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Isotope Facilities

The Integrated Stable Isotope Research Facility (ISIRF) has four purposes:

1) Conduct state-of-the-science technical development for isotopic measurements in supporting the mission of the Western Ecology Division (WED) to use stable isotopes to understand ecosystem processes as related to the EPA mission.

2) Provide scientific support and consultation to all WED researchers who wish to use stable isotopes in their research, and the broader isotope community of research scientists.

3) Provide isotopic analytical service for WED Principle Investigators (We do not accept samples from researchers outside WED).

4) Participate with the international community in developing standard methods for measuring stable isotopes, including collaborating to organize and participate in international studies assessing our and other laboratories’ abilities to produce precise and accurate stable isotopic abundance measurements.

ISIRF is equipped with two Isotope Ratio Mass Spectrometers (IRMS). One, a Finnigan MAT Delta Plus XL, is outfitted for both continuous flow and dual inlet measurements interfaced with a gas chromatograph (HP 6890 series), a high temperature conversion elemental analyzer (TC/EA ThermoQuest Finnigan) and a gas bench. The other IRMS, a Finnigan MAT Delta Plus XP, is equipped with two elemental analyzers (Costech).  These instruments provide the capability of analyzing the stable isotopic ratio of hydrogen, carbon, nitrogen, and oxygen in liquids, gases and organic solids. ISIRF also has extensive isotopic preparation facilities for cellulose extraction, cryogenic water extraction, nitrate extraction from water, as well as miscellaneous vacuum lines for other sample preparation procedures. ISIRF is equipped with a special isolated facility for processing and handling isotopically enriched samples.

Staff at ISIRF

Bill Rugh: IRMS Specialist and Analytical Chemist, 541-754-4604, rugh.william@epa.gov
Kent Rodecap: Extraction laboratory and facilities manager, 541-754-4641 rodecap.kent@epa.gov
Warren Evans: Sample preparation specialist and all around handyman, 541-754-4583, evans.warren@epa.gov

 ISIRF Advisory Committee

Robbins Church (FEB) Chemical limnologist, Environmental chemist
Jim Kaldy (PCEB) Plant ecologist, Evolutionary biologist
Don Phillips (EEB)  Climate change, Statistical ecologist


ISIRF Quality Management Plan and Standard Operating Procedures (SOP)

As part of our Quality Assurance and Quality Control procedures at the EPA, we have developed SOPs for the analyses we perform, and on sample collection and processing procedures for Principle Investigators wishing to use stable isotopes in their research. These SOPs are available for anyone who is interested. The SOPs are specific for our laboratory, but they can be adapted and modified for other isotopic laboratories. If you have any questions or need more information about ISIRF SOP’s please contact Kent Rodecap.

Western Ecology Division ISIRF SOPs (Note - these documents are all in PDF format and may download very slowly using a dial-up modem. If you have any problems please contact any of the individuals above for assistance.)

Current Research Topics at ISIRF

• Model C and N Isotope Fluxes over Time in Forest Plants and Soils Under Climate Change
• Model C and N in Arctic Tundra Plants and Soils Through Time to Constrain General Ecosystems Models
• Isotopic Patterns in Soil Density Fractions: Linking N and C Turnover in Soil Organic Matter
• Importance of the Hydraulic Lift of Ground Water to the Surface Soils for Water Balance in Forest Ecosystems
• Terrestrial Versus Marine Sources of Nutrient Upwelling in Yaquina Bay
• River and Riparian Zone Interactions for Nutrient Cycling
• Develop a Combined Stable Carbon and Oxygen Isotopic Signature for Ozone Damage in Tree-Ring Cellulose
• Tracing Marine Derived Nutrients in Riparian and River Systems
• Importance of Coastal Mash Habitats for Pacific Salmon.
• Modeling Root Turnover Using Isotopic Tracers
• International Certification of Reference Materials Used in Environmental and Ecological Research

ISIRF Extraction Facilities

Soxlet Device for Cellulose Extraction


Soxlet Device for
Cellulose Extraction

Device for Extracting Water (DEW)


Device for Extracting Water (DEW)

Complete DEW System

Complete DEW System


ISIRF Isotope Ratio Mass Spectrometer and Processing Devices

Isotope Ratio Mass Spectrometer
with Gas Bench in foreground



Isotope Ratio Mass Spectrometer and Gas Chromatograph

Elemental Analyzer

High Temperature Conversion Elemental Analyzer

High Temperature Conversion
Elemental Analyzer with gas Chromatograph in foreground


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