Keeling plot

The above analysis has shown that two expressions for interpreting gradients in air isotopic composition, the Keeling plot and the Yakir-Wang expression for distinguishing assimilation and respi-... 

FIGURE 7 Application of IL method to calculate profiles of 8 (air) and (plant) in a canopy, for CO2 and C02- The dispersion matrix is as in Figure 1. (a) Assumed profile of CO2 source density (f (ju-mol m s ) (b) assumed profile of 5, (c) inferred CO2 concentration profile c, from Eq. (17) in forward mode (d) inferred profile of S(air), from Eq. (38) in forward mode (solid symbols), and profiles of 8 with added random noise to simulate measurement error (open symbols) (e) Keeling plot of against 1/c, using values in (c) and (d) (f) inverse inference of dp (plant), using profiles of 8 and c in air from (d) and (c). 

Plots of fully allowed (inner solid lines) and partially allowed (outer solid lines) conformations of ( > and ip for (A) D-glucuronic acid, which is (3-(l 3)-lin keel to IV-acetyl glucosamine, and (B) /V-acctyl glucosamine, which is P-(l-4)-linkcd to D-glucuronic acid. Note that the allowed conformations center around 0°,0° and show that hyaluronan has flexibility. 

Equation (32) describes a linear relationship, with an intercept 5s, which represents the signature of the net sources/sinks in the ecosystem. Note that even if the ecosystem source/sink is composed of several different sub-sources/sinks the Keeling type plot can still be used as long as the relative contribution of each of these sub-components remain fixed. 

Two major sources of error should be considered for the estimates obtained from field measurements, errors associated with the d C of tropospheric COy and the d C of respired COj. The precision of the tropospheric background data, e.g., collected by NOAA/CMDL is <0.5 ppm for [CO,], and 0.03%o for S C (Conway et al, 1994 Trolier et al, 1996). The larger error is associated with the estimates of S Cer due to the nature of regression analysis (extrapolating to the y-intercept). Summarizing 49 Keel-ing-plot analyses, the standard error for S C of respired COy averaged 0.98%o (Buchmann etal, 1998). 

---