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The Bacteria Process

The Bacteria Process
The Bacteria Process
The Bacteria Process
The Bacteria Process
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495061
Cook, John E.
The Bacteria Process
Illustration
12/01/2010
Bacteria_Vertical.jpg
Caption from Oceanus magazine, Vol. 48, No. 2, pg. 24:
1. Ionized mercury (Hg+2) in seawater and sediments cannot enter bacterial cells.
2. With little or no oxygen available, some bacteria use sulfates (SO4^-2) for respiration. They expel sulfide (S^-2) as a waste product.
3. Sulfide combines with ionized mercury (Hg^+2) in seawater to form mercuric sulfide (HgS).
4. Mercuric sulfide can diffuse into bacterial cells.
5. Inside bacterial cells, chemical reactions remove the sulfide from the mercury and add a methyl group (CH3) to produce monomethylmercury (MMHg). Scientists have not identified the reactions responsible for making MMHg. The MMHg does not appear to benefit or harm the bacteria.
6. Monomethylmercury diffuses out of bacterial cells into seawater, where it is taken up by phytoplankton. This starts the journey of MMHg up the oceanic food chain.
Illustration by Jack Cook
© Woods Hole Oceanographic Institution
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