Guaciara M Santos
Biographic Data
| ID | 3903533 |
|---|---|
| NAME | Guaciara M Santos |
| GIVEN NAMES | Guaciara M |
| FAMILY NAME | Santos |
| SIGNATURE | SANTOS G M |
| AFFILIATIONS | University of California, Irvine |
| ORCID | 0000-0003-1755-6390 |
| VERIFIED | Yes |
| TOTAL WORKS | 25 |
| TOTAL CITATIONS | 225 |
| AUTHOR COUNT | 25 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2001 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 7 |
Fossil CO 2 emissions from warehouse and distribution centers in Southern California’s Inland Empire
The rise of e-commerce has led to a rapid expansion of warehouses and distribution centers (W&DCs). However, impacts of e-commerce logistics, including emissions of fossil fuel-derived carbon dioxide (ffCO 2 ) on urban greenhouse gas inventories, remain poorly quantified. Here, we developed a 40 year tree-ring radiocarbon ( 14 C) record to isolate ffCO 2 enhancements within a W&DC cluster and in the urban background of Southern California’s Inlan…
Radiocarbon dating of a monumental dragon tree ( Dracaena draco (L.) L.)
Some arboreal monocotyledons, such as the dragon trees ( Dracaena sp.), can develop impressive trunks (>5 m perimeter) through a lateral meristem, but their ages are difficult to determine. We report here a series of calibrated radiocarbon ( 14 C) dates obtained from a stem section of Dracaena draco (L.) L. subsp. draco growing on the island of Tenerife, Canary Islands, Spain. This radial section, about 40 cm long, was cut on October 18, 2023, fr…
Evaluating possible sources of error in tree-ring 14C data using multiple trees across South America
A limitation in fine-tuned tree-ring radiocarbon ( 14 C) data is normally associated with overall data uncertainty. Tree-ring 14 C data variance as a result of sample heterogeneity can be reduced by adopting best practices at the time of sample collection and subsequent preparation and analysis. Variance-reduction of 14 C data was achieved by meticulous sample handling during increment core or cross-sectional cuttings, in-laboratory wood reductio…
Atmospheric Radiocarbon for the Period 1950–2019
This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling 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 c…
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples 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 samples at four differen…
Misunderstandings Concerning the Significance of AMS Background 14 C Measurements
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 (>100,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience,…
Bag of Tricks: A Set of Techniques and other Resources to Help 14 C Laboratory Setup, Sample Processing, and Beyond
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 sample 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 progr…
From radiocarbon analysis to interpretation: A comment on “Phytolith Radiocarbon Dating in Archaeological and Paleoecological Research: A Case Study of Phytoliths from Modern Neotropical Plants and a …
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destine au dpt et la diffusion de documents scientifiques de niveau recherche, publis ou non, manant des tablissements d'ense…
Matching Dendrochronological Dates with the Southern Hemisphere 14 C Bomb Curve to Confirm Annual Tree Rings in Pseudolmedia rigida from Bolivia
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 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar date…
C Measurements Elucidate Isotopic Differences between Nails and Hair in Modern Humans
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 shampoo, which …
Changes in Holocene tree cover density in Cabo Frio (Rio de Janeiro, Brazil): Evidence from soil phytolith assemblages
Simple, Rapid, and Cost Effective: A Screening Method for 14 C Analysis of Small Carbonate Samples
We have developed a simple, rapid method to screen carbonates for survey applications, which provides radiocarbon dates with decreased precision at lower cost. The method is based on previous work by Longworth et al. (2011) and involves mixing pulverized CaCO 3 with Fe powder, followed by pressing into aluminum target holders for direct 14 C accelerator mass spectrometry (AMS) measurements. An optimum beam current averaging ∼10% of those produced…
Behavioral Variability in ABA Chemical Pretreatment Close to the 14 C Age Limit
The acid-base-acid (ABA) procedure is a common chemical pretreatment used on most organic matter samples. Although this pretreatment is straightforward, there is no consensus among labs about the optimum strength of the chemicals, or even the temperature, to be used for digestions. Comparisons between 14 C results obtained by samples undergoing ABA against other wet oxidations, such as acid-base oxidation followed by stepped-combustion (ABOX-SC) …
Δ 14 C and Δ 13 C of Seawater DIC as Tracers of Coastal Upwelling: A 5-Year Time Series from Southern California
Marine radiocarbon ( 14 C) is a widely used tracer of past ocean circulation, but very few high-resolution records have been obtained. Here, we report a time series of carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from the Newport Beach pier in Orange County, within the Southern California Bight, from 2005 to 2010. Surface seawater was collected bimonthly and analyzed for Δ 14 C, δ 13 C, and salinity.…
