McMurdo Dry Valleys LTER
Published on McMurdo Dry Valleys LTER (https://mcm.lternet.edu)


Summary

Abstract: 

Surface water and hyporheic porewater samples were collected at high frequency during the 2017-18 (01/20/2018-01/21/2018) and 2018-19 (01/10/2019-01/12/2019) flow seasons, and opportunistically throughout the 2019-20 flow season (12/17/2019-1/25/2020) from the lower reaches of Von Guerard Stream, Taylor Valley, McMurdo Dry Valleys, Antarctica. Porewater samples were collected using plastic tubing inserted to depths of 15 or 30 cm and drawn out by syringe. This data package includes sampling locations and water chemistry data (including concentrations for dissolved organic nitrogen species, dissolved organic carbon, silica, as well as water isotopes). A laboratory nitrification potential assay was performed on sediments collected from Von Guerard stream during the 2017-18 flow season to assess the functional microbial potential of the hyporheic microbial community to perform nitrification. 

Date Range: 

January 20, 2018 to January 25, 2020
Dataset(s)

Description: 

Water chemistry data for concurrent surface and porewater samples, organized by sampling location, sampling time, and solute (DIN species, DOC, and water isotopes).

Variables (click to expand): 

DATASET_CODE
  • Label: Dataset Code
  • Definition: Internal dataset code.
  • Type: Nominal
  • Missing values: None specified
STRMGAGEID
  • Label: Stream Gage ID
  • Definition: Stream Gage ID.
  • Type: Nominal
  • Missing values: None specified
STREAM_NAME
  • Label: Stream Name
  • Definition: Name of the stream.
  • Type: Nominal
  • Missing values: None specified
SAMPLE_ID
  • Label: Sample ID
  • Definition: Alphanumeric code indicating sample year and sequential number.
  • Type: Nominal
  • Missing values: None specified
DATE_TIME
  • Label: Date and Time
  • Definition: Date and time of sample collection (MM/DD/YYYY HH:MM UTC+13).
  • Type: Date/time
  • Date format: MM/DD/YYYY HH:MM UTC+13
  • Missing values: None specified
SAMPLE_TYPE
  • Label: Sample Type
  • Definition: Type of sample.
  • Type: Code list
  • Codes:
    • surface = surface water
    • pore = hyporheic porewater
  • Missing values: None specified
SAMPLE_YEAR
  • Label: Sample Year
  • Definition: Year of sample collection.
  • Type: Date/time
  • Date format: YYYY
  • Missing values: None specified
TRANSECT
  • Label: Transect
  • Definition: Alphanumeric code identifying longitudinal transect, numbered from upstream to downstream. Transect locations shifted among years as noted in the associated data table ‘VGPW_LOCATIONS’. T1 = Transect 1, and so on.
  • Type: Nominal
  • Missing values: None specified
SITE
  • Label: Site
  • Definition: Letter identifying the lateral location on the transect. Values for lateral porewater sites are A-D with A at the channel center and D the wetted margin. SW indicates surface water.
  • Type: Nominal
  • Missing values: None specified
DEPTH_CM
  • Label: Sample depth
  • Definition: For pore samples, indicates the depth of sampler intake below streambed surface, where 0 = surface water, 15 = 15 cm, and 30 = 30 cm.
  • Type: Physical quantity
  • Unit: centimeter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NO3_MGL
  • Label: Nitrate concentration
  • Definition: Concentration of nitrogen as nitrate + nitrite in milligrams of nitrogen per liter.
  • Type: Physical quantity
  • Unit: milligramsPerLiter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NO3_COMMENTS
  • Label: Nitrate Concentration Comments
  • Definition: Comments regarding nitrate concentrations, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
N_NH4_MGL
  • Label: Ammonium concentration
  • Definition: Concentration of nitrogen as ammonium in milligrams of nitrogen per liter.
  • Type: Physical quantity
  • Unit: milligramsPerLiter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NH4_COMMENTS
  • Label: Ammonium Concentration Comments
  • Definition: Comments regarding ammonium concentrations, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
SI_MGL
  • Label: Dissolved silica concentration
  • Definition: Dissolved silica concentration in milligrams of silica per liter.
  • Type: Physical quantity
  • Unit: milligramsPerLiter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
SI_COMMENTS
  • Label: Dissolved Silica Concentration Comments
  • Definition: Comments regarding dissolved silica concentrations, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
DOC_MGL
  • Label: Dissolved organic carbon
  • Definition: Dissolved organic carbon concentration in milligrams of carbon per liter.
  • Type: Physical quantity
  • Unit: milligramsPerLiter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
DOC_COMMENTS
  • Label: Comments regarding DOC
  • Definition: Comments regarding dissolved organic carbon concentrations, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
D18O_PERMIL
  • Label: Oxygen-18 Isotope Ratio
  • Definition: δ18O isotope ratio reported in reported in parts per thousand (per mil, ‰).
  • Type: Physical quantity
  • Unit: perMil
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
DD_PERMIL
  • Label: Deuterium Isotope Ratio
  • Definition: δD isotope ratio reported in reported in parts per thousand (per mil, ‰).
  • Type: Physical quantity
  • Unit: perMil
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
DEXCESS
  • Label: Deuterium excess
  • Definition: Deuterium excess as calculated by δD-8*δ18O.
  • Type: Physical quantity
  • Unit: perMil
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
ISOTOPE_COMMENTS
  • Label: Comments regarding isotopes
  • Definition: Comments regarding all isotope values, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
SC_USCM
  • Label: Specific conductivity
  • Definition: Specific conductivity in microSiemens per centimeter.
  • Type: Physical quantity
  • Unit: microSiemensPerCentimeter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
SC_COMMENTS
  • Label: Comments regarding specific conductivity
  • Definition: Comments regarding specific conductivity, where ND = not detected and NM = not measured.
  • Type: Nominal
  • Missing values: None specified
INUNDATED
  • Label: Inundation Code
  • Definition: Identifies whether sampling location was inundated by surface water at time of sample collection. Surface water samples are noted with “Yes”.
  • Type: Code list
  • Codes:
    • Yes = Inundated
    • No = Not inundated
  • Missing values: None specified

