scholarly journals Interpreting 14C Measurements on 3rd–4th Century AD Iron Artifacts from Nydam, Denmark

Radiocarbon ◽  
2019 ◽  
Vol 61 (5) ◽  
pp. 1517-1529
Author(s):  
C Matthias Hüls ◽  
John Meadows ◽  
Andreas Rau
Keyword(s):  
Isotopic Composition ◽  
Combustion Temperature ◽  
Peat Bog ◽  
Iron Production ◽  
Aging Effects ◽  
Carbon Dissolution ◽  
Fossil Carbon ◽  
Common Effect ◽  
Iron Artifacts ◽  
Good Agreement

ABSTRACTRadiocarbon (14C) ages were determined for 10 iron samples from the war booty offering site in the Nydam peat bog (SE Denmark), and compared to archaeologically inferred periods of deposition. Additional 14C measurements were carried out for modern iron standards made with charcoal of known isotopic composition to evaluate possible effects of handling. Modern iron standards give depleted 14C concentrations, compared to the initial charcoal 14C composition, and may indicate carbon fractionation effects during carbon dissolution in the iron lattice. Further studies are needed to verify if this is a common effect during iron production. 14C dating of two swords and one ax head are in comparatively good agreement with expected deposition times and indicate only small old-wood effects. In contrast, 14C dating of iron rivets from the Nydam (B) oak boat proved difficult due to corrosion with siderite (FeCO3) and conservation with wax. A step-combustion procedure was applied, using a low (∼570–600°C) temperature prior to the high (∼970–1000°C) combustion temperature for carbon extraction, aiming to remove siderite and wax before collecting the original carbon dissolved in the iron lattice. Nevertheless, measured 14C ages of the iron rivets differ by about 200–300 years from the dendro-date of the Nydam (B) oak boat they belong to, indicating persisting aging effects (e.g. old-wood, contamination with fossil carbon added during iron making and/or handling prior 14C dating). Also, a possible recycling of older iron cannot be excluded.

Absolute Dating of Early Iron Objects from the Ancient Orient: Radiocarbon Dating of Luristan Iron Mask Swords

Radiocarbon ◽  
2019 ◽  
Vol 61 (5) ◽  
pp. 1229-1238
Author(s):  
C Matthias Hüls ◽  
Ingo Petri ◽  
Helmut Föll
Keyword(s):  
Radiocarbon Dating ◽  
Carbon Sources ◽  
Iron Production ◽  
Museum Collections ◽  
Fossil Carbon ◽  
Slag Inclusions ◽  
Metallurgical Analysis ◽  
Absolute Dating ◽  
Production Period ◽  
Two Sides

ABSTRACTLuristan Iron Mask Swords have been recovered mostly from illegal diggings in the 1920s. The about 90 known objects are characterized by a disk-shaped pommel on the top of the handle with two mounted bearded heads on two sides. According to the similarity in form and radiocarbon (14C) measurements on two swords from museum collections, an overall short production period was assumed around 1000 BC (Moorey 1991; Rehder 1991). Here we present the results of metallurgical analysis and 14C measurements for three newly acquired Luristan swords, which were donated to the Royal Museums of Art & History, Brussels. Metallurgical analysis indicates an iron production via the bloomary furnace technique. Analyzed samples show large slag inclusions (Fayalite, Wüstite, glass) within a mostly ferritic and pearlitic iron. The carbon contents varied between 0.2 wt% to around 0.8 wt%). 14C measurements on thermally extracted carbon give 14C ages between 2800 BP–3360 BP (calibrated ∼1745 BC–900 BC). The reliability of the 14C measurements are discussed with respect to external (contamination during handling) and intrinsic contamination (e.g. fossil carbon sources during manufacture).

scholarly journals Radiocarbon and Stable Carbon Analysis of Dissolved Methane and Carbon Dioxide from the Profile of a Raised Peat Bog

Radiocarbon ◽  
2011 ◽  
Vol 53 (1) ◽  
pp. 71-83 ◽  
Author(s):  
M H Garnett ◽  
S M L Hardie ◽  
C Murray
Keyword(s):  
Isotopic Composition ◽  
Molecular Sieve ◽  
Carbon Isotopic Composition ◽  
Peat Bog ◽  
Stable Carbon ◽  
Near Surface ◽  
Carbon Isotopic ◽  
Deep Layers ◽  
Carbon Analysis

