Gatineau Park foliage reveals local Cold War nuclear testing legacy

nature & planetPhys.org

Gatineau Park foliage reveals local Cold War nuclear testing legacy

from Phys.org

For more than six decades, local scientists have collected sugar maple leaves from Gatineau Park to measure their radiocarbon levels, creating the longest continuous record of its kind. Now, a study of those leaves led by the André E. Lalonde National Facility for Accelerator Mass Spectrometry (AEL-AMS) located at the University of Ottawa shows that the effects of Cold War–era nuclear weapons testing have only recently disappeared from the local biosphere. The study, titled "Stored carbohydrates buffer Bomb and Suess radiocarbon effects in maple leaves across a 65-year Ottawa region record," was published in Scientific Reports.

explained

The bomb pulse is the sudden increase of carbon-14 (14C) in Earth's atmosphere due to the hundreds of above-ground nuclear tests that started in 1945 and intensified after 1950 until 1963, when the Limited Test Ban Treaty was signed by the United States, the Soviet Union and the United Kingdom. These blasts were followed by an almost doubling of the relative concentration of 14C in the atmosphere.

Measurements of 14C levels by mass spectrometers are most accurately made by comparison to another carbon isotope, often the common isotope 12C. The figure shows how the relative concentration of 14C in the atmosphere, of order only 1 part per 1012, changed following the first bomb test in 1945. The increase in atmospheric 12C since 1955 has reduced the relative concentration of 14C to pre-1955 values, even though the absolute 14C concentration remains elevated.

14C is naturally produced in trace amounts in the atmosphere and can be detected in all living things. Carbon of all types is continually used to form the molecules of the cells of organisms. Doubling of the concentration of 14C in the atmosphere is reflected in the tissues and cells of all organisms that lived around the period of nuclear testing. This property has many applications in biology and forensics.

From Wikipedia: Bomb pulse (CC BY-SA 4.0) ↗

how it works

Carbon-14 spikes in the air, trees fix it into sugars during photosynthesis, and stored sugars are used again in later seasons. So leaves keep echoing old air for years.

so what

The same 'bomb pulse' is used to date human tissue, wine and illegal ivory. A clean, long leaf record lets researchers measure how fast carbon cycles through living things and how fossil-fuel carbon is diluting the air's radiocarbon.

the bigger pattern

The signal peaked in 1963-64, just before the Partial Test Ban Treaty, and has declined ever since as the oceans and plants absorbed the excess.

fun fact

Because of bomb carbon, the age of a person's tooth enamel can be pinned down to within a year or two.

D. W. Griffith’s A Corner in Wheat (1909)

the gist

In 1909 D. W. Griffith made a 14-minute film about a speculator who corners the wheat market and doubles the price of bread. A farmer sows his field while a 'Wheat King' gambles in the Chicago wheat pit; bakers raise the loaf from five cents to ten and the poor line up for bread. Griffith cut back and forth between the farm, the feast and the breadline, a technique called parallel editing, so audiences saw both ends of the economy at once. The film drew on Frank Norris's stories and on a real scheme: months earlier Chicago financier James Patten had cornered wheat, sent bread prices up and made about $5 million, roughly $185 million today.

how it works

To corner a market, a trader buys up most of the available supply and the futures contracts that promise more. Anyone who has to deliver the commodity must then buy from the cornerer at whatever price is demanded. The trader profits until the stock is released or the scheme collapses.

so what

A century on, it still shows how markets can be rigged by someone who controls supply, and how the people at either end, farmers and eaters, pay for it. It also helped establish editing as a way to argue a point, not just tell a story.

the bigger pattern

Corners have recurred whenever supply could be locked up, from the Hunt brothers' attempt on silver in 1979 to 1980 to the 'Black Friday' gold panic of 1869. Many such schemes end by collapsing, and the response is often new rules on speculation.

fun fact

In the film the Wheat King dies by falling into a grain elevator and being buried in the wheat he hoarded, an ending borrowed from Norris's novel The Octopus.

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