Refer to the attribute accuracy and process step sections for further details. Producer-defined 0.41 37.1 unitless d13C The isotopic ratio of 13C to 12C in the soil sample relative to Pee Dee Belemnite (PDB) standard. All 245 NA designations for this attribute indicate the sample was not measured. Refer to the attribute accuracy and process step sections for further details. Producer-defined -27.55 -17.03 parts per thousand OR per mil wtS Total amount of sulfur by weight percent in soil. All 245 NA designations for this attribute indicate the sample was not measured. Refer to the attribute accuracy and process step sections for further details. Producer-defined 0.01 3.18 unitless d34S The isotopic ratio of 34S to 32S in the soil sample relative to air. Of the 262 NA designations for this attribute, 17 NA indicate the measurement was below detection. Refer to the attribute accuracy, logical consistency, and process step sections for further details. Producer-defined -27.3 17.35 parts per thousand OR per mil wtN Total amount of nitrogen by weight percent in soil. Of the 247 NA designations for this attribute, 2 NA indicate the measurement was below detection. Refer to the attribute accuracy, logical consistency, and process step sections for further details. Producer-defined 0.01 1.95 unitless d15N The isotopic ratio of 15N to 14N in the soil sample relative to air. Of the 255 NA designations for this attribute, 10 NA indicate the measurement was below detection. Refer to the attribute accuracy, logical consistency, and process step sections for further details. Producer-defined -3.65 3.76 parts per thousand OR per mil VAR_LL Vertical Accretion Rate at the lower limit of the 6 percent confidence interval; Bayesian 6 percent probability lower limit of vertical accretion. Accretion rates were obtained from each chronology using the “accrate depth” function in Plum at 1 cm depth intervals. Producer-defined 0.56 6.24 millimeters per year VAR_50 Mean Vertical Accretion Rate; Bayesian 50 percent lower limit of vertical accretion. Accretion rates were obtained from each chronology using the “accrate depth” function in Plum at 1 cm depth intervals. Producer-defined 0.89 7.5 millimeters per year VAR_UL Vertical Accretion Rate at the upper limit of the 94 percent confidence interval; Bayesian 94 percent probability lower limit of vertical accretion. Accretion rates were obtained from each chronology using the “accrate depth” function in Plum at 1 cm depth intervals. Producer-defined 1.33 127.71 millimeters per year Year_LL The year corresponding to the soil horizon at the lower limit of the 6% confidence interval based on the age-depth models generated by radiometric dating and Plum models. Calculated as collection date minus age of sediment at each depth interval. Producer-defined. 1827.85 2020.98 calendar year Year_50 Mean of the year corresponding to the soil horizon based on the age-depth models generated by radiometric dating and Plum models. Calculated as collection date minus age of sediment at each depth interval. Producer-defined. 1834.97 2021 calendar year Year_UL The year corresponding to the soil horizon at the upper limit of the confidence interval, 96th percentile based on the age-depth models generated by radiometric dating and Plum models. Calculated as collection date minus age of sediment at each depth interval. Producer-defined. 1848.99 2021.02 calendar year CAR_50 Carbon accretion rate calculated from dry bulk density, weight percent carbon, and the 50% probability vertical accretion rate. NA indicates the parameter was not calculated (either due to a missing value for carbon or because the core was not able to be dated at depth). Producer-defined 8.81 389.94 grams carbon per square meter per year U.S. Geological Survey ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov The dataset contains one CSV file containing the data (Data_Alabama2021_Sediment.csv), the browse graphic (ImpoundedWetland_WestWenzel.JPG), and the FGDC CSDGM metadata in XML format (Meta_AL21_cores.xml). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CSV The data release includes 1 comma separated files. 1 https://www.sciencebase.gov/catalog/file/get/69c14714b66b01d4f71ecb05 https://www.sciencebase.gov/catalog/item/69c14714b66b01d4f71ecb05 https://doi.org/10.5066/P1XVJEZG The first link in network resources downloads all the data to a zip file. The second link goes to the landing page of the dataset where individual files (data and metadata) can be downloaded manually, and the third link points to the main data release landing page. None The zip file resulting from the first network resource link contains data in CSV format. The user must have software capable of uncompressing the zip file and reading the data formats. 20260522 Jennifer A. O'Keefe Suttles Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER Chemist mailing and physical

384 Woods Hole Road

Woods Hole MA 02543 United States 508-548-8700 x2385 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with USGS. Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998