Particulate organic carbon (POC) and nitrogen (PON) concentrations in discrete water column samples collected from lakes in the McMurdo Dry Valleys, Antarctica (1993-2022, ongoing)

Abstract:

An important part of the McMurdo Long Term Ecological Research (LTER) is evaluating carbon and nitrogen budgets in perennial ice-covered lakes. This dataset addresses this core area of research and quantifies the particulate organic carbon (POC) and nitrogen (PON) found at specific depths in lakes across the McMurdo Dry Valleys of Antarctica.

LTER Core Areas:

organic matter

Dataset ID:

Associated Personnel:

1076

807

459

460

461

462

463

Short name:

limncn.dat

Data sources:

LIMNO_POC_PON

Methods:

Lake water samples were collected at specific depths with a five-liter Niskin bottle during normal LTER limnological sampling. Sub-samples were decanted into three 1 L Nalgene bottles (two light and one amber), two 500 mL amber Nalgene bottles, three 150 mL borosilicate glass bottles, two 20 mL scintillation vials, and one 30 mL serum vial. A 500 mL sample from the one liter amber Nalgene bottle was decanted and filtered through a combusted Whatman 25 mm GF/F filter (475 °C for 4 hours). The filter was placed onto an aluminum weighing pan and air dried. Once the filters were dry, the pans were stacked together and frozen for later analysis.

Filters were acidified with HCL fumes, and analyzed using an Elemental Analyzer (currently a CE Elantech Flash EA 1112 Elemental Analyzer). Total particulate organic carbon (POC) and particulate organic nitrogen (PON) was obtained by comparison with an acetanilide standard curve.

Prior to the 0304 season, analysis was done on a 10 mm diameter sub-sample punch of the GF/F filter; from 0304 to present, the entire GF/F filter was analyzed. See the maintenance section for further details regarding data from 2003-04 thru the 2019-20 field seasons.

Instrument detection limits for POC and PON are 10 μg punch^-1 and 5 μg punch^-1 respectively.

Maintenance:

Data from this table was submitted to INSTAAR by John Priscu's team at Montana State University. The raw data files listed under 'file name' are the names of the original files submitted. The 1993/94 and 1994/95 datasets are Microsoft Excel version 6.0 files, and the 1995/96, 1996/97 and 1997/98 datasets are ascii text files. 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 obtained from the Metachn9697.rtf file. The file was called up using Microsoft Word version 6.0. Text from this file was used to create this page in html format.

Data for the 2005-6 and 2006-7 season was updated in Oct 2009

Metadata was standardized to EML in 2006, and enhanced in 2014 using the Drupal Ecological Information Management System

In 2020, issues regarding how filter blank corrections were applied to the particulate organic carbon data were identified. The errors applied to the carbon data from the 2003-04 through the 2009-10 austral summer field seasons. All data from this period were re-processed according to the equations in the MCM LTER limno methods manual, and these corrections were applied to this data package in April 2021.

Additional information:

Funding for this work has been provided by several grants from the US National Science Foundation for Long Term Ecological Research, most recently under award #OPP-1637708.