Judy Woodruff:

In the coming midterm election, environmental issues have played an unusually large role in the state of Florida, in part due to the explosion of two blooms of algae that have crippled part of the state's tourism economy and killed hundreds of thousands of fish and wildlife.

There are many factors driving these blooms, but scientists believe that the mining of phosphorous is one of them. Mining this mineral is a huge business in Florida.

And special correspondent Laura Newberry and producer Alan Toth tell us, the fight over a new mine is sharply dividing one Florida town.

It's the focus of this week's on the Leading Edge of science and technology.