ORCID Profile
0000-0003-1755-6390
Current Organisations
Albert-Ludwigs-Universität Freiburg
,
Robert Koch Institute
,
University of California, Irvine
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Related Links
Publications
Simple, rapid, and cost effective: a screening method for^(14) C analysis of small carbonate samples.
Publisher: Cambridge University Press (CUP)
Date: 2013
A new look at old carbon in active margin sediments
Publisher: Geological Society of America
Date: 03-2009
DOI: 10.1130/G25351A.1
Misunderstandings Concerning the Significance of AMS Background 14C Measurements
Publisher: Cambridge University Press (CUP)
Date: 30-05-2018
DOI: 10.1017/RDC.2018.15
Abstract: We consider one misconception of those who currently reject the general validity of radiocarbon ( 14 C) age determinations older than, at most, 10,000 BP. There is an allegation that the presence of 14 C reported by accelerator mass spectrometry (AMS) laboratories in their measurements of 14 C infinite age ( ,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience, primarily for those who have questions about the validity of these arguments. However, they may not be familiar with the literature relevant to providing a clear response to the claims of these in iduals. We conclude that, in our view, of all of the possible explanations for the reports of the presence of 14 C in these background s les, the least probable explanation has been advanced by those rejecting the validity of the 14 C time scale in excess of, at most, 10,000 BP.
Determining VOCs Reactivity for Ozone Forming Potential in the Megacity of São Paulo
Publisher: Taiwan Association for Aerosol Research
Date: 2018
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
Publisher: Cambridge University Press (CUP)
Date: 04-2018
DOI: 10.1017/RDC.2018.18
Abstract: We performed a new series of measurements on s les that were part of early measurements on radiocarbon ( 14 C) dating made in 1948–1949. Our results show generally good agreement to the data published in 1949–1951, despite vast changes in technology, with only two exceptions where there was a discrepancy in the original studies. Our new measurements give calibrated ages that overlap with the known ages. We dated several s les at four different laboratories, and so we were also able to make a small intercomparison at the same time. In addition, new measurements on s les from other Egyptian materials used by Libby and co-workers were made at UC Irvine. S les of tree rings used in the original studies (from Broken Flute Cave and Centennial Stump) were obtained from the University of Arizona Laboratory of Tree-Ring Research archive and remeasured. New data were compared to the original studies and other records.
Radiocarbon dating from 40 to 60kaBP at Border Cave, South Africa
Publisher: Elsevier BV
Date: 04-2003
Radiocarbon bomb-peak signal in tree-rings from the tropical Andes register low latitude atmospheric dynamics in the Southern Hemisphere
Publisher: Elsevier BV
Date: 06-2021
Seasonal Cycle of Isotope‐Based Source Apportionment of Elemental Carbon in Airborne Particulate Matter and Snow at Alert, Canada
Publisher: American Geophysical Union (AGU)
Date: 05-12-2020
DOI: 10.1029/2020JD033125
Abstract: Elemental carbon (EC) is a major light‐absorbing component of atmospheric aerosol particles. Here, we report the seasonal variation in EC concentrations and sources in airborne particulate matter (PM) and snow at Alert, Canada, from March 2014 to June 2015. We isolated the EC fraction with the EnCan‐Total‐900 (ECT9) protocol and quantified its stable carbon isotope composition (δ 13 C) and radiocarbon content (∆ 14 C) to apportion EC into contributions from fossil fuel combustion and biomass burning (wildfires and biofuel combustion). Ten‐day backward trajectories show EC aerosols reaching Alert by traveling over the Arctic Ocean from the Russian Arctic during winter and from North America ( °N) during summer. EC concentrations range from 1.8–135.3 ng C m −3 air (1.9–41.2% of total carbon [TC], n = 48), with lowest values in summer (1.8–44.5 ng C m −3 air, n = 9). EC in PM (Δ 14 C = ‐532 ± 114‰ [ave. ± SD, n = 20]) and snow (−257 ± 131‰, n = 7) was depleted in 14 C relative to current ambient CO 2 year‐round. EC in PM mainly originated from liquid and solid fossil fuels from fall to spring (47–70% fossil), but had greater contributions from biomass burning in summer (48–80% modern carbon). EC in snow was mostly from biomass burning (53–88%). Our data show that biomass burning EC is preferentially incorporated into snow because of scavenging processes within the Arctic atmosphere or long‐range transport in storm systems. This work provides a comprehensive view of EC particles captured in the High Arctic through wet and dry deposition and demonstrates that surface stations monitoring EC in PM might underestimate biomass burning and transport.
