If the levels of synthetic organic chemicals are very low in seawater, then how is chlorinated hydrocarbons found in dolphins at dangerous levels?
?The level of synthetic organic chemicals in seawater is usually very low, but some organisms at higher levels in the food chain can concentrate these toxic substances in their flesh. This biomagnification is especially hazardous to top carnivores in a food web. Biologists have discovered that some nearshore dolphins off U.S. coasts are intensely contaminated. Past studies have found concentration of chlorinated hydrocarbons in these animals as high as 6,900 parts per million (ppm), which is high enough to disrupt the dolphins' immune systems, hormone production, reproductive success, neural function, and ability to stave off cancers. These levels vastly exceed the 50 ppm limit the U.S. government considers hazardous for animals, and 5 ppm considered the maximum acceptable for humans!
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Why will nuclear fission probably not be used directly for powering automobiles?
A. Massive shielding would be required to protect against radioactivity exposure. B. It's more practical for cars to use the electricity generated by nuclear fission power plants. C. Radioactive wastes could not be adequately controlled. D. All of the above are true.
If the earth's axis were parallel with its orbital plane around the Sun
A) there would be no significant weather. B) the South Pole would always be in darkness. C) the North Pole would always be in darkness. D) there would be at least one day a year when every spot on Earth would receive 12 hours of daylight.
What must a country give up in order to be a member of the World Trade Organization?
A) a large membership fee B) part of its sovereignty C) some land that can be used for WTO functions D) its language E) all of the above
Global circulation systems are essential to the maintenance of Earth's energy balance
Indicate whether the statement is true or false