Minnesota's three major U.S. Senate candidates held a debate in Duluth Sunday, answering questions posed by an audience at the College of St. Scholastica. In the first debate outside the Twin Cities, Republican incumbent Rod Grams, DFL candidate Mark Dayton and Independence party candidate James Gibson squared off on issues that haven't gotten much attention in the campaign, dealing with the environment and the use of federal lands. Minnesota Public Radio's Amy Radil reports.