Advances in the graphitization protocol at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF) in Brazil
Publisher: Elsevier BV
Date: 10-2015
Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds
Publisher: Elsevier BV
Date: 2019
Re-anchoring the late Pleistocene tephrochronology of New Zealand based on concordant radiocarbon ages and combined 238U/230Th disequilibrium and (U–Th)/He zircon ages
Publisher: Elsevier BV
Date: 10-2012
Method development for 234U and 230Th determination and application to fossil deep-water coral and authigenic carbonate dating from the Campos Basin - Brazil
Publisher: FapUNIFESP (SciELO)
Date: 03-2012
Blank Corrections for Ramped Pyrolysis Radiocarbon Dating of Sedimentary and Soil Organic Carbon
Publisher: American Chemical Society (ACS)
Date: 04-12-2014
DOI: 10.1021/AC502874J
Abstract: R ed pyrolysis (RP) targets distinct components of soil and sedimentary organic carbon based on their thermochemical stabilities and allows the determination of the full spectrum of radiocarbon ((14)C) ages present in a soil or sediment s le. Extending the method into realms where more precise ages are needed or where smaller s les need to be measured involves better understanding of the blank contamination associated with the method. Here, we use a compiled data set of RP measurements of s les of known age to evaluate the mass of the carbon blank and its associated (14)C signature, and to assess the performance of the RP system. We estimate blank contamination during RP using two methods, the modern-dead and the isotope dilution method. Our results indicate that during one complete RP run s les are contaminated by 8.8 ± 4.4 μg (time-dependent) of modern carbon (MC, fM ∼ 1) and 4.1 ± 5.5 μg (time-independent) of dead carbon (DC, fM ∼ 0). We find that the modern-dead method provides more accurate estimates of uncertainties in blank contamination therefore, the isotope dilution method should be used with caution when the variability of the blank is high. Additionally, we show that RP can routinely produce accurate (14)C dates with precisions ∼100 (14)C years for materials deposited in the last 10,000 years and ∼300 (14)C years for carbon with (14)C ages of up to 20,000 years.
234 U and 230 Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples.
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.JENVRAD.2005.12.012
Abstract: A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference s le and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. S les from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky(-1) was calculated. S les from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.
Behavioral variability in ABA chemical pretreatment close to the 14C age limit.
Publisher: Cambridge University Press (CUP)
Date: 2013
Redating the onset of burning of Lynch's Crater (North Queensland): Implications for human settlement in Australia
Publisher: Wiley
Date: 2001
DOI: 10.1002/JQS.643
Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon
Publisher: Proceedings of the National Academy of Sciences
Date: 25-04-2006
Abstract: An ammonia-oxidizing, carbon-fixing archaeon, Candidatus “ Nitrosopumilus maritimus ,” recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ . If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show that the archaea in surface waters incorporate modern carbon into their membrane lipids, and archaea at 670 m incorporate carbon that is slightly more isotopically enriched than inorganic carbon at the same depth. An isotopic mass balance model shows that the dominant metabolism at depth indeed is autotrophy (83%), whereas heterotrophic consumption of modern organic carbon accounts for the remainder of archaeal biomass. These results reflect the in situ production of the total community that produces tetraether lipids and are not subject to biases associated with incubation and/or culture experiments. The data suggest either that the marine archaeal community includes both autotrophs and heterotrophs or is a single population with a uniformly mixotrophic metabolism. The metabolic and phylogenetic ersity of the marine archaea warrants further exploration these organisms may play a major role in the marine cycles of nitrogen and carbon.
Bag of Tricks: A Set of Techniques and other Resources to Help 14C Laboratory Setup, Sample Processing, and Beyond
Publisher: Cambridge University Press (CUP)
Date: 26-07-2017
DOI: 10.1017/RDC.2016.43
Abstract: Over the last few decades, radiocarbon laboratories have used different procedures for measuring a broad range of carbonaceous materials. To produce reliable results, the processes employed for s le processing, graphite target production, and spectrometer measurement must be rigorous, well tested, and reproducible. Most of the procedures have been developed, improved, and published as part of the laboratories’ quality control and research programs, and can be frequently found in the literature. Nevertheless, there are suites of laboratory techniques (or “small useful skills”), products, and other resources that either have never been described in publications, or have been somewhat hidden in much larger scientific articles and reports. We feel that with the rapid rise of newer laboratories and facilities, a set of resourceful suggestions might come in handy. Here we gathered these skill sets that can be used in all aspects of 14 C s le processing, with the intention to simplify and expedite procedures, from glass-tube making to graphitization and measurements. We also included some miscellaneous items to help in laboratory setup.
Disgust, contempt, and anger and the stereotypes of obese people
Publisher: Springer Science and Business Media LLC
Date: 25-09-2013
DOI: 10.1007/S40519-013-0067-2
Abstract: Emotions form an important part of stereotyping and prejudice, but little is known about how intergroup emotions are associated with anti-fat prejudice. This study examined the relation between negative intergroup emotions (disgust, contempt, and anger) and the stereotypes of obese people. A community s le (n = 380) and an undergraduate s le (n = 96) rated obese people on common obesity stereotypes (e.g., lazy, sloppy), and also indicated the extent to which they felt disgust, contempt, and anger toward obese people. In both s les, participants reported feeling more disgust and contempt than anger toward obese people. Furthermore, regression analyses indicated that disgust was a significant positive predictor of obesity stereotypes, but contempt and anger were not. Overall, these findings provide further evidence that disgust plays an important role in prejudice toward obese people.
