Naturally Occurring Radiogenic Elements Make Effective Groundwater Flow Tracers . Getting the lead out . On Freeze, Thaw Cycles of Hundreds of U.S. Lakes . Chemical may deter starfish from devouring endangered coral reefs . Do not hide from rain under a firetree .
Satellite sniffs out chemical traces of atmospheric pollution .
Silt formation better understood . Alaska's speedy Columbia Glacier on likely disintegration course . Less pollution with new system . Scientists fight to bring the American chestnut tree back to life . Mouse allergy contributes to inner-city asthma crisis .