scholarly journals Institut Fondamental D'Afrique Noire Radiocarbon Dates I

Radiocarbon ◽  
1974 ◽  
Vol 16 (3) ◽  
pp. 304-306 ◽  
Author(s):  
Cheikh Anta Diop
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Radiocarbon Dating ◽  
Chromic Acid ◽  
Barium Carbonate ◽  
Ammonium Hydroxide ◽  
Complete Oxidation ◽  
Foreign Material ◽  
Radiocarbon Dates ◽  
Inorganic Carbonate

We follow the same method of radiocarbon dating used in the Gif-Sur-Yvette dating laboratory. Samples are inspected and foreign material removed. Wood and charcoal samples are treated with 0.1N ammonium hydroxide and 0.1N hydrochloric acid. Shells are treated with 10% hydrochloric acid to eliminate surface contamination. Bone samples are treated with 0.1N ammonium hydroxide to remove humic acids and 10% HCl to remove inorganic carbonate and retain collagen for radiocarbon measurements. Sample CO2 is produced by combustion in oxygen. The stream of gases passes over CuO at 600°C to insure complete oxidation of C to CO2 and through traps containing, respectively, silver nitrate and sulfuric chromic acid solution for purification; barium carbonate is precipited from barium hydroxide bubblers. After filtering and drying, CO2 is liberated from barium carbonate by sulfuric acid. The CO2 is used to fill a 1.2L steel proportional counter at 740mm Hg. Age calculations are based on a 14C half-life of 5568 ± yr and 0.95 of activity of the NBS oxalic acid standard; ages are quoted in yr before 1950. Finite ages are quoted with 1σ criterion corresponding to the standard deviation based only on counting errors; the maximum age is quoted with 4 σ criterion above background.

When Dental Enamel is Put to the Acid Test: Pretreatment Effects and Radiocarbon Dating

Radiocarbon ◽  
2016 ◽  
Vol 58 (4) ◽  
pp. 893-904 ◽  
Author(s):  
Rachel J A Hopkins ◽  
Christophe Snoeck ◽  
Thomas F G Higham
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Radiocarbon Dating ◽  
Dental Enamel ◽  
Chemical Pretreatment ◽  
Acid Pretreatment ◽  
Radiocarbon Dates ◽  
Pretreatment Effects ◽  
High Level ◽  
Acid Test

AbstractThe influence of hydrochloric acid pretreatment on F14C and radiocarbon dates from dental enamel was investigated. Samples from modern equine incisors, a Roman cattle molar, and a Paleolithic woolly rhino molar were sampled and subsequently divided into five fractions. Each fraction was pretreated with a different acid solution, analyzed with Fourier transform infrared spectroscopy (FTIR), and accelerator mass spectrometry (AMS) 14C dated at the Oxford Radiocarbon Accelerator Unit (ORAU). When compared to a control date (e.g. dentine collagen), better results were observed when increased concentrations of hydrochloric acid solution were used in the chemical pretreatment. This pilot study suggests that decontamination of younger samples may be possible. However, for more fossilized samples with a high level of contamination (e.g. from the European Paleolithic), acid pretreatment under the conditions used in this study does not remove all contamination.

scholarly journals Reduction of Ash Content in Raw Coal Using Acids and Alkali

2010 ◽  
Vol 7 (4) ◽  
pp. 1254-1257 ◽  
Author(s):  
K. H. Shivaprasad ◽  
M. M. Nagabhushana ◽  
C. Venkataiah
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Coal Sample ◽  
Toxic Elements ◽  
Thermal Power ◽  
Calorific Value ◽  
Ash Content ◽  
Subsequent Removal ◽  
Inorganic Matter ◽  
Leaching Experiments

Ash, an inorganic matter present in coal is amenable for dissolution using suitable reagents. Thus the dissolution of ash and its subsequent removal reduces the release of many toxic elements into the environment by coal based industries. Removal of ash also enhances the calorific value. In the present investigation an attempt has been made to reduce the ash content of raw coal obtained from nearest thermal power by using hydrochloric acid, sulfuric acid and sodium hydroxide. A series of leaching experiments were conducted on coal of different size fractions by varying the parameters like concentration, temperature and time of leaching. The results indicate that it is possible to remove nearly 75% of ash from coal sample by leaching.

