Our directory of things of interest

University Directory

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.

Related items

Geographical Week

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

Subscribe to Geographical!

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The 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

  • The Human Game – Tackling football’s ‘slave trade’
    Few would argue with football’s position as the world’s number one sport. But as Mark Rowe discovers, this global popularity is masking a sinister...
    Essential oil?
    Palm oil is omnipresent in global consumption. But in many circles it is considered the scourge of the natural world, for the deforestation and habita...
    National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    The green dragon awakens
    China has achieved remarkable economic success following the principle of developing first and cleaning up later. But now the country with the world's...
    The Nuclear Power Struggle
    The UK appears to be embracing nuclear, a huge U-turn on government policy from just two years ago. Yet this seems to be going against the grain globa...

MORE DOSSIERS

NEVER MISS A STORY - Follow Geographical on Social

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...

Oceans

With the war against plastic gaining publicity and popularity, one…

Wildlife

India’s booming domestic dog population is attacking some of the…

Energy

Soaring sales of air conditioning units over the next thirty…

Climate

Well-meaning promises and actions don't always have the best outcomes.…

Geophoto

With the days at their longest and more light in…

Oceans

Tourism might be an economic pillar for many countries surrounding…

Wildlife

Brain sizes directly shown to correlate to survival rates among…

Wildlife

Celebrated author Professor Tim Birkhead provides a fascinating insight into…

Oceans

The world’s most biodiverse seagrass region – Indonesia’s Coral Triangle…

Oceans

Ocean conservation group urges world governments to step up action…

Climate

As climate conditions at the 100th meridian, the traditional United…

Climate

International shipping may be attempting to reduce its carbon footprint, but…

Geophoto

So much photographic theory is dedicated to image sharpness that…

Wildlife

Changing temperatures in East Africa are set to upset a delicate…

Climate

As the planet warms and tensions rise, Marco Magrini finds that…

Oceans

A deep-sea mission in the ocean around Bermuda confirms the…

Oceans

An oxygen-deprived ‘dead zone’ in the Arabian Sea is much…

Wildlife

Scientists working with new drone technology are hoping to reveal…

Oceans

A new virtual reality experience, ‘BBC Earth: Life in VR’,…

Nature

Faced with protecting a country more than 30 times the…