File: 

mcmlter-strm-singley-vgpw-chemistry-20210325.csv (46.42 KB)

Description: 

Location information for sampling transects along Von Guerard Stream.

Variables (click to expand): 

DATASET_CODE
  • Label: Dataset Code
  • Definition: Internal dataset code.
  • Type: Nominal
  • Missing values: None specified
STRMGAGEID
  • Label: Stream Gage ID
  • Definition: Stream gage ID.
  • Type: Nominal
  • Missing values: None specified
STREAM_NAME
  • Label: Stream Name
  • Definition: Name of the stream.
  • Type: Nominal
  • Missing values: None specified
TRANSECT
  • Label: Transect
  • Definition: Alphanumeric transect identifier, number increases from upstream to downstream.
  • Type: Nominal
  • Missing values: None specified
SAMPLE_YEAR
  • Label: Sample Year
  • Definition: Year in which sample was collected.
  • Type: Date/time
  • Date format: YYYY
  • Missing values: None specified
LATITUDE
  • Label: Latitude
  • Definition: Sampling transect latitude.
  • Type: Physical quantity
  • Unit: decimalDegrees
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
LONGITUDE
  • Label: Longitude
  • Definition: Sampling transect longitude.
  • Type: Physical quantity
  • Unit: decimalDegrees
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified

File: 

mcmlter-strm-singley-vgpw-locations-20210325.csv (865 bytes)

Description: 

Laboratory nitrification potential assay data for sediments collected from Von Guerard Stream. 

Variables (click to expand): 

DATASET_CODE
  • Label: Dataset code
  • Definition: Internal dataset code.
  • Type: Nominal
  • Missing values: None specified
STRMGAGEID
  • Label: Stream Gage ID
  • Definition: Stream Gage ID.
  • Type: Nominal
  • Missing values: None specified
STREAM_NAME
  • Label: Stream Name
  • Definition: Name of the stream.
  • Type: Nominal
  • Missing values: None specified
SAMPLE_ID
  • Label: Sample ID
  • Definition: Code indicating sediment sample location, prior to replication.
  • Type: Nominal
  • Missing values: None specified
SAMPLE_YEAR
  • Label: Sample Year
  • Definition: Year sample was collected.
  • Type: Date/time
  • Date format: YYYY
  • Missing values: None specified
TRANSECT
  • Label: Transect.
  • Definition: Alphanumeric transect identifier, number increases from upstream to downstream.
  • Type: Nominal
  • Missing values: None specified
SITE
  • Label: Site
  • Definition: Lateral site on the transect.
  • Type: Code list
  • Codes:
    • A = Center of channel
    • C = Wetted margin
  • Missing values: None specified
REPLICATE
  • Label: Replicate
  • Definition: Replicate identifier within the same sampling site.
  • Type: Nominal
  • Missing values: None specified
ELAPSED_TIME_DAY
  • Label: Elapsed Time
  • Definition: Time (in days) since the beginning of the nitrification potential assay.
  • Type: Physical quantity
  • Unit: day
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NO2_UGL
  • Label: Nitrite concentration
  • Definition: Concentration of nitrogen as nitrite in aliquot, reported in micrograms of nitrogen per liter.
  • Type: Physical quantity
  • Unit: microgramsPerLiter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NO2_COMMENTS
  • Label: Comments regarding nitrate concentration
  • Definition: Comments regarding nitrate concentration, where NM = not measured.
  • Type: Nominal
  • Missing values: None specified
DRY_SED_G
  • Label: Dry mass of sediment
  • Definition: Dry mass of sediment in flask, reported as grams of sediment.
  • Type: Physical quantity
  • Unit: grams
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
VOLUME_L
  • Label: Volume
  • Definition: Volume of incubation solution in liters.
  • Type: Physical quantity
  • Unit: liter
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
N_NO2_UGKG
  • Label: Nitrate concentration normalized to dry mass sediment
  • Definition: Nitrogen as nitrate concentration normalized to dry mass sediment, reported as micrograms of nitrogen per kilogram of sediment.
  • Type: Physical quantity
  • Unit: microgramsPerKilogram
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified

