Storm riders: how mercury is transported by bad weather

Storm riders: how mercury is transported by bad weather Mihai Simonia
17 Nov
2016
Thunderstorms in the US could be transporting harmful mercury from the atmosphere to the ground

Southeastern states in the US, such as Florida and Louisiana, receive higher deposits of mercury from the atmosphere compared to the rest of the North American continent. They also have the stormiest weather. Scientists at the University of Florida do not think this is a coincidence.

‘Tall thunderstorms are bringing mercury down to Earth,’ says atmospheric scientist Christopher Holmes. In a recent study, Holmes found thunderheads (the cumulonimbus clouds seen during a storm) to be carrying 50 per cent higher levels of the harmful pollutant than other cloud types, even when the rainfall itself was of equal amounts. ‘The highest concentrations of mercury occurred during thunderstorms,’ he says, ‘and the lowest during a regular rainstorm.’

It seems the storms scour the mercury from the higher atmosphere and deposit it on the ground

The link could be the thunderclouds’ height. Most mercury in the atmosphere sits at high altitudes, in the upper troposphere. While normal rain clouds are just a few kilometres thick, storms can form towering clouds that plume 15 kilometres in the air. ‘It seems the storms scour the mercury from the higher atmosphere and deposit it on the ground,’ says Holmes. The pollutant’s affinity for rough weather would explain why mercury levels are high in the southeast – often double those of northern states – despite the fact that Florida and Louisiana emit less mercury than many northern regions.

Mercury is a rogue element. Often emitted as an unwanted by-product of fossil burning and small-scale gold mining, it can remain in the upper atmosphere for decades, drifting thousands of miles from its original source. When it comes back down, it can accumulate in the food chain as methylmercury, which is highly toxic to animals and humans. In fact, the consumption of many fish species in southeastern states are banned due to excessive contamination.

This was published in the November 2016 edition of Geographical magazine.

Share this story...

Submit to FacebookSubmit to Google PlusSubmit to Twitter

Related items

Leave a comment

ONLY registered members can leave comments and each comment is held pending authorisation before publishing. Please login or register to voice your opinion.

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe Today

EDUCATION PARTNERS

Aberystwyth UniversityUniversity of GreenwichThe University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • REDD+ or Dead?
    The UN-backed REDD+ (Reducing Emissions from Deforestation and Forest Degradation) scheme, under which developing nations would be paid not to cut dow...
    The true cost of meat
    As one of the world’s biggest methane emitters, the meat industry has a lot more to concern itself with than merely dietary issues ...
    Long live the King
    It is barely half a century since the Born Free story caused the world to re-evaluate humanity’s relationship with lions. A few brief decades later,...
    London: a walk in the park
    In the 2016 London Mayoral election, the city’s natural environment was high on the agenda. Geographical asks: does the capital has a green future, ...
    The Money Trail
    Remittance payments are a fundamental, yet often overlooked, part of the global economy. But the impact on nations receiving the money isn’t just a ...

MORE DOSSIERS

NEVER MISS A STORY - follow Geographical

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Energy

Geographical’s regular look at the world of climate change. This…

Climate

Was last year’s El Niño a practice run for future…

Wildlife

The continuing adventures of Aaron Gekoski as he joins the…

Geophoto

What do Ethiopia’s ‘church forests’, the incipient HS2 high-speed rail…

Wildlife

Aaron Gekoski continues working alongside the Wildlife Rescue Unit

Geophoto

Today, the camera is regarded as an essential smartphone feature.…

Oceans

An innovative new theory hopes to save millions of lives…

Wildlife

Aaron Gekoski continues his personal adventure into the wilds of…

Wildlife

Simple tracking devices have enabled conservationists to amass big data,…

Climate

In a new report, researchers have calculated the global emissions…

Climate

Geographical’s regular look at the world of climate change. This…

Wildlife

The latest episode sees ‘Bertie’ enlisting in wildlife rescue boot…

Energy

Icelandic engineers are attempting to harness the powerful geothermal energy…

Wildlife

New video series tracks the journey of Aaron Gekoski as…

Energy

Newly-developed ‘sustainable rubber’, produced using recycled food waste, could one…

Geophoto

This winter has seen frequent storms and flooding hitting many…

Wildlife

The bison, Poland’s symbol of nature conservation, already faces controversial…

Wildlife

Wolves have arrived at a wildlife park in Devon as…

Climate

An unassuming beach in Denmark is absorbing record-breaking levels of…

Energy

The environmental cost of military activities is significant. Could new…