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Researchers Discover How Mercury Gets Into Fish We Eat: Oxidation

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JERUSALEM, Israel -- Researchers from the Hebrew University of Jerusalem and the US have discovered the mechanism whereby dangerous mercury eventually finds its way into the fish we eat from the open seas and oceans.

The researchers, Prof. Menachem Luria from the Fredy and Nadine Herrmann Institute of Earth Sciences at the Hebrew University and Dr. Daniel Obrist of the University of Nevada, found that "passive" mercury normally found in the atmosphere is converted into an "active," oxidized form in the presence of bromine. The passive mercury is generally non-transferable, whereas the active form is readily absorbed into the environment.

The air over the Dead Sea was chosen for the experiments on mercury oxidation even though it does not contain any fish since it has unusually high levels of bromine that is emitted from the surface into the atmosphere, converting the mercury there into the oxidized mercury.

"In the world generally, the amount of oxidized mercury in the atmosphere constitutes about one percent of all the mercury in the atmosphere," said Prof. Luria, "while above the Dead Sea the oxidized mercury often amounts up to about 50 percent."

In fact, the bromine in the air over the Dead Sea is 200 times greater than over other bodies of water, say the researchers, due not only to the high level of bromine present on the surface but also to the high rate of its evaporation into the atmosphere because of the very high temperatures there. It is important to note, they emphasize, that this process of conversion of passive into active mercury occurs over all bodies of water, even though it may be at much lower levels than at the Dead Sea.

Although health officials in the world have issued warnings from time to time about the danger of mercury found in fish, the process by which the inactive mercury is converted into the active, oxidized form was previously unknown. The current research has now revealed how this occurs, with the resultant introduction of this dangerous, active form of mercury into the fish food chain and ultimately into humans through the consumption of sea food.

The research by Prof. Luria and Obrist was supported by the National Science Foundation of the US, and the results were published in Nature Geoscience Journal. This is the latest of numerous research projects conducted in the Dead Sea area, which serves as a natural laboratory for a long list of biological-chemical and geophysical research projects, commented Prof. Luria.

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Reader Comments

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I don,t know too mutch about murcury in the oceans marine life I know when I was a kid here in the wv. mts. the gass drillers came to the mts. drill for gass & oil wells they had lots of murcury and they gave lots of it to us to play with. I was amazed at how heavy it was , and how U could make a dime ,nickle, or any silver coins shine. I had a cigar box full and it was just about all I could lift and Iwas in the navy befor I knew how dangerous the stuff was.They used it to test sertin tipes of shale and they would drill a hole down a few thousand ft. then they would lower a container of what they called nitro and send us kids far around the ridge then they woulddrop a cilender of murcury down and run as fast as they could as far as yhey could. Then the ground would shake hard enough to shake walnuts and chestnuts off the trees, befor the wv.chestnuts died off from a blite that took all of the best nuts ever. They replanted some orinteal chestnuts but they never truely replaced the West Virginia chestnuts .I wishI would have known how dangerous the stuff was at the time !
   comment# 1   - john peters · eastbank,wv.usa · Jul 18, 2011 @ 2:54pm
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