pass query string on url to filter media

As per the given url http....url.../author/name?MediaTag=tag1, below code may helpful…

if(isset($_GET['MediaTag']))  //It will check the value of MediaTag (from address bar after ?)
{
  $tag1 = $_GET['MediaTag'];  //Assigning value of MediaTag to the variable
  if($tag1)  //Checking if variable have some value or not
  {
    query_posts('cat=1&author=" . $post->post_author . "&order=DESC&tag=' .  $tag1 .'&posts_per_page=12' . '&paged=' . get_query_var('paged'));
  } else {
        query_posts('cat=1&author=" . $post->post_author . "&order=DESC&posts_per_page=12' . '&paged=' . get_query_var('paged'));
 }}