U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Soil and Water Management Research: St. Paul, MN
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area St. Paul, Minnesota Soil and Water Management Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            ZHANG, J - UNIV OF MINNESOTAitem
                                            GRIFFIS, T - UNIV OF MINNESOTAitem
                                            Baker, John
  Submitted to: American Geophysical Union
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 7/20/2004
                                    Publication  Date: 12/14/2004
                                    Citation: Zhang, J.M., Griffis, T.J., Baker, J.M. 2004. Estimating the isotope ratio of ecosystem respiration using the keeling plot and the flux ratio method. American Geophysical Union. Vol. 85, p. 47.Interpretive Summary:
                                Technical Abstract: The isotope ratio of ecosystem respiration (delta 13Cr) is a critical parameter in applying stable isotope techniques to study the carbon cycle.  It has commonly been determined with the Keeling plot technique, which has limitations related to insufficient range of CO2 concentration and extrapolation of the regression well beyond the data. We have developed a method that uses a newly developed tunable diode laser to directly measure the surface/atmosphere exchange of both stable isotopes of CO2. This provides much better resolution of the temporal dynamics of delta 13Cr and avoids the uncertainties of the Keeling plot method. We found that the methods agreed well in the spring and in the fall when no crop is present, but that they diverged during the growing season, probably due to errors inherent in the Keeling plot approach. The tunable diode laser method will be particularly useful in studying short-term (e.g.- diurnal) variations in carbon cycling.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov