| 1. |
- Alexandrescu, E, et al.
(författare)
-
Os fossils humains des grottes Muierii et Cioclovina, Roumanie
- 2010
-
Ingår i: L'Anthropologie. - : Elsevier BV. - 0003-5521. ; 114:3, s. 341-353
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the cultural and archaeological context of the human fossil bones from Muierii Cave, dated by us to the age of 30 150 ± 800 14C years BP (Before Present) or 34 810 ± 927 cal years BP (calibrated years Before Present), and from Cioclovina Cave, dated to the age of 29 000 ± 700 14C years BP or 33 540 ± 832 cal years BP, in the Southern Carpathians. These are among the most ancient dated human fossil remains from Central and South-Eastern Europe and are described in conjunction with other sites with Mousterian assemblages of the recent Neanderthal population, and sites with Aurignacian assemblage of early modern humans, from Romanian region, for the interval of time 34,000–26,000, the transitional period from the Middle Paleolithic to the Upper Paleolithic.
|
|
| 2. |
- Genberg, Johan, et al.
(författare)
-
Development of graphitization of μg-sized samples at Lund University
- 2010
-
Ingår i: Radiocarbon. - 0033-8222. ; 52:3, s. 1270-1276
-
Konferensbidrag (refereegranskat)abstract
- To be able to successfully measure radiocarbon with accelerator mass spectrometry (AMS) in atmospheric aerosol samples, graphitization of small sample sizes (< 50 µg carbon) must provide reproducible results. At Lund University, a graphitization line optimized for small samples has been constructed. Attention has been given to minimize the reduction reactor volume and each reactor is equipped with a very small pressure transducer that enables constant monitoring of the reaction. Samples as small as 25 µg of carbon have been successfully analyzed, and the mass detection limit of the system has probably not been reached.
|
|
| 3. |
- Genberg, Johan, et al.
(författare)
-
Radiocarbon and hydrocarbon analysis of pm sources during whtc tests on a biodiesel-fueled engine
- 2014
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 1
-
Konferensbidrag (refereegranskat)abstract
- PM in diesel exhaust has been given much attention due to its adverse effect on both climate and health. As the PM emission levels are tightened, the portion of particles originating from the lubrication oil is likely to increase. In this study, exhausts from a biodiesel-fueled Euro 5 engine were examined to determine how much of the carbonaceous particles that originated from the fuel and the lubrication oil, respectively. A combination of three methods was used to determine the PM origin: chain length analysis of the hydrocarbons, determination of organic and elemental carbon (OC and EC), and the concentration of 14C found in the exhausts. It was found that the standard method for measuring hydrocarbons in PM on a filter (chain length analysis) only accounted for 63 % of the OC, meaning that it did not account for all non-soot carbon in the exhausts. Comparing the chain length method to the 14C-based method showed that the non-extractable organic carbon originated both from the oil and fuel. Elemental carbon (EC), also known as soot, was found to originate mainly from the fuel. However, excessive amounts of oil in the engine cylinders increased the relative contribution from the oil as well as the absolute emissions of EC. This could either be due to the surplus oil forming soot, or to the soot particles being coated by oil and thereby less efficiently oxidized during the late cycle. The results demonstrate the importance of carefully regulating the amount of lubrication oil reaching the cylinder.
|
|
| 4. |
- Genberg, Johan, et al.
(författare)
-
Sealed Glass Tube Combustion of mu g-Sized Aerosol Samples
- 2013
-
Ingår i: Radiocarbon. - 0033-8222. ; 55:2-3, s. 617-623
-
Tidskriftsartikel (refereegranskat)abstract
- It is important to evaluate each step in radiocarbon analysis to ensure that the whole process is as efficient and accurate as possible. Aerosol filter samples contain a myriad of carbonaceous compounds with varying resistance to oxidation. Complete combustion of the sample is thus of great importance to ensure that the graphitized sample is representative of the original filter sample. We have evaluated sealed tube combustion of mu g-sized aerosol samples using different types and amounts of reagents. Successful analysis of aerosol samples as small as 20 mu g C was possible following small changes to our standard on-line method. The sealed tube combustion method performs well for standard samples containing 11 mu g C.
|
|
| 5. |
- Genberg, Johan, et al.
(författare)
-
Source apportionment of carbonaceous aerosol in southern Sweden
- 2011
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:22, s. 11387-11400
-
Tidskriftsartikel (refereegranskat)abstract
- A one-year study was performed at the Vavihill background station in southern Sweden to estimate the anthropogenic contribution to the carbonaceous aerosol. Weekly samples of the particulate matter PM10 were collected on quartz filters, and the amounts of organic carbon, elemental carbon, radiocarbon (14C) and levoglucosan were measured. This approach enabled source apportionment of the total carbon in the PM10 fraction using the concentration ratios of the sources. The sources considered in this study were emissions from the combustion of fossil fuels and biomass, as well as biogenic sources. During the summer, the carbonaceous aerosol mass was dominated by compounds of biogenic origin (80%), which are associated with biogenic primary and secondary organic aerosols. During the winter months, biomass combustion (32%) and fossil fuel combustion (28%) were the main contributors to the carbonaceous aerosol. Elemental carbon concentrations in winter were about twice as large as during summer, and can be attributed to biomass combustion, probably from domestic wood burning. The contribution of fossil fuels to elemental carbon was stable throughout the year, although the fossil contribution to organic carbon increased during the winter. Thus, the organic aerosol originated mainly from natural sources during the summer and from anthropogenic sources during the winter. The result of this source apportionment was compared with results from the EMEP MSC-W chemical transport model. The model and measurements were generally consistent for total atmospheric organic carbon, however, the contribution of the sources varied substantially. E.g. the biomass burning contributions of OC were underestimated by the model by a factor of 2.2 compared to the measurements.
|
|
| 6. |
- Georgiadou, Elisavet, et al.
(författare)
-
Bomb-pulse (14)C analysis combined with (13)C and (15)N measurements in blood serum from residents of Malmö, Sweden.
- 2013
-
Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 52:2, s. 175-187
-
Forskningsöversikt (refereegranskat)abstract
- The (14)C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of (14)C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was -1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the (14)C date has been evaluated using stable isotope δ(13)C and δ(15)N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ(13)C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ(13)C and the age deviation. No significant correlation was found between the age deviation and the δ(15)N values of any dietary group. No influence of sex or year of birth was found on neither the (14)C nor the δ(13)C and δ(15)N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ(15)N in the samples. The consumption of high δ(15)N-valued fish and birds can be responsible for this clustering.
|
|
| 7. |
- Georgiadou, Elisavet, et al.
(författare)
-
Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The 14C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of 14C bomb-pulse dating. The difference between the date estimated by using the Calibomb software and sampling date varied between -3±0.4 and +0.2±0.5 years. The average age deviation of all samples was -1.5±0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the 14C date has been evaluated using stable isotope δ13C and δ15N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ13C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ13C and the age deviation. No significant correlation was found between the age deviation and the δ15N values of any dietary group. No influence of sex or year of birth was found on neither the 14C nor the δ13C and δ15N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ15N in the samples. The consumption of high δ15N-valued fish and birds can be responsible for this clustering.
|
|
| 8. |
- Georgiadou, Elisavet, et al.
(författare)
-
Bomb-pulse dating of human material – modelling the influence of diet
- 2010
-
Ingår i: Radiocarbon. - 0033-8222. ; 52:2, s. 800-807
-
Konferensbidrag (refereegranskat)abstract
- The atmospheric testing of nuclear weapons during the 1950s and early 1960s produced large amounts of radiocarbon. This 14C bomb pulse provides useful age information in numerous scientific fields, e.g. in geosciences and environmental sciences. Bomb-pulse dating can also be used to date human material (e.g. in forensics and medical science). Bombpulse dating relies on precise measurements of the declining 14C concentration in atmospheric carbon dioxide collected at clean-air sites. However, local variations in the 14C specific activity of air and foodstuffs occur, which are caused by natural processes as well as by various human activities. As 14C enters the human body mainly through the diet, variations of 14C concentration in foodstuffs need to be considered. The marine component of the diet is believed to be of particular importance due to the non-equilibrium in 14C specific activity between the atmosphere and aquatic reservoirs during the bomb pulse. This article reviews the 14C concentration in marine foodstuffs during the bomb-pulse era, and models how the marine component in one’s diet can affect the precision of bomb-pulse dating of human material.
|
|
| 9. |
- Georgiadou, Elisavet, et al.
