Maura Pellegrini | University of Oxford (original) (raw)
Papers by Maura Pellegrini
Grotta del Romito has been the subject of numerous archaeological, chronological and palaeoenviro... more Grotta del Romito has been the subject of numerous archaeological, chronological and palaeoenvironmental investigations for more than a decade. During the Upper Palaeolithic period the site contains evidence of human occupation through the Gravettian and Epigravettian periods, multiple human burials, changes in the pattern of human occupation, and faunal, isotopic and sedimentological evidence for local environmental change. In spite of this rich record, the chronological control is insufficient to resolve shifts in subsistence and mobility patterns at sufficiently high resolution to match the abrupt climate fluctuations at this time. To resolve this we present new radiocarbon and tephrostratigraphic dates in combination with existing radiocarbon dates, and develop a Bayesian age model framework for the site. This improved chronology reveals that local environmental conditions reflect abrupt and long-term changes in climate, and that these also directly influence changing patterns of human occupation of the site. In particular, we show that the environmental record for the site, based on small mammal habitat preferences, is chronologically in phase with the main changes in climate and environment seen in key regional archives from Italy and Greenland. We also calculate the timing of the transitions between different cultural phases and their spans. We also show that the intensification in occupation of the site is chronologically coincident with a rapid rise in Mesic Woody taxa seen in key regional pollen records and is associated with the Late Epigravettian occupation of the site. This change in the record of Grotta del Romito is also closely associated stratigraphically with a new tephra (the ROM-D30 tephra), which may act as a critical marker in environmental records of the region.
We report here on an isotopic study of carbon, nitrogen and oxygen isotopes in Equus tooth enamel... more We report here on an isotopic study of carbon, nitrogen and oxygen isotopes in Equus tooth enamel and dentine from multiple layers from the site of Combe Grenal, France, which date to between approximately 150,000 and 50,000 years BP. We found that there were significant variations in all three elemental isotope ratios through time, although the variations were not synchronous. This study shows the utility of using herbivore tooth dentine carbon and nitrogen isotope values as indicators of environmental changes, in addition to their use as dietary indicators.
Chemical Geology, 2015
A large variety of bioapatite pre-treatments is found in the literature for a wide range of appli... more A large variety of bioapatite pre-treatments is found in the literature for a wide range of applications going from mineralogy to diagenesis. Additionally, stable carbon and oxygen isotopes in bioapatite carbonates are often measured after pre-treatment to study ancient diets and reconstruct past environments. It is common to pre-treat the samples to remove contributions from competing sources associated to organic material and secondary carbonates. Several chemical methods are described in the literature to pre-treat archaeological and fossil bioapatites (bone and teeth) for isotopic measurements with no consistency on their efficiency. Infrared and elemental analyses are combined in this study to highlight the effects of the different pre-treatments on the structure and chemistry of bioapatite. The different pre-treatments can variably affect the organic and carbonate contents of bioapatites, with some, such as sodium hypochlorite, apparently adding carbonate to the system. This may lead to a change in the biological isotopic signature of bioapatite carbonate, with effects on the correct interpretation of the results. According to the findings of our study, hydrazine hydrate seems to be the best chemical to remove organic matter without affecting the carbonate content of bioapatites, while the use of acetate buffered acetic acid solutions is recommended for removing adsorbed carbonates, when necessary. Sodium hypochlorite, instead, induces the adsorption of exogenous carbonates, while hydrogen peroxide does not remove organic matter efficiently even at high temperatures. These two chemicals should not be used to remove organic matter, especially from bone and dentine.
