8. Given that the real number $a$ satisfies
$$
|2006-a|+\sqrt{a-2007}=a \text {. }
$$

Then, the value of $a-2006^{2}$ is ( ).
(A) 2005
(B) 2006
(C) 2007
(D) 2008
8.C.

Since $a \geqslant 2007$, we have $a-2006+\sqrt{a-2007}=a$. Therefore, $\sqrt{a-2007}=2006$, which means $a-2006^{2}=2007$.