Blank Assessment for Ultra-Small Radiocarbon Samples: Chemical Extraction and Separation Versus AMS
The Keck Carbon Cycle AMS facility at the University of California, Irvine (KCCAMS/UCI) has developed protocols for analyzing radiocarbon in samples as small as ∼0.001 mg of carbon (C). Mass-balance background corrections for modern and 14 C-dead carbon contamination (MC and DC, respectively) can be assessed by measuring 14 C-free and modern standards, respectively, using the same sample processing techniques that are applied to unknown samples. …
Carbon Isotope Measurements of Surface Seawater from a Time-Series Site Off Southern California
We report carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from a time-series site off the Newport Beach Pier in Orange County, California. These data represent the first time series of Δ 14 C data for a coastal southern California site. From a suite of samples collected daily from 16 October to 11 November 2004, Δ 14 C values averaged 32.1 ± 4.4‰. Freshwater input from the Santa Ana River to our site ca…
The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Status Report
We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2–3‰ for 1-mg samples (Santos et al. 2007c) are presented
The Phytolith 14 C Puzzle: A Tale of Background Determinations and Accuracy Tests
Over the past decades, analysis of occluded carbon in phytoliths (opaline silica mineral bodies that form in and between plant cells) has become a workhorse of paleoclimate and archaeological studies. Since different plant types exhibit distinctive phytolith morphologies, their assemblages are used in identifying vegetation histories or food culture adaptations. A few direct radiocarbon AMS measurements of phytoliths have been carried out, but th…
Comment on Atmospheric carbon isotope signatures in phytolith occluded carbon, Carter, J.A., Quaternary International, this volume
Palaeodietary inferences based on isotopic data for pre-Hispanic populations of the Central Mountains of Argentina
The aim of this study is to investigate spatial and temporal patterns of palaeodiet diversification through isotopic measurements (δ13CCOL and δ15N) from individuals who inhabited the Central Mountains of Argentina during the Holocene. Isotopic measurements were obtained from bone and tooth samples from ten human skeletons, corresponding to the Middle and Late Holocene (4500-300 14C BP). Isotopic results show the consumption of C3, C4 and CAM pla…
Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility
Variability of Monthly Radiocarbon During the 1760S in Corals from the Galapagos Islands
Radiocarbon (Δ 14 C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average Δ 14 C value of −62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High Δ 14 C values were found during January through March, when upwelling was …
Buang Merabak: Early Evidence For Human Occupation In The Bismarck Archipelago, Papua New Guinea
[Extract] This paper reports new radiocarbon estimates for the age of human occupation of Buang Merabak, an archaeological site in central New Ireland, Papua New Guinea. Previously, the oldest radiocarbon date for human occupation in New Ireland was 35,410 ± 430 BP (Leavesley and Allen 1998:80). The radiocarbon determinations reported here, although preliminary, may extend the first evidence of human occupation in New Ireland to beyond 40,000 BP …
New Abox Ams- 14 C Ages Remove Dating Anomalies At Puritjarra Rock Shelter
Short Reports more generally to gain an appreciation of what information is in existence, its location and how to obtain it. The creation of the Bowen Basin Collection originated as a response to this. Information within the collection largely (but not solely) derives fiom material amassed throughout the nearly seven year course of the Bowen Basin Project. As the Collection took shape, major gaps in the information held and the incomplete nature …
Radiocarbon Dating of the Human Occupation of Australia Prior to 40 ka BP—Successes and Pitfalls
Charcoal samples from ancient human occupation sites in Australia have been subjected to a rigorous pretreatment and stepped combustion regime in order to explore the possibility that these sites may be older than previous radiocarbon dating had suggested. In one case, the Devil's Lair site in southwest Australia, the methodology has clearly removed vestiges of contamination by more modern carbon and has led to a revised radiocarbon chronology th…
Atmospheric Radiocarbon for the Period 1950–2019
This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling 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 c…
Radiocarbon Dating of the Human Occupation of Australia Prior to 40 ka BP—Successes and Pitfalls
Charcoal samples from ancient human occupation sites in Australia have been subjected to a rigorous pretreatment and stepped combustion regime in order to explore the possibility that these sites may be older than previous radiocarbon dating had suggested. In one case, the Devil's Lair site in southwest Australia, the methodology has clearly removed vestiges of contamination by more modern carbon and has led to a revised radiocarbon chronology th…
Behavioral Variability in ABA Chemical Pretreatment Close to the 14 C Age Limit
