Transcript:

Acid From the SkiesAmbience: StreamIn 1963, in the White Mountains of New Hampshire, a scientist took a sample of rain which led to a remarkable discovery. I'm Jim Metzner and this is the Pulse of the Planet.Likens: It was about 100 times more acid than we expected that it should be. So, that was when we discovered acid rain in North America.Gene Likens is the founding director of the Cary Institute of Ecosystem Studies. Likens: It was one of those serendipitous events that you have occasionally as a scientist, where you find something interesting and you jump on it and try to find out what it's all about, and that's what we did.We had to answer questions like, how long has it been that way, where did it come from, what is the cause of the acidity. So, one of the things we did, was we set up monitoring locations in some of the remotest regions of the world, remote from human activity - to try to find out what the acidity might have been like before humans polluted it, the rain and snow. Gene Likens and his team found the acidity of rain water in these remote regions was much lower than the acidity of rainwater in New Hampshire.Likens: We thought first that it might not be human activity, but then, the dominant acids were sulfuric and nitric, and we found that emissions of sulfur dioxide to the atmosphere and nitrogen oxides to the atmosphere were being converted to these very strong acids, sulfuric and nitric, two of the strongest acids, and that's what was coming down and making the rain and snow acidic. Well, humans produce a lot of sulfuric acid by generating sulfur dioxide and burning of coal primarily, but also oil, and nitrogen oxides from combustion of motor fuel in cars and buses and airplanes. So, the finger quickly pointed towards humans But Dr Likens and his colleagues had to prove that was the case. We'll find out how they did that in our next program. I'm Jim Metzner and this is the Pulse of the Planet.