SS3.17 Global Mercury Cycling: From Natural to Anthropogenic Sources
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
HallGE, Geological Survey of Canada, Ottawa, Canada, ghall@nrcan.gc.ca
Pelchat, P, , Geological Survey of Canada, Ottawa, Canada, ppelchat@nrcan.gc.ca
 
MERCURY DISTRIBUTION IN SOILS AND SEDIMENTS BY SEQUENTIAL EXTRACTION METHODS
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The extraction scheme examined for mercury partitioned the element into these nominal associations: labile organics by pyrophosphate; amorphous iron and aluminum oxides by hydroxylamine hydrochloride in HCl; crystalline oxides by hydroxylamine hydrochloride in acetic acid; and sulphides and residual organics by aqua regia. Samples containing different synthetic and natural forms of mercury were subjected to this scheme and it was determined that mercury reporting to the labile organic component was surprisingly low. Development and insertion of an HNO3 step prior to aqua regia dissolved a large amount of organically associated mercury which was not affected by pyrophosphate leaching, indicating that the original scheme can lead to misinterpretation of results. The new scheme allowed for the separation of all mercury associated with various organic phases from that associated with sulphides and as cinnabar and that associated with oxides. Examination of different electrolytic leaches (e.g. MgCl2, Ca(NO3)2) to measure weakly bound exchangeable mercury as a first step showed that resorption of mercury is a major problem in these procedures.