The acid-base-acid (ABA) procedure is a common chemical pretreatment used on most organic matter samples. Although this pretreatment is straightforward, there is no consensus among labs about the optimum strength of the chemicals, or even the temperature, to be used for digestions. Comparisons between 14 C results obtained by samples undergoing ABA against other wet oxidations, such as acid-base oxidation followed by stepped-combustion (ABOX-SC) …
Blank Assessment for Ultra-Small Radiocarbon Samples: Chemical Extraction and Separation Versus AMS
The Keck Carbon Cycle AMS facility at the University of California, Irvine (KCCAMS/UCI) has developed protocols for analyzing radiocarbon in samples as small as ∼0.001 mg of carbon (C). Mass-balance background corrections for modern and 14 C-dead carbon contamination (MC and DC, respectively) can be assessed by measuring 14 C-free and modern standards, respectively, using the same sample processing techniques that are applied to unknown samples. …
The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Status Report
We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2–3‰ for 1-mg samples (Santos et al. 2007c) are presented
Palaeodietary inferences based on isotopic data for pre-Hispanic populations of the Central Mountains of Argentina
The aim of this study is to investigate spatial and temporal patterns of palaeodiet diversification through isotopic measurements (δ13CCOL and δ15N) from individuals who inhabited the Central Mountains of Argentina during the Holocene. Isotopic measurements were obtained from bone and tooth samples from ten human skeletons, corresponding to the Middle and Late Holocene (4500-300 14C BP). Isotopic results show the consumption of C3, C4 and CAM pla…
Buang Merabak: Early Evidence For Human Occupation In The Bismarck Archipelago, Papua New Guinea
[Extract] This paper reports new radiocarbon estimates for the age of human occupation of Buang Merabak, an archaeological site in central New Ireland, Papua New Guinea. Previously, the oldest radiocarbon date for human occupation in New Ireland was 35,410 ± 430 BP (Leavesley and Allen 1998:80). The radiocarbon determinations reported here, although preliminary, may extend the first evidence of human occupation in New Ireland to beyond 40,000 BP …
Simple, Rapid, and Cost Effective: A Screening Method for 14 C Analysis of Small Carbonate Samples
We have developed a simple, rapid method to screen carbonates for survey applications, which provides radiocarbon dates with decreased precision at lower cost. The method is based on previous work by Longworth et al. (2011) and involves mixing pulverized CaCO 3 with Fe powder, followed by pressing into aluminum target holders for direct 14 C accelerator mass spectrometry (AMS) measurements. An optimum beam current averaging ∼10% of those produced…
Bag of Tricks: A Set of Techniques and other Resources to Help 14 C Laboratory Setup, Sample Processing, and Beyond
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 sample 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 progr…
Variability of Monthly Radiocarbon During the 1760S in Corals from the Galapagos Islands
Radiocarbon (Δ 14 C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average Δ 14 C value of −62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High Δ 14 C values were found during January through March, when upwelling was …
New Abox Ams- 14 C Ages Remove Dating Anomalies At Puritjarra Rock Shelter
Short Reports more generally to gain an appreciation of what information is in existence, its location and how to obtain it. The creation of the Bowen Basin Collection originated as a response to this. Information within the collection largely (but not solely) derives fiom material amassed throughout the nearly seven year course of the Bowen Basin Project. As the Collection took shape, major gaps in the information held and the incomplete nature …
Carbon Isotope Measurements of Surface Seawater from a Time-Series Site Off Southern California
We report carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from a time-series site off the Newport Beach Pier in Orange County, California. These data represent the first time series of Δ 14 C data for a coastal southern California site. From a suite of samples collected daily from 16 October to 11 November 2004, Δ 14 C values averaged 32.1 ± 4.4‰. Freshwater input from the Santa Ana River to our site ca…
The Phytolith 14 C Puzzle: A Tale of Background Determinations and Accuracy Tests
Over the past decades, analysis of occluded carbon in phytoliths (opaline silica mineral bodies that form in and between plant cells) has become a workhorse of paleoclimate and archaeological studies. Since different plant types exhibit distinctive phytolith morphologies, their assemblages are used in identifying vegetation histories or food culture adaptations. A few direct radiocarbon AMS measurements of phytoliths have been carried out, but th…
Matching Dendrochronological Dates with the Southern Hemisphere 14 C Bomb Curve to Confirm Annual Tree Rings in Pseudolmedia rigida from Bolivia
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 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar date…
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples 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 samples at four differen…
