U.S. Environmental Protection Agency, Office of Research and Development, Large Lakes Research Station, MI 48138, USA.
Environ Sci Technol. 2010 Feb 1;44(3):935-40. doi: 10.1021/es902307c.
Samples of opportunity from Pb-210 dated sediment cores collected from Lake Michigan between 1994 and 1996 were analyzed for mercury. The storage of anthropogenic and total (post-1850) mercury in the lake is calculated to be 186 and 228 t, respectively. By setting the sum of mercury stored in a representative core equal to the mercury storage within the entire lake, the time variation of annual mercury loading to the lake is calculated. The modern (1980-2002) mercury flux to the lake represented by the surface of the core at the time of collection in 1994 was 21.4 microg/m(2)/y. The preindustrial flux (< or =1850) was 3.09 microg/m(2)/y, and the peak flux in 1946 was 53.3 microg/m(2)/y. These yield modern and peak enrichment factors of 6.92 and 17.2, respectively. Modern fluxes exceed published atmospheric deposition estimates and, therefore, include terrestrial point sources, atmospheric deposition to watersheds, and atmospheric deposition to the lake. The modern net mercury load to the lake's sediments was 1157 kg/y in 1994. The atmosphere is estimated to contribute 91% of this load directly to the lake.
取自 1994 年至 1996 年期间在密歇根湖采集的 Pb-210 定年沉积物岩芯中的机会样本，被分析了汞含量。计算得出，该湖人为汞和总汞（1850 年后）的储量分别为 186 吨和 228 吨。通过设定一个有代表性的岩芯中储存的汞总量等于整个湖中的汞储存量，可以计算出每年向湖中的汞负荷的时间变化。通过设定一个有代表性的岩芯中储存的汞总量等于整个湖中的汞储存量，可以计算出每年向湖中的汞负荷的时间变化。通过设定一个有代表性的岩芯中储存的汞总量等于整个湖中的汞储存量，可以计算出每年向湖中的汞负荷的时间变化。通过设定一个有代表性的岩芯中储存的汞总量等于整个湖中的汞储存量，可以计算出每年向湖中的汞负荷的时间变化。通过设定一个有代表性的岩芯中储存的汞总量等于整个湖中的汞储存量，可以计算出每年向湖中的汞负荷的时间变化。现代（1980-2002 年）汞通量代表了 1994 年采集时岩芯表面的通量，为 21.4 微克/平方米/年。工业前通量（<=1850 年）为 3.09 微克/平方米/年，1946 年的峰值通量为 53.3 微克/平方米/年。这分别产生了现代和峰值的富集因子 6.92 和 17.2。现代通量超过了已发表的大气沉降估计值，因此包括了陆地点源、向流域的大气沉降和向湖泊的大气沉降。1994 年，现代汞净负荷向湖泊沉积物的输入量为 1157 千克/年。据估计，大气直接向湖泊贡献了这一负荷的 91%。
