Data file describing the biogeochemistry of samples collected at various sites near Toolik Lake on the North Slope of Alaska. Sample site descriptors include a unique assigned number (sortchem), site, date, time, depth, and category (level of thermokarst disturbance). Physical measures collected in the field include temperature, electrical conductivity, and pH. Chemical analyses include alkalinity; dissolved organic carbon (DOC); inorganic and total dissolved nutrients (NH4, PO4, NO3, TDN, TDP); particulate carbon, nitrogen, and phosphorus (PC, PN, and PP); cations (Ca, Mg, Na, K); anions (Cl, SO4); and silica. A synthesis of much of the data presented here is published in Cory et al. 2013, PNAS 110:3429-3434; Cory et al. 2014, Science 345:925-928; and Page et al. 2013, Environment, Science, &amp; Technology 47:12860−12867.
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The detailed water sampling and analysis protocols are found at http://www-personal.umich.edu/~gwk (click on the protocol link at the bottom of the page), or at the NSF Arctic LTER website under the Landscape Interactions mainpage at http://ecosystems.mbl.edu/ARC/landwater/landwaterdefault.html. Specific methodologies are described in the protocol book, and a general description is provided below.
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. DOC, TDN, TDP, particulate C, N, and P, and dissolved ions were brought back to the University of Michigan for analysis. DOC and TDN are analyzed on a Shimadzu TOC-5000 or a TOC-V CPH. Particulate Carbon and Nitrogen are analyzed on a Perkin Elmer CHN 2400. TDP and NO3 are analyzed on an OI Alpkem autoanalyzer, Cl and SO4 on a Dionex ion chromatograph, and cations and silica on an inductively coupled plasma optical emission spectrometer (ICP-OES Perkin Elmer Optima 4300 or 8000). Alkalinity samples were analyzed on a Radiometer autotitrator.
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.
Further descriptions of sites and methods can be found in these publications:
1. Cory et al. 2013, PNAS 110:3429-3434.
2. Page et al. 2013, Environment, Science, &amp; Technology 47:12860−12867.
3. Cory et al. 2014, Science 345:925-928.
Field and Lab Methods & Protocols
December 2014: created this file, version .01