How do I pass Hidden Field in Eloqua URL?

We are using Eloqua as our CRM, and want to pass along email address in our URL as a hidden field.

https://9m6smm79z8i.typeform.com/to/KXOphuUY#email=xxxxx

Does anyone know the merge tag that I’d use for Eloqua to pass along email address? I’ve successfully done this in Pardot but cannot figure it out for Eloqua.

Thanks!