We developed and tested a new method to separate CO2 and CH4 from bulk gas samples for radiocarbon and stable-carbon analysis that utilizes a zeolite molecular sieve. To validate the technique, tests were performed using a suite of standard gases, composed of CO2 and CH4 of distinctly different isotopic composition. We employed the method to investigate the carbon isotopic composition of samples of dissolved CO2 and CH4 collected in situ from the near surface to deep layers of an ombrotrophic raised peat bog. Results showed that the age of both the CO2 and CH4 components of the dissolved gases increased with depth from ≃0–300 BP at 0.25 m to ≃4000 BP at 4 m. CH4 was mainly similar or slightly older in age compared to CO2, with the greatest difference in ages occurring at 1 m depth where CH4 was older by 430–615 yr. The δ13C values of CO2 increased with depth from −12.4‰ and −8.0‰ at 0.25 m to +6.9‰ and +8.3‰ at 4 m, whereas the δ13C of CH4 stayed in the range −58.4‰ to −70.6‰. The 14C results from the deepest layers are consistent with a similar source for both gases. 14C ages for the CO2 component were younger compared to CH4, within the shallower depths of the peat bog (≤1 m) and demonstrate the incorporation of acrotelm-derived respired CO2 into the catotelm.

scholarly journals Radiocarbon method in monitoring of fossil fuel emission

2011 ◽  
Vol 38 (4) ◽  
pp. 314-324 ◽  
Author(s):  
Andrzej Rakowski
Keyword(s):  
Isotopic Composition ◽  
Fossil Fuels ◽  
Fossil Fuel ◽  
Isotope Composition ◽  
Carbon Isotopic Composition ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Fossil Carbon ◽  
Fossil Fuel Emission ◽  
Urbanized Areas

AbstractThe traditional radiocarbon method widely used in archaeology and geology for chronological purposes can also be used in environmental studies. Combustion of fossil fuels like coal, natural gas, petroleum, etc., in industrial and/or heavily urbanized areas, has increased the concentration of carbon dioxide in the atmosphere. The addition of fossil carbon caused changes of carbon isotopic composition, in particular, a definite decrease of 14C concentration in atmospheric CO2 and other carbon reservoirs (ocean and terrestrial biosphere), known as the Suess effect. Tree rings, leaves, as well as other annual growing plants reflected the changes of radiocarbon concentration in the atmosphere due to processes of photosynthesis and assimilation of carbon from the air. By measuring radiocarbon concentration directly in atmospheric CO2 samples and/or biospheric material growing in industrial and/or highly urbanized areas where high emission of dead carbon is expected, it is possible to estimate the total emission of dead CO2. Based on equations of mass balance for CO2 concentration, stable isotopic composition of carbon and radiocarbon concentration it is possible to calculate CO2 con-centration associated with fossil fuel emission into the atmosphere. The procedure use differences between the radiocarbon concentration and stable isotope composition of carbon observed in clean areas and industrial or/and highly urbanized areas.

New Peat Bog Record of Atmospheric Lead Pollution in Switzerland:  Pb Concentrations, Enrichment Factors, Isotopic Composition, and Organolead Species

2002 ◽  
Vol 36 (18) ◽  
pp. 3893-3900 ◽  
Author(s):  
W. Shotyk ◽  
D. Weiss ◽  
M. Heisterkamp ◽  
A. K. Cheburkin ◽  
P. G. Appleby ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Enrichment Factors ◽  
Peat Bog ◽  
Lead Pollution ◽  
Atmospheric Lead Pollution

scholarly journals Comparison of total ozone from the satellite instruments GOME and TOMS with measurements from the Dobson network 1996–2000

