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Methyl Mercury

Methyl mercury is a generic term for organic mercury compounds including: mono-methyl mercury (CH3Hg, also abbreviated MMHg), dimethyl mercury [(CH3)2Hg], and ethyl methyl mercury [(CH3)(CH3CH2)Hg].

Quantification of methyl mercury in precipitation samples is important as methyl mercury is a neurotoxin, it bioaccumulates in organisms, and it biomagnifies as it travels up the food chain. On a percent basis, organic mercury is believed to comprise a small portion of the total mercury in a precipitation sample.

Methods

Methyl mercury analysis follows U.S. EPA Method 1630 (Methyl Mercury in Water by Distillation, Aqueous Ethylation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry).

Analysis for methyl mercury in NADP wet-deposition samples is available either as a split sample or a composite sample. For a split sample, an aliquot is taken from a single MDN (total mercury) sample for methyl mercury analysis. For a composite sample, a percentage of each MDN sample is taken over a period of four consecutive weeks. The resulting composite sample is then analyzed for methyl mercury. In this dataset, the number of samples and the number of samples with volume can be used to identify the type of analysis. A single sample indicates a split sample. 2 or more samples indicate a composite sample.

Site List

Methyl Mercury Site List

SiteIDStart DateEnd Date
AZ0204/04/200607/02/2013
BC1604/13/201003/01/2011
FL0407/03/200103/08/2005
FL0501/20/199807/26/2005
FL1107/03/200109/27/2005
FL3209/23/200309/25/2007
FL3407/03/200103/08/2005
GA0901/20/199807/26/2005
GA3309/25/2007
IL1104/08/2003
IN2009/24/200204/06/2004
IN2109/24/200208/31/2005
IN2809/24/200209/06/2005
IN3409/24/200203/30/2004
KY1009/14/2004
LA0501/26/199906/30/2009
LA1001/26/199906/09/2009
LA2309/24/200206/09/2009
LA2801/26/199907/01/2009
MI3112/13/200503/20/2007
MN1610/01/1996
MN1810/01/1996
MN2310/01/1996
MN2710/01/1996
MN9802/04/2008
MS1203/09/201001/29/2013
NJ3001/17/2006
NM9809/01/200910/09/2012
NS0110/01/200203/01/2011
NY2011/19/200209/06/2005
NY6806/20/200611/19/2013
ON1804/26/201011/30/2010
OR0103/09/200401/04/2011
OR1012/17/200201/04/2011
PQ1704/13/201003/01/2011
SC0912/13/200501/06/2009
TN1106/27/2006
VA9812/17/200401/03/2012
WA1809/24/200211/19/2013
WI0801/07/199701/14/2014
WI0901/07/199711/26/2013
WI2203/11/200312/04/2013
WI3110/01/200201/14/2014
WI3601/07/199701/08/2014
WI9901/07/199701/14/2014

Data

Important information regarding the dataset is available in the Explanatory Notes file associated with the dataset.



Recomended Dataset: In this dataset, methyl mercury concentrations less than the reporting limit are sequestered and shown as "<RL". Such values may result from the sample having a mass of methyl mercury less than the minimum for quantification, from the sample being of low volume, or both.

mdnMethyl.xlsx:


Not recomended: The unfiltered dataset contains all methyl mercury concentration values, including those below the reporting limit. Concentration values below the reporting limit have greater uncertainty. Users are cautioned against the use of this dataset.

MDNMethyl_unsequestered.xlsx


References

The following references are recommended for additional information on methyl mercury and methyl mercury analysis.

  1. Bloom, N. S., and C. J. Watras. "Observations of methylmercury in precipitation." Science of the Total Environment 87 (1989): 199-207.
  2. Hall, B. D., H. Manolopoulos, J. P. Hurley, J. J. Schauer, VL St Louis, D. Kenski, J. Graydon, C. L. Babiarz, L. B. Cleckner, and G. J. Keeler. "Methyl and total mercury in precipitation in the Great Lakes region." Atmospheric Environment 39, no. 39 (2005): 7557-7569.
  3. Parker, J.L. and N.S. Bloom. “Preservation and storage techniques for low-level aqueous mercury speciation.” Science of the Total Environment, 337 (2005): 253-263.
  4. U.S. Environmental Protection, Method 1630: Methyl Mercury in Water by Distillation, Aqueous Ethylation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrophotometry. EPA Method 1630

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