DULUTH (AP) - Researchers have conducted a large-scale test of a new system to kill invasive species hiding in the ballast water of Great Lakes freighters and expect to get results back next month.

Crews recently pumped lye into two of 10 ballast tanks in a freighter as it left Gary, Indiana. The chemical then was neutralized with carbon dioxide as the boat traveled across Lake Superior before releasing the ballast water in the Duluth-Superior harbor.

It's believed to be the first such major-scale test on the Great Lakes.

Tests on shore indicated a 98 percent kill rate.

Phyllis Green, superintendent of Isle Royale National Park and the instigator of the effort, says researchers hope to test it on all 10 tanks in the boat soon.

(Copyright 2011 by The Associated Press. All Rights Reserved.)