2002 ◽  
Vol 2 (4) ◽  
pp. 1131-1157 ◽  
Author(s):  
K. Bramstedt ◽  
J. Gleason ◽  
D. Loyola ◽  
W. Thomas ◽  
A. Bracher ◽  
...  
Keyword(s):  
Total Ozone ◽  
Stratospheric Ozone ◽  
Network Data ◽  
Global Changes ◽  
Hemispheric Differences ◽  
Aging Effects ◽  
Data Processor ◽  
Ozone Column ◽  
Good Agreement

Abstract. Over the last 3 decades, satellite data have been used to monitor long-term global changes in stratospheric ozone. The TOMS series (1978 -- present) and GOME (1995 -- present) are two very important instruments in this context. In this paper, TOMS total ozone and three approaches to derive total ozone from GOME measurements are validated with ground-based Dobson network data. Beyond the operational products of both instruments, e.g. TOMS Version 7 and GOME Data Processor Version 2.7, total ozone is calculated by integrating FURM ozone profiles and by applying the TOMS algorithm to the GOME spectra. All algorithms show in general good agreement with ground-based measurements. The operational GOME total ozone shows seasonal variations, most likely introduced by difficulties in the derivation of airmass factors, which convert measured slant columns into vertical columns. The TOMS algorithm estimates on average 2% higher total ozone in the southern hemisphere than in the northern for both instruments as compared to the ground-based data, indicating that the source of the observed hemispheric differences is in the TOMS algorithm. Both instruments show aging effects in 2000, leading to enhanced variability in the ozone column differences with respect to Dobson data. In addition, the integrated GOME ozone profiles and the TOMS algorithm applied to GOME data show larger mean deviations in 2000.

scholarly journals Comparing past accumulation rate reconstructions in East Antarctic ice cores using <sup>10</sup>Be, water isotopes and CMIP5-PMIP3 models

2015 ◽  
Vol 11 (3) ◽  
pp. 355-367 ◽  
Author(s):  
A. Cauquoin ◽  
A. Landais ◽  
G. M. Raisbeck ◽  
J. Jouzel ◽  
L. Bazin ◽  
...  
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Atmospheric Composition ◽  
Water Isotopes ◽  
Polar Regions ◽  
Antarctic Plateau ◽  
Good Agreement

Abstract. Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 kyr in Antarctica. Inferring the variations in past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic Plateau, the accumulation rate is so small that annual layers cannot be identified and accumulation rate is mainly deduced from the water isotopic composition assuming constant temporal relationships between temperature, water isotopic composition and accumulation rate. Such an assumption leads to large uncertainties on the reconstructed past accumulation rate. Here, we use high-resolution beryllium-10 (10Be) as an alternative tool for inferring past accumulation rate for the EPICA Dome C ice core, in East Antarctica. We present a high-resolution 10Be record covering a full climatic cycle over the period 269 to 355 ka from Marine Isotope Stage (MIS) 9 to 10, including a period warmer than pre-industrial (MIS 9.3 optimum). After correcting 10Be for the estimated effect of the palaeomagnetic field, we deduce that the 10Be reconstruction is in reasonably good agreement with EDC3 values for the full cycle except for the period warmer than present. For the latter, the accumulation is up to 13% larger (4.46 cm ie yr−1 instead of 3.95). This result is in agreement with the studies suggesting an underestimation of the deuterium-based accumulation for the optimum of the Holocene (Parrenin et al. 2007a). Using the relationship between accumulation rate and surface temperature from the saturation vapour relationship, the 10Be-based accumulation rate reconstruction suggests that the temperature increase between the MIS 9.3 optimum and present day may be 2.4 K warmer than estimated by the water isotopes reconstruction. We compare these reconstructions to the available model results from CMIP5-PMIP3 for a glacial and an interglacial state, i.e. for the Last Glacial Maximum and pre-industrial climates. While 3 out of 7 models show relatively good agreement with the reconstructions of the accumulation–temperature relationships based on 10Be and water isotopes, the other models either underestimate or overestimate it, resulting in a range of model results much larger than the range of the reconstructions. Indeed, the models can encounter some difficulties in simulating precipitation changes linked with temperature or water isotope content on the East Antarctic Plateau during glacial–interglacial transition and need to be improved in the future.

