May 25, 2019 | 69° F

Rutgers professor researches effects of climate change on mercury accumulation

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Professor in the Department of Environmental Science, Jeffra Shaefer, co-authored a research paper predicting the ways coastal estuaries will be altered by global warming. She said changes in the food web will contribute to increases in methylmercury in ecosystems.

Jeffra Schaefer, a professor in the Department of Environmental Science, has taken part in important research regarding the effects of climate change.

She recently helped co-author a research paper investigating the effects of climate change on the bioaccumulation of methylmercury in coastal estuaries.

Mercury is toxic in all forms but it is the methylmercury found in marine life that poses the greatest risk to humanity, Schaefer said. Mercury is converted to methylmercury by bacteria at the base of the food web in coastal estuaries.

In addition to warming the planet, climate change will cause an increase in precipitation, she said. This will lead to more runoff which will transport soil nutrients, or terrestrial organic matter, along with it.

When runoff reaches coastal estuaries, terrestrial organic matter is consumed by certain bacteria, Schaefer said. While benefiting these bacteria, the terrestrial organic matter makes the water murky, thereby reducing the light available for photosynthetic organisms.

This shift in primary producer at the base of the food web attracts different organisms for feeding, she said. The organisms that consume the bacteria were not previously very common.

The magnitude of the problem is compounded by the fact that methylmercury accumulation increases with each trophic level, Schafer said. When zooplankton consume bacteria, for instance, it consumes all the methylmercury the bacteria has produced in its life.

The expanded food web increases methylmercury accumulation in coastal ecosystems by a multiple of two to five, she said.

The world may require a greater reduction in mercury than previously expected due to climate change, Schaefer said.

By 2050, climate change may increase runoff by 15 to 20 percent, she said. This modest increase makes a significant impact when the bioaccumulation of methylmercury is factored in.

Even if humanity could stop emitting mercury today, it is not clear how long it would take aquatic ecosystems to recover, Schafer said.

Methylmercury is a danger to humans because it is fat soluble, she said. This means that it can cross the intestinal wall as well as the blood-brain barrier. Once present, methylmercury is difficult to cleanse from the body as it does not travel through the bloodstream.

Methylmercury poses the greatest danger to the very young, Schaefer said. It is a neuromuscular toxin which means it can affect the development of muscles and brain connections.

The solution to this problem is to reduce mercury emissions and eliminate mercury from household products such as compact fluorescent light bulbs, she said.

When asked how the Rutgers community could help, Schaefer said students should be informed and look up the consumer fact sheets that detail safe consumption amounts. People should pay with their pocketbook and insist on proper labeling that includes a site of origin.

“I never like to leave an impression where I scare people from eating fish. I like to leave them informed,” she said.

One thing students can do to educate themselves is consult federal consumption advisories and guidelines before eating fish, said John Reinfelder, a professor at Rutgers’ Department of Environmental Sciences.

“We consider mercury to be a global pollutant in the sense that it may be emitted in Asia or Europe, but it actually travels around the atmosphere quite long distances before it deposits,” Reinfelder said.

There is three to five times more mercury in the atmosphere today than there was in 1850, Reinfelder said. The combustion of coal in power plants, mercury mining, gold mining, and medical waste all contribute to the problem.

Ken Kurtulik is a School of Arts and Sciences junior. He is a contributing writer for The Daily Targum.

Ken Kurtulik

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