Integrated genomic surveillance enables tracing of person-to-person SARS-CoV-2 transmission chains during community transmission and reveals extensive onward transmission of travel-imported infections
Publisher: European Centre for Disease Control and Prevention (ECDC)
Date: 27-10-2022
DOI: 10.2807/1560-7917.ES.2022.27.43.2101089
Abstract: Tracking person-to-person SARS-CoV-2 transmission in the population is important to understand the epidemiology of community transmission and may contribute to the containment of SARS-CoV-2. Neither contact tracing nor genomic surveillance alone, however, are typically sufficient to achieve this objective. We demonstrate the successful application of the integrated genomic surveillance (IGS) system of the German city of Düsseldorf for tracing SARS-CoV-2 transmission chains in the population as well as detecting and investigating travel-associated SARS-CoV-2 infection clusters. Genomic surveillance, phylogenetic analysis, and structured case interviews were integrated to elucidate two genetically defined clusters of SARS-CoV-2 isolates detected by IGS in Düsseldorf in July 2021. Cluster 1 (n = 67 Düsseldorf cases) and Cluster 2 (n = 36) were detected in a surveillance dataset of 518 high-quality SARS-CoV-2 genomes from Düsseldorf (53% of total cases, s led mid-June to July 2021). Cluster 1 could be traced back to a complex pattern of transmission in nightlife venues following a putative importation by a SARS-CoV-2-infected return traveller (IP) in late June 28 SARS-CoV-2 cases could be epidemiologically directly linked to IP. Supported by viral genome data from Spain, Cluster 2 was shown to represent multiple independent introduction events of a viral strain circulating in Catalonia and other European countries, followed by diffuse community transmission in Düsseldorf. IGS enabled high-resolution tracing of SARS-CoV-2 transmission in an internationally connected city during community transmission and provided infection chain-level evidence of the downstream propagation of travel-imported SARS-CoV-2 cases.
Use of 14C-AMS in the study of biological production in coastal upwelling areas
Publisher: FapUNIFESP (SciELO)
Date: 09-2004
Inter-comparison of elemental and organic carbon mass measurements from three North American national long-term monitoring networks at a co-located site
Publisher: Copernicus GmbH
Date: 26-08-2019
Abstract: Abstract. Carbonaceous aerosol is a major contributor to the total aerosol load and being monitored by erse measurement approaches. Here, 10 years (2005–2015) of continuous carbonaceous aerosol measurements collected at the Centre of Atmospheric Research Experiments (CARE) in Egbert, Ontario, Canada, on quartz-fiber filters by three independent networks (Interagency Monitoring of Protected Visual Environments, IMPROVE Canadian Air and Precipitation Monitoring Network, CAPMoN and Canadian Aerosol Baseline Measurement, CABM) were compared. Specifically, the study evaluated how differences in s le collection and analysis affected the concentrations of total carbon (TC), organic carbon (OC), and elemental carbon (EC). Results show that different carbonaceous fractions measured by various networks were consistent and comparable in general among the three networks over the 10-year period, even with different s ling systems/frequencies, analytical protocols, and artifact corrections. The CAPMoN TC, OC, and EC obtained from the DRI model 2001 thermal–optical carbon analyzer following the IMPROVE-TOR protocol (denoted as DRI-TOR) method were lower than those determined from the IMPROVE_A TOR method by 17 %, 14 %, and 18 %, respectively. When using transmittance for charring correction, the corresponding carbonaceous fractions obtained from the Sunset-TOT were lower by as much as 30 %, 15 %, and 75 %, respectively. In comparison, the CABM TC, OC, and EC obtained from a thermal method, EnCan-Total-900 (ECT9), were higher than the corresponding fractions from IMPROVE_A TOR by 20 %–30 %, 0 %–15 %, and 60 %–80 %, respectively. Ambient OC and EC concentrations were found to increase when ambient temperature exceeded 10 ∘C. These increased ambient concentrations of OC during summer were possibly attributed to secondary organic aerosol (SOA) formation and forest fire emissions, while elevated EC concentrations were potentially influenced by forest fire emissions and increased vehicle emissions. Results also show that the pyrolyzed organic carbon (POC) obtained from the ECT9 protocol could provide additional information on SOA although more research is still needed.
The local marine reservoir effect at Kalba (UAE) between the Neolithic and Bronze Age: An indicator of sea level and climate changes
Publisher: Elsevier BV
Date: 10-2017
Reassessment of the 13C/12C and 14C/12C isotopic fractionation ratio and its impact on high-precision radiocarbon dating
Publisher: Elsevier BV
Date: 09-2017
Evaluation of iron and cobalt powders as catalysts for 14 C-AMS target preparation.
Publisher: Elsevier BV
Date: 06-2007
Assessment of the regional fossil fuel CO2 distribution through Δ14C patterns in ipê leaves: The case of Rio de Janeiro state, Brazil
Publisher: Elsevier BV
Date: 09-2019
Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon
Publisher: Proceedings of the National Academy of Sciences
Date: 25-04-2006
Abstract: An ammonia-oxidizing, carbon-fixing archaeon, Candidatus “ Nitrosopumilus maritimus ,” recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ . If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show that the archaea in surface waters incorporate modern carbon into their membrane lipids, and archaea at 670 m incorporate carbon that is slightly more isotopically enriched than inorganic carbon at the same depth. An isotopic mass balance model shows that the dominant metabolism at depth indeed is autotrophy (83%), whereas heterotrophic consumption of modern organic carbon accounts for the remainder of archaeal biomass. These results reflect the in situ production of the total community that produces tetraether lipids and are not subject to biases associated with incubation and/or culture experiments. The data suggest either that the marine archaeal community includes both autotrophs and heterotrophs or is a single population with a uniformly mixotrophic metabolism. The metabolic and phylogenetic ersity of the marine archaea warrants further exploration these organisms may play a major role in the marine cycles of nitrogen and carbon.
