nitrite

Macronutrient Concentrations (NH4 - NO3 - NO2 - PO4) in Lakes

Abstract: 

An important part of the McMurdo Long Term Ecological Research (LTER) project is identifying patterns and movements of nutrients in perennial ice-covered lakes. This data set addresses this core area of research and quantifies macronutrient concentrations found at specific depths in McMurdo Dry Valley lakes.

Data set ID: 

56

Core Areas: 

Additional Project roles: 

30
696
697

Short name: 

Nutrients (NH4 - NO3 - NO2 - PO4)

Methods: 

Lake water samples are collected at specific depths with a five-liter Niskin bottle during normal LTER limnological sampling.  Sub-samples for nutrient analysis are decanted into a 1 L amber Nalgene bottle.  One 100 mL sub-sample is taken from the one-liter amber Nalgene bottle.  The sample is filtered through a combusted (475 degree centigrades for 4 hours) and acidified (the acidification step began with the 2008-2009 season) Whatman 25 mm GF/F using a bell jar apparatus. The filter is used for chlorophyll-a analysis.  The filtrate is collected in a 125 mL acid washed Nalgene bottle and stored at -20 degrees centigrades until analysis  at the Crary Analytical Lab.  Nutrient assays are performed with a Lachat Quickchem AE Autoanalyzer using standard methods.  Ammonia is analyzed using the phenol hypochlorite method.  Nitrite is determined by diazotization with sulfanilamide  and NED. Nitrate is determined by reducing nitrate to nitrite by passing a sample through a copperized cadmium column and analyzing for nitrite, which yields nitrate + nitrite (N+N) concentration. The nitrate concentration is determined by subtracting the nitrite concentration from the N+N concentration.  Soluble  Reactive Phosphorus is determined using ammonium molybdate methods.  Lakes Fryxell, Miers and Hoare are analyzed with a Lachat Quickchem Autoanalyzer.  East and West Lobes of Lake Bonney are analyzed manually (spectrophotometrically) using a 5cm cuvette.
 
Methods and Notes for 2011-2012 season samples:
Samples from the 2011-2012 season were analyzed by Skalar San++ CFA at The Ohio State University. Ammonia was analyzed using a salicylate method. Nitrite was determined by diazotization with sulfanilamide and NED. Nitrate was determined by reducing nitrate to nitrite by passing a sample through a copperized cadmium column and analyzing for nitrite, which yields nitrate + nitrite (N+N) concentration. The nitrate concentration was determined by subtracting the nitrite concentration from the N+N concentration. Soluble Reactive Phosphorus was determined using ammonium molybdate methods. Lakes Miers, Fryxell and Hoare were analyzed with a Skalar CFA instrument. East and West Lobes of Lake Bonney were analyzed manually (spectrophotometrically) using a 10cm cuvette. Method Detection Limit (MDL) and dilutions are listed in the data file for each sample. All values were reported with 2 decimal places for informational purposes; 1 decimal place is significant for N analytes, except for values over 100, for which no decimal places are significant; 2 decimal places are significant for P, except for values over 10, for which 1 decimal place is significant.
 

Data sources: 

LIMNO_NUTRIENTS

Maintenance: 

Data and metadata were improved for compliance with mandates and standards for LTER during 2014.  
 
Data and metadata were offered through the DEIMS system since 2015 (San Gil)
 
 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 Metanut9697.rtf and Metanut9798.rtf files. The files were called up using Microsoft Word version 6.0. Text from these files was used to create this page in html format.

Additional information: 

Data contained in these files has been subjected to quality control standards imposed by the investigator. The user of this data should be aware that, while efforts have been taken to ensure that these data are of the highest quality, there is no guarantee of perfection for the data contained herein and the possibility of errors exists. If you encounter questionable data, please contact the MCM LTER data manager corrected or qualified. Thus, these data may be modified and future data will be appended.
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