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Environmental impact of hydraulic fracturing in the United States has been an issue of public concern, and includes the potential contamination of ground and surface water, methane emissions,〔http://thinkprogress.org/climate/2014/10/22/3582904/methane-leaks-climate-benefit-fracking/〕 air pollution, migration of gases and hydraulic fracturing chemicals and radionuclides to the surface, the potential mishandling of solid waste, drill cuttings, increased seismicity and associated effects on human and ecosystem health.〔〔 A number of instances with groundwater contamination have been documented, however opponents of water safety regulation claim hydraulic fracturing has never caused any drinking water contamination.〔 As early as 1987, researchers at the United States Environmental Protection Agency (EPA) concluded that hydraulic fracturing can contaminate and has contaminated groundwater. According to former EPA employees, evidence of the negative environmental impact of fracking was systematically removed from congressional reports to support the energy industry under the direction of the Office of Legal Counsel during the Reagan administration.〔 With the growth of hydraulic fracturing in the United States, "public exposure to the many chemicals involved in energy development is expected to increase over the next few years, with uncertain consequences" per science writer Valerie Brown in 2007.〔 ==Air quality and methane emissions== Methane emissions from wells raise global warming concerns. There is a 2,500 square-mile methane plume hovering over the Four Corners area of the western US.〔http://www.mintpressnews.com/2500-square-mile-methane-plume-silently-hovering-western-us/200313/〕 The magnitude of the plume was such that NASA researcher Christian Frankenberg reported to the press that, "We couldn’t be sure that the signal was real."〔http://www.commondreams.org/news/2014/12/30/2500-square-mile-methane-plume-silently-hovering-over-western-us〕 According to NASA: "The study's lead author, Eric Kort of the University of Michigan, Ann Arbor, noted the study period predates the widespread use of hydraulic fracturing, known as fracking, near the hot spot. This indicates the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico's San Juan Basin, which is the most active coalbed methane production area in the country."〔(U.S. METHANE 'HOT SPOT' BIGGER THAN EXPECTED ) NASA, 9 Oct. 2014.〕 Other concerns are related to emissions from the hydraulic fracturing chemicals and equipment such as volatile organic compound (VOC) and ozone. In 2008, ozone concentrations in ambient air near drilling sites in Sublette County, Wyoming were frequently above the National Ambient Air Quality Standards (NAAQS) of 75 ppb〔 and have been recorded as high as 125 ppb. In DISH, Texas, elevated levels of disulfides, benzene, xylenes and naphthalene have been detected in the air, emitted from compressor stations.〔 In Garfield County, Colorado, an area with a high concentration of drilling rigs, VOC emissions increased 30% between 2004 and 2006.〔 Researchers from the University of Michigan analyzed the emissions produced from the hydraulic fracturing equipment at the Marcellus Shale and Eagle Ford Shale plays, and concluded that hydraulic pumps accounted for about 83% of the total emissions in the hydraulic fracturing fleet. NOx emission ranged between 3,600–5,600 lb/job, HC 232–289 lb/job, CO 859–1416 lb/job, and PM 184–310 lb/job. If the fuel efficiencies of the hydraulic fracturing pumps are improved, the emissions can be reduced.〔 On April 17, 2012, the EPA issued cost-effective regulations, required by the Clean Air Act, which include the first federal air standards for natural gas wells that are hydraulically fractured.〔 The final rules are expected to yield a nearly 95% reduction in VOC emissions from more than 11,000 new hydraulically fractured gas wells each year. This reduction would be accomplished primarily through capturing natural gas that escapes into the air, and making it available for sale. The rules also will reduce air toxics, which are known or suspected of causing cancer and other serious health effects, and emissions of methane, a potent greenhouse gas.〔 Stanford University in the American Journal of Science, looked at 200 studies and claimed the United States Environmental Protection Agency has been underestimating US methane emissions.〔http://www.rt.com/usa/methane-emissions-fracking-underestimated-epa-024/〕 A survey of hydraulic fracturing sites in Pennsylvania revealed drilling operations releasing plumes of methane 100 to 1,000 times the rate the EPA expects from that stage of drilling.〔https://www.washingtonpost.com/apps/g/page/national/unexpected-loose-gas-from-fracking/950/〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Environmental impact of hydraulic fracturing in the United States」の詳細全文を読む スポンサード リンク
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