Fracking, or hydraulic fracturing, is a technique used to extract natural gas and oil from underground rock formations, using a high-pressure jet of water mixed with sand and other chemicals to force gas to the surface. This practice has been adopted in the United States for over a decade, yet the effects it has on the environment and wildlife remain largely unknown.

Understanding the consequences of fracking

Precisely to address this lack of information, researchers at the University of Wisconsin are conducting a study to understand the environmental impact that gas extraction may have in the United States and Canada. "We know that the soil is contaminated both at the surface and at depth by chemical substances," said Sara Souther, one of the authors of the research, "but we don't know the consequences, since no data have so far been collected on the impact these substances may have on water, air, land or wildlife."

Groundwater contamination

Spills, accidents, leaks and the discharge of toxic wastewater into watercourses are far from infrequent problems, yet no one knows their precise extent. Many states do not even require drilling companies to report "minor" spills or accidents. Fracking companies have long argued that there is no evidence of water contamination. And indeed such evidence does not exist — but only because no analyses have so far been carried out in the areas being drilled.

The effects on animals remain unknown

The problem of water contamination represents the greatest danger, compounded by air and noise pollution and habitat fragmentation. "The information available is too scarce to build a realistic picture of the impact that fracking has on the environment and on biodiversity," said Sara Souther. The fracking industry also benefits from an exemption from the Safe Drinking Water Act, the amendment that regulates the use of water basins in the United States; each individual state must manage controls on its own wells. This means that the US Environmental Protection Agency does not regulate the injection of chemicals into wells. According to the research, two thirds of the wells examined by the researchers used at least one prohibited chemical substance.

Appalachia, one of the areas most heavily exploited for gas extraction, is home to the temperate forests with the greatest concentration of biodiversity in the world. Fracking accounted for 39 per cent of all natural gas produced in the United States last year.