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Study confirms contamination near some “fracking” sites

June 24, 2013
World Science staff

A new study backs up as­ser­tions that “frack­ing”—a con­tro­ver­sial meth­od of ex­tract­ing nat­u­ral gas that has trans­formed U.S. en­er­gy pro­duc­tion—can lead to ground­wa­ter con­tamina­t­ion.

The study found that “frack­ing,” in which nat­u­ral gas­es are ex­tracted from shale rock un­der­ground, can lead stray gas­es to con­tam­i­nate drink­ing wa­ter. The au­thors blamed the prob­lem mainly on faulty or in­ad­e­quate ex­trac­tion meth­ods, which could pre­sumably be im­proved.

The re­search­ers found el­e­vat­ed eth­ane and meth­ane lev­els in drink­ing wa­ter near “frack­ing” sites in north­east­ern Penn­syl­va­nia. Drink­ing gas-con­tam­i­nated wa­ter is not linked to any known health haz­ards, al­though the con­tamina­t­ion can cre­ate an ex­plo­sion and fire haz­ard.

The find­ings are pub­lished in this week’s early on­line is­sue of the jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces.

Rob­ert B. Jack­son of Duke Uni­vers­ity in Dur­ham, N.C. and col­leagues an­a­lyzed wa­ter from 141 wells in Penn­syl­va­nia’s Mar­cel­lus re­gion. They found that meth­ane lev­els in wa­ter for homes with­in 1 km (0.6 miles) of nat­u­ral gas wells were six times high­er on av­er­age than for homes far­ther away. Eth­ane con­centra­t­ions were 23 times high­er on av­er­age, they found.

Frack­ing, which is short for hy­drau­lic frac­tur­ing, in­volves cre­at­ing hor­i­zon­tal pipes through which drillers pump flu­ids at high pres­sure, break­ing up rocks that trap en­er­gy-rich gas­es and oils. 

Jack­son and col­leagues wrote that “The two sim­plest ex­plana­t­ions for the high­er dis­solved gas con­centra­t­ions that we ob­served in drink­ing wa­ter are (i) faulty or in­ad­e­quate steel cas­ings, which are de­signed to keep the gas and any wa­ter in­side the well from leak­ing in­to the en­vi­ron­ment, and (ii) im­per­fec­tions in the ce­ment seal­ing of the an­nu­lus or gaps be­tween cas­ings and rock that keep flu­ids from mov­ing up the out­side of the well.”

They stressed that not all “fracking” sites are linked to contam­ination, add­ing that geolo­gical fac­tors like­ly play a role as well. 


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A new study backs up assertions that “fracking”—a controversial method of extracting natural gas that has revolutionized U.S. energy production—can lead to water contamination. The study found that “fracking,” in which natural gases are extracted from shale rock underground, can lead stray gases to contaminate drinking water. The authors blamed the problem mainly on faulty or inadequate extraction methods, which could presumably be improved. The researchers found elevated ethane and methane levels in drinking water near “fracking” sites in northeastern Pennsylvania. Drinking gas-contaminated water is not linked to any known health hazards, although the contamination can create an explosion and fire hazard. The findings are published in this week’s early online issue of the journal pnas. Robert B. Jackson of Duke University in Durham, N.C. and colleagues analyzed water from 141 wells in Pennsylvania’s Marcellus region. They found that methane levels in water within 1 km (0.6 miles) of natural gas wells “were six times higher on average than concentrations for homes farther away.” Ethane concentrations were 23 times higher on average, they found. Fracking, which is short for hydraulic fracturing, involves creating horizontal pipes through which drillers pump fluids at high pressure, breaking up rocks in that trap energy-rich gases and oils. Jackson and colleagues wrote that “The two simplest explanations for the higher dissolved gas concentrations that we observed in drinking water are (i) faulty or inadequate steel casings, which are designed to keep the gas and any water inside the well from leaking into the environment, and (ii) imperfections in the cement sealing of the annulus or gaps between casings and rock that keep fluids from moving up the outside of the well.”