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The toxic metal is poisoning polar wildlife but it can't all come from the atmosphere. Are polluted Siberian rivers to blame?
The Natural Resources Defense Council works to safeguard the earth - its people, its plants and animals, and the natural systems on which all life depends.
There is a good reason for colonizing another planet, which is to avoid extinction if the Earth is hit by a 10km or larger asteroid, as has happened many times in the Earth's history. Colonization of Mercury appears to be a very real and practical possibility, whereas colonization of Mars or the other planets, moons or asteroids is really more in the realm of fantasy. The first thought about Mercury is that it would have very high temperatures and no water, because the equatorial surface temperature ranges between -183oC and 427oC as the planet rotates. But an analysis of temperature vs. latitude and depth shows that the temperature is nearly constant at room temperature (22+/-1oC) in underground rings circling the planet's poles, and deeper than .7 meter below the surface. Similar results are found using numerical techniques in an Icarus paper, Vol. 141, 179150193 (1999). Researchers at Arecibo observatory have found high radar-reflective areas near Mercury's poles in permanently shadowed crater bottoms, and this material was recently proven to be nearly pure water ice using neutron spectrometry data from the Mercury MESSENGER spacecraft, as described in Thermal Stability of Volatiles in the North Polar Region of Mercury and Evidence for Water Ice Near Mercury's North Pole from MESSENGER Neutron Spectrometer Measurements. Many of the craters are 1-2 km deep. The wavelength dependence of radar signals indicates a minimum of several meters of water ice over a total area of 1010m2, resulting in 1014-1015kg of water. A more recent estimate using MESSENGER data is .5-20 meters of water ice over 5.65x1010m2, resulting in 2x1013-1015kg of water. Laser altimeter reflections indicate that most of the ice is covered by a dark material which is thought to be a layer of hydrocarbons about 10cm thick (amounting to ~5.65x109m3), as described in Bright and Dark Polar Deposits on Mercury: Evidence for Surface Volatiles.
Seventy scientists spent two years putting together a complete picture of mercury in the ocean and in seafood. Will the results convince the U.S. to control emissions?