A phenomenon called “mercury sunrise” was discovered in 1995 by Canadian atmospheric researcher Bill Schroeder working in the Arctic. The phenomenon occurs when the sun first returns after the long dark winter, producing high levels of one form of mercury, called reactive gaseous mercury. In fact the highest levels of this form of mercury ever recorded were found in the Canadian Arctic. At the same time, levels of elemental mercury drop dramatically. When he first saw the mercury readings on his instruments fluctuate wildly, Dr. Schroeder assumed the instruments were not working properly. Scientists are just beginning to understand what is causing this phenomenon and why it is seen in the Arctic (and recently in the.
