Transcript:

Smoking GunAmbience: StreamBack in the sixties, a group of scientists in New Hampshire measure high levels of acidity in local streams and rainfall. Then they began looking for its cause, the proverbial smoking gun. I'm Jim Metzner and this is the Pulse of the Planet.Likens: So, to find out whether these were sources or not, we knew large amounts of sulfur dioxide particularly was being emitted from power plants in the Midwest, we had to try to trace those pollutants and see in fact if they came to our location in New Hampshire. Gene Likens is founding director of the Cary Institute of Ecosystem Studies.Likens: Back then, there were pretty simple methods. We actually tried to follow plumes in a small plane and we had a collector that we would hold out the window of the small plane and collect samples of the plume that we were following. We had a van on the ground and we would try to follow the plume on the van, and then, if it were to rain, we would quickly collect samples of the rain and see what its acidity was. And so, these were rather crude but they worked. We could see that the pollutants were actually being transported long distances, maybe a thousand miles. So, from the Midwest to the eastern coast. We used more sophisticated methodology later like using isotopes that were found in the coal or oil that were burned. So, over a very long period of time, we finally found that there was a smoking gun, because the electrical utility industry was burning huge amounts of coal and oil to produce electricity, which we all use, of course, and need. And as a part of the way of reducing local smog and pollution, they were increasing the height of chimneys and smokestacks. So, the smoking gun was the taller smokestack that was changing the pollution from a local condition to a more regional long term, long range condition. We'll hear more about acid rain in future programs. Im Jim Metzner and this is the Pulse of the Planet.