For water sampling protocol, see the Land-Water protocol accessible from the Land-Water main page 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. See also,
Kling, G. W., B. Fry, and W. J. O'Brien. 1992. Stable isotopes and planktonic trophic structure in arctic lakes. Ecology 73:561-566.

All organic matter samples (sediments, algae, animals, etc.) were dried at temperatures less than 45 degC to prevent volatization.

Particulate organic carbon (POM) samples were collected from the water column by filtering as much sample water through a 25 or 45 mm Whatman GF/F filter as possible. Attached algae were collected from surfaces (sediments, rocks, plants), and aquatic macrophytes were collected using the most recent growth tissues.

Zooplankton species were identified and individuals were separated by hand, then grouped by species for isotopic determination. Other benthic or pelagic organisms were separated by hand to species or to the nearest taxonomic group. Species with carbonate shells were bathed in weak acid to remove inorganic C contamination before drying and analysis.

Samples for the determination of 13C-DIC were collected using serum vials following the DIC collection technique described in detail in the Kling laboratory protocol (Old DIC method). Samples are collected at depths representative of the epilimnion, metalimnion, and hypolimnion (if present) or from the epilimnion in shallow lakes. The depths were commonly 1 m, 3 - 5 m, and 8 - 9 m for lake E5 and 1 m for lake E6. The sampling depths are determined in the field and are based upon the depth profile of temperature and chlorophyll estimated by fluorescence using a Hydrolab multisensor datalogger. Samples were collected using a Van Dorn water sampler lowered to the specific depths and subsampled using large Nalgene bottles. A bubble-free subsample (no exposure to the atmosphere) was then over-filled (for flushing to remove bubbles) into 30 or 60 mL serum vials. A supersaturated solution of mercuric chloride was added (0.1 mL solution per 10 mL sample) to the sample to stop biological activity in the bottle and the vial was capped with an aluminum cap lined with a teflon septa.

Organic and sediment samples were analyzed mainly at the Marine Biological Laboratory (MBL) Stable Isotope Laboratory for 13C and 15N.(1)

13C-DIC samples were analyzed by the Stable Isotope Laboratory at the University of Michigan on a Finnigan MAT Delta S. (2)

(1) Marine Biological Laboratory (MBL) Stable Isotope Laboratory: http://ecosystems.mbl.edu/SILAB/default.html
The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 U.S.A.
(2) University of Michigan Stable Isotope Laboratory: http://www-personal.umich.edu/%7Eloraw/

http://www-personal.umich.edu/~gwk