Growth Assessment of Native Tree Species from the Southwestern Brazilian Amazonia by Post-AD 1950 14C Analysis: Implications for Tropical Dendroclimatology Studies and Atmospheric 14C Reconstructions
Publisher: MDPI AG
Date: 31-08-2021
DOI: 10.3390/F12091177
Abstract: Tree-ring width chronologies of cedro (Cedrela fissilis Vell.) (1875 to 2018), jatobá (Hymenaea courbaril L.) (1840 to 2018) and roxinho Peltogyne paniculata Benth.) (1910 to 2018) were developed by dendrochronological techniques in the southern Amazon Basin. Acceptable statistics for the tree-ring chronologies were obtained, and annual calendar dates were assigned. Due to the lack of long-term chronologies for use in paleoclimate reconstructions in degraded forest areas, dendrochronological dating was validated by 14C analysis. Tree-rings selected for analysis corresponded to 1957, 1958, 1962, 1963, 1965, 1971, and 1972. Those are critical calendar years in which atmospheric 14C changes were the highest, and therefore their tree-ring cellulose extracts 14C signatures when in alignment with existing post-AD 1950 atmospheric 14C atmospheric curves would indicate annual periodicity. Throughout our correlated calendar years and post-AD 1950 14C signatures, we indicate that H. courbaril shows an erratic sequence of wood ages. The other two tree species, C. fissilis and P. paniculata, are annual in nature and can be used successfully as paleoclimate proxies. Moreover, due to the s ling site’s strategic location in relation to the Tropical Low-Pressure Belt over South America, these trees can be used to enhance the limited amount of observational data in Southern Hemisphere atmospheric 14C calibration curves.
Dynamic Nuclear Polarization NMR as a new tool to investigate the nature of organic compounds occluded in plant silica particles
Publisher: Springer Science and Business Media LLC
Date: 13-06-2017
DOI: 10.1038/S41598-017-03659-Z
Abstract: The determination of the chemical nature of the organic matter associated with phytoliths remains a challenge. This difficulty mainly stems from amounts of organic carbon (C) that are often well below the detection limit of traditional spectroscopic tools. Conventional solid-state 13 C Nuclear Magnetic Resonance (NMR) is widely used to examine the nature and structure of organic molecules, but its inherent low sensitivity prohibits the observation of diluted s les. The recent advent of commercial microwave source in the terahertz range triggered a renewed interest in the Dynamic Nuclear Polarization (DNP) technique to improve the signal to noise ratio of solid-state NMR experiments. With this technique, the 13 C spectrum of a phytolith s le containing 0.1% w/w C was obtained overnight with sufficient quality to permit a semi-quantitative analysis of the organic matter, showing the presence of peptides and carbohydrates as predominant compounds. Considering the natural abundance of the 13 C isotope, this experiment demonstrates that DNP NMR is sufficiently sensitive to observe spin systems present in amounts as low as a few tens of ppm.
A comparison of
U
/
T
h and rapid‐screen
14
C
dates from
Publisher:
American Geophysical Union (AGU)
Date:
03-2016
DOI:
10.1002/2015GC005893
Publisher: American Geophysical Union (AGU)
Date: 03-2016
DOI: 10.1002/2015GC005893
Accuracy and precision of <sup>14</sup>C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol
Publisher: Copernicus GmbH
Date: 16-09-2015
Abstract: Abstract. Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small s le sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal–optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to a vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average, 91 % of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our setup, we quantified the total amount of extraneous carbon introduced during the TOA s le processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of s le size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) s les with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our setup were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively, based on multiple measurements of ultra-small s les. The extraction procedure (Swiss_4S protocol and cryo-trapping only) contributed 0.37 ± 0.18 μg of modern carbon and 0.13 ± 0.07 μg of fossil carbon to the total blank of our system, with consistent estimates obtained for the two laboratories. There was no difference in the background correction between the OC and EC fractions. Our setup allowed us to efficiently isolate and trap each carbon fraction with the Swiss_4S protocol and to perform 14C analysis of ultra-small OC and EC s les with high accuracy and low 14C blanks.
Intercomparison of 14C Analysis of Carbonaceous Aerosols: Exercise 2009
Publisher: Cambridge University Press (CUP)
Date: 2013
Influence of the6 , 7 Publisher:
American Physical Society (APS)
Date:
04-1999
Publisher: American Physical Society (APS)
Date: 04-1999
Understanding Holocene variations in the vegetation of Sao Joao River basin, southeastern coast of Brazil, using phytolith and carbon isotopic analyses
Publisher: Elsevier BV
Date: 12-2014
Enhanced El Niño–Southern Oscillation Variability in Recent Decades
Publisher: American Geophysical Union (AGU)
Date: 04-04-2020
DOI: 10.1029/2019GL083906
Life with MC-SNICS. Part II: Further ion source development at the Keck carbon cycle AMS facility.
