Copper Could Contribute to Ozone Depletion, New Study Finds

Copper wire scraps are seen during the construction of the new R240 electric engine of French carmaker Renault at their factory in Cleon, France, June 18, 2015. (Reuters)
Copper wire scraps are seen during the construction of the new R240 electric engine of French carmaker Renault at their factory in Cleon, France, June 18, 2015. (Reuters)
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Copper Could Contribute to Ozone Depletion, New Study Finds

Copper wire scraps are seen during the construction of the new R240 electric engine of French carmaker Renault at their factory in Cleon, France, June 18, 2015. (Reuters)
Copper wire scraps are seen during the construction of the new R240 electric engine of French carmaker Renault at their factory in Cleon, France, June 18, 2015. (Reuters)

Copper released into the environment from fungicides may be contributing significantly to stratospheric ozone depletion, according to a new study from the University of California (UC).

In a paper published Jan. 14 in the journal Nature Communications, UC geochemists show that copper in soil and seawater acts as a catalyst to turn organic matter into both methyl bromide and methyl chloride, two potent halocarbon compounds that destroy ozone. Sunlight worsens the situation, boosting production of these methyl halides by a factor of 10. The findings answer, at least in part, a long-standing mystery about the origin of much of the methyl bromide and methyl chloride in the stratosphere.

Since the worldwide ban on chlorofluorocarbon (CFC) refrigerants and brominated halons used in fire extinguishers starting in 1989, these methyl halides have become the new dominant sources of ozone-depleting bromine and chlorine in the stratosphere. As the long-lived CFCs and halons slowly disappear from the atmosphere, the role of methyl halides increases.

"By 2050, we should be back to relatively normal ozone, but things like the continued emissions of methyl bromide and methyl chloride are road bumps in the road to recovery. Copper usage in the environment is projected to increase rapidly in the next few years, and this should be considered when predicting future halogen load and ozone recovery," said the paper's senior author, Robert Rhew, UC professor of environmental science and policy.

Earth's ozone layer is critical to protecting us from cancer-causing ultraviolet light from the sun, but chemicals containing chlorine and bromine -- such as CFCs and halons -- were found in the 1980s to destroy the ozone, creating thinner layers in the stratosphere that let in more of the dangerous radiation.

Despite a ban on production of CFCs and halons, the ozone layer has yet to repair itself.

The persistence of the ozone hole is, for the most part, due to the persistence of banned ozone-depleting compounds, which take decades to dissipate in the stratosphere. But some ozone-depleting chemicals are still being emitted.

Among the major contributors today are methyl chloride and methyl bromide. One atom of bromine is 50 times more destructive to ozone than one atom of chlorine.

Though methyl bromide is banned for use as an agricultural soil fumigant, it is still used as a pesticide for quarantine and pre-shipment of agricultural products. And methyl chloride is used as a chemical feedstock, although most of its emissions are believed to be from biomass burning or natural in origin. But the total amount of these methyl halides produced each year still do not add up to the observed yearly addition of these chemicals to the atmosphere, a fact that has puzzled scientists for more than 20 years.

About one-third of the methyl bromide and methyl chloride in the atmosphere comes from unknown sources, Rhew said. The new findings suggest that copper is an important, if not the major, source of the missing methyl bromide and methyl chloride.

"We've banned methyl bromide, but are other changes that we're making in the environment causing large emissions of this compound into the atmosphere? With the increase in the use of copper, it appears that copper-catalyzed production is an increasing source, as well," Rhew said.

First author and former UC doctoral student Yi Jiao, now a postdoctoral fellow at the University of Copenhagen in Denmark, noted that copper compounds are allowed on organic crops, a legacy of its use in farming since the 1700s, including as a major antifungal agent in the Bourdeax mixture used since the 1880s in France to prevent downy mildew on grapes. Copper contamination of soils is a major issue today in Europe because of this history, and the ozone-depleting power of copper is another cause for concern.

"With widespread use of copper in the environment, this potentially growing impact should be considered when predicting future halogen load and ozone recovery. Copper combined with soil and sunlight produce more methyl halides," said Jiao.



