uid=MCM,o=EDI,dc=edirepository,dc=org all public read snyder_iodinesed Glen Snyder

Earth Science-MS 126 Houston TX 77251 US

(713) 348-4054 gsnyder@rice.edu W. Berry Lyons

275 Mendenhall Lab Columbus OH 43210 US

(614) 688-3241 lyons.142@osu.edu http://research.bpcrc.osu.edu/EnvironmentalGeochemistry/ https://orcid.org/0000-0002-3143-7251 McMurdo Dry Valleys LTER http://mcmlter.org/ Chris Gardner gardner.177@osu.edu https://orcid.org/0000-0003-0400-3754 data manager Inigo San Gil

Department of Biology, MSC03 2020 University of New Mexico Albuquerque NM 87131 US

(505) 277-2625 (505) 277-2541 isangil@lternet.edu data manager 2014-01-01 English

As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.    Presented  in this file is the total iodine content and I-129 isotopic composition of lake-bottom sediments from Lakes Joyce and Fryxell. An attempt was made to determine the  iodine and chlorine isotopic content  of gypsum cored from the bottom of Lake Vanda, but the total iodine content was below detection.             

chemistry Cl-36 I-129 lake limnology sediment Station Keywords inorganic nutrients LTER Core Areas FUNDING: This material is based upon work supported by the National Science Foundation under Grant No.0440686

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https://mcm.lternet.edu/content/iodine-content-and-i-129-isotopic-composition-mcmurdo-lake-bottom-sediments The Lake Fryxell basin is formed by a moraine depression in a wider portion of the Taylor Valley. It has a number of moraine islands and shallower areas, as well as several relatively well developed deltas. The lake is fed by at least 10 meltwater streams with a total drainage catchment of 230 km2. The lake is dammed to the southwest by the Canada Glacier and is topographically closed. It is perennially ice covered; during summer months, an ice-free moat generally forms around much of the lake margin. Lake levels have risen ~2 m between 1971 and 1996. There are no surface outflows; the only known water loss is through ice ablation (evaporation, sublimation and physical scouring). Valley: Taylor Distance to Sea : 9 Maximum Length (km): 5.8 Maximum Width (km): 2.1 Maximum Depth (m): 20 Surface Area (km^2): 7.08 Ice Thickness Average Surface (m): 3.3 - 4.5 Volume (m^3 * 10^6): 25.2 163.048782348633 163.259582519531 -77.597076416016 -77.622711181641 18 18 meter Lake Joyce lies in the Pearse Valley against the Taylor Glacier. Valley: Pearse Distance to Sea : 44 Maximum Length (km): 1 Maximum Width (km): 1 Maximum Depth (m): 35 Surface Area (km^2): 0.83 Ice Thickness Average Surface (m): 3.9 - 5.6 Volume (m^3 * 10^6): 4.9 161.608886718750 161.662445068359 -77.715972900391 -77.726486206055 301 301 meter 2005-12-21 2005-12-27 This dataset was created Oct 1, 2008 by MCM-LTER information manager (Chris Gardner) after email discussion with PI Glen Snyder.   In 2014, this metadata was enhanced using the Drupal Ecological Information Management System (Inigo San Gil)   Metadata completed in 2016 McMurdo Dry Valleys LTER http://mcmlter.org/ McMurdo Dry Valleys LTER http://mcmlter.org/ McMurdo Dry Valleys LTER

Waters were sampled by first drilling through the ice and then lowering a Go-Flo bottle to the indicated depths. Retrieved samples were then spit into separate containers for analysis. Following the sampling of water, a shallow gravity corer with plastic lining was  attached to steel cable  and lowered through the ice hole and down to the lake bottom. The corer was dropped the final 3 meters. Core recovery ranged from only a few centimeters to 25 centimeters. Once recovered, the sediments were stoppered and transported vertically to Crary Laboratory at McMurdo station. Sediment was separated along several intervals of each core and sediment and pore waters were separated by centrifugation.     Sediment samples were shipped to Rice University where they were freeze dried and then powdered. Iodine was volatilized from the samples using a pyrohydrolysis apparatus at 900 degrees Celsius, and the vapors were trapped in a solution of tetramethylammonium hydroxide. The trapped iodine was diluted then analyzed for stable I-127 at the ICP-MS facility of Cin-Ty Lee at Rice University. Methods for analysis are described in: Schnetger, B., and Muramatsu, Y., Determination of the halogens, with special reference to iodine, in geological and biological samples using pyrohydrolysis for preparation of inductively coupled plasma mass spectrometry and ion chromatography for measurement, Analyst, 121:1627-1631.                     

ANCILLARY_SNYDER_IODINESED This is the description of the spreadsheet fo the iodine study, with columns description and units used ANCILLARY_SNYDER_IODINESED.csv 2762 27 1 \n column , " https://mcm.lternet.edu/sites/default/files/ANCILLARY_SNYDER_IODINESED.csv DATASET_CODE DATASET_CODE Table Identifier string Table Identifier LOCATION_NAME Location Name Name of lake where measurement was made string Name of lake where measurement was made Location_Type Location_Type Sample type description and/or location string Sample type description and/or location Sample_ID Sample_ID Sample identification code string Sample identification code Latitude Latitude Sample Latitude degree real Null None given Longitude Longitude Sample Longitude degree real Null None given Date_time Date_time Date sample was collected date mm/dd/yyyy Depth (m) Depth (m) Average sediment depth in centimeters below the lake floo centimeter real Null None given I(umol/kg) I(umol/kg) Total sedimentary iodine content in micromoles per kilogram umol/kg real 2.32 545 NULL None given I(umol/kg) I(umol/kg) Total dissolved iodine in micromoles per kilogram umol/kg real 0.004 8.109 NULL None given 129I/I(E-15) 129I/I(E-15) Molar ratio of I-129 to total iodine (10^-15) dimensionless real 216 12929 NULL None given +/-129I/I(E-15) +/-129I/I(E-15) 1-sigma error in molar ratios of I-129/I-127 (10^-15) dimensionless real 49.02 3454 NULL None given 129I(at/uL) 129I(at/uL) Concentration of I-129 in atoms per microliter at/uL real 0.39 142.7 NULL None given +/-129I(at/uL) +/-129I(at/uL) 1-sigma error for I-129 concentration dimensionless real 0.09 38.07 NULL None given