Carbon Blacks and Their Use in Rubber. III—Aging Effects

1928 ◽  
Vol 1 (3) ◽  
pp. 475-484
Author(s):  
L. B. Cox ◽  
C. R. Park
Keyword(s):  
Zinc Oxide ◽  
Carbon Black ◽  
Stearic Acid ◽  
Weight Increase ◽  
Aging Effects ◽  
Carbon Blacks ◽  
Aging Properties ◽  
Good Agreement

Abstract The aging properties of compounded rubber stocks are affected by the carbon black which is used. The order of increasing superiority for the blacks tried is Super Spectra, Micronex, Charlton, Goodwin, and Thermatomic. The order of increasing superiority of accelerators is diphenylguanidine, hexamethylenetetramine, ethylidene-aniline, mercaptobenzothiazole. The last two are put in this order mainly because of the inferior original properties of ethylidene-aniline. Results of tensile, abrasion, and weight increase tests are in reasonably good agreement. The effect of acidity in any compounding material is neutralized in a stock containing zinc oxide. Stearic acid is without effect upon aging properties of cured rubber.

Americium-241 in peat bogs as a marker of the beginning of the Anthropocene: examples from Europe and North America.

2021 ◽  
Author(s):  
Andrii Oleksandrenko ◽  
Peter Appleby ◽  
Tommy Noernberg ◽  
William Shotyk
Keyword(s):  
North America ◽  
Excellent Agreement ◽  
Half Life ◽  
High Yield ◽  
Small Scale ◽  
Peat Bogs ◽  
Peat Bog ◽  
Poor Agreement ◽  
Polar Snow ◽  
Good Agreement

&lt;p&gt;Americium-241 (&lt;sup&gt;241&lt;/sup&gt;Am) is present in the terrestrial and aquatic environment around the globe as a result of the atmospheric testing of high yield thermonuclear weapons carried out mainly in the 1950s and 1960s. Radioactive debris (including mainly &lt;sup&gt;137&lt;/sup&gt;Cs, &lt;sup&gt;90&lt;/sup&gt;Sr, and various Pu isotopes) from the tests was injected high into the stratosphere where it was rapidly dispersed around the world. Over a period of months this material slowly returned to the troposphere, and from there was quickly removed by wet and dry fallout onto the earth&amp;#8217;s surface. Amounts of &lt;sup&gt;241&lt;/sup&gt;Am in freshly deposited weapons test debris were essentially zero. Its presence today is through in-growth from its short-lived precursor &lt;sup&gt;241&lt;/sup&gt;Pu (half-life 14.4 years). By this process concentrations of &lt;sup&gt;241&lt;/sup&gt;Am have steadily increased with time and will continue to do so through to around 2040. Widely considered to be immobile in soils and sediments, with its well-known origins and long half-life (432 years), &lt;sup&gt;241&lt;/sup&gt;Am is in many ways an ideal chronostratigraphic marker of the nuclear age. Calculations show that the &lt;sup&gt;241&lt;/sup&gt;Am record in any ideal natural archive is a faithful representation of the history of weapons test fallout. Beginning in the early 1950s, fallout reached a peak in 1963 and then declined rapidly following the implementation of the test ban treaty. A number of scientists have proposed that the weapons test fallout peak could be used to mark the start of the Anthropocene. Various geological archives preserve the record of fallout, though with varying degrees of fidelity. They include polar snow and ice, marine and lacustrine sediments, and peat bogs. Bogs are ombrotrophic peatlands in that the plants growing there receive nutrients and contaminants exclusively from the atmosphere. The purpose of this study is to determine the fidelity of &lt;sup&gt;241&lt;/sup&gt;Am records in peat bog cores.&lt;br&gt;Specifically, we compare the position of the &lt;sup&gt;241&lt;/sup&gt;Am concentration peak with the 1963 depth determined by &lt;sup&gt;210&lt;/sup&gt;Pb dating. We use 39 peat cores from Europe, North America, and Indonesia collected by our team during the past 30 years for studies of atmospheric deposition of trace metals, all of which had been independently dated using &lt;sup&gt;210&lt;/sup&gt;Pb. We find that 18 of the cores provide an excellent agreement between the &lt;sup&gt;241&lt;/sup&gt;Am and &lt;sup&gt;210&lt;/sup&gt;Pb dates, 12 were in good agreement, and 9 agreed poorly. Possible reasons for the discrepancy in the 9 cores with the poor agreement are 1) the sensitivity of the gamma spectrometer for detecting &lt;sup&gt;241&lt;/sup&gt;Am, and 2) disruptions to the fallout records caused e.g. by disturbances to the peat bog or changes in the peat topography or hydrology. Small scale horizontal and vertical variations in bogs help explain why in a triplicate of peat cores collected from Wildseemoor in the Black Forest of Germany, excellent agreement was found in one core, good agreement in a second, and poor agreement in the third. A peat core collected from Gola di Lago, a small fen in Switzerland, showed excellent agreement; this suggests that samples from minerotrophic peatlands may also be useful to mark the start of the Anthropocene.&lt;/p&gt;

