David Brankovits John W. Pohlman 20200318 1.0 tabular digital data data release DOI:10.5066/P9N4H6Y4 Reston, VA U.S. Geological Survey Suggested citation: Brankovits, D., and Pohlman, J.W., 2020, Vertical chemical profiles collected across haloclines in the water column of the Ox Bel Ha cave network within the coastal aquifer of the Yucatan Peninsula in January 2015 and January 2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9N4H6Y4 . This data release is in support of: Brankovits, D., and Pohlman, J.W., 2020, Methane oxidation dynamics in a karst subterranean estuary: Geochimica et Cosmochimica Acta, https://doi.org/10.1016/j.gca.2020.03.007 . https://doi.org/10.5066/P9N4H6Y4 https://www.sciencebase.gov/catalog/item/5e503065e4b0ff554f72d6be Natural cave passages penetrating a coastal aquifer in the Yucatan Peninsula (Mexico) were accessed to test the hypothesis that chemoclines associated with salinity gradients (haloclines) within the flooded cave networks of the karst subterranean estuary are sites of methane oxidation. Two field trips were carried out to the fully-submerged cave system located 6.6 km inland from the coastline in January 2015 and January 2016. Vertical chemical profiles across the water column haloclines were obtained using the OctoPiPi (OPP), a high-resolution water sampler built by the U.S. Geological Survey (USGS). The sampling efforts resulted in cm-scale profiles of major ions (e.g., chloride and sulfate), as well as concentrations and stable carbon isotopic values of methane, dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC). Field activities were carried out by the USGS Coastal and Marine Geology Program in conjunction with Texas A&M University at Galveston These data are used to investigate how salinity-driven density stratification influences carbon cycling and methane dynamics in the karst subterranean estuary. Additional information regarding the field activities associated with these data can be obtained from https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-013-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2016-003-FA. 20150115 20150116 20160122 20160123 ground condition of individual sampling events Complete None planned -87.5693 -87.4164 20.2829 20.1084 USGS Metadata Identifier USGS:5e503065e4b0ff554f72d6be ISO 19115 Topic Category environment inlandWaters None USGS U.S. Geological Survey cenote anchialine ecosystem aquatic ecosystem biogeochemical cycling cave coastal aquifer subterranean estuary ecosystem function environment geochemical data geochemistry karst inland waters chemical records hydrologic records USGS Thesaurus hydrology hydrogeology salinity field inventory and monitoring groundwater freshwater ecosystems estuarine ecosystems carbon cycling carbon isotope analysis biogeochemical cycling coastal ecosystems estuarine mixing None Cenote Bang Ox Bel Ha Cave System Quintana Roo Yucatan Peninsula Mexico None. None. John Pohlman U.S. Geological Survey Research Geochemist mailing and physical

