  We investigate the properties of the gap-edge states of half-filled
interacting disordered zigzag graphene nanoribbons. We find that the midgap
states can display the quantized fractional charge of 1/2. These gap-edge
states can be represented by topological kinks with their site probability
distribution divided between the opposite zigzag edges with different
chiralities. In addition, there are numerous spin-split gap-edge states,
similar to those in a Mott-Anderson insulator.
