Methylmercury sulfate

The seed-dressing effect of methylmercury sulfate (3) was first investigated by Melnikov and Rokitskaya (1937), and subsequently found widespread... 

FIGURE 17.38 The methylmercury-sulfate connection in the Everglades. Hg, mercury P, phosphorus MeHg, methylmercury. (From Orem and Krabbenhoft, 2004.)... 

In Hg-resistant bacteria that are resistant to organic forms of Hg such as phenylmercuric acetate and methylmercury chloride, lyases are involved in the fission of the C-Hg to form Hg + and benzene or methane, and the enzyme has been partly purified (Schottel 1978). The Hg + may then be reduced to nontoxic Hg°. The situation under anaerobic conditions for sulfate-reducing bacteria is complicated by the possibility of both methylation and demethylation in the same strain (Pak and Bartha 1998), plausibly by operation of the acetyl-CoA pathway (Choi et al. 1994 Ekstrom et al. 2003). Under anaerobic conditions, demethylation, though not methylation, has been reported for a methanogen (Pak and Bartha 1998). 

King JK, Harmon SM, Fu TT, Gladden JB. 2002. Mercury removal, methylmercury formation, and sulfate-reducing bacteria profiles in wetland mesocosms. Chemosphere 46 859-870. 

SYNS ARETAN-NIEinOC B 4992 BIS-(METHYD MERCURY)-SULFATE BIS-(METHYLMERKURI)-SULFAT CERESAN UNIVERSAL-FEUCHTBEIZE CEREWET COMPOUND-4992 MERCURY, SULFATOBIS(METHYL- METHYLMERCURIC SULFATE SULFURIC ACID, BIS(METHYLMERCURY) SALT... 

Sorokin, Yu.I., 1975. On the ability of sulfate-reducing bacteria to utilize methane for the reduction of sulfate to hydrogen sulfide. Dokl. Akad. Nauk SSSR, 115 816—818. Spangler, W.J., Spigarelli, J.L., Rose, J.M. and Miller, H.M., 1973. Methylmercury bacterial degradation in lake sediments. Science, 180 192—193. 

Commonly occuring form of methyl mercury proprietary names include bis-methylmercuric sulfate (cerewet), methylmercury cyanoguanidine or methylmercury dicyanodiamide (agrosol, morsodren, panogen, panospray), methylmercury nitrile (chipcote) and methylmercury propionate (metasol MP)... 

Human activities have resulted in the release of a wide variety of both inorganic and organic forms of mercury. The electrical industry, chloro-alkali industry, and the burning of fossil fuels (coal, petroleum, etc.) release elemental mercury into the atmosphere. Metallic mercury has also been released directly to fresh water by chloro-alkali plants, and both phenylmer-cuiy and methylmercury compounds have been released into fresh and sea water -phenylmercury by the wood paper-pulp industry, particularly in Sweden, and methyl-mercury by chemical manufacturers in Japan. Important mercury compounds which also may be released into the environment include mercury(II) oxide, mercury(II) sulfide (cinnabar), mercury chlorides, mer-cury(II) bromide, mercury(II) iodine, mer-cury(II) cyanide, mercury(II) thiocyanate, mercury(II) acetate, mercury nitrates, mercury sulfates, mercury(II) amidochloride monoalkyl- and monoarylmercury(II) halides, borates and nitrates dialkylmercury compounds like dimethylmercury, alkoxyal-kylmercury compounds or diphenylmercury (Simon and Wiihl-Couturier 2002) (for quantities involved, see Section 17.4). 

The main difficulty in preparing a sediment reference material for interlaboratory studies on chemical species is to achieve the stability of the relevant compounds [12]. With respect to methylmercury, the main source of instability is due to bacteria, either by demethylation [88,89] or formation of volatile dimethylmercury [90]. The conversion is indirectly provoked by the biological activity of various types of bacteria, such as (i) aerobic mesophilic heterotrophic microorganisms, (ii) anaerobic sulfate-reducing bacteria and (iii) anaerobic spore-forming bacteria. In order to control the remaining bacteria present after different irradiation treatments, a bacterial enumeration was performed on samples which were dehydrated after homogenization and irradiated at various 7-ray doses (0, 4, 8, 12, 25 and 50 kGy). The determination of the sulfate-... 

A different type of metal is Hg. The toxic, bio-available form of Hg (methylmercury) may be formed in sediments when sulfate-reducing bacteria incorporate HgS° and methylate the Hg. This process appears to occur where sulfate reduction is important, but dissolved sulfide levels are less than 10pM. Under these conditions, sediments can be an important source of methylmercury to the coastal water column. 

Areas with high sulfate concentrations have low-to-moderate methylmercury production stimulated by sulfate reduction but inhibited by sulfide accumulation. 

Interior oligotrophic areas have low methylmercury production because of low sulfate concentrations that limit sulfate reduction. 

Highest rates of methylmercury production can potentially occur in areas where sulfate concentrations are moderate (2-10 mg L ) and sulfide levels are not high enough to inhibit methylmercury production. 

In the Everglades, highest production of methylmercury was observed in the center of WCA-3, where sulfate concentrations are low. 

Mercury accumulation by two species of freshwater teleosts eastern mosquitofish (Gambusia holbrookv, lake chubsucker, Erimyzon sucetta) in an artificial wetland ecosystem was sigifificantly enhanced by sulfate addition. Authors conclude that sulfate additions result in elevated production of methylmercury in sediment and porewater -possibly due to increased mercury methylation by sulfate-reducing bacteria - which is readily evident in fish and water with subsequent increases through the food web. 

The increase in the concentration of methylmercury in predators is apparently not offset by the synthesis of hydrogen sulfide from sulfate by Desulfovibrio species in the sediments. Sulfide precipitates all mercuric salts and H2S has been shown to disproportionate methylmercury to dimethylmercury. However, dimethylmercury is hydrolyzed back to methylmercury in acidic conditions." ... 

Cellulose itself has had limited applications for concentrating iorganic pollutants, but modified celluloses have been more successful. Kaputskii et al. (330, 331) have used a cellulose sulfate for the selective extraction of thallium(I) and a monocarboxycellulose for the removal of silver(I) and thallium(I). Esterified cellulose was used to scavenge heavy metals from solution (332) and a cellulose thiourethane was used to extract silver(I), nickel(II), copper(II), and mercury(II) (333). Using a 2,3-dimercaptopropyl cellulose, mercury and methylmercury can be extracted from aqueous solution and brine with no coextraction of several other metals (334). 

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