Methodology:
Methodology_Type: Field
Methodology_Description:
Water samples (DOC and DIC) were filtered through a 0.45 micrometer Gelman Capsule filter. For delta14C-DOC measurements, we filtered 375 mL of stream water using a pre-rinsed 0.45-μm high-capacity capsule filter in three replicate 125 mL square Nalgene polypropylene bottles in the field, and froze samples prior to processing. For delta14C-DIC measurements, we collected unfiltered stream water in 1 L Pyrex glass bottles and preserved with 100 µL of saturated HgCl2 solution.
Methodology:
Methodology_Type: Field
Methodology_Description:
Soil samples (Humic, Moss, and Mesic) were collected by digging a vertical pit and sampling the various soil layers.
Methodology:
Methodology_Type: Field
Methodology_Description:
Biofilm samples were collected scrubbing material from streambed rocks. Samples were stored in a nalgene bottle.
Methodology:
Methodology_Type: Field
Methodology_Description:
Aquatic macroinvertebrates (Stoneflies and Chironomids) were sampled by kick-netting (n = 8 per tributary) in all tributaries and then frozen for transport back to the laboratory. In the laboratory, samples were thawed and identified to Family (Merrit, Cummins, and Berg 2008). Stoneflies and chironomids from each location were freeze-dried for 48 hours and submitted for del13C and delta14C analysis.
Methodology:
Methodology_Type: Lab
Methodology_Description:
Samples were thawed and identified to Family (Merrit, Cummins, and Berg 2008). Stoneflies and chironomids from each location were freeze-dried for 48 hours and submitted for del13C and delta14C analysis.
Methodology_Citation:
Citation_Information:
Originator: Merritt, R.W.
Originator: Cummins, K.W.
Originator: Berg, M.B.
Publication_Date: 2008
Title: An Introduction to the Aquatic Insects of North America
Edition: 4
Geospatial_Data_Presentation_Form: book chapter
Methodology:
Methodology_Type: Field
Methodology_Description:
Fish were collected in all tributaries with minnow traps and backpack electrofishing. All fish were identified to species and measured (Fork Length, nearest mm) in the field. Dolly Varden (Salvelinus malma) and Arctic Grayling (Thymallus arcticus) were sacrificed and frozen in a standard freezer (-19 degrees Celsius) for transport back to the laboratory.
Methodology:
Methodology_Type: Lab
Methodology_Description:
Epaxial muscle tissue was dissected from Dolly Varden and Arctic Grayling and freeze dried for 48 hrs before being submitted for stable isotope and radiocarbon analysis.)
Process_Step:
Process_Description:
Delta14C and del13C of DOC in arctic stream samples were determined at the National Ocean Sciences Acceleratory Mass Spectrometry laboratory at the Woods Hole Oceanographic Institute (
http://www.whoi.edu/nosams/home). For delta14C, DOC samples were diluted with ultra-low-carbon, 18.2 Mohm Milli-Q water, acidified with 85% phosphoric acid, purged with ultra-high purity helium gas, and oxidized to CO2 using UV light for 4 hours (Beaupre and others 2007). Del13C of DOC was determined using an Optima stable isotope ratio mass spectrometer.
Beaupre SR, Druffel ERM, Griffin S. 2007 A low-blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon. Limnology & Oceanography Methods 5: 174-184.
Process_Date: Unknown
Process_Step:
Process_Description:
For delta14C-DIC, samples were prepared for graphitization using the head-space extraction technique (Gao and others 2014). del13C of DIC was determined using a Gas Bench coupled with an isotope ratio mass spectrometer (IRMS, Finnigan Delta Plus XL, Thermo Fisher Scientific, Pittsburgh, PA, USA), with a method similar to Torres and others (2005).
Source_Used_Citation_Abbreviation:
Gao P, Xu X, Zhou L, Pack MA, Griffin S, Santos GM, Southon JR, Liu K. 2014. Rapid sample preparation of dissolved inorganic carbon in natural waters using a headspace‐extraction approach for radiocarbon analysis by accelerator mass spectrometry. Limnology and Oceanography: Methods 12: 174-190.
Source_Used_Citation_Abbreviation:
Torres ME, Mix AC, Rugh WD. 2005. Precise δ13C analysis of dissolved inorganic carbon in natural waters using automated headspace sampling and continuous‐flow mass spectrometry. Limnology and Oceanography: Methods 3: 349-360.
Process_Date: Unknown