The conduction in Gr mostly dominated by carrier transport through pi bond hopping. At atmospheric conditions O2 and OH from atmosphere, provide some sort of p-type doing to graphene and promote hole conduction. If you take Gr to high Vac condition and remove Oxygen effects, you can easily observe Gr's ambipolarity. Generally, there is no ion (charged atom) conduction in Gr. Hope this will provide some information to your question.

Thanks for your valuable answer. I appreciate it.