Talk:Carbon-14

box

COMMENTED OUT UNTIL AN EXPLANATORY CAPTION (clarifying the meaning and relationship of each one of the entries) IS WRITTEN FOR THIS BOX:

The Hydrocarbons

The article tells:

Many man-made chemicals are derived from fossil fuels (such as petroleum or coal) in which 14 C is greatly depleted because the age of fossils far exceeds the half-life of 14 C.

My questions are: should there be mentioned the chemical compound called the hydrocarbons instead of fossil fuels?

For the man-made chemical petroleum products, such as oil or diesel oil, are produced or derived from the hydrocarbons they claim.

And do You think that is possible to extract oil from the hydrocarbons called the coal?

Just an inquiry... Kartasto (talk) 07:41, 6 July 2023 (UTC)

Chemicals can be made from recent organic matter, such as vegetable oils. So, biodiesel will be new, and refined from oil wells will be old. So, it should say fossil fuel when it is sourced from oil well products. Gah4 (talk) 05:20, 7 July 2023 (UTC)

Human-made...

According to latest edit by the user HeyElliott human-made chemicals are derived from fossil fuels (such as petroleum or coal)...

There is, however, an article concerning the Abiotic staff in Wikipedia:

https://en.wikipedia.org/wiki/Abiogenic_petroleum_origin

The text inside it is guiding us:

The presence of methane on Saturn's moon Titan and in the atmospheres of Jupiter, Saturn, Uranus and Neptune is cited as evidence of the formation of hydrocarbons without biological intermediate forms...

My interpretation regarding the term intermediate is related to the consept of fossils (without biological intermediate forms).

May I inquiry how do You interpret further the abiotic hydrocarbons such as methane for this article? Kartasto (talk) 04:39, 7 July 2023 (UTC)

Methane is the simplest hydrocarbon, easiest to make, and expected to exist in many places in the universe. There had to be someone complicated organic compounds before life began, but then early life ate them up. Fossil fuels have biological origin, as that is where the name comes from, but lost most of the actual biology. If you take earth life, heat it up without air, you get either hydrocarbons (gas and oil), or, eventually, coal. Gah4 (talk) 05:28, 7 July 2023 (UTC)

Chemicals

User User:Gah4 wrote:

Chemicals can be made from recent organic matter, such as vegetable oils. So, biodiesel will be new, and refined from oil wells will be old. So, it should say fossil fuel when it is sourced from oil well products.

I would like to know if the vegetable oils are chemicals by definition?

So biodiesel is likewise produced from hydrocarbons, such as the new vegetable oil?

The definition of the fossil after Wikipedia explains:

A fossil (from Classical Latin fossilis, lit. 'obtained by digging') is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the fossil record.

And:

Specimens are usually considered to be fossils if they are over 10,000 years old

Are those vegatable oils digged? Kartasto (talk) 05:35, 7 July 2023 (UTC)

Food, water, air, gasoline, alcohol, are all chemicals. Vegetable oils are made by heating up vegetables, often seeds, and collecting the oils that come out. There are industrial processes that use chemicals extracted from recently living plants, and others that use fossil oil and gas. Usually the one that is cheaper is the one that is used. Gah4 (talk) 07:26, 7 July 2023 (UTC)

Background abundance of 14C in the atmosphere

In the body, the article says:

...and carbon-14 (¹⁴C), which occurs in trace amounts, making up about 1 or 1.5 atoms per 10¹² atoms of carbon in the atmosphere.

The sidebar says something slightly different:

Natural abundance: 1 part per trillion = $1/10^{12}$

The sidebar, unfortunately, doesn't mention whether that's a molar fraction or a mass fraction, nor whether that's the abundance within in the atmosphere or some sort of average (atmosphere & ocean?).

Neither the article nor the sidebar give references for the figures.

I found a recent paper which reports a "standard isotopic fractional abundance" ¹⁴r_std (¹⁴C/C) = 1.170 × 10⁻¹²:

Orr, J.C. et al (2017). Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP), Geosci. Model Dev., 10, 2169–2199, https://doi.org/10.5194/gmd-10-2169-2017.

It also mentions an earlier figure of 1.176 × 10⁻¹² which, it says, is not quite correct.

I think that the 1.170 × 10⁻¹² figure is a molar fraction in the atmosphere, not a mass ratio, but I'm not 100% certain. Does anyone know for sure?

Also, I don't know whether or not that "standard" ratio is believed to be the "preindustrial" (1700s?) level. Does anyone know?

It is my understanding that the combination of now-mostly-decayed "14C bomb spike" (increase) and Suess dilution (decrease) have given us a current (2024) atmospheric ¹⁴C/C ratio which is, coincidentally, almost exactly equal to the preindustrial ratio. However, that won't last. Fossil CO2 emissions are continuing to reduce the ratio.

I also found a paper which makes it sound like the terminology used in the academic literature is a bewildering mess:

Stenström. K.E. et al (2011). A guide to radiocarbon units and calculations. Lund University, Department of Physics, Division of Nuclear Physics Internal Report LUNFD6(NFFR-3111)/1-17/(2011). https://www.hic.ch.ntu.edu.tw/AMS/A%20guide%20to%20radiocarbon%20units%20and%20calculations.pdf

It gets worse. Here's a plot indicating that (¹⁴C/C) was at roughly 50% higher 24,000 years ago! I have no idea whether that is correct. If it is correct, it suggests a much higher rate of 14C production in the stratosphere in the past (presumably indicating a strong cosmic radiation flux, perhaps due to a weaker solar magnetosphere), and it means that "preindustrial" is a rather imprecise term, in this context.

https://physics.stackexchange.com/questions/467480/what-exactly-is-delta-14c-and-why-are-there-periodic-plateaus-in-the-delta-14c-c

Correction (20 May 2024): The reason ¹⁴C was roughly 50% higher 24,000 years ago is simply that the total carbon (mostly CO2) level was 1/3 lower 24K years ago. The total amount of ¹⁴C in the air was about the same. Since ¹⁴C is formed from ¹⁴N (rather than ¹²C or ¹³C), the rate of ¹⁴C formation is independent of the amount of CO2 in the air, and when the CO2 level is higher the ¹⁴CO2 is a smaller fraction of it.

NCdave (talk) 03:44, 26 February 2024 (UTC) (edited 20 May 2024)