News Scan Briefs; January 2005; Scientific American Magazine; by Charles Q. Choi, JR Minkel; 2 Page(s)
Earthquakes jostle matter within the crust, thereby modifying local gravity. But because of imprecise, unstable instruments, scientists could monitor these changes only with the aid of long records before and after quakes. Japanese investigators have devised a much quicker method. They monitored how superconducting balls respond to gravity while trapped floating in ultrastable magnetic fields generated by superconducting coils. After accounting for the separate pulls of the sun, moon, air, ocean and the earth's rotation, the researchers detected a permanent increase in gravity roughly a half billionth that of the earth's pull southeast off the coast of Hokkaido, the epicenter of the magnitude 8 Tokachi-oki quake in 2003. The results, in the October 15 Science, agree with theoretical predictions, suggesting that superconducting gravimeters can help satellites chart the earth's gravity to map changes in polar ice cap thickness, seawater levels, atmospheric density and planetary geology.
A neurotoxic poison, mercury is especially worrisome to developing fetuses. A nationwide study reveals that a significant number of women of child-bearing age have too much of the metal in their systems. Researchers at the University of North Carolina at Asheville based their results on hair samples from nearly 1,500 people of all ages. As hair grows, it incorporates mercury from the bloodstream. Interim results from the Greenpeace-commissioned survey released October 20 revealed that one fifth of those studied had mercury levels above the EPA recommendation of one part per million in hair. The investigators report no other pollutant has anywhere near this high a percentage of the U.S. population with exposure levels above federal standards. The biggest sources of airborne mercury are coal-fired power plants. The investigators will gather an estimated 5,000 samples or more in total and issue their final report in March.