受限于水资源？

Enter hydraulic fracturing for shale gas.  The water footprint for shale gas is defined in two main ways—water consumed and water polluted.

Water Consumed:  Fracking is a water intensive process requiring an average 5 million gallons of water per well and up to 9 million gallons for some of the longest well bores.  Between 8-10 percent of the volume injected in Pennsylvania’s Marcellus Shale wells returns to the surface as flowback. That means up to 90 percent of the fresh water injected in the fracking process is sequestered in deep geologic formations.

This depletion is fundamentally different than evaporative losses for agriculture, electricity generation, and recreational uses like golf courses, which essentially recycle the water used into the atmosphere where it returns as precipitation. Water injected for fracking is locked away from the earth’s natural hydrologic cycle, a total loss that doesn’t return to its source.

The ecological and socio-economic implications of this true consumptive loss have not been studied or quantified, but considering the finite nature of potable water and our expanding consumption rate, this must be recognized by water managers as a key in assessing fracking’s water footprint and setting gas extraction policies. Very little data exists to quantify groundwater in many aquifers so that accurate water footprint accounting is difficult to develop.^[6]  And yet the trajectory we are on must be exposed in order to change course so we have to gather that data and do the needed analyses.

Water Polluted: The other way fresh water is depleted is through pollution. Frack water is deliberately polluted by the addition of frack chemicals and inadvertently but inescapably contaminated by contact with naturally occurring highly toxic pollutants where the shale gas is contained. Chemical additives make up to 2 percent of the frack fluid injected in gas extraction.^[7] Up to 750 chemicals have been used across the nation in frack fluids^[8]; in Pennsylvania and West Virginia 322 unique chemicals and at least another 21 additional compounds whose ingredients are kept secret by drillers have been documented in frack fluids used in the Marcellus Shale.^[9] Many of these chemical additives are toxic and are known carcinogens and endocrine disruptors; long term exposure can cause nervous system, respiratory and organ damage.  Some, such as benzene, are so dangerous that even miniscule amounts can cause disease.[10]

http://ecowatch.org/2012/the-water-footprint-of-shale-gas-development/