Data file describing 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), 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, average thaw depth, well height, discharge, stage height, and light (lakes). Chemical analysis for the sample 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 (SO4 and Cl); silica and oxygen.
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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 ammonium. 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. 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-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.
Field and Lab Methods & Protocols
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