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Heliograph (heliograph@mastodon.au)'s status on Sunday, 08-Sep-2024 00:40:42 JST Heliograph

TIL about the "bomb pulse" - when carbon-14 in the earth atmosphere doubled as a result of nuclear bombs and tests in the 1940s, 50s and 60s.
This increase in carbon-14 allows researchers to date human and organic samples precisely, sometimes all the way down to the month. Using the #bombpulse to accurately date samples will end when carbon-14 levels return to baseline.
Around the year 2030 the bomb pulse will die out. Every organism born after this will not bear detectable bomb pulse traces and their cells cannot be dated in this way.
https://en.wikipedia.org/wiki/Bomb_pulse
👀 💣 ☢️ ☣️ :skellysplode: someone go tell spuds about #nuclear outcomes and #carbon14
In conversation about 3 months ago from mastodon.au permalink
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  Bomb pulse
  
  The bomb pulse is the sudden increase of carbon-14 (14C) in the Earth's atmosphere due to the hundreds of aboveground nuclear bombs 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 hundreds of blasts were followed by a doubling of the relative concentration of 14C in the atmosphere. The reason for the term “relative concentration”, is because the measurements of 14C levels by mass spectrometers are most accurately made by comparison to another carbon isotope, often the common isotope 12C. Isotope abundance ratios are not only more easily measured, they are what 14C carbon daters want, since it is the fraction of carbon in a sample that is 14C, not the absolute concentration, that is of interest in dating measurements. The figure shows how the fraction of carbon in the atmosphere that is 14C, of order only a part per trillion, has changed over the past several decades following the bomb tests. Because 12C concentration has increased by about 30% over...

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