Publisher: Elsevier BV
Date: 06-2007
Improved radiocarbon analyses of modern human hair to determine the year-of-death by cross-flow nanofiltered amino acids: common contaminants, implications for isotopic analysis, and recommendations
Publisher: Wiley
Date: 25-08-2015
DOI: 10.1002/RCM.7273
Abstract: In forensic investigation, radiocarbon ((14)C) measurements of human tissues (i.e., nails and hair) can help determine the year-of-death. However, the frequent use of cosmetics can bias hair (14)C results as well as stable isotope values. Evidence shows that hair exogenous impurities percolate beyond the cuticle layer, and therefore conventional pretreatments are ineffective in removing them. We conducted isotopic analysis ((14)C, δ(13)C, δ(15)N and C/N) of conventionally treated and cross-flow nanofiltered amino acid (CFNAA)-treated s les (scalp- and body-hair) from a single female subject using fingernails as a reference. The subject studied frequently applies a permanent dark-brown dye kit to her scalp-hair and uses other care products for daily cleansing. We also performed pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses of CFNAA-treated scalp-hair to identify contaminant remnants that could possibly interfere with isotopic analyses. The conventionally treated scalp- and body-hair showed (14)C offsets of ~21‰ and ~9‰, respectively. These offsets confirm the contamination by petrochemicals in modern human hair. A single CFNAA extraction reduced those offsets by ~34%. No significant improvement was observed when sequential extractions were performed, as it appears that the procedure introduced some foreign contaminants. A chromatogram of the CFNAA scalp-hair pyrolysis products showed the presence of petroleum and plant/animal compound residues, which can bias isotopic analyses. We have demonstrated that CFNAA extractions can partially remove cosmetic contaminants embedded in human hair. We conclude that fingernails are still the best source of keratin protein for year-of-death determinations and isotopic analysis, with body-hair and/or scalp-hair coupled with CFNAA extraction a close second.
Smoke radiocarbon measurements from Indonesian fires provide evidence for burning of millennia-aged peat
Publisher: Proceedings of the National Academy of Sciences
Date: 19-11-2018
Abstract: We report radiocarbon ( 14 C) measurements of carbonaceous aerosol originating from fires on the islands of Sumatra and Borneo. These data provide information about what types of ecosystems burned and are critical for linking the human health effects of fires to the anthropogenic build-up of atmospheric CO 2 . Our measurements confirm that peat emissions were the dominant source of aerosols in Singapore during the 2015 El Niño and provide a means for monitoring the success of policies designed to protect peatland areas during future drought events.
Investigating δ13 C and Δ14 C within Mytilus californianus shells as proxies of upwelling intensity
Publisher: American Geophysical Union (AGU)
Date: 06-2013
DOI: 10.1002/GGGE.20090
Towards producing pure phytolith concentrates from plants that are suitable for carbon isotopic analysis
Publisher: Elsevier BV
Date: 10-2013
Brazilian accelerator mass spectrometry program
Publisher: Elsevier BV
Date: 03-1997
Source signatures from combined isotopic analyses of PM2.5 carbonaceous and nitrogen aerosols at the peri-urban Taehwa Research Forest, South Korea in summer and fall
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.SCITOTENV.2018.11.157
Abstract: Isotopes are essential tools to apportion major sources of aerosols. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM
Matching dendrochronological dates with the southern hemisphere<sup>14</sup>c bomb curve to confirm annual tree rings in Pseudolmedia rigida from Bolivia
Publisher: Cambridge University Press (CUP)
Date: 2015
Abstract: This study used high-precision radiocarbon bomb-pulse dating of selected wood rings to provide an independent validation of the tree growth periodicity of Pseudolmedia rigida (Klotzsch & H. Karst) Cuatrec. from the Moraceae family, collected in the Madidi National Park in Bolivia. 14 C content was measured by accelerator mass spectrometry (AMS) in 10 s les from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar dates were determined by dendrochronological techniques and were also used to select the s les for 14 C AMS. In order to validate these preliminary dates using the established Southern Hemisphere (SH) 14 C atmospheric concentration data set, the targeted rings were selected to be formed during periods before and after the 14 C bomb spike nuclear tests (i.e. 1950s–1960s). The excellent agreement of the dendrochronological dates and the 14 C signatures in tree rings associated with the same dates provided by the bomb-pulse 14 C atmospheric values for the SH (SHCal zone 1–2) confirms the annual periodicity of the observed growth layers, and thus the high potential of this species for tree-ring analysis. The lack of discrepancies between both data sets also suggests that there are no significant latitudinal differences between the 14 C SHCal zone 1–2 curve and the 14 C values obtained from the selected tree rings at this geographic location (14°33′S, 68°49′W) in South America. The annual resolution of P. rigida tree rings opens the possibility of broader applications of dendrochronological analysis for ecological and paleoclimatic studies in the Bolivian tropics, as well as the possibility of using wood s les from some tree species from this region to improve the quality of the bomb-pulse 14 C SHCal curve at this latitude.
