Before 1970, there was no law in place regulating the amount of pollution that could be emitted by any single entity. However, in 1970, the Clean Air Act was passed and today there is clear evidence that it has indeed helped to reduce pollution.
A collaborative project involving Jesse Nippert, a Kansas State University associate professor of biology, Richard Thomas, professor of biology at West Virginia University, Scott Spal, master's graduate from West Virginia University, and undergraduate Kenneth Smith from West Virginia University, shows that the Clean Air Act has helped forests systems recover from decades of sulfur pollution and acid rain. In four years,
centuries of eastern red cedar tree, or Juniperus virginiana, rings were studied in the Central Appalachian Mountains of West Virginia.
This region is of particular concern because it is directly downwind of the Ohio River Valley coal power plants and has experienced years of acidic pollution.
Red cedar trees were chosen because they are abundant, long-lived, and a good recorder of environmental variability.
They grow slowly and rely on surface soil moisture, which made them sensitive to environmental change. According to Nippert, their abilities to live for centuries meant that researchers could analyze hundreds of years of tree rings.
|