For an explanation you may want to inspect [*Recommendations for Biochemical Equilibrium Data*][1] [1], which states:

> Buffer and pH. If only  a limited number of measurements are to be
> made, they  should be carried out at pH =  7.0 and, if possible, also
> at a  pH value at which the apparent equilibrium constant $K_c^\prime$, has
> little or no dependence on pH. ($K_c^\prime$ is defined in a  later
> section.) **If direct measurements at pH = 7.0 are not practicable, the
> calculated values for this pH should be reported.** The procedure used
> in making these calculations must be carefully  described. Care should
> be taken that the solution is adequately  buffered so that the pH is
> well  defined throughout the experiment. It is desirable to determine
> the effect of varying the nature and concentration of the buffer in
> order to identify  buffer effects. Buffers that are known to interact
> with reactants (including macromolecules) or salts, such as phosphate
> or pyrophosphate in the presence of divalent metal ions, should be
> avoided.

The highlighted portion means that reported values for biochemical reactions are (or *should be*) referenced to pH 7.0. The data in Table 3.6 refer to this *biochemical* standard state. 

[Another question][2] on the subject of equilibrium constants also addresses the importance of properly considering reference states.

**Reference**

[1] The Journal of Biological Chemistry (1976), Vol. 261,  No. 22, pp.  6859-6885. 

  [1]: http://www.jbc.org/content/251/22/6879.full.pdf
  [2]: https://chemistry.stackexchange.com/questions/5811/unit-of-the-equilibrium-constant-contradiction-of-bridgmans-theorem/104004#104004