<script src="http://code.jquery.com/jquery-latest.js"></script>
  <script type = "text/javascript">

  function getUrlVars() {
    var vars = {};
    var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) {
        vars[key] = value;
    });
    return vars;
  }

  $(document).ready(function() {

       var getParams = getUrlVars();
       if (getParams) {
          $('#dynamic-select').val(getParams.selected);
       }

      $('#dynamic-select').bind('change', function () {

          var url = $(this).val();
          if (url != '') {
              window.location.href = window.location.href + "?selected="+url;
          }
          return false;
      });
  });

  </script>