384 Woods Hole Road.

Woods Hole MA 02543 USA 508-548-8700 x2213 jpohlman@usgs.gov https://www.sciencebase.gov/catalog/file/get/5e503065e4b0ff554f72d6be/?name=CenoteBang_OPP-gechem-data_2015-2016_browse.jpg Browse graphic of the conceptual model of the karst subterranean estuary in an unconfined coastal aquifer setting (top). Mixing between freshwater and marine-derived saline groundwater occurs within the aquifer’s porous geologic setting, including its sinkholes and cave conduits. Mixing zones were accessed through flooded cave networks to obtain high-resolution vertical profiles of chemical parameters (bottom box). Samples were collected with 12-cm spacing in (a) January 2015 and (b) January 2016, as well as with the 2.5-cm spacing (c) in January 2016. The blue line is the sulfate to chloride ratio (0.0515) of the regional seawater. JPEG U.S. Geological Survey, Chesapeake Biological Laboratory, Texas A&M University at Galveston Windows 10 Enterprise (version: 1803); Microsoft Excel Professional Plus 2016. Cédric Magen Laura L. Lapham John W. Pohlman Kathleen Marshall Samantha Bosman Michael Casso Jeffrey P. Chanton 20140908 Limnology and Oceanography: Methods vol. 12, issue 9 New Jersey Wiley pp. 637-650 https://doi.org/10.4319/lom.2014.12.637 David Brankovits John W. Pohlman 2020 Geochimica et Cosmochimica Acta in press Cambridge Elsevier This publication is the journal article related to this data release. The journal article contains detailed information with regard to the data collection, processing of the samples, storage, analysis, and attribute accuracy. https://doi.org/10.1016/j.gca.2020.03.007 The accuracy of each attribute is determined by that analysis specific to that attribute. The accuracy is provided in the process step for each measurement. All data provided in this release were obtained by David Brankovits during his Ph.D. studies under the supervision of USGS Research Geochemist John Pohlman. Data were obtained during two consecutive deployments. The obtained data were processed and handled the same way after each deployment.This dataset only includes samples with unique sample IDs that were collected with the high-resolution water sampler, and, thus, it excludes discrete samples that were collected manually during the same field campaign. For missing values, the sample has not been analyzed or it was not possible to analyze. The condition of the missing values (i.e., why it was not analyzed) is not specified. The horizontal position (coordinates) of the entrance pool of Cenote Bang was obtained with a Garmin GPSmap 60CSx GPS, which has a positional accuracy of less than 10 meters. Coordinates for the locations where the individual profiles were collected are not available because the GPS does not operate in overhead or underwater settings. The bounding coordinates provided in this data release are intended to incorporate the horizontal extent of the passages investigated in this study. However, as stated previously, the precise locations of the passages are unknown. The depth associated with deployed devices was obtained from the diver's depth gauge, which is accurate to +/- 0.3 m. Discrete water samples were collected from Cenote Bang during four sampling events: January 15 and January 16 of 2015, and January 22 and January 23 of 2016. Cave samples were collected by scuba divers and followed protocols established by the American Academy of Underwater Sciences and the National Speleological Society Cave Diving Section. Water samples for geochemical analysis of dissolved materials were collected near sonde profile locations in plastic 60 ml syringes fitted with 3-way stopcocks. The syringes were loaded into the sampler-rack prior to deployment. The samplers used to collect the water samples were the OctoPiPi (OPP) consisting of a rack of ten 60 ml plastic syringes mounted and evenly distributed along an aluminum frame with a mechanical, spring-powered trigger-system that fills syringes when activated. An OPP with fixed 12 cm syringe spacing and another with 2.5 cm syringe spacing (the mini-OPP) were deployed during this study. The OPPs were mounted vertically across interfaces and left in place for at least 24 hours to allow the water column to re-stratify before being triggered. The top-mount of the OPP was connected to either an inflated dive lift bag or elastic bands carefully attached to the cave ceiling. The bottom-mount was connected to 1/8” braided nylon line deployed by dive reel and attached to at least 5 kg of lead for stability. When triggered, the OPP slowly and simultaneously filled the syringes with sample water. Following OPP recovery, the syringes were transported on ice to the field lab, where they were processed within eight hours. The 60-ml water sample was divided into subsamples for geochemical analyses of dissolved constituents, including methane, dissolved inorganic carbon, dissolved organic carbon, inorganic nutrients and ions. Samples for ion analysis were filtered through a 0.45 micrometer (µm) Acrodisc syringe filter and collected in a 2-ml plastic screw-top vial. 30-ml serum vials for methane water samples were prepared prior to sample collection by adding 0.5 ml 8M NaOH into the empty vial as a preservative, sealing the container with 1 cm thick butyl septa, and vacating the vial of air with a vacuum pump. An unfiltered 20-ml water sample was then transferred from the syringe into the serum vial by piercing the septum with a 20-gauge syringe needle and regulating water flow with the stopcock. Water samples were stored in the fridge at 7 degree C. Processing took place after each deployment period in 2015 and 2016. 2016 David Brankovits U.S. Geological Survey, Northeast Region postdoc scholar physical and mailing address