(författare)
-
Potential Influence of Diet on Bomb-Pulse Dating of Human Plaque Samples
- 2013
-
Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222. ; 55:2-3, s. 874-884
-
Tidskriftsartikel (refereegranskat)abstract
- The radiocarbon concentration of different atherosclerotic plaque fragments obtained from 20 patients in Portugal, operated in 2000-2001, has been measured in order to define the year of plaque formation. A difference of 1.8-15 yr was observed, with the mean and median both 9 yr, between the bomb-pulse date estimated with the CALIBomb software and the operation date. Stable isotope (delta C-13 and delta N-15) analysis was also performed and provides insight to the diet of the subjects. The wide range of measured stable isotope values could indicate that the subjects' diet varied, including an abundance of marine foodstuffs. It could also mean a different isotope fractionation process for the different plaque fragments (cap, core, interface to media) and a possible difference in tissues in which the various fragments are formed. Analysis of delta C-13 and delta N-15 values of each patient separately revealed subjects considered more influenced by marine foodstuffs consumption.
|
|
| 10. |
- Gilardoni, S., et al.
(författare)
-
Better constraints on sources of carbonaceous aerosols using a combined C-14 - macro tracer analysis in a European rural background site
- 2011
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 11:12, s. 5685-5700
-
Tidskriftsartikel (refereegranskat)abstract
- The source contributions to carbonaceous PM2.5 aerosol were investigated at a European background site at the edge of the Po Valley, in Northern Italy, during the period January-December 2007. Carbonaceous aerosol was described as the sum of 8 source components: primary (1) and secondary (2) biomass burning organic carbon, biomass burning elemental carbon (3), primary (4) and secondary (5) fossil organic carbon, fossil fuel burning elemental carbon (6), primary (7) and secondary (8) biogenic organic carbon. The mass concentration of each component was quantified using a set of macro tracers (organic carbon OC, elemental carbon EC, and levoglucosan), micro tracers (arabitol and mannitol), and C-14 measurements. This was the first time that C-14 measurements covered a full annual cycle with daily resolution. This set of 6 tracers, together with assumed uncertainty ranges of the ratios of OC-to-EC, and the reference fraction of modern carbon in the 8 source categories, provides strong constraints to the source contributions to carbonaceous aerosol. The uncertainty of contributions was assessed with a Quasi-Monte Carlo (QMC) method accounting for the variability of OC and EC emission factors, the uncertainty of reference fractions of modern carbon, and the measurement uncertainty. During winter, biomass burning composed 64% (+/- 15%) of the total carbon (TC) concentration, while in summer secondary biogenic OC accounted for 50% (+/- 16%) of TC. The contribution of primary biogenic aerosol particles was negligible during the entire year. Moreover, aerosol associated with fossil sources represented 27% (+/- 16%) and 41% (+/- 26%) of TC in winter and summer, respectively. The contribution of secondary organic aerosol (SOA) to the organic mass (OM) was significant during the entire year. SOA accounted for 30% (+/- 16 %) and 85% (+/- 12 %) of OM during winter and summer, respectively. While the summer SOA was dominated by biogenic sources, winter SOA was mainly due to biomass burning and fossil sources. This indicates that the oxidation of semi-volatile and intermediate volatility organic compounds co-emitted with primary organics is a significant source of SOA, as suggested by recent model results and Aerosol Mass Spectrometer measurements. Comparison with previous global model simulations, indicates a strong underestimate of wintertime primary aerosol emissions in this region. The comparison of source apportionment results in different urban and rural areas showed that the sampling site was mainly affected by local aerosol sources during winter and regional air masses from the nearby Po Valley in summer. This observation was further confirmed by back-trajectory analysis applying the Potential Source Contribution Function method to identify potential source regions.
|
|