A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p) in Britain is p... more A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as 'non-local' to the areas where they were buried (spatial outliers). A marked variation in δ 18 O p is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ 18 O values–a process known to be problematic. Understanding and reconstructing the mobility of past populations and individuals is important in archaeological and forensic studies. One of the ways to address this topic is through the chemical analysis of skeletal remains, for the life history of an individual is recorded in the chemistry and isotopes of his or her body tissues. The use of isotope geochemistry techniques to trace mobility of individuals 1–7 relies on the fact that the chemical composition of human (and animal) tissues is acquired principally through ingested food and drink, and the isotopic composition of these items is in turn determined by local climate and environmental conditions. Isotope ratios such as 18 O/ 16 O and 87 Sr/ 86 Sr are employed in soft and hard tissues to investigate origins and mobility of past populations. The relationship between the isotopic composition of local environments and the different biological tissues varies with the type of element and isotopes investigated, the tissue, and often the type of animal species 8,9. The partitioning of isotopes in the environment is, in turn, contingent on many factors, including the geological nature of the substrate, environmental conditions, soil type, hydrological circulation, amount of precipitation, plant species and their distribution 2,8,9. Oxygen isotopes in human hard tissues are commonly used in archaeological and forensic science to study residential changes between childhood and adulthood 10–13. Here, and for the rest of the paper, oxygen isotope ratios (18 O/ 16 O) are expressed with the delta (δ) notation as δ 18 O per mil (‰), where δ = R sa /R st –1, R being the isotopic ratio, sa the sample and st the reference standard. In obligate drinkers, such as is the case for humans, oxygen isotope values (δ 18 O) in bones and teeth are related to those of local water (rain-and groundwater). Longinelli and Peretti Padalino 14 demonstrated that a direct relationship exists between the δ 18 O of drinking water and the δ 18 O of blood water in mice and humans. Following these observations, Longinelli 15 and Luz et al. 16 found that a linear correlation also exists between the δ 18 O of human skeletal bone phosphate (δ 18 O p) and the mean annual precipitation (δ 18 O w) characteristic of the area where the individual lived. This correlation is explained by the fact that the mean annual isotopic value of the precipitation falling on a certain area is similar to that of plant food and water available to individuals dwelling in the area. If the nutrients are locally sourced, their isotopic composition is reflected in that of the body water. Since biological apatite precipitates in near equilibrium with body water, it
Proceedings of the Prehistoric Society, 2010
Rapid Communications in Mass Spectrometry, 2008
The hunter-gatherer transhumance model presents foragers as specialised hunters of migratory ungu... more The hunter-gatherer transhumance model presents foragers as specialised hunters of migratory ungulates, which moved seasonally between coastal lowlands and interior uplands. We studied six animal teeth of horse (Equus hydruntinus) and red deer (Cervus elaphus) from four different archaeological sites: the Grotta di Vado all'Arancio, Grotta di Settecannelle, Grotta Polesini and Grotta di Pozzo, in central Italy to test whether the migratory patterns and seasonal variations recorded in their teeth were consistent with expectations of the transhumance model for this region during the late Upper Palaeolithic. Sequential sub-samples of enamel were analysed from each tooth for oxygen, carbon and strontium isotope ratios to reconstruct mobility and yearly seasonal variations. The results show little evidence that these animals were moving over different geological terrains throughout the year, although small variations in Sr isotope ratios and concentrations were detected that corresponded to probable seasonal variations as shown by variability in oxygen isotope sequences. The results do, however, demonstrate that Cervus elaphus and Equus hydruntinus had different ranging behaviours, with the former moving over wider areas than the latter. This methodology produces results appropriate to assess animal migratory behaviour and, in turn, to test the consistency of proposed models of hunter-gatherer subsistence and mobility strategies. Copyright © 2008 John Wiley & Sons, Ltd.
1.1 Cambiamenti climatici e biosfera terrestre Gli ecosistemi terrestri svolgono un ruolo rile-va... more 1.1 Cambiamenti climatici e biosfera terrestre Gli ecosistemi terrestri svolgono un ruolo rile-vante nei cicli biogeochimici (es. ciclo del car-bonio). Le emissioni antropogeniche di C sono molto maggiori dell'incremento di concentra-zione di CO 2 ([CO 2 ]) atmosferica osservato, a causa dell'assorbimento da parte degli oceani e degli ecosistemi terrestri. Tenendo conto del-l'entità del sink oceanico, i modelli individua-no un considerevole sink nella biosfera terre-stre, particolarmente ampio nell'emisfero set-tentrionale. Pertanto, lo studio del bilancio del carbonio e degli scambi vegetazione-atmosfe-ra è di primaria importanza per valutare la pro-duttività della biosfera terrestre e per compren-derne le riposte al cambiamento globale e la capacità di mitigazione dell'aumento di [CO 2 ]. Il ciclo del carbonio negli ecosistemi terrestri è spesso studiato con approcci micrometeorolo-gici come la tecnica eddy covariance. Queste metodologie consentono di quantific...
Palaeogeography, Palaeoclimatology, Palaeoecology, 2011
Proceedings of the Prehistoric Society, 2010
Journal of Geophysical Research, 2009
Mineralogical, geochemical, and melt inclusion analyses have been performed on scoria samples fro... more Mineralogical, geochemical, and melt inclusion analyses have been performed on scoria samples from a small scoria fall deposit interbedded between the Cape Riva (21 ka) pyroclastic deposits and the Minoan (3.6 ka) Plinian eruptions of Santorini volcano and located near the resort ...