scholarly journals Coupled isotopes of plant wax and hemicellulose markers record information on relative humidity and isotopic composition of precipitation

2015 ◽  
Vol 12 (3) ◽  
pp. 2459-2489
Author(s):  
M. Tuthorn ◽  
R. Zech ◽  
M. Ruppenthal ◽  
Y. Oelmann ◽  
A. Kahmen ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Arid Regions ◽  
Mechanistic Model ◽  
Leaf Water ◽  
Deuterium Excess ◽  
Leaf Wax ◽  
Climate Reconstructions ◽  
Relative Air Humidity ◽  
Plant Wax ◽  
Good Agreement

Abstract. The δ2H isotopic composition of leaf waxes is used increasingly for paleohydrological and -climate reconstructions. However, it is challenging to disentangle past changes in the isotopic composition of precipitation and changes in evapotranspirative enrichment of leaf water. We analyzed δ2H on n-alkanes and fatty acids in topsoils along a climate transect in Argentina, for which we had previously measured δ18O on plant-derived sugars. Our results indicate that leaf wax biomarker δ2H values (δ2Hlipids) primarily reflect δ2Hsource water (precipitation), but are modulated by evapotranspirative enrichment. A mechanistic model is able to produce the main trends in δ2Hlipids along the transect, but seems to slightly underestimate evapotranspirative enrichment in arid regions and overestimate it in grass-dominated ecosystems. Furthermore, the (i) coupling of the δ2Hlipid and δ18Osugar biomarker results and (ii) application of biosynthetic fractionation factors allows calculating the δ2H-δ18O isotopic composition of leaf water along the transect. This also yields the deuterium excess (d excess) of leaf water, which mainly reflects evapotranspirative enrichment, and can be used to model relative air humidity (RH). The high correlation of modeled (reconstructed based on biomarker results) and measured RH, as well as the good agreement between modeled and actual δ2H and δ18O of precipitation along the transect lends support to the coupled δ2Hlipid and δ18Osugar biomarker approach for future paleoclimate research.

Variations in the Isotopic Composition of Volatilized Lead and the Age of the Western Granodiorite, Yellowknife, Northwest Territories

1975 ◽  
Vol 12 (4) ◽  
pp. 558-573 ◽  
Author(s):  
G. L. Cumming ◽  
F. Tsong
Keyword(s):  
Isotopic Composition ◽  
Time Interval ◽  
Short Time Interval ◽  
Mineral Isochron ◽  
Ore Minerals ◽  
Igneous Activity ◽  
Different Temperatures ◽  
Almost All ◽  
Short Time ◽  
Good Agreement

Large variations in the isotopic composition of Pb volatilized at different temperatures from rocks occur, and are linearly related. The line so obtained may be treated as a mineral isochron and interpreted in the same way as for the equivalent Rb/Sr case. For the western granodiorite at Yellowknife, we obtain a whole rock Pb/Pb age of 2675 m.y. and a series of mineral ages ranging from this upper limit down to about 2500 m.y. The whole rock age is in good agreement with other work and the range of mineral isochron ages is consistent with a cooling interval of about 150 m.y. as deduced by others. A comparison with other recent age determinations from the same area indicates that almost all the significant igneous activity and the emplacement of the ore minerals occurred in a very short time interval around 2650 m.y. ago.

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