Misunderstandings Concerning the Significance of AMS Background 14 C Measurements
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 (>100,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience,…
Δ 14 C and Δ 13 C of Seawater DIC as Tracers of Coastal Upwelling: A 5-Year Time Series from Southern California
Marine radiocarbon ( 14 C) is a widely used tracer of past ocean circulation, but very few high-resolution records have been obtained. Here, we report a time series of carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from the Newport Beach pier in Orange County, within the Southern California Bight, from 2005 to 2010. Surface seawater was collected bimonthly and analyzed for Δ 14 C, δ 13 C, and salinity.…
C Measurements Elucidate Isotopic Differences between Nails and Hair in Modern Humans
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 shampoo, which …
New Abox Ams- 14 C Ages Remove Dating Anomalies At Puritjarra Rock Shelter
Short Reports more generally to gain an appreciation of what information is in existence, its location and how to obtain it. The creation of the Bowen Basin Collection originated as a response to this. Information within the collection largely (but not solely) derives fiom material amassed throughout the nearly seven year course of the Bowen Basin Project. As the Collection took shape, major gaps in the information held and the incomplete nature …
Radiocarbon Dating of the Human Occupation of Australia Prior to 40 ka BP—Successes and Pitfalls
Charcoal samples from ancient human occupation sites in Australia have been subjected to a rigorous pretreatment and stepped combustion regime in order to explore the possibility that these sites may be older than previous radiocarbon dating had suggested. In one case, the Devil's Lair site in southwest Australia, the methodology has clearly removed vestiges of contamination by more modern carbon and has led to a revised radiocarbon chronology th…
Buang Merabak: Early Evidence For Human Occupation In The Bismarck Archipelago, Papua New Guinea
[Extract] This paper reports new radiocarbon estimates for the age of human occupation of Buang Merabak, an archaeological site in central New Ireland, Papua New Guinea. Previously, the oldest radiocarbon date for human occupation in New Ireland was 35,410 ± 430 BP (Leavesley and Allen 1998:80). The radiocarbon determinations reported here, although preliminary, may extend the first evidence of human occupation in New Ireland to beyond 40,000 BP …
Variability of Monthly Radiocarbon During the 1760S in Corals from the Galapagos Islands
Radiocarbon (Δ 14 C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average Δ 14 C value of −62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High Δ 14 C values were found during January through March, when upwelling was …
Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility
Comment on Atmospheric carbon isotope signatures in phytolith occluded carbon, Carter, J.A., Quaternary International, this volume
Palaeodietary inferences based on isotopic data for pre-Hispanic populations of the Central Mountains of Argentina
The aim of this study is to investigate spatial and temporal patterns of palaeodiet diversification through isotopic measurements (δ13CCOL and δ15N) from individuals who inhabited the Central Mountains of Argentina during the Holocene. Isotopic measurements were obtained from bone and tooth samples from ten human skeletons, corresponding to the Middle and Late Holocene (4500-300 14C BP). Isotopic results show the consumption of C3, C4 and CAM pla…
Blank Assessment for Ultra-Small Radiocarbon Samples: Chemical Extraction and Separation Versus AMS
The Keck Carbon Cycle AMS facility at the University of California, Irvine (KCCAMS/UCI) has developed protocols for analyzing radiocarbon in samples as small as ∼0.001 mg of carbon (C). Mass-balance background corrections for modern and 14 C-dead carbon contamination (MC and DC, respectively) can be assessed by measuring 14 C-free and modern standards, respectively, using the same sample processing techniques that are applied to unknown samples. …
Carbon Isotope Measurements of Surface Seawater from a Time-Series Site Off Southern California
We report carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from a time-series site off the Newport Beach Pier in Orange County, California. These data represent the first time series of Δ 14 C data for a coastal southern California site. From a suite of samples collected daily from 16 October to 11 November 2004, Δ 14 C values averaged 32.1 ± 4.4‰. Freshwater input from the Santa Ana River to our site ca…
The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Status Report
We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2–3‰ for 1-mg samples (Santos et al. 2007c) are presented
The Phytolith 14 C Puzzle: A Tale of Background Determinations and Accuracy Tests
Over the past decades, analysis of occluded carbon in phytoliths (opaline silica mineral bodies that form in and between plant cells) has become a workhorse of paleoclimate and archaeological studies. Since different plant types exhibit distinctive phytolith morphologies, their assemblages are used in identifying vegetation histories or food culture adaptations. A few direct radiocarbon AMS measurements of phytoliths have been carried out, but th…
