  We construct a family of additive endomorphisms $\Psi_k, k=1, 2...$ of the
Grothendieck ring of quasiprojective varieties and the Grothendieck ring of
Chow motives similar to the Adams operations in the K-theory. The speciality of
the $\lambda$-structure on the Grothendieck ring of motives (proved by F.
Heinloth) gives a set of natural equations for these operations. We discuss
this construction in a general setting and relate it to the concept of power
structures introduced by S. Gusein-Zade, I. Luengo and A. Melle-Hernandez. Some
interpretation of the E. Getzler's formula for the equivariant Hodge-Deligne
polynomial of the configuration spaces is also discussed.
