Microbial methylation of mercury in estuarine sediments
Mercury is a common and potentially hazardous pollutant. Although all forms of the element are toxic, alkylated mercurials are particularly toxic and accumulate in living tissues. Factors affecting the availability of mercury and the microorganisms responsible for methylation are described. The methylation of mercuric ions (Hg/sup + +/) was investigated in pure culture, in estuarine sediments, and as a function of the anionic constituents of seawater. Studies on abiotic methylation of Hg/sup + +/ by methylcobalamin in the presence of sea salts showed that only the sulfide (formed in sulfate reduction) and bicarbonate components interfere with Hg/sup + +/ methylation. Other sea salt anions have no significant influence on the methylation of Hg/sup + +/. Methylation, demethylation, and volatilization of Hg/sup + +/ were studied in estuarine sediments maintained at present values of pH, redox, and salinity. Volatilization of Hg/sup 0/ and CH/sub 3/HgCH/sub 3/ were found to be minimal. Methylation was favored at low redox potential (-220 mW) and low salinity (0.4%) conditions. High salinity (2.5%) decreased methylation at -220 mV, but not at (+110 mV). Demethylation of CH/sub 3/HgCl was favored at +110 mV regardless of the salinity level. Low redox potential under low salinity conditions inhibited demethylation, but high salinity reversed this inhibition. The sulfate-reducing bacteria were identified as the principal Hg/sup + +/ methylating population in anaerobic estuarine sediments.
- Research Organization:
- Rutgers-the State Univ., New Brunswick, NJ (USA)
- OSTI ID:
- 6069130
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
MERCURY
METHYLATION
ORGANIC MERCURY COMPOUNDS
SULFATE-REDUCING BACTERIA
GROWTH
ANIONS
CATIONS
ESTUARIES
PH VALUE
REDOX POTENTIAL
SEAWATER
SEDIMENTS
BACTERIA
CHARGED PARTICLES
CHEMICAL REACTIONS
ELEMENTS
HYDROGEN COMPOUNDS
IONS
MERCURY COMPOUNDS
METALS
MICROORGANISMS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SURFACE WATERS
WATER
520200* - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)
560302 - Chemicals Metabolism & Toxicology- Microorganisms- (-1987)