Historical Record of Mercury in the Snow Pack

Mercury in Upper Fremont Glacier. [From P. F. Schuster, D. P. Krabbenhoft, D. L. Naftz, L. D. Cecil, M. L. Olson, 

Mercury flux to Lake Michigan estimated from sediment cores. Most Fig is deposited from the air and is due to anthropogenic sources such as burning of coal. [From R. Rossmann, Environ. Sci. Technol. 2010,44, 935.] 

Hg from melted ice was measured by reduction to Hg(0), which was purged from solution by bubbling Ar gas. Hg(g) was trapped by metallic Au coated on sand. (Mercury is soluble in gold.) For analysis, the trap was heated to liberate Hg, which passed into a cuvet. The cuvet was irradiated with a mercury lamp, and fluorescence from Hg vapor was observed. The detection limit was 0.04 ng. Blanks prepared by performing all steps with pure water in place of melted glacier had 0.66 0.25 ng Hg/L, which was subtracted from glacier readings. All steps in trace analysis are carried out in a scrupulously clean environment. 

What is the difference between atomic absorption and atomic emission spectroscopy  

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