Δ 14 C and Δ 13 C of Seawater DIC as Tracers of Coastal Upwelling: A 5-Year Time Series from Southern California
Marine radiocarbon ( 14 C) is a widely used tracer of past ocean circulation, but very few high-resolution records have been obtained. Here, we report a time series of carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from the Newport Beach pier in Orange County, within the Southern California Bight, from 2005 to 2010. Surface seawater was collected bimonthly and analyzed for Δ 14 C, δ 13 C, and salinity.…
Changes in Holocene tree cover density in Cabo Frio (Rio de Janeiro, Brazil): Evidence from soil phytolith assemblages
Simple, Rapid, and Cost Effective: A Screening Method for 14 C Analysis of Small Carbonate Samples
We have developed a simple, rapid method to screen carbonates for survey applications, which provides radiocarbon dates with decreased precision at lower cost. The method is based on previous work by Longworth et al. (2011) and involves mixing pulverized CaCO 3 with Fe powder, followed by pressing into aluminum target holders for direct 14 C accelerator mass spectrometry (AMS) measurements. An optimum beam current averaging ∼10% of those produced…
Behavioral Variability in ABA Chemical Pretreatment Close to the 14 C Age Limit
The acid-base-acid (ABA) procedure is a common chemical pretreatment used on most organic matter samples. Although this pretreatment is straightforward, there is no consensus among labs about the optimum strength of the chemicals, or even the temperature, to be used for digestions. Comparisons between 14 C results obtained by samples undergoing ABA against other wet oxidations, such as acid-base oxidation followed by stepped-combustion (ABOX-SC) …
C Measurements Elucidate Isotopic Differences between Nails and Hair in Modern Humans
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 shampoo, which …
Matching Dendrochronological Dates with the Southern Hemisphere 14 C Bomb Curve to Confirm Annual Tree Rings in Pseudolmedia rigida from Bolivia
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 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar date…
From radiocarbon analysis to interpretation: A comment on “Phytolith Radiocarbon Dating in Archaeological and Paleoecological Research: A Case Study of Phytoliths from Modern Neotropical Plants and a …
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destine au dpt et la diffusion de documents scientifiques de niveau recherche, publis ou non, manant des tablissements d'ense…
Bag of Tricks: A Set of Techniques and other Resources to Help 14 C Laboratory Setup, Sample Processing, and Beyond
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 sample 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 progr…
Radiocarbon Dating and Intercomparison of Some Early Historical Radiocarbon Samples
We performed a new series of measurements on samples 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 samples at four differen…
Misunderstandings Concerning the Significance of AMS Background 14 C Measurements
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 (>100,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience,…
Atmospheric Radiocarbon for the Period 1950–2019
This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling 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 c…
Evaluating possible sources of error in tree-ring 14C data using multiple trees across South America
A limitation in fine-tuned tree-ring radiocarbon ( 14 C) data is normally associated with overall data uncertainty. Tree-ring 14 C data variance as a result of sample heterogeneity can be reduced by adopting best practices at the time of sample collection and subsequent preparation and analysis. Variance-reduction of 14 C data was achieved by meticulous sample handling during increment core or cross-sectional cuttings, in-laboratory wood reductio…
Radiocarbon dating of a monumental dragon tree ( Dracaena draco (L.) L.)
Some arboreal monocotyledons, such as the dragon trees ( Dracaena sp.), can develop impressive trunks (>5 m perimeter) through a lateral meristem, but their ages are difficult to determine. We report here a series of calibrated radiocarbon ( 14 C) dates obtained from a stem section of Dracaena draco (L.) L. subsp. draco growing on the island of Tenerife, Canary Islands, Spain. This radial section, about 40 cm long, was cut on October 18, 2023, fr…
Fossil CO 2 emissions from warehouse and distribution centers in Southern California’s Inland Empire
The rise of e-commerce has led to a rapid expansion of warehouses and distribution centers (W&DCs). However, impacts of e-commerce logistics, including emissions of fossil fuel-derived carbon dioxide (ffCO 2 ) on urban greenhouse gas inventories, remain poorly quantified. Here, we developed a 40 year tree-ring radiocarbon ( 14 C) record to isolate ffCO 2 enhancements within a W&DC cluster and in the urban background of Southern California’s Inlan…
Radiocarbon dating (16 works) · Geology and Paleoclimatology Research (14 works) · Geology (12 works) · Accelerator mass spectrometry (11 works) · Archaeology (11 works) · Archaeology and ancient environmental studies (11 works) · Geography (11 works) · Chemistry (10 works) · Paleontology (10 works) · Isotope Analysis in Ecology (9 works)