S.Africa's Iconic Protea Flower Relocates as Climate Warms

Protea flower grower Nico Thuynsma cultivates the blooms north of Johannesburg, 1,500 km (930 miles) from their natural home at the southern tip of Africa. Phill Magakoe / AFP
Protea flower grower Nico Thuynsma cultivates the blooms north of Johannesburg, 1,500 km (930 miles) from their natural home at the southern tip of Africa. Phill Magakoe / AFP
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S.Africa's Iconic Protea Flower Relocates as Climate Warms

Protea flower grower Nico Thuynsma cultivates the blooms north of Johannesburg, 1,500 km (930 miles) from their natural home at the southern tip of Africa. Phill Magakoe / AFP
Protea flower grower Nico Thuynsma cultivates the blooms north of Johannesburg, 1,500 km (930 miles) from their natural home at the southern tip of Africa. Phill Magakoe / AFP

On his farm two hours north of Johannesburg, Nico Thuynsma gestured towards thousands of orange, yellow and pink proteas in flower and thriving 1,500 kilometers (930 miles) from their natural home at the southern tip of Africa.

"They're all different," the 55-year-old farmer said of the assorted blooms from the diverse Proteaceae family that has more than 350 species in South Africa, from firework-like "pincushion" varieties to delicate "blushing brides".

He picked out a majestic pink and white crown, nearly the size of his head, that has taken four years to reach its impressive size. "The King Proteas are very slow to grow," Thuynsma said.

The largest of the proteas, the King Protea, is South Africa's national flower.

It has lent its name to the national cricket team and countless brands. It features on the currency and is the logo for South Africa's presidency this year of the G20 group of leading economies, which convenes a summit in November.

It is also the country's largest flower export with more than 10 million stems sent abroad last year, worth close to 275 million rand ($15 million), according to the Cape Flora industry organization, said AFP.

Its status offers the King Protea some protection but almost half of South Africa's other protea species face extinction because of pressures on their native habitats in the mountains of the Cape, according to South Africa's National Biodiversity Institute (SANBI).

These include habitat loss to agriculture, the proliferation of invasive alien species and "changes to natural fire cycles", SANBI said in a 2021 report.

Icon

"People come to South Africa to see proteas," Nigel Barker, a professor in plant sciences at the University of Pretoria, told AFP. "It's the plant equivalent of the elephant or the lion."

Most proteas are endemic or semi-endemic to the Cape Floral Kingdom biome of "fynbos" ("fine bush") that stretches across the southern tip of South Africa and is one of the world's richest flora biodiversity hotspots.

But climate projections predict "hotter, drier conditions", Barker said. "We'll be looking at a completely different vegetation type in the future, semi-desert almost in some places."

"Many species, because they're so range-restricted, will probably go extinct under those scenarios," he said.

"The only solution we have is to cultivate them artificially... in greenhouses or farms where you control irrigation," Barker said.

An example is Thuynsma's farm in the grasslands of the north, where he began planting proteas three decades ago.

Here, winters are dry and frosty, and the summers rainy -- conditions very different to those in the far south where the proteas are at home.

Gel for irrigation

Through trial and error, Thuynsma has been able to cultivate close to 200 protea varieties, including some long forgotten and abandoned by farmers in their original habitats.

In his latest experiment, he has planted 36 varieties with just two liters (four pints) of saturated gel for irrigation.

"I hope to unlock the power of some of these varieties," Thuynsma said. "They come from the Western Cape out of very harsh conditions, so they do have it in them."

"I learn from them, I learn with them. And, hopefully, in the future I can advise my nursery public -- and even estates -- how to plant this lovely fynbos without irrigation," he said.

"I don't think I have a solution for climate change," he joked, crouched over a small seedling in freshly turned soil. "But I do have a solution: to plant proteas."

A few meters (yards) away, in a warm nursery, thousands of protea sprouts awaited their turn in the soil.

"I love them, I protect them, I collect them," Thuynsma said. "The protea is part of South Africa's DNA."