"Fracking" stories about shale gas extraction hit the news daily, fueling a growing conflagration between environmental protectionism and economic interests. Otherwise known as hydraulic fracturing, fracking has become a profitable venture thanks to advances in horizontal drilling technology, opening up large US reservoirs and vastly changing the natural gas market.

Touted as a clean energy source and a bridge fuel to transition from fossil fuels, natural gas via fracking is also frought with public health and environmental concerns. A session at the upcoming annual meeting of the Ecological Society of America will look at the natural gas process chain, from extraction and processing to transport and distribution.

In the United States, most shale gas resources lie in the Northeast, South Central and Rocky Mountain regions of the country. Among the largest of these is the Marcellus shale, which underlies a broad swath of the Northeast.

Robert Jackson and his colleagues at Duke University have been researching fracking impacts on drinking water, sampling the shallow groundwater systems of more than 200 homeowners, most of them in the Marcellus formation of Pennsylvania and New York. Jackson will be among the presenters discussing the ecological and environmental dimensions of shale gas extraction in the session "Natural Gas: Ecology, Environment and Economics."

"In our first study of 68 homes published in 2011," says Jackson, "we found no evidence of increased salt concentrations or fracturing fluids. But we did find that dissolved methane concentrations were on average 17 times higher for water wells located within 1 kilometer of gas wells."

Jackson's presentation will include additional sampling results taken since the group's May 2011 study.

Shanna Cleveland, with the Conservation Law Foundation, will talk about policy strategies that could encourage cleaner natural gas distribution. Focusing on leaks in the antiquated natural gas pipelines of Massachusetts, Cleveland will draw on data supplied by the state's departments of environmental protection and public utilities.

"In Massachusetts alone," says Cleveland, "leaking pipelines release an estimated 8 - 12 billion cubic feet of methane. Unfortunately, current state and federal policies actually provide disincentives for pipeline owners to find and fix leaks."

Methane, the main constituent of natural gas, can pose a public safety threat and contributes to climate change. Cleveland will talk about how a mechanism called Targeted Infrastructure Recovery Factor (TIRF) could foster repairs by allowing gas companies to recover their capital costs for replacing certain types of pipelines on a yearly basis.

Gas leaks also cause significant changes to the soil. Margaret Hendrick and colleagues at Boston University conducted a study in Boston that looked at the effects of pervasive natural gas leaks from aging pipelines on urban ecosystems. They found that gassed soils often had levels of methane exceeding 90 percent and oxygen levels below 10 percent.

"Soil at leak sites often looks black and viscous, with a crusty substance at its surface," says Hendrick. "Dried out and oxygen-deprived, these soils become inhospitable to many organisms that live in the soil."

The researchers also found that plants at leak sites suffered from higher mortality rates and that methane gas invades plant tissues growing both above and below-ground. Hendrick and her colleagues hope their findings will help city planners and advance understanding of methane's role in global warming.

Robert Howarth, of Cornell University, will summarize the magnitude of methane emissions from all parts of societal use of natural gas as a fuel and compare its greenhouse gas footprint with that of other fossil fuels, such as oil and coal.

"Methane emissions dominate the greenhouse gas footprint of natural gas," says Howarth, who will also discuss the extent to which methane pollution from natural gas can be reduced.