The phytolith carbon sequestration concept: Fact or fiction? A comment on “Occurrence, turnover and carbon sequestration potential of phytoliths in terrestrial ecosystems by Song et al. doi: 10.1016/j
Publisher: Elsevier BV
Date: 2017
Method development for 234U and 230Th determination and application to fossil deep-water coral and authigenic carbonate dating from the Campos Basin - Brazil
Publisher: FapUNIFESP (SciELO)
Date: 03-2012
Radiocarbon measurements at LAC-UFF: Recent performance
Publisher: Elsevier BV
Date: 10-2015
Plant growth conditions alter phytolith carbon
Publisher: Frontiers Media SA
Date: 17-09-2015
Elastic scattering of27
Publisher:
American Physical Society (APS)
Date:
12-1998
Publisher: American Physical Society (APS)
Date: 12-1998
14C AMS dating of fires in the central Amazon rain forest
Publisher: Elsevier BV
Date: 10-2000
Elastic, inelastic scattering and fusion of the 14N +59Co system at energies close to the coulomb barrier
Publisher: Springer Science and Business Media LLC
Date: 02-1998
Possible source of ancient carbon in phytolith concentrates from harvested grasses
Publisher: Copernicus GmbH
Date: 29-05-2012
Abstract: Abstract. Plants absorb and transport silicon (Si) from soil, and precipitation of Si within the living plants results in micrometric amorphous biosilica particles known as phytoliths. During phytolith formation, a small amount of carbon ( %) can become occluded in the silica structure (phytC) and therefore protected from degradation by the environment after plant tissue decomposition. Since the major C source within plants is from atmospheric carbon dioxide (CO2) via photosynthesis, the current understanding is that the radiocarbon (14C) content of phytC should reflect the 14C content of atmospheric CO2 at the time the plant is growing. This assumption was recently challenged by 14C data from phytoliths extracted from living grasses that yielded ages of several thousand years (2–8 kyr BP in radiocarbon years "Before Present" (BP), "Present" being defined as 1950). Because plants can take up small amounts of C of varying ages from soils (e.g., during nutrient acquisition), we hypothesized that this transported C within the plant tissue could be attached to or even embedded in phytoliths. In this work, we explore this hypothesis by reviewing previously published data on biosilica mineralization and plant nutrient acquisition as well as by evaluating the efficiency of phytolith extraction protocols from scanning electron microscope (SEM) images and energy dispersive spectrometer (EDS) analyses from harvested grasses phytolith concentrates. We show that current extraction protocols are inefficient since they do not entirely remove recalcitrant forms of C from plant tissue. Consequently, material previously measured as "phytC" may contain at least some fraction of soil-derived C (likely radiocarbon-old) taken up by roots. We also suggest a novel interpretation for at least some of the phytC – which enters via the root pathway during nutrient acquisition – that may help to explain the old ages previously obtained from phytolith concentrates.
HPLC Purification of Higher Plant-Dervied Lignin Phenols for Compound Specific Radiocarbon Analysis
Publisher: American Chemical Society (ACS)
Date: 10-2010
DOI: 10.1021/AC1016584
Abstract: The ability to measure the radiocarbon content of compounds isolated from complex mixtures has begun to revolutionize our understanding of carbon transformations on earth. Because s les are often small, each new compound isolation method must be tested for background carbon contamination (C(ex)). Here, we present a new method for compound-specific radiocarbon analysis (CSRA) of higher plant-derived lignin phenols. To test for C(ex), we compared the Δ(14)C values of unprocessed lignin phenol containing standard materials (woods, leaves, natural vanillin, and synthetic vanillin) with those of lignin phenols liberated by CuO oxidation and purified by two-dimensional high-pressure liquid chromatography (HPLC) coupled to mass spectrometry (MS) and UV detection. We assessed C(ex) associated with (1) microwave assisted CuO oxidation of bulk s les to lignin phenol monomers, (2) HPLC purification, and (3) accelerator mass spectrometry (AMS) s le preparation. The Δ(14)C of purified compounds (corrected for C(ex)) agreed, within error, with those of bulk materials for s les that were >10 μg C. This method will allow routine analysis of the Δ(14)C of lignin phenols isolated from terrestrial, aquatic, and marine settings, revealing the time scale for the processing of one of the single largest components of active organic carbon reservoirs on earth.
Application of the ECT9 protocol for radiocarbon-based source apportionment of carbonaceous aerosols
Publisher: Copernicus GmbH
Date: 17-05-2021
Abstract: Abstract. Carbonaceous aerosol is mainly composed of organic carbon (OC) and elemental carbon (EC). Both OC and EC originate from a variety of emission sources. Radiocarbon (14C) analysis can be used to apportion bulk aerosol, OC, and EC into their sources. However, such analyses require the physical separation of OC and EC. Here, we apply of ECT9 protocol to physically isolate OC and EC for 14C analysis and evaluate its effectiveness. Several reference materials are selected, including two pure OC (fossil “adipic acid” and contemporary “sucrose”), two pure EC (fossil “regal black” and “C1150”), and three complex materials containing contemporary and/or fossil OC and EC (“rice char”, NIST urban dust standards “SRM1649a” and “SRM8785”, i.e., fine fraction of resuspended SRM1649a on filters). The pure materials were measured for their OC, EC, and total carbon (TC) mass fractions and corresponding carbon isotopes to evaluate the uncertainty of the procedure. The average accuracy of TC mass, determined via volumetric injection of a sucrose solution, was approximately 5 %. Ratios of EC/TC and OC/TC were highly reproducible, with analytical precisions better than 2 % for all reference materials, ranging in size from 20 to 100 µg C. Consensus values were reached for all pure reference materials for both δ13C and fraction modern (F14C), with an uncertainty of 0.3 ‰ and approximately 5 %, respectively. The procedure introduced 1.3 ± 0.6 µg of extraneous carbon, an amount compatible to that of the Swiss_4S protocol. In addition, OC and EC were isolated from mixtures of pure contemporary OC (sucrose) with pure fossil EC (regal black) and fossil OC (adipic acid) with contemporary EC (rice char EC) to evaluate the effectiveness of OC and EC separation. Consensus F14C values were reached for all OC (∼ 5–30 µg) and EC (∼ 10–60 µg) fractions with an uncertainty of ∼ 5 % on average. We found that the ECT9 protocol efficiently isolates OC or EC from complex mixtures. Based on δ13C measurements, the average contribution of charred OC to EC is likely less than 3 % when the OC loading amount is less than 30 µg C. Charring was further assessed by evaluating thermograms of various materials, including aerosol s les collected in the Arctic and from tailpipes of gasoline or diesel engines. These data demonstrate that the ECT9 method effectively removes pyrolyzed OC. Thus, the ECT9 protocol, initially developed for concentration and stable isotope measurements of OC and EC, is suitable for 14C-based apportionment studies, including µg C-sized s les from arctic environments.