384 Woods Hole Road

Woods Hole MA 02543 USA 508-548-8700 x2235 dbrankovits@usgs.gov Analysis of the samples was performed at the Woods Hole Oceanographic Institution (WHOI) and U.S. Geological Survey (USGS) in Woods Hole MA, USA. Sulfate and chloride concentrations were determined using a Metrohm 881 Compact Plus ion chromatograph (IC) equipped with a Metrosep A Supp 5-250 anion column. Chloride concentrations millimol (mM) were converted to milligram per liter (mg l-1) and multiplied by 0.0018066 to determine salinity (psu). The analytical error for chloride and sulfate was +/- 3.5% of the IAPSO standard sulfate and chloride values. Dissolved inorganic carbon (DIC) concentrations were determined with a Model 5011 UIC coulometer and quantified relative to a seawater certified reference material (CRM) with a relative standard deviation of 4% relative to the CRM value (2.2 millimolar, mM). The stable carbon isotopic content of the DIC was measured with a Thermo-Finnigan DELTAplus XP IRMS with an analytical error (1-sigma) of 1.1 per mil. Headspace methane concentrations were determined using a Shimadzu 14-B gas chromatograph (GC) equipped with a flame ionization detector (FID). Headspace concentrations were converted to dissolved concentrations using the method of Magen and others, 2014 and are reported with a relative standard deviation of 2%. The stable carbon isotope composition of methane from the headspace of the serum vials was determined using a Thermo-Finnigan DELTAPlus XL isotope ratio mass spectrometer (IRMS) coupled to an Agilent 6890 Gas Chromatograph (GC) via a Finnigan GCCIII combustion interface with 1-sigma deviation of 1.6 per mil. DOC concentration and d13C were analyzed by high-temperature combustion-isotope ratio mass spectrometry (HTC-IRMS) at the USGS-WHOI Dissolved Carbon Isotope Lab (DCIL). The DCIL HTC-IRMS system consists of an OI 1030C total carbon analyzer and a Graden molecular sieve trap interfaced to a Thermo-Finnigan DELTA-PLUS XL IRMS. DOC concentrations are reported with relative standard deviation (RSD) of less than 5% of the measured value. Stable carbon isotope ratios for DIC, methane, and DOC are reported in the standard delta-notation relative to VPDB (Vienna Pee Dee Belemnite) with a 1-sigma deviation of less than 0.5 per mil. All sample analyses were performed by David Brankovits under the supervision of John Pohlman. Full details of the laboratory analysis of samples is described in the Methods section and Supplementary Materials of Brankovits, D., Pohlman, J.W., Hiemann, H., Leigh, M.B., Leewis, M.C., Becker, K.W., Iliffe, T.M., Alvarez, F., Lehmann, M.F., and Phillips, B., 2017, Methane- and dissolved organic carbon-fueled microbial loop supports a tropical subterranean estuary ecosystem: Nature Communications, vol. 8, 1835, https://doi.org/10.1038/s41467-017-01776-x. Sample processing occurred between January 2015 and September 2016. 2016 David Brankovits U.S. Geological Survey, Northeast Region postdoc scholar physical and mailing address

384 Woods Hole Road

Woods Hole MA 02543 USA 508-548-8700 x2235 dbrankovits@usgs.gov The data were organized into a Microsoft Excel spreadsheet (O365). The first three header rows of that Excel file were deleted, and the resulting header row and data were exported as an MS-DOS CSV file so the data are available in both XLSX and CSV formats. 2020 David Brankovits U.S. Geological Survey, Northeast Region postdoc scholar mailing address

