[fortheDeclaration]

Natural Corrections

Reservoir effects
Radiocarbon samples which obtain their carbon from a different source (or reservoir) than atmospheric carbon may yield what is termed apparent ages. A shellfish alive today in a lake within a limestone catchment, for instance, will yield a radiocarbon date which is excessively old. The reason for this anomaly is that the limestone, which is weathered and dissolved into bicarbonate, has no radioactive carbon. Thus, it dilutes the activity of the lake meaning that the radioactivity is depleted in comparison to 14C activity elsewhere. The lake, in this case, has a different radiocarbon reservoir than that of the majority of the radiocarbon in the biosphere and therefore an accurate radiocarbon age requires that a correction be made to account for it.

One of the most commonly referenced reservoir effects concerns the ocean. The average difference between a radiocarbon date of a terrestrial sample such as a tree, and a shell from the marine environment is about 400 radiocarbon years (see Stuiver and Braziunas, 1993). This apparent age of oceanic water is caused both by the delay in exchange rates between atmospheric CO2 and ocean bicarbonate, and the dilution effect caused by the mixing of surface waters with upwelled deep waters which are very old (Mangerud 1972). A reservoir correction must therefore be made to any conventional shell dates to account for this difference. Reservoir corrections for the world oceans can be found at the Marine Reservoir Correction Database, a searchable database online at Queen’s University, Belfast and the University of Washington. Human bone may be a problematic medium for dating in some instances due to human consumption of fish, whose C14 label will reflect the ocean reservoir. In such a case, it is very difficult to ascertain the precise reservoir difference and hence apply a correction to the measured radiocarbon age.

Spurious radiocarbon dates caused by volcanic emanations of radiocarbon-depleted CO2 probably also come under the category of reservoir corrections. Plants which grow in the vicinity of active volcanic fumeroles will yield a radiocarbon age which is too old. Bruns et al. (1980) measured the radioactivity of modern plants growing near hot springs heated by volcanic rocks in western Germany and demonstrated a deficiency in radiocarbon of up to 1500 years through comparison with modern atmospheric radiocarbon levels. Similarly, this effect has been noted for plants in the bay of Palaea Kameni near the prehistoric site of Akrotiri, which was buried by the eruption of the Thera volcano over 3500 years ago (see Weninger, 1989). The effect has been suggested as providing dates in error for the eruption of Thera which has been linked to the demise of the Minoan civilisation in the Aegean. One modern plant growing near the emanations had an age of 1390 yr. The volcanic effect has a limited distance however. Bruns et al. (1980) found that at 200 m away from the source, plants yielded an age in agreement with that expected. They suggested that the influence of depleted CO2 declined rapidly with increasing distance from the source. Radiocarbon discrepancies due to volcanic CO2 emissions are a popular source of ammunition for fundamentalist viewpoints keen to present evidence to show that the radiocarbon method is somehow fundamentally flawed.

http://www.c14dating.com/corr.html

[Coyoteman]

You keep posting basic low-level facts on the radiocarbon method, such as that it only extends some 50,000 years into the past, as if that should be hot news! Archaeologists are way ahead of you. We know those types of limitations and more, and we don't need cut-and-paste creationists to try to teach us how to do our jobs.

You also cite the reservoir effect as if that's something that is a serious problem for archaeologists. The reservoir effect is old news, I deal with that all the time. I have even done numerous comparisons of charcoal vs. shell to see what the extent of the reservoir effect is in the areas in which I work.

Your cut-and-paste also cites the problem of the reservoir effect when dealing with human bone, as fish in the diet can throw the age off. Actually sea mammals can be worse than fish. That's why when I radiocarbon date human bone I obtain the ¹³C and ¹⁵N stable isotope readings so that the percent of marine organisms in the diet can be ascertained and accounted for.

You are way out of your depth here. You seem to believe that radiocarbon dating is wrong (for religious reasons I presume) and you are surfing the net for anything that might help your position -- without understanding much about the subject at all.

Not very impressive. If you wish to convince anyone that the radiocarbon method is inaccurate, you have to really study and understand it first.