Seasonal and spatial variations in mercury methylation and demethylation in an oligotrophic lake

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Appl. Environ. Microbiol.; (United States)

OSTI ID:6993460

Korthals, E T; Winfrey, M R

Microbial mercury methylation and methylmercury decomposition were examined in Lake Clara, an oligotrophic northern Wisconsin seepage lake, using radioisotopic tracers. Methylation activity was near background in the water column, was greatest in the profundal surficial sediments, and decreased with depth in sediment cores. Active demethylation occurred in the water column but was variable. Demethylation was greatest in the surficial sediments and decreased slightly with sediment depth. The methylation/demethylation ratio (M/D) was > 1 in the water column, exhibited a sharp peak in surface sediments, and decreased in deeper sediments. Methylation and demethylation activity varied in surface sediments collected along a lake transect. The M/D ratio in surface sediments ranged from 1.4 to 5.8. Methylation in attached microbial communities was near background, while demethylation was high. The M/D ratios in the attached communities were all < 0.20. Methylation activity in surface sediments incubated at in situ temperature increased from spring to late summer and decreased in the fall. Demethylation increased from early midsummer and then declined. The M/D ratio in surface sediments increased from mid- to late summer, and decreased in the fall. These results indicate that the greatest potential for methylation in Lake Clara occurs in the surficial sediments and that methylation in surficial sediments is greatest from mid-July through September. In addition, the net rate of methylmercury production may be significantly affected by demethylation.

• Research Organization: Univ. of Wisconsin, La Crosse (USA)
• OSTI ID: 6993460
• Journal Information: Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 53:10; ISSN AEMID
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIODEGRADATION
CHEMICAL REACTIONS
CONTAMINATION
DECOMPOSITION
DISTRIBUTION
ELEMENTS
FEDERAL REGION V
LAKES
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MERCURY COMPOUNDS
METALS
METHYLATION
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ORGANIC MERCURY COMPOUNDS
SEASONAL VARIATIONS
SEDIMENTS
SPATIAL DISTRIBUTION
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USA
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WISCONSIN