Calibrated Radiocarbon Dating at Keatley Creek: The Chronology of Occupation at a Complex Hunter-Gatherer Village

2003 ◽  
Vol 68 (4) ◽  
pp. 719-735 ◽  
Author(s):  
William C. Prentiss ◽  
Michael Lenert ◽  
Thomas A. Foor ◽  
Nathan B. Goodale ◽  
Trinity Schlegel
Keyword(s):  
British Columbia ◽  
Radiocarbon Dating ◽  
Climatic Factors ◽  
Climatic Warming ◽  
Radiocarbon Dates ◽  
Population Aggregation ◽  
Selective Environment

This paper provides an analysis of radiocarbon dates acquired during earlier and recent field seasons at the Keatley Creek site, southern British Columbia. Results indicate that early occupations predating 1900 cal. B.P. occurred, but were not likely associated with population aggregation and large housepits. The aggregated village appears to have emerged by approximately 1700 cal. B.P. and was abandoned at approximately 800 cal. B.P. A break in the occupational sequence is recognized at 1450-1350 cal. B.P. and one other short break may have occurred shortly after 1250 cal. B.P. Peak socioeconomic complexity appears to have been achieved between 1350 and 800 cal B.P. Climatic warming may have provided a selective environment favoring population aggregation and intensification during this time. The final abandonment of the Keatley Creek village appears to have been part of a regional phenomenon suggesting the possibility that climatic factors were important in this case as well.

scholarly journals Paleoclimatic Implications of Radiocarbon Dating Of Speleothems from the Cracow-Wieluń Upland, Southern Poland

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Anna Pazdur ◽  
Mieczysław F. Pazdur ◽  
Jacek Pawlyta ◽  
Andrzej Górny ◽  
Michał Olszewski
Keyword(s):  
Systematic Study ◽  
Radiocarbon Dating ◽  
Karst Region ◽  
Radiocarbon Dates ◽  
Preliminary Results ◽  
Last Glaciation ◽  
Geological Museum ◽  
Paleoclimatic Records ◽  
Age Range

We report preliminary results of a long-term systematic study intended to gather paleoclimatic records from precisely dated speleothems. The research project is limited to speleothems deposited in caves of the Cracow-Wieluń Upland, the largest and best-explored karst region in Poland, covering ca. 2900 km2 with >1000 caves. Speleothem samples were selected from collections of the Geological Museum of the Academy of Mining and Metallurgy in Cracow. Radiocarbon dates of these samples from ca. 45–20 ka bp almost exactly coincide with age range of the Interplenivistulian. A break in speleothem formation between ca. 20 and 10 ka bp may be interpreted as a result of serious climatic deterioration associated with the maximum extent of the last glaciation. We observed differences among 14C, U/Th and AAR dating results. Changes of δ13C and δ18O in speleothems that grew between ca. 30 and 20 ka bp may be interpreted as changes of paleoclimatic conditions.

Recovery Gemanium from Pulverized Fuel Ash through the Method of H2SO4-NH4F-NaClO3 - Leaching-Tannin Precipitation

2013 ◽  
Vol 669 ◽  
pp. 377-383
Author(s):  
Shi Kun Pu ◽  
Yao Zhong Lan ◽  
Yan Jun Li ◽  
Zhong Hui Zhang
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Ammonium Fluoride ◽  
Sodium Chlorate ◽  
Sulphuric Acid Solution ◽  
Fuel Ash ◽  
Pulverized Fuel ◽  
Leaching Solution ◽  
Pulverized Fuel Ash

