Well, they could be stored somewhere relative to the address of main, but not generally. main is in the code section, but the arguments are data. I suggest that you print out the addresses of argv and main and see if they maintain a relationship ... but even if so, it could change later.
I got email saying there was a comment but it isn't shown here. Anyway, you can simply do
printf("%ld\n", (char*)argv - (char*)main);
... this is not guaranteed to work by the C standard, but should work in normal implementations. However, I doubt that this will be a fixed value or that it would be useful even if it were.