Data file of the biogeochemistry of samples collected at various sites near Toolik Lake, North Slope of Alaska. Sample site descriptors include a unique assigned number (sortchem), site, date, time, depth, distance (downstream from a reference location), elevation, treatment, date-time, category, and water type (lake, surface, soil). Physical measures collected in the field include temperature (water, soil, well water), conductivity, pH, and average thaw depth in soil. Chemical analyses for the sample include alkalinity; dissolved inorganic and organic carbon (DIC and DOC); dissolved gases CO2 and CH4; inorganic and total dissolved nutrients (NH4, PO4, NO3, TDN, TDP); particulate carbon, nitrogen, and phosphorus (PC, PN, and PP); cations (Ca, Mg, Na, K, and Si); and anions (SO4 and Cl).
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For water sampling protocols see the Arctic LTER Landscape Interactions group protocol book accessible from the Landscape Interactions Group 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. DIC samples were acidified in the field and analyzed on a gas chromatograph at Toolik Field Station. Dissolved gases CO2 and CH4 were determined using a syringe equilibration method and analyzed at Toolik Field Station on a gas chromatograph. 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-V or TOC-L; particulate carbon and nitrogen are analyzed on a Perkin Elmer CHN 2400 (or equivalent); TDN is analyzed on a Shimadzu TOC-V, TOC-L (or equivalent) or using a persulfate digestion; TDP and NO3 are analyzed on an OI Alpkem autoanalyzer; anions are analyzed on a Dionex ion chromatograph, and cations are analyzed on an inductively coupled plasma optical emission spectrometer (ICP-OES Perkin Elmer Optima 4300 or 8000). Alkalinity samples were analyzed potentiometrically 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.
Version 1 (.01): file created 23-May-2019 by J. Dobkowski and G. Kling
Version 2 (.02): added 2018-2020 data March 2022 -J. Dobkowski