Annual growth rings in a sample of Paraná pine (Araucaria angustifolia): Toward improving the 14C calibration curve for the Southern Hemisphere
Publisher: Elsevier BV
Date: 02-2015
Changes in Holocene tree cover density in Cabo Frio (Rio de Janeiro, Brazil): Evidence from soil phytolith assemblages
Publisher: Elsevier BV
Date: 02-2013
Nonannual tree rings in a climate-sensitivePrioria copaiferachronology in the Atrato River, Colombia
Publisher: Wiley
Date: 06-07-2017
DOI: 10.1002/ECE3.2905
Recent (<4 year old) leaf litter is not a major source of microbial carbon in a temperate forest mineral soil
Publisher: Elsevier BV
Date: 07-2010
Does Cedrela always form annual rings? Testing ring periodicity across South America using radiocarbon dating
Publisher: Springer Science and Business Media LLC
Date: 20-08-2017
Deep sea corals off Brazil verify a poorly ventilated Southern Pacific Ocean during H2, H1 and the Younger Dryas
Publisher: Elsevier BV
Date: 05-2010
Revealing Polylepis microphylla as a suitable tree species for dendrochronology and quantitative wood anatomy in the Andean montane forests
Publisher: Elsevier BV
Date: 12-2022
Direct uptake of organically derived carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence
Publisher: Copernicus GmbH
Date: 18-03-2016
Abstract: Abstract. In the rhizosphere, the uptake of low-molecular-weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relative to total uptake is important, organic C uptake is supposed to be low relative to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and to what extent organically derived C absorbed by grass roots can feed the C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled amino acids (AAs) to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C excess and 15N excess) in the roots, stems and leaves as well as phytoliths were measured relative to a control experiment in which no labeled AAs were added. Additionally, the 13C excess was measured at the molecular level, in AAs extracted from roots and stems and leaves. The net uptake of labeled AA-derived 13C reached 4.5 % of the total AA 13C supply. The amount of AA-derived 13C fixed in the plant was minor but not nil (0.28 and 0.10 % of total C in roots and stems/leaves, respectively). Phenylalanine and methionine that were supplied in high amounts to the nutritive solution were more 13C-enriched than other AAs in the plant. This strongly suggested that part of AA-derived 13C was absorbed and translocated into the plant in its original AA form. In phytoliths, AA-derived 13C was detected. Its concentration was on the same order of magnitude as in bulk stems and leaves (0.15 % of the phytolith C). This finding strengthens the body of evidences showing that part of organic compounds occluded in phytoliths can be fed by C entering the plant through the roots. Although this experiment was done in nutrient solution and its relevance for soil C uptake assessment is therefore limited, we discuss plausible forms of AA-derived 13C absorbed and translocated in the plant and eventually fixed in phytoliths, and implications of our results for our understanding of the C cycle at the soil–plant–atmosphere interface
Socioeconomic conditions and fossil fuel CO2 in the Metropolitan Area of Rio de Janeiro
Publisher: Elsevier BV
Date: 05-2022
Unambiguous evidence of old soil carbon in grass biosilica particles
Publisher: Copernicus GmbH
Date: 03-2016
Abstract: Abstract. Plant biosilica particles (phytoliths) contain small amounts of carbon called phytC. Based on the assumptions that phytC is of photosynthetic origin and a closed system, claims were recently made that phytoliths from several agriculturally important monocotyledonous species play a significant role in atmospheric CO2 sequestration. However, anomalous phytC radiocarbon (14C) dates suggested contributions from a non-photosynthetic source to phytC. Here we address this non-photosynthetic source hypothesis using comparative isotopic measurements (14C and δ13C) of phytC, plant tissues, atmospheric CO2, and soil organic matter. State-of-the-art methods assured phytolith purity, while sequential stepwise-combustion revealed complex chemical-thermal decomposability properties of phytC. Although photosynthesis is the main source of carbon in plant tissue, it was found that phytC is partially derived from soil carbon that can be several thousand years old. The fact that phytC is not uniquely constituted of photosynthetic C limits the usefulness of phytC either as a dating tool or as a significant sink of atmospheric CO2. It additionally calls for further experiments to investigate how SOM-derived C is accessible to roots and accumulates in plant biosilica, for a better understanding of the mechanistic processes underlying the silicon biomineralization process in higher plants.
