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Environment

Oceans, From the Deep Currents to the Big Oxygen Generators

By Jeremy JacquotJanuary 24, 2011 6:00 AM

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3.2 Flow rate, in billions of gallons per second, of a newfound deep-ocean current that carries oxygenated water northward from Antarctica, ultimately replenishing the deep layers of the Indian and Pacific oceans. That flow is equivalent to 40 Amazon Rivers. The largest ocean current by flow volume is the Antarctic Circumpolar Current, which averages a stunning 34.3 billion gallons per second.

0.4 Projected drop in seawater pH, from 8.2 to 7.8, by the end of the century if present trends hold, according to a 2009 report from the National Oceanic and Atmospheric Administration. This would represent a 150 percent increase in ocean acidity since the beginning of the Industrial Revolution. The change could threaten shell-building species, corals, and fish larvae.

35 Typical salt content of ocean water, in parts per thousand (ppt). That includes chlorine, the most abundant dissolved element in seawater, at concentrations of about 19 ppt, followed by sodium (11 ppt), sulfate (2.7 ppt), magnesium (1.3 ppt), calcium (0.4 ppt), and potassium (0.4 ppt).

1 million Approximate number of bacterial cells in a typical cubic centimeter of ocean water. The total number of microorganisms in the ocean may be as high as 10^30. They account for at least half of all oceanic biomass and produce half of the oxygen in our atmosphere. Collectively, they weigh more than 240 billion African elephants.

250,000 Estimated number of known ocean species, according to the decade-long Census of Marine Life, which concluded in October. The census turned up more than 6,000 candidates for new marine species. The number of species yet undiscovered, including microbes, could run anywhere from a million to hundreds of millions.

1 Number of planets (Earth) known to have oceans. But Saturn’s largest moon, Titan, has lakes of ethane; smaller Enceladus may have a subsurface ocean of fizzy seawater. And Jupiter’s Europa may harbor a water ocean beneath its icy surface.

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