In living things, what is the source of the carbon-14 that is used in radiocarbon dating?
A. Carbon dioxide in rocks
B. Carbonic acid in caves
C. Carbon dioxide in the atmosphere
D. Carbon dioxide in water
Isn't Wikipedia untrustworthy??
No. I would, of course, get other opinions on a controversial subject -- but Wikipedia is right on scientific and historical questions. No one has any motivation to change anything that is not controversial.
However -- feel free to use another source.
Give me six water, six carbon dioxide. . . I take that and look what I do on the inside. Sunlight as my engine, I can’t wait to taste The glucose I make, chuck six oxygen as waste. I’m the chloroplast. Photosynthesis is my task. It’s a blast and I’m jazzed. Why’d I tell you? ‘cause you asked
The source of the carbon-14 used in radiocarbon dating is carbon dioxide in the atmosphere. To arrive at this answer, we need to understand the process of radiocarbon dating and how carbon-14 is produced in nature.
Radiocarbon dating is a method used to determine the age of organic materials by measuring the radioactive decay of carbon-14. Carbon-14 is an isotope of carbon, meaning it has the same number of protons but a different number of neutrons compared to the more common and stable carbon-12.
In the Earth's atmosphere, carbon-14 is continually produced through the interaction of cosmic rays, high-energy particles from outer space, with nitrogen-14 atoms. These cosmic rays collide with nitrogen-14 atoms and transform them into carbon-14.
Once carbon-14 is formed in the atmosphere, it enters the carbon cycle, which involves the exchange of carbon between the atmosphere, plants, and animals. Through the process of photosynthesis, plants absorb atmospheric carbon dioxide, including carbon-14, and incorporate it into their tissues.
When living organisms consume plants or other organisms, they also take in carbon, including carbon-14. While an organism is alive, the amount of carbon-14 in its tissues is in equilibrium with the carbon-14 in the atmosphere.
However, when an organism dies, it no longer takes in new carbon-14 from the environment. Over time, the carbon-14 in its tissues undergoes radioactive decay, meaning it gradually transforms back into nitrogen-14. By measuring the ratio of carbon-14 to carbon-12 in a sample, scientists can determine the time that has elapsed since the organism died.
To summarize, the source of carbon-14 used in radiocarbon dating is carbon dioxide in the atmosphere. Through a series of natural processes, carbon-14 is formed in the atmosphere and subsequently taken up by plants and ultimately incorporated into living organisms.
"The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide."
Carbon-14 - Wikipedia