One thing you might be interested in knowing is the term "game designer." A lot of the colleges that advertise game courses always tend to group their graphics courses as "game design" courses. My school did that too.

The game artists in game studios, however, actually have very little design input for the most part. When I was hired at my first job, I found this out when I mentioned that I was a designer and they said, "I thought you were an artist?" lol

Another thing you probably know is that to create a zone (and I assume you mean a level or like an area in a MMOG) lots of people go into creating it. Not just one.

So, if being an environment artist is what you are interested in, I'd suggest building your portfolio up with environment objects and not an entire environment itself. Take a look at my site if you'd like, I have some examples of my own environment work up there.