384 Woods Hole Road

Woods Hole MA 02543 United States 508-548-8700 x2235 dbrankovits@usgs.gov Added keywords section with USGS persistent identifier as theme keyword. 20200807 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543-1598 508-548-8700 x2251 508-457-2310 vatnipp@usgs.gov Point Point 59 0.00001 0.00001 Decimal degrees World Geodetic System 1984 WGS-84 6378137 298.257 Local surface 0.01 meters Attribute values CenoteBang_OPP-gechem-data_2015-2016 Aquatic biogeochemical data from samples collected from Cenote Bang in the Yucatan Peninsula near the city of Tulum between January 2015 and January 2016. The first two rows of the Excel spreadsheet are dataset descriptors. The third row is columns headings, some of which contain special characters. The fourth row, used as the labels in the metadata, represent plain text formats of the column headers. The CSV file contains only this fourth row as the header row. U.S. Geological Survey Location General description of location where samples were obtained U.S. Geological Survey Character set (text). Latitude Latitude of cave entrance as determined by Garmin GPSmap 60CSx GPS in decimal degrees U.S. Geological Survey 20.21026 20.21026 decimal degrees Longitude Longitude of the cave entrance as determined by Garmin GPSmap 60CSx GPS in decimal degrees. U.S. Geological Survey -87.50107 -87.50107 decimal degrees Station Sampling location. U.S. Geological Survey CavePassage_1 Flooded interior cave passage where samples were acquired. CavePassage_1 is the main corridor located approximately 30m upstream from the cave entrance in a domed room. U.S. Geological Survey CavePassage_2 Flooded interior cave passage where samples were acquired. CavePassage_2 is the main corridor located approximately 300m upstream beyond the domed room near the entrance. U.S. Geological Survey Sample_ID Format for sample id for the study. YUC represents "Yucatan Peninsula," and the numeric code is the unique identifier. U.S. Geological Survey Character set (text). depth(m) Water depth where sample was collected by diver, obtained with a Piezo-resistive depth sensor in Shearwater Petrel dive computer. U.S. Geological Survey 3.52 20.54 meters Date Calendar date data were obtained in the format M/DD/YYYY U.S. Geological Survey Character set (text). Salinity(psu) Salinity value of water sample calculated by multiplying the ion chromatograph determined chloride concentration by 0.0018066 U.S. Geological Survey 0.17 35.95 unitless Chloride(milliM) Chloride concentration of water sample measured by ion chromatography. Blank values indicate section sample has not been analyzed for this attribute. U.S. Geological Survey 2.61 561.28 millimolar (mM) Sulfate(milliM) Sulfate concentration of water sample measured by ion chromatography. Blank values indicate section sample has not been analyzed for this attribute. U.S. Geological Survey 0.13 28.88 millimolar (mM) SO4/Cl Calculated ratio of sulfate to chloride concentration of the water sample. Blank values indicate measurements needed to determine this attribute were not analyzed. U.S. Geological Survey 0.01 0.06 unitless DIC(milliM) Dissolved inorganic carbon concentration of the water samples as measured by coulometry. Blank values indicate sample was either not collected or has not been analyzed. U.S. Geological Survey 1.30 7.93 millimolar (mM) delta13C-DIC(permil) Carbon isotopic ratio (13C/12C) of dissolved inorganic carbon (DIC) of the water samples relative to the Vienna Pee Dee Belemnite (VPDB) standard expressed in the standard permil notation. Blank values indicate sample was either not collected or has not been analyzed. U.S. Geological Survey -17.84 0.90 per mil relative to VPDB CH4(nanoM) Dissolved methane concentration of the water sample determined by analysis by gas chromatography flame-ionization detection. Blank values indicate sample was either not collected or has not been analyzed. U.S. Geological Survey 8.67 7793.30 nanomolar (nM) delta13C-CH4(permil) Carbon isotopic ratio (13C/12C) of dissolved methane (CH4) in the water sample relative to the Vienna Pee Dee Belemnite (VPDB) standard expressed in the standard permil notation. Blank values indicate section sample has not been analyzed for this attribute. U.S. Geological Survey -67.51 -44.55 per mil relative to VPDB DOC(microM) Dissolved organic carbon (DOC) of the water sample determined by high temperature combustion (HTC) oxidation. Blank values indicate sample was either not collected or has not been analyzed. U.S. Geological Survey 67.66 986.17 micromolar (microM) delta13C-DOC(permil) Carbon isotopic ratio (13C/12C) of dissolved organic carbon (DOC) of the water sample relative to the Vienna Pee Dee Belemnite (VPDB) standard expressed in the standard permil notation. Blank values indicate sample was either not collected or has not been analyzed. U.S. Geological Survey -27.96 -14.43 per mil relative to VPDB Sampler OctoPiPi (OPP) samplers consist of a rack of ten 60 ml plastic syringes mounted and evenly distributed along an aluminum frame with a mechanical, spring-powered trigger-system that fills syringes when activated. U.S. Geological Survey OPP OPP with fixed 12 cm syringe spacing U.S. Geological Survey mini-OPP OPP with fixed 2.5 cm syringe spacing U.S. Geological Survey Deployment_ID Numeric value representing the deployment order. Samples with the same deployment ID were collected collectively at the same time with the same sampler. U.S. Geological Survey Character set (text). These data are also available in a XLSX format. The first line of the CSV file is a header line and those labels are the same as the fourth row of the Excel spreadsheet. The first row of the Excel spreadsheet identifies the project and its duration. The second row is additional project description. The third row is the same information as these attributes, but some columns include special characters. U.S. Geological Survey U.S. Geological Survey - ScienceBase physical and mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 USA 1-888-275-8747 sciencebase@usgs.gov This dataset contains data in an Excel spreadsheet (CenoteBang_OPP-gechem-data_2015-2016.xlsx) and the same information in a CSV file (CenoteBang_OPP-gechem-data_2015-2016.csv). Additionally, the dataset contains a browse graphic (CenoteBang_OPP-gechem-data_2015-2016_browse.jpg) and the CSDGM metadata in XML format. Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. XLSX Microsoft Excel O365 The dataset contains the data in XLSX and CSV formats, browse graphic, and associated metadata. 1 https://www.sciencebase.gov/catalog/file/get/5e503065e4b0ff554f72d6be https://doi.org/10.5066/P9N4H6Y4 The first link downloads all the data on the landing page, the second link is to the dataset landing page. CSV Microsoft Excel O365 The dataset contains the data in XLSX and CSV formats, browse graphic, and associated metadata. 1 https://www.sciencebase.gov/catalog/file/get/5e503065e4b0ff554f72d6be https://doi.org/10.5066/P9N4H6Y4 The first link downloads all the data on the landing page, the second link is to the dataset landing page. None 20211119 U.S. Geological Survey David Brankovits Postdoc Scholar mailing and physical

384 Woods Hole Rd.

Woods Hole MA 02543 USA 508-548-8700 x2235 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the metadata contact is no longer with the USGS or the email is otherwise invalid. FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999