This paper will conduct a systematic study on method of recovering Ge from pulverized fuel ash in Lincang prefecture, Yunnan province. Details are like this, in view of the fact that Ge contained in pulverized fuel ash is wrapped up by a lot of Silica, Cao, magnesium oxide and is difficult to react with hydrochloric acid, so, first, have the pulverized fuel ash grinded to 200 meshes; then, ammonium fluoride should be put into 85-90°Cdilute sulphuric acid solution to produce hydrogen fluoride so as to destroy silicon dioxide and calcium oxide contained in the pulverized fuel ash. Meanwhile, dilute sulphuric acid solution dissolves magnesium oxide, by doing so, Ge will be released to react with sulfuric acid and produce Sulfuric acid Ge, and Ge will go into the solution；as for low state Ge（e.g,GeO,GeS）contained in the pulverized fuel ash which is difficult to be dissolved by sulfuric acid, sodium chlorate will be used as a kind of oxidant to change bivalence Ge into tetravalence Ge, then dissolve it into the solution, after the liquid-solid separation, sulfuric acid leaching solution rich in Ge will be obtained. Then, tannic acid will be used as precipitant to recover Ge from the leaching solution, and Ge concentrate will be produced through distillation and roasting. After this, put Ge concentrate on hydrochloric acid distillation to get germanium tetrachloride, After going through strenuous evaporation, distillation and hydrolysis, germanium dioxide with high purity will be yield. This paper has conducted conditional tests and discussion on the process parameters which will influence recovery Ge from pulverized fuel ash, including the dosage of Sulfuric acid, ammonium fluoride, sodium chlorate ,tannic acid and extraction time to find out the prior controlling condition of Ge recovery，under this prior condition, Ge leaching rate is as high as 84%，and tannic sinking Ge rate is as high as 98%. The pulverized fuel ash, after recovering Ge, can be used to backfill the mine pit, besides, most of the lixivium after recovering Ge can be recycled, and the rest of it will be released after neutralized up to the standard by lime. This process enjoys the following quality: high Ge recovery rate, less time used during the process ,less consumption of auxiliary material, easier to control the process, avoiding the potential pollution on the environment and lower cost involved in it, therefore, which is a kind of efficient and economic process of recovering Ge from pulverized fuel ash.

Radiocarbon dates from Fazzan, southern Libya

2002 ◽  
Vol 33 ◽  
pp. 9-19 ◽  
Author(s):  
David Mattingly ◽  
David Edwards ◽  
John Dore
Keyword(s):  
Radiocarbon Dating ◽  
Short Paper ◽  
Important Conclusion ◽  
Historic Period ◽  
Radiocarbon Dates ◽  
Full List ◽  
Ams Dating ◽  
The 1960S ◽  
Early Islamic

AbstractThis short paper presents a full list of the currently available radiocarbon dates from the work of Charles Daniels in the 1960s-1970s and the Fazzan Project (1997-2001). The dates can be grouped into several categories, by site or area, and demonstrate the potential of radiocarbon dating being applied to historic-period archaeology in the Sahara. This complements earlier Italian work on later prehistory. One of the most important conclusions to emerge is that the construction of castle-like buildings in Fazzan began within the Garamantian period and that some of the numerous well-preserved mudbrick fortified sites are thus rather earlier than has previously been envisaged. A second important conclusion is that the use of AMS dating can help to identify and confirm activity of the post-Garamantian and early Islamic phases, which has hitherto been elusive.

scholarly journals The Integration of Radiocarbon Dating in Archaeology

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 639-644 ◽  
Author(s):  
H T Waterbolk
Keyword(s):  
Radiocarbon Dating ◽  
The Other ◽  
New Method ◽  
Time Range ◽  
Traditional Methods ◽  
Radiocarbon Dates ◽  
Fully Integrated ◽  
Expected Time ◽  
The Past