A large variety of bioapatite pre-treatments is found in the literature for a wide range of appli... more A large variety of bioapatite pre-treatments is found in the literature for a wide range of applications going from mineralogy to diagenesis. Additionally, stable carbon and oxygen isotopes in bioapatite carbonates are often measured after pre-treatment to study ancient diets and reconstruct past environments. It is common to pre-treat the samples to remove contributions from competing sources associated to organic material and secondary carbonates. Several chemical methods are described in the literature to pre-treat archaeological and fossil bioapatites (bone and teeth) for isotopic measurements with no consistency on their efficiency. Infrared and elemental analyses are combined in this study to highlight the effects of the different pre-treatments on the structure and chemistry of bioapatite. The different pre-treatments can variably affect the organic and carbonate contents of bioapatites, with some, such as sodium hypochlorite, apparently adding carbonate to the system. This may lead to a change in the biological isotopic signature of bioapatite carbonate, with effects on the correct interpretation of the results. According to the findings of our study, hydrazine hydrate seems to be the best chemical to remove organic matter without affecting the carbonate content of bioapatites, while the use of acetate buffered acetic acid solutions is recommended for removing adsorbed carbonates, when necessary. Sodium hypochlorite, instead, induces the adsorption of exogenous carbonates, while hydrogen peroxide does not remove organic matter efficiently even at high temperatures. These two chemicals should not be used to remove organic matter, especially from bone and dentine.
In M. O'Sullivan, C. Scarre and M. Doyle (eds.), Tara - From the Past to the Future, 165-190., 2013
Journal of Archaeological Science
Anomalously 13C-depleted carbon stable isotope values from closed forest ecosystems have been ter... more Anomalously 13C-depleted carbon stable isotope values from closed forest ecosystems have been termed the ‘canopy effect’. Originally this was ascribed to recycling of depleted carbon from forest floor decomposition of organic material, although others have suggested that it is equally likely to be due to variations in leaf-level processes in response to increased shade. This depletion in the heavier carbon isotope is passed on to woodland herbivores feeding within the forest environments. A similar isotopic depletion has also been reported in the archaeological literature from more open temperate woodland settings, but no measurements have been made on the plants at the base of the food chain in order to quantify the effect. In this study we attempt this by examining the carbon and nitrogen stable isotopic values of different species of grasses from a range of open to closed habitat settings within Wytham Wood, Oxfordshire, UK. We find a strong relationship between carbon isotopic depletion of plant tissue and lowered light intensity with an up to 5‰ shift between grass grown in open and closed locations. In order to follow this up the food chain, we also report data on wool from sheep grazing in open pastures near the Wood, and on fallow deer living within the woodland, but which turn out not to show a strong canopy effect, probably related to their feeding strategies. We conclude that there is indeed a strong ‘canopy effect’ in temperate woodland, probably related to differential light levels, but that not all apparently woodland-dwelling mammals show such an effect. We also show considerable isotopic variation at the base of the food chain, which should counsel caution when attempting to interpret dietary isotopes using mixing models.
Rapid Communication in Mass Spectrometry
RATIONALEThe integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be... more RATIONALEThe integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be contingent upon the complete removal of competing sources of oxygen such as associated organic matter. A range of pretreatment methods to purify phosphate material from competing sources of oxygen has been reported, with contradictory evidence on the usefulness and efficiency of one or another. Yet, a systematic comparison of these techniques for bioapatite phosphate has not been conducted.The integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be contingent upon the complete removal of competing sources of oxygen such as associated organic matter. A range of pretreatment methods to purify phosphate material from competing sources of oxygen has been reported, with contradictory evidence on the usefulness and efficiency of one or another. Yet, a systematic comparison of these techniques for bioapatite phosphate has not been conducted.METHODSChemical and thermal pretreatment techniques were tested for their effectiveness at removing organic matter and the likelihood that they modify original δ18O values. The test was performed in inorganic (synthetic apatite and a phosphorite rock) and organic (bone and tooth tissues) phosphate materials for which we had an expectation of the actual original δ18Op value. Analysis of nitrogen content (wt.%), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed.Chemical and thermal pretreatment techniques were tested for their effectiveness at removing organic matter and the likelihood that they modify original δ18O values. The test was performed in inorganic (synthetic apatite and a phosphorite rock) and organic (bone and tooth tissues) phosphate materials for which we had an expectation of the actual original δ18Op value. Analysis of nitrogen content (wt.%), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed.RESULTSWe detected variable efficiency at removing organic matter between pretreatment methods with no correlation to any specific structural change. The δ18Op results showed considerable variation between samples pretreated with the different methods and the untreated samples, with a compositional range of up to 4.5 ‰ in the bone samples. Variations of the δ18Op values within error were found for tooth enamel, phosphorite rock and inorganic apatite.We detected variable efficiency at removing organic matter between pretreatment methods with no correlation to any specific structural change. The δ18Op results showed considerable variation between samples pretreated with the different methods and the untreated samples, with a compositional range of up to 4.5 ‰ in the bone samples. Variations of the δ18Op values within error were found for tooth enamel, phosphorite rock and inorganic apatite.CONCLUSIONSWe recommend a cautious approach when interpreting and comparing δ18Op data from bone samples treated with different pretreatment protocols. In general, the untreated samples seem to show δ18Op values closer to the expected ones. According to our results, pretreatment is completely unnecessary in highly mineralized tissues. Copyright © 2012 John Wiley & Sons, Ltd.We recommend a cautious approach when interpreting and comparing δ18Op data from bone samples treated with different pretreatment protocols. In general, the untreated samples seem to show δ18Op values closer to the expected ones. According to our results, pretreatment is completely unnecessary in highly mineralized tissues. Copyright © 2012 John Wiley & Sons, Ltd.