File: 

mcmlter-strm-singley-vgpw-nitrification-20200820.csv (8.76 KB)

Short name: 

VGPW

Dataset ID: 

9032
People

Principal Investigator(s): 

Joel G. Singley
Michael N. Gooseff
Diane M. McKnight
Eve-Lyn Hinckley

Contact: 

McMurdo Dry Valleys LTER Information Manager

Associated Personnel: 

Lab Technician
Kathleen A. Welch
Lab Technician
Anna J. Bergstrom
Data Manager
Renée F. Brown
Methodology

Methods: 

Samples were collected in the lower reaches of Von Guerard stream from below the playa to about 200 m upstream of the F6 gage. Samples were taken on lateral transects extending from the channel center to the wetted margin. Full transect locations are included as a csv file.

Porewater samplers were flexible polyethylene tubing (3/16” inner diameter) encased in a rigid plastic tube and screened at the bottom with fine metal mesh. We installed samplers to depths of both 15 and 30 cm at locations A-D on each transect. Nutrient and DOC samples were filtered through pre-combusted (4 hr at 450ºC) Whatman GF/C glass fiber filters. Nutrient samples were stored frozen in 60 mL HDPE bottles, while DOC and isotope samples were kept chilled (+4ºC) in the dark prior to analysis. Silica and DIN were measured colorimetrically immediately after thawing at room temperature by the Arikaree Environmental Laboratory, University of Colorado Boulder, using a Lachat (USA) QuikChem 8500 Flow Injection Autoanalyzer. Nitrate (as NO3– + NO2–) was analyzed by standard method 4500-NO3 I (cadmium reduction flow injection) with a detection limit of 0.004 mg NO3––N L–1. Samples were analyzed for NH4+ by standard method 4500-NH3 H (phenolate flow injection, detection limit of 0.005 mg NH4+–N L–1). For Si, the detection limit was 0.004 mg Si L–1 by standard method 4500-SiO2 F. We measured water isotopes (δ18O and δD) using a cavity ring-down spectrometer (Picarro, USA) and calculated deuterium excess as δD – 8*δ18O.

For the nitrification potential assay we used sediment from two pilot transects during January 2018. We first removed the top 5 cm of the streambed to avoid contamination from benthic algal mats, then scooped sediment from approximately 5–10 cm depth into sterile Whirlpaks. These sediment samples were stored frozen and shipped to the University of Colorado Boulder for analysis. After thawing the samples at room temperature, we subsampled 20 g of wet sediment from each site in triplicate into sterile 250 mL HDPE bottles and an additional 20 g in triplicate into pre-weighed aluminum weigh boats. We dried the subsamples in the aluminum weigh boats at 105ºC for 24 hours and reweighed to calculate mean volumetric water content for each sampling location. For the samples in 250 mL HDPE bottles, we performed a nitrification potential assay using perchlorate and NH4+ in a phosphate (KH2PO4 and K2HPO4) buffered solution, which was mixed constantly with the sediment on a shaker table at room temperature. A detailed description of the assay protocol and solution concentrations is provided by Schmidt & Belser [1994]. We took subsamples from each replicate flask at 0, 1 and 8 hours then 1, 2, 3, and 5 days from the start of the assay. All subsamples were immediately filtered through Whatman GF/C glass fiber filters and stored frozen (-20ºC) until thawed for analysis. As perchlorate in the incubation solution inhibits the final oxidation of nitrite (NO2–) to NO3–, we analyzed the filtered aliquots for NO2– colorimetrically using a Lachat QuikChem 8500 Flow Injection Autoanalyzer. Accumulated NO2– concentrations were converted to mass NO2––N normalized by the calculated dry weight of sediment in each replicate flask.

Categories

Research Section: 

  • Streams
  • Stream Chemistry

LTER Core Areas: 

  • inorganic nutrients

MCM Keywords: 

  • Antarctic desert streams
  • deuterium isotope ratio
  • dissolved inorganic nitrogen
  • dissolved organic carbon
  • DOC
  • hyporheic zone
  • inorganic nitrogen
  • isotope
  • isotope ratio
  • LTER
  • McMurdo Dry Valleys
  • nitrogen
  • oxygen isotope ratio
  • sediment
  • specific conductivity
  • streamflow
  • Taylor Valley

Keywords: 

  • dissolved inorganic nitrogen
  • dissolved nutrients
  • dissolved organic carbon
  • hyporheic zone
  • inorganic nitrogen
  • isotopes
  • nitrate
  • nitrification
  • nitrite
  • nitrogen
  • nitrogen cycling
  • nutrient cycles
  • nutrient cycling
  • sediments
  • silica
  • specific conductivity
  • streamflow
  • streams

Source URL: https://mcm.lternet.edu/content/surface-and-hyporheic-porewater-chemistry-and-sediment-nitrification-potentials-von-guerard