Atmospheric Δ¹⁴CO₂ trend in Western European background air from 2000 to 2012

Abstract

C values at Schauinsland are considered best suited as input for studies of biospheric carbon cycling in midnorthern latitudes or for dating of organic material of the last half century.

Radiocarbon dating of seized ivory confirms rapid decline in African elephant populations and provides insight into illegal trade

“…Both Vogel et al (23) and Uno et al (25) note that the 14 C/ 12 C atmospheric record gives ivory ages that are, in general, 0-2 y earlier than the known age of the sample. This age mismatch likely results from several processes: (i) differing 14 C/ 12 C ratios between the NH and SH compounded by the lack of atmospheric 14 CO 2 measurements in the mixing zone between the hemispheres (i.e., equatorial Africa), (ii) the remobilization of nonstructural carbon during plant growth, (iii) the time lag between C fixation by plants and ingestion of plants by an elephant, and (iv) recycling of proteins in mammals. Each of these is discussed below.…”

“…Atmospheric samples collected near the equator should have a time-F 14 C relationship between that of the NH and SH due to mixing across the ITCZ. Atmospheric 14 C (as 14 CO 2 ) enters the terrestrial biosphere by photosynthesis; 14 C is subsequently incorporated into herbivore tissues as the animals ingest plants for food. The bomb- 14 C signal has been used in human forensic studies (17)(18)(19)(20)(21) and has also been used previously to date ivory and other animal tissues including hair, horn, and tooth enamel (22)(23)(24)(25).…”

“…1B). We assume that the incorporation of 14 C from diet into proteinaceous tissue is the same for elephant hair keratin as it is for elephant ivory collagen and thus use the calibration curve to determine the date of death of the elephant from which each seized tusk originated. If a calibration curve can be generated from ivory of known age-and differs significantly from the calibration curve generated from elephant hair-dates can be recalculated using such new data.…”

“…Significance C-14 dating methods can be used to determine the time of death of wildlife products. We evaluate poaching patterns of elephants in Africa by using 14 C to determine lag time between elephant death and recovery of ivory by law enforcement officials. Most ivory in recent seizures has lag times of less than 3 y. Lag times for ivory originating in East Africa are shorter, on average, than the lag times for ivory originating in the Tridom region (CameroonGabon-Congo).…”

“…Future calibrations for ivory, or for other wildlife products, to obtain "age" determinations using F 14 C measurements should focus on obtaining samples near regions of interest; such calibrations will further improve the age estimates of this and other studies. 14 Ivory for date-of-death determination was sampled from the pulp cavity of tusks (the proximal end of the tusk; Fig. 2 and Fig.…”