In the United States, natural-gas production from shale rock（页岩） has increased by more than 700 percent since 2007. Yet scientists still do not fully understand the industry's effects on nature and wildlife, according to a report in the journal Frontiers in Ecology and the Environment. As gas extraction continues to vastly outpace scientific examination, a team of eight conservation biologists from various organizations and institutions, including Princeton University, concluded that determining the environmental impact of gas-drilling sites -- such as chemical contamination from spills, well-casing failures and other accidents -- must be a top research priority.

With shale-gas production projected to surge during the next 30 years, the authors call on scientists, industry representatives and policymakers to cooperate on determining -- and minimizing -- the damage inflicted on the natural world by gas operations such as hydraulic（液压的） fracturing, or "fracking." A major environmental concern, hydraulic fracturing releases natural gas from shale by breaking the rock up with a high-pressure blend of water, sand and other chemicals, which can include carcinogens（致癌物） and radioactive substances.

"We can't let shale development outpace our understanding of its environmental impacts," said co-author Morgan Tingley, a postdoctoral research associate in the Program in Science, Technology and Environmental Policy in Princeton's Woodrow Wilson School of Public and International Affairs.

"The past has taught us that environmental impacts of large-scale development and resource extraction, whether coal plants, large dams or biofuel monocultures, are more than the sum of their parts," Tingley said.

The researchers found that there are significant "knowledge gaps" when it comes to direct and quantifiable evidence of how the natural world responds to shale-gas operations. A major impediment to research has been the lack of accessible and reliable information on spills, wastewater disposal and the composition of fracturing fluids. Of the 24 American states with active shale-gas reservoirs, only five -- Pennsylvania, Colorado, New Mexico, Wyoming and Texas -- maintain public records of spills and accidents, the researchers report.