未来或每天能喝8杯海水

EarthSky spoke with water expert Amy Zander about desalination - the process of removing salt from water. She said that rising demand for water will mean increased use of desalination in the United States, in the coming years.

Amy Zander: Well, we've been turning sea water into fresh water for centuries by desalination. Now the state of the science appears to be reverse osmosis, which is where we push the salty water through a membrane, and clean water comes out the other side and we have a salty concentrate solution remaining.

Zander led an assessment in 2008 by the U.S. National Research Council on desalination, she said she's concerned about desalination's possible environmental effects.

Amy Zander: We have worries about what to do with that concentrate, both inland and in sea water. We need to know what kind of environmental effects there are from gathering the water from those places. And we're also worried about potential greenhouse gas emissions from the energy that goes into desalting water.

Zander said that the desalination process - while actually very efficient - still uses enormous amount of energy.

Amy Zander: Probably we'll have to supplement it with other ways like conservation and water reuse in order to get the full water supply portfolio for the nation.

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