del 13C and del 15N ratios were measured for plant and lichen in watertracks in the Toolik Lake drainage and the east facing slope of the Imnavait Creek area. Sampling locations for each species for a specific date were chosen across an elevation gradient starting from the lakeside and leading to ridge crest. The vegetation was dried and analyzed for stable isotopes.
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Plants were sampled at five different locations within a water track from Imnavait Creek and Toolik Lake. These locations were determined by dividing the water track into five segments beginning at the ridge crest and extending to the end fo the track in the stream floodplain. For each sampling date attempts were made to collect species representing several different plant growth forms along the entire water track. For each species, collection of branches, leaves and roots were made from at least five healthy green individuals and placed inside plastic bags. Samples were stored frozen until processed.
Eriophorum was ____ collected at 5 locations along a water track draining into the western edge of Toolik Lake. The stations comprise anelevation gradient starting from the lakeside and leading toridge crest. Vegetation was dried, ground to a fine powderand prepared for stable isotope analysis.
Vegetation was dried, ground to a fine powder and prepared for stable isotope analysis.
Carex and lichens were collected at 5 locations along a water track draining theeastern facing slope of the Imnavait watershed. Thestations followed an elevation gradient starting from thefootslope and leading to ridge crest. Vegetation was dried,ground to a fine powder and prepared for stable isotopeanalysis.
For isotopic analysis 30 mg of dried plant matter was ground with 1.1 to 1.5 g of CuO per 30 mg of sample in a Wig-L-Bug dental amalgam mixer. The CuO sample mixture was then placed in a 5 cm by 6 mm quartz tube and inserted into a 30 cm by 9 mm quartz tube. To obtain sufficient quantities of nitrogen gas for anlaysis, 2 to 3 such tubes were processed for each sample. Tubes with samples were then dried for an additional 12 hours at 70 degrees C, evacuated wot < 1mTorr on a vacuum manifold and sealed with an oxygen-gas torch. The evacuated tubes were combusted in a muffle furnace at 870 degrees C for one hour and allowed to cool slowly for at least 12 hours.
Gases liberated by combustrion were separated and collected by cryogenic distillation on a vacuum manifold using the procedures described by Handley et al (1991). Briefely the sample were introduced into an evacuated line with a stainless steel tube cracker (Des Marais and Hayes, 1976). Carbon dioxide and water vapour were isolated by a liquid nitrogen cooled distilation loop and the remaining nitrogen was cleansed of any trace CO2 and H2O vapours by passage through a second liquid nitrogen cooled loop. N2 gas was compressed into a 15 cm by 6 mm borosilicate glass tube and sealed off with an oxygen-gas torch. Temperature of the CO2 trap was raised to about -80 deg. C and the CO2 sublimed from the trap. the CO2 was collected in glass tubes cooled with liquid N2 and sealed with a torch. Isotopic ratios of collected gasses were measured on a VG Isogas Sira-9 or a VG Series II dual inlet mass spectrometer.
del 13C = [(13C/12C sample / 13C/12C standard) - 1] x 1000
del 15N = [(15N/14N sample / 15N/14N standard) - 1] x 1000
Barnett, Bruce Alan, 1994. Carbon and Nitrogen Isotope Ratios of Caribou tissues, vascular plants and Lichens from Northern Alaska. Masters Thesis, University of Alaska, Fairbanks, School of Fisheries and Ocean Sciences. Supervisor Don Schell, Aug 3, 1994.
Notes: I believe the Toolik Lake water track enters the shore of the far western bay of Toolik Lake. Jim Laundre 2011
Log of changes:
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Version 1: Old computer files were amalgamated into one single file; Missing data was entered from the original thesis (source below) and methods were updated and clarified from the original source.
Version 2: Checked keywords against the LTER network preferred list and replaced non-preferred terms. Jim L 27Jan14
Version 3: Changed Distrubution URL since the LTER network DAS system is being discontinued. JimL 9Apr2015
Version 4: Changed Distrubution URL since the LTER network DAS system is being discontinued. JimL 9Apr2015