Radiocarbon - Science topic

I have completed the age-depth model Using Bacon 2.2 software for radiocarbon age dating, where the calibrated age range (minimum-maximum), mean and median values are only provided. However, there is no uncertainties value are given at the output. I want to add the error bars on the calibrated obtained chronology, as they could be an important factor. How to add error bar to the obtained chronology?

I need to find the records for a radiocarbon analysis done in the 1970s. I have found out that the lab was Teledyne Isotopes, in Germany (lab code I). Radiocarbon's list on lab codes says that the Lab is no longer operational. I did find in the Radiocarbon journal several reports of dates from Teledyne but none are the ones I am looking for.  Any suggestions? The samples I need info on are I-9248, I-9249 and I-9250. The author who originally published the dates does not report the radiocarbon age, just a calendar date and the lab code, and he has no additional information (I spoke to him already). 

I could find younger radiocarbon age ( of the thermocline dwelling species compare to the surface-dwelling planktic foraminifera species, for a particular duration. Also, the radiocarbon age difference of the benthic species and surface species is quite low at the same time (near to 0).

I've de-fatted some bone samples and analysed the "waste solution" via GC-MS to see how well the de-fatting worked before I gelatinise them. However, I don't know what the expected initial lipid content of bone is in mg/L to determine how much has been removed from the bone. The only publication I could find was by During et al. (2015), and they give the lipid content of bone in g/100g. Are there any publications that refer to the lipid content of bone in mg/L?

The radiocarbon ages (say for the Holocene) is calibrated to Before Present (1950) by using calibration curves and with software such as OXCal. If you use other dating methods such as U series or Luminescence, the age is calculated (Before Sampling Year, lets say 2018). What would be the best way to calibrate these two type of ages, simply add 68 years to 14C age? or calibrate U/Th or Lum ages to 1950?

Hi,

I recently cores a site in the Snowy Mountains in Australia and got AMS dating done on three depths (51, 61, 67 cm). 51 cm and 61 cm came out with what I would think of as normal ages, as in 757 +-16 for 51 cm and 591+-18 for 61 cm. However, the sample at 67 cm came back as 114.7 +- 0.3%, which I found means it has a percentage of modern carbon in it(not sure how to explain it exactly). When I looked this up it was suggested that I put it into the modern carbon function of Rbacon pMC.Age to get a 'real age'. Rbacon pumped out -1102 +- 21, then they packed up and called it a night, leaving me to wonder what exactly that number means. My guess is that I should subtract it from 1950, giving me the age 848. I've talked to others who said this is completely wrong and I have no room to dispute that. Could someone give me a definitive answer on what to do with this type of data?

Thanks!

Mark

I am looking for a book

"Radiocarbon dating practices at ANU" by Gupta and Polach, published in 1985.

Can anyone please provide the link or source from where I can get this book?

Thank you

Do you now any alternative (and cheaper) method to radiocarbon for biological museum samples datation?

Thank you

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By using floating chambers and the SrCl2 precipitation method, I collected radiocarbon isotope (C14) samples of CO2 evasion from river water surface. For the emitted CO2, the measured stable carbon isotopes ( δ13C) varied from -30.2‰ to -23.2‰, and the conventional age calculated from Δ14C values ranged from 800 to 1900 years. Could I conclude that it is the old fraction of riverine organic carbon, not the young fraction, that was degraded during fluvial delivery and emitted into the atmosphere? While numerous studies have been conducted on C14 fractionation in various biogeochemical processes, such as respiration and photosynthesis, very little has been done for the process of CO2 evasion.

Any help will be greatly appreciated. Many thanks.

Dear colleagues,

we've been looking for synthetic (14C-free) ethanol for some time, unfortunately it seems that commercial suppliers, at least those we have contacted, are not interested in selling small quantities (thanks again Florian Glodeanu for the tips). Does anyone know about a laboratory / department which has a spare amount (e.g., 0.5 L) of synthetic ethanol in possession and would be willing to "devote" it to our research?

Does anyone know about a supplier which could provide ethanol free of ¹⁴C (radiocarbon), i.e. made from oil (petroleum) or any other fossil fuel?

Question about radiocarbon :

(1) which tissues (part) should be measured, if I want to know the defoliation effect on current year NSC allocation to growth of trees.

(2) What is the difference between dry matter radiocarbon content and extracted mobile sugar-carbon-14 ? 

Suppose there is a lake receiving DIC only from the atmosphere. Thus the radiocarbon reservoir age is zero. Also suppose we have two samples from this lake: one is terregenic leaves with a 14C specific activity of 90 PMC and a delta-13C value of -25 per mil, and the other is an in-situ gastropods with a 14C specific activity of 90 PMC too but a delta-13C value of -6 per mil (e.g., same to that of the contemporaneous atmosphere). The samples were dated in year 2016. Therefore, the conventional radiocarbon age of these samples are calculated to be 780 and 1090 yr BP. The difference is ca. 300 years, which defines the reservoir age. Clearly, this is due to the mass-dependent fractionation effect, rather than the inclusion of old carbon. The actual situation is much more complicated than this case and the lake always receives 14C-depleted DIC from other sources. My question is how to exclude this isotopic fractionation effect when studying the hard-water effect in practice?

I faced a problem with AMS dates of human bones. The dates of a sample of human remains appeared apparently too old, and I tend to explain this by the freshwater reservoir effect. As far as I understand, AMS dates of herbiovare animals should reflect the true age or something much closer to it, as they are not affected by the freshwater reservoir effect. But the thing is that everything I have in most of the cases is human remains. But there are several burials in the region of my interest of humans and horses buried together. So I am wondering if AMS dating alongside stable isotope (δ13C and δ15N) analysis of both individuals could help to measure the freshwater reservoir effect? Simply speaking, is it possible to detect the relationship between the level of aquatic food in human bone and deviation of its radiocarbon age (using the horse bone as a background, i.e. something with zero freshwater reservoir effect)? Could this approach be used to model true AMS dates for those human individuals with no related herbiovares, too? E.g. x=y+z, where x is the true age, y is radiocarbon age, and z is freshwater age (calculated on the basis of stable isotope levels in particular human compared to those of herbiovares in a given area).

I have been trying to calibrate some F14C data by 3 different ways: Oxcal, CALIbomb and clam, my samples are recent but then when I am doing the calibration it shows for a sample of 2015 as it was from 195, so I am not getting any logical calibration curve in any of the mentioned programs, does anyone know how can I fix this?

SOM radiocarbon (Δ14C) data provide a useful metric for benchmarking predictions of SOM dynamics because it can be used to characterize the residence time in soil since fixation from the atmosphere. 14C profiles in soils show a monotonic decline with depth. What physical factors control the monotonic depletion of 14C at depths?

Smaller alterations in radiocarbon dated samples are often very hard to recognise. Is it possible to use the N14 content as an indicator of samples reliability?

This discussion is a spin-off of a post intiated from https://www.researchgate.net/post/How_do_you_see_the_integration_of_Archaeology_and_Archaeometry?_tpcectx=qa_overview&_trid=53ba748dd039b166518b462b_1

Is one C14 date sufficient to do age calibration and age-depth model? I am working on a peat deposit from which a 120 cm peat sample was extracted.

Dead roots approx 40m long found in deep soil profile up to 100m, which formed on rock of ~3Ga age. What is the best tool to date the sample like this? I will appreciate your answers.

Dating lab comparison.