Mercury in California's Coastal Fog Could Disrupt Food Chain: Report

When coastal fog rolls into Northern California, a special form of mercury is coming along with it, according to new research.

At a Dec. 16 meeting with the American Geophysical Union, researchers announced that the amount of coastal fog is increasing. And while that might not be surprising to scientists, the amount of monomethylmercury present in the fog certainly is – it’s coming in at levels 19 times higher in fog than in rain.

So, what does that mean?

The level of mercury in the fog doesn't pose an immediate threat to humans, but it could prove dangerous for coastal ecosystems, especially if the chemical works its way up the food chain, The Santa Cruz Sentinel reports.

"We’re seeing that there’s mercury along the coast at every level in the plants, in the herbivores, and in the carnivores," said atmospheric chemist Peter Weiss-Penzias in an interview with the Sentinel.

Mercury, which is naturally present in the environment, has increased as humans have become more industrious. The chemical finds its way into the air from smokestack emissions, power plants and mining operations.

Mercury is toxic to humans and is damaging to the nervous, digestive and immune systems, according to the World Health Organization. 

It poses an even greater threat to pregnant woman, who are especially sensitive and are usually advised to avoid some types of fish due to mercury levels, according to the Food and Drug Administration.   

"While it might not be a human health issue at this point, it looks like it is an ecosystem health issue in the long run," oceanographer Kenneth Coales said to the Sentinel. "And it’s coming from human sources…"

Coales reports that scientists have also found mercury in the whiskers of mountain lions, and it’s even been found in wolf spiders at a level the FDA deems dangerous.

Though arachnids aren’t typically a staple in human diets, they are a valuable food source to birds and other creatures.

Coales and Weiss-Penzias plan to continue their research into mercury-laden fog and its effects on land-based food webs. Both hope to one day use drone technology to monitor Northern California fog, Popular Science reports.

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