In the past 30 years many hundreds of archaeologic samples have been dated by radiocarbon laboratories. Yet, one cannot say that 14C dating is fully integrated into archaeology. For many archaeologists, a 14C date is an outside expertise, for which they are grateful, when it provides the answer to an otherwise insoluble chronologic problem and when it falls within the expected time range. But if a 14C date contradicts other chronologic evidence, they often find the ‘solution’ inexplicable. Some archaeologists are so impressed by the new method, that they neglect the other evidence; others simply reject problematic 14C dates as archaeologically unacceptable. Frequently, excavation reports are provided with an appendix listing the relevant 14C dates with little or no discussion of their implication. It is rare, indeed, to see in archaeologic reports a careful weighing of the various types of chronologic evidence. Yet, this is precisely what the archaeologist is accustomed to do with the evidence from his traditional methods for building up a chronology: typology and stratigraphy. Why should he not be able to include radiocarbon dates in the same way in his considerations?

scholarly journals PICKLING EXPERIMENTAL STUDY ON PREPARATION OF DIESEL OIL WITH PYROLYSIS OIL FROM WASTE RUBBER

2017 ◽  
Vol 1 ◽  
pp. 169
Author(s):  
Wang Lei ◽  
Wang Yun ◽  
Jin Jie
Keyword(s):  
Experimental Study ◽  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Diesel Oil ◽  
Pyrolysis Oil ◽  
Waste Rubber ◽  
Pickling Process ◽  
Concentrated Sulfuric Acid ◽  
Better Than

The research has been done for removing asphaltene by pickling process of diesel oil from pyrolysis oil self-made by waste rubber in this paper, and the study showed that pickling effect of concentrated sulfuric acid was better than concentrated hydrochloric acid. The best pickling effect was found when the concentration of sulfuric acid was 18.4mol/L, acid to oil ratio, namely, the amount of concentration of sulfuric acid to the amount of diesel oil ratio, was 25%. This experiment proved that removing asphaltene by pickling process using concentrated sulfuric acid was remarkable.

scholarly journals Freshwater reservoir offsets on radiocarbon-dated dog bone from the headwaters of the St. Lawrence River, USA

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7174
Author(s):  
John P. Hart ◽  
Robert S. Feranec ◽  
Timothy J. Abel ◽  
Jessica L. Vavrasek
Keyword(s):  
Native Americans ◽  
Radiocarbon Dating ◽  
Aquatic Organisms ◽  
Human Bone ◽  
Bone Collagen ◽  
Canis Lupus Familiaris ◽  
Radiocarbon Dates ◽  
Dog Bone ◽  
Freshwater Reservoir ◽  
St Lawrence River

Isotopic analysis of dog (Canis lupus familiaris) bone recovered from archaeological sites as proxies for human bone is becoming common in North America. Chronological placement of the dogs is often determined through radiocarbon dating of dog bone. The Great Lakes, their tributaries, and nearby lakes and streams were important fisheries for Native Americans prior to and after sustained European presence in the region. Carbon entering the food web in freshwater systems is often not in full isotopic equilibrium with the atmosphere, giving rise to spuriously old radiocarbon ages in fish, other aquatic organisms, and their consumers. These freshwater reservoir offsets (FROs) have been noted on human and dog bone in several areas of the world. Here we report the results of multi-tracer Bayesian dietary modeling using δ15N and δ13C values on dog bone collagen from mid-fifteenth to mid-sixteenth-century Iroquoian village sites at the headwaters of the St. Lawrence River, New York, USA. Results indicate that fish was an important component of dog diets. A comparison of radiocarbon dates on dog bone with dates on deer bone or maize from the same sites indicate FROs ranging from 97 ± 24 to 220 ± 39 14Cyr with a weighted mean of 132 ± 8 14Cyr. These results suggest that dog bone should not be used for radiocarbon dating in the absence of modeling to determine fish consumption and that previously reported radiocarbon dates on human bone from the larger region are likely to have FROs given the known importance of fish in regional human diets.

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