The Academy of Natural Sciences is calling for a comprehensive research plan that would result in guidelines and an assessment tool for regulators and managers in order to minimize the environmental impact of Marcellus Shale gas drilling.
"At this time, there is very little information available as to the impacts of long-term exposure of a watershed to Marcellus Shale drilling activities," said Dr. David Velinsky, vice president of the Academy's Patrick Center for Environmental Research. "Nor do we know if there is a cumulative impact of drilling activity on the ecosystem services of a small watershed."
Initial research by Academy scientists working with University of Pennsylvania graduate student Frank Anderson shows the environmental impact of drilling may be directly related to the amount of drilling in a specific area, referred to as the "density" of drilling. "The question that needs to be addressed is whether there is a threshold point past which a certain amount of drilling activity has an impact on the ecological health and services of the watershedregardless of how carefully drilling is conducted," Velinsky said.
Loss of salamanders signals ecological impact
In the preliminary research conducted this summer, scientists examined small watersheds in northeastern Pennsylvaniathree in which there had been no drilling, three in which there had been some drilling and three in which there had been a high density of drilling. At each site, they tested the water, the abundance of certain sensitive insects, and the abundance of salamanders. The presence of salamanders is particularly important because amphibians are especially vulnerable to changes in the environment. The absence of amphibians is often an ecological early-warning system.
For each of the measures, there was a significant difference between high-density drilling locations and locations with no drilling or less drilling. The studies showed that water conductivity (which indicates the level of contamination) was almost twice as high in the high density sites as the other sites, and the number of both sensitive insects and salamanders were reduced by 25 percent.
"This suggests there is indeed a threshold at which drillingregardless of how it is practicedwill have a significant impact on an ecosystem," Velinsky said. "Conversely, it also suggests there may be lower densities of drilling at which ecological impact cannot be detected."
Velinsky stressed that the data is preliminary and that a larger, more comprehensive study must be done before definitive conclusions can be drawn. The Academy has applied to the Pennsylvania Department of Environmental Protection's Growing Greener Program to fund such a study.
"When this study has been completed we will be able to indicate with a much higher level of certainty what the ecological risks are of drilling in the shale and how they might be managed."
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