Tuesday, August 16

This researcher has been poisoning a lake with mercury for 15 years to see what happens to the fish that live inside: now, finally, he has an answer

There are aquatic beings that are a health hazard and I am not talking about piranhas, sharks and killer whales. That also. I’m talking about fish “loaded” with methylmercury, a powerful neurotoxin that originates in aquatic ecosystems due to mercury discharges, accumulates in fish and represents a threat to the health of everyone who consumes it.

We have known this for a long time and it has improved the lives of many people than we could have imagined. It has also caused innumerable food problems because what we do not know is what happens to those contaminated ecosystems. Do we have to give them up forever? Is there any way to rescue them? Is it enough to stop dumping mercury or do we have to develop techniques to clean up the lakes and get them back? Today the magazine ‘Nature’ brings an answer.

Fresh and freshly caught neurotoxins

The process, as I said, begins with the mercury released as a result of human activity reaching aquatic ecosystems. There it is converted into methylmercury and enters the food chain. The problem is that our knowledge of the effectiveness of mercury emission controls to remove this pollutant is limited.

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Especially since it is not an easy subject to study. Paul Blanchfield and team have spent 15 years manipulating a lost lake in Canada to understand how fish are recovered after the cessation of spills. During the first seven years, the researchers supplied specific isotopes of mercury (to directly monitor added mercury) to the lake and verified how methylmercury concentrations increased between 45% and 57% in invertebrates and small fish, and by more than 40% in large fish, such as pike and whitefish populations.

From that moment on, they stopped pouring mercury and the effects on the food chain were observed for eight years. The marked methylmercury decreased rapidly in the smaller fish to the point that the concentrations decreased by at least 85% at the end of 15 years. Thus, little by little the amounts of methylmercury were reduced in the larger fish. In some species, at the end of that period, it decreased by 76%, while in others the reduction only reached 38%.

However, this is very good news. That these data, recreated in real space, show rapid reductions in methylmercury contamination shows that reducing mercury discharges is a good solution for ensure the medium-term safety of fish for human consumption.

Image | Father Vescei


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