Decadal file describing the water chemistry in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 2010 to 2018. Chemical analyses were conducted on samples from various depths in the sample lakes either once, or multiple times during the spring, summer and fall months (May to September). Chemical analyses for the samples include alkalinity, dissolved organic and inorganic carbon (DIC/DOC), inorganic and total dissolved nutrients (NH4, PO4, NO3, TDN, TDP), particulate carbon, nitrogen and phsphorous (PC, PN, PP), cations (Ca, Mg, K, Na and Si) and anions (SO4, Cl).
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For water sampling protocols see the Arctic LTER Land-Water group protocol book accessible from the Land-Water mainpage on the Arctic LTER web page or at http://www-personal.umich.edu/~gwk and clicking on the protocol link at the bottom of the page. Specific methodologies are described in the protocol book listed above and a general description is provided below.
General analyses: In general water samples from soils, streams, and lakes are filtered in the field and kept cold and dark or preserved until analysis. Dissolved inorganic nutrients (NH4 and PO4) were analyzed by wet chemistry techniques at Toolik Field Station usually within 24 hours of sampling. Prior to 1999, the phenate method was used to analyze the ammonium content. In the years 1999-2001, a comparison study of the OPA method and the phenate method were performed. Starting in 2001, OPA was used to analyze ammonium content. Gas samples were analyzed at Toolik Field Station. DIC samples were acidified in the field and analyzed on a gas chromatograph at Toolik Field Station. DOC, TDN, TDP, particulate C, N, and P, and dissolved ions were brought back to the University of Michigan for analysis. DOC is analyzed on a Shimadzu TOC-5000. Particulate Carbon and Nitrogen on a Perkin Elmer CHN 2400, TDN is analyzed on a Shimadzu TOC-5000 or using a persulfate digestion. TDP and NO3 are analyzed on an OI Alpkem autoanalyzer, ions on a Dionex ion chromatograph, and cations on an inductively coupled plasma optical emission spectrometer (ICP-OESPerkin Elmer Optima 4300 or 8000). Alkalinity samples were run on a Radiometer autotitrator either at Toolik Field Station or at the University of Michigan.
For all analyses, sample values that were less than zero were assigned a value of zero. See specific protocols for limits of detection. Missing values (not sampled or analyzed) are represented by a period " . " in the dataset.
May 1995 Original Data entered by Neil Bettez and Julie Pallant
April 2013 - Data from all lakes compiled into one spreadsheet per year - C. Harris
Jan 2014 - Version Checked for keywords against LTER network preferred list and non-preferred terms replaced - J.Laundre
Jan 2015 - Data compiled by decade and missing values added - J.Drysdale
Version 2: February - Data values, sites, dates and metadata corrected and updated and version 2 of this file was created. A word file "ARC_Lakes_Chemistry_2010-2014_Version2_update.docx" was created to record all changes made between version 1 and version 2. All previous versions of data from these sites should be replaced by this file - Dan White
Version 4: Update to 2018 and standardized the site names. Dan and Jim June 2019
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