Annual nature of the growth rings of Araucaria araucana confirmed by radiocarbon analysis
Publisher: Elsevier BV
Date: 10-2015
High-precision 14C measurements of parenchyma-rich Hymenolobium petraeum tree species confirm bomb-peak atmospheric levels and reveal local fossil-fuel CO2 emissions in the Central Amazon
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.ENVRES.2022.113994
Abstract: Atmospheric radiocarbon (
Use of 14C-AMS in the study of biological production in coastal upwelling areas
Publisher: FapUNIFESP (SciELO)
Date: 09-2004
ATMOSPHERIC RADIOCARBON FOR THE PERIOD 1950–2019
Publisher: Cambridge University Press (CUP)
Date: 23-11-2021
DOI: 10.1017/RDC.2021.95
Abstract: This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 s ling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon ( 14 C) data sets, with monthly data sets for 5 zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1–2). Our new compilation includes smooth curves for zonal data sets that are more suitable for dating applications than the previous approach based on simple averaging. Our new radiocarbon dataset is intended to help facilitate the use of atmospheric bomb 14 C in carbon cycle studies and to accommodate increasing demand for accurate dating of recent (post-1950) terrestrial s les.
Palaeodietary inferences based on isotopic data for pre‐Hispanic populations of the Central Mountains of Argentina.
Publisher: Wiley
Date: 03-2009
DOI: 10.1002/OA.1064
14C measurements elucidate isotopic differences between nails and hair in modern humans.
Publisher: Cambridge University Press (CUP)
Date: 2014
DOI: 10.2458/56.17503
Abstract: In forensic sciences, radiocarbon found in modern human nails and hair is evaluated to determine the year of death. However, 14 C analyses presented herein of fingernails and hair from the same infant demonstrated 14 C values of hair that were lower than would be expected (e.g. depleted relative to the fingernails by at least 10‰). These results prompted a series of 14 C measurements on infant hair strands, fingernails, and infant sh oo, which suggested the presence of C contamination due to cosmetic products. To further evaluate these discrepancies, several hair strands and fingernail s les from multiple donors were collected, pretreated by several approaches, and measured using isotopic analysis (δ 13 C, δ 15 N, and C/N as well as 14 C accelerator mass spectrometry). SEM images of the surface of chemically pretreated hair strands were also taken to inspect the performance of the chemical pretreatments applied. Our 14 C and stable isotope results show that modern human hair is likely contaminated with fossil-fuel-derived carbon, which is found in most hair care products. Currently, the various chemical pretreatments available in the literature and presented herein show that it is not possible to completely remove foreign carbon contaminates. Thus, the human 14 C and δ 13 C values between keratinous tissues (fingernails and hair) arc not in agreement. From these observations, it becomes apparent that isotopic interpretations using human hair should be used with extreme caution and additional work is needed for its use in forensic and dietary research.
CARVE: Fire-Related Aerosol and Soil Elemental and Isotopic Composition, Alaska, 2013
Publisher: ORNL Distributed Active Archive Center
Date: 2016
Applications of AMS 14C Measurements in Environmental and Economical Problems
Publisher: Elsevier BV
Date: 04-2004
Main ozone-forming VOCs in the city of Sao Paulo: observations, modelling and impacts
Publisher: Springer Science and Business Media LLC
Date: 22-08-2016
Black carbon aerosol dynamics and isotopic composition in Alaska linked with boreal fire emissions and depth of burn in organic soils
Publisher: American Geophysical Union (AGU)
Date: 11-2015
DOI: 10.1002/2015GB005247
When the carbon being dated is not what you think it is: Insights from phytolith carbon research
Publisher: Elsevier BV
Date: 10-2018
Using radiocarbon to constrain black and organic carbon aerosol sources in Salt Lake City
Publisher: American Geophysical Union (AGU)
Date: 19-09-2017
DOI: 10.1002/2017JD026519
New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results
Publisher: Copernicus GmbH
Date: 12-02-2015
Abstract: Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle have been the subject of increasing debate. Inconsistencies were fed by the scarcity of in situ characterizations of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-D structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technique has been widely used for 3-D reconstruction of biological systems it has never been applied in high-resolution mode to silica particles. Simultaneously, we investigated the location of phytC using nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the NanoSIMS technique. However, another pool of phytC, continuously distributed in and protected by the silica structure, was observed. Its N/C ratio (0.27) is in agreement with the presence of amino acids. These findings constitute a basis to further characterize the origin, occlusion process, nature and accessibility of phytC, as a prerequisite for assessing its significance in the global C cycle.
The Brazilian Bragg curve detector built for AMS studies
Publisher: Elsevier BV
Date: 10-2000
Current status of the Brazilian AMS program
Publisher: Elsevier BV
Date: 10-2000
Related Organisations
Medizinische Fakultät, Heinrich-Heine-Universität Düsseldorf
Location: Germany
Related Funding Activities
No related grants have been discovered for Guaciara Santos.