Lake Chemistry

Hydrogen ion concentrations (pH) in discrete water column samples collected from lakes in the McMurdo Dry Valleys, Antarctica (1993-2022, ongoing)


As part of the McMurdo Long Term Ecological Research (LTER) project in the Dry Valleys of Antarctica, hydrogen ion concentrations were monitored in various lakes of the region. An Orion portable pH meter was used to record hydrogen ion concentrations at depth specific intervals in perennial ice-covered lakes.

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Lake water samples were collected at specific depths with a five-liter Niskin bottle during normal LTER limnological sampling. Sub-samples for pH analysis were decanted into 20 mL scintillation vials. A portable Beckman phi 10 or 12 PH meter (until 1415 season) or a Beckman phi 265 PH/Temp/mV meter (1516 season until current) with a combination pH electrode was used to record hydrogen ion concentration and temperature of each sample. The meter and probe were double endpoint calibrated with pH 4, 7, or 10 buffers (phi 10 or 12 meter) or calibrated with 4, 7 and 10 buffers using automatic buffer recognition. The probe was manually agitated by slowly moving in an up and down motion (~1 cm). Once the probe stabilized, the data were recorded.


202312: Suspect pH values from the following limno runs were removed and also noted in the comments field for the respective measurements:

  • 06/07 Lake Fryxell L1
  • 06/07 Lake Hoare L1
  • 06/07 West Lobe Bonney L1
  • 08/09 East Lobe Bonney L1
  • 15/16 East Lobe Bonney L1
  • 15/16 West Lobe Bonney L1 (top value only)
  • 15/16 Lake Fryxell L2
  • 16/17 Lake Miers L1
  • 18/19 West Lobe Bonney L2 (25-35m values only)

Data from this table was submitted to INSTAAR by the MCM LTER limnology team based out of Montana State University and the University of Alabama. The 1993-94, 1994-95, 1995-96, 1996-97 and 1997-98 data was submitted by Kathy Welch at the University of Alabama. 1996-97 and 1997-98 data was also submitted by Craig Wolf at Montana State University. Since 1998, there was some overlap between these files, the records from Montana State University were used. Only two of the records in the pH9697.txt file (from Kathy Welch at the University of Alabama) were added to this dataset since they were not in the files from Montana. The raw data files listed under 'file name' are the names of the original ascii text files used. Upon arrival at INSTAAR, the data manager fine-tuned the location codes and limno runs to match those provided in the "locations, dates, codes for lake chemistry, biology samples" file. The file was imported into Microsoft Access on INSTAAR's Unix system, and can currently be found there. The file was then exported in ascii, comma delimited text and MS-DOS text (table layout) to present on the MCM LTER web site. Both of these files are linked to this web page above. Information for the metadata was submitted by Craig Wolf at Montana State University in the MetapH9697.rtf file. The file was called up using Microsoft Word version 6.0, allowing its text to be used to create this page in html format. In 2006 metadata was standardized to the EML format and served through the website using an XSLT transform. The pH data is entered in the database each season after curation by Amy (Priscu's group). From there, data is accessed through the MCM LTER website, using java server scripts producing a comma delimited format. In October 2007, the data manager (Chris Gardner) removed the DO columns in this table at the request of John Priscu. The DO values were found to be innacurate, but the table was kept for the temperature readings In 2014, the dependency on the EML format for metadata was removed. All information about the datasets was managed by the Drupal Ecological Information Management System (San Gil). Services for external clearinghouses were expanded using ISO, BDP and EML to offer metadata and data holdings to third parties.

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