American Journal of Physical Anthropology, May 3, 2011
ABSTRACT It has become a widespread practice to convert d18Op values measured in human and anima... more ABSTRACT It has become a widespread practice to
convert d18Op values measured in human and animal
dental enamel to a corresponding value of d18Ow and compare
these data with mapped d18Ow groundwater or meteoric
water values to locate the region where the owner of
the tooth lived during the formation of the enamel.
Because this is a regression procedure, the errors associated
with the predicted d18Ow values will depend critically
on the correlation between the comparative data
used to perform the regression. By comparing four widely
used regression equations we demonstrate that the smallest
95% error is likely to be greater than 61% in d18Ow,
and could be as large as 63.5%. These values are significantly
higher than those quoted in some of the recent
literature, and measurements with errors at the higher
end of this range would render many of the published
geographical attributions statistically unsupportable.
We suggest that the simplest solution to this situation is
to make geographical attributions based on the direct
comparison of measured values of d18Op rather than on
predicted values of d18Ow.
![Research paper thumbnail of Exploring the variation of the [delta] 18Op and [delta] 18Oc relationship in enamel increments](https://attachments.academia-assets.com/31697840/thumbnails/1.jpg)
](Palaeogeography, …, Jan 1, 2011
Palaeogeography, Palaeoclimatology, …, Jan 1, 2008
Grotta del Romito has been the subject of numerous archaeological, chronological and palaeoenviro... more Grotta del Romito has been the subject of numerous archaeological, chronological and palaeoenvironmental investigations for more than a decade. During the Upper Palaeolithic period the site contains evidence of human occupation through the Gravettian and Epigravettian periods, multiple human burials, changes in the pattern of human occupation, and faunal, isotopic and sedimentological evidence for local environmental change. In spite of this rich record, the chronological control is insufficient to resolve shifts in subsistence and mobility patterns at sufficiently high resolution to match the abrupt climate fluctuations at this time. To resolve this we present new radiocarbon and tephrostratigraphic dates in combination with existing radiocarbon dates, and develop a Bayesian age model framework for the site. This improved chronology reveals that local environmental conditions reflect abrupt and long-term changes in climate, and that these also directly influence changing patterns of human occupation of the site. In particular, we show that the environmental record for the site, based on small mammal habitat preferences, is chronologically in phase with the main changes in climate and environment seen in key regional archives from Italy and Greenland. We also calculate the timing of the transitions between different cultural phases and their spans. We also show that the intensification in occupation of the site is chronologically coincident with a rapid rise in Mesic Woody taxa seen in key regional pollen records and is associated with the Late Epigravettian occupation of the site. This change in the record of Grotta del Romito is also closely associated stratigraphically with a new tephra (the ROM-D30 tephra), which may act as a critical marker in environmental records of the region.
We report here on an isotopic study of carbon, nitrogen and oxygen isotopes in Equus tooth enamel... more We report here on an isotopic study of carbon, nitrogen and oxygen isotopes in Equus tooth enamel and dentine from multiple layers from the site of Combe Grenal, France, which date to between approximately 150,000 and 50,000 years BP. We found that there were significant variations in all three elemental isotope ratios through time, although the variations were not synchronous. This study shows the utility of using herbivore tooth dentine carbon and nitrogen isotope values as indicators of environmental changes, in addition to their use as dietary indicators.
Chemical Geology, 2015
A large variety of bioapatite pre-treatments is found in the literature for a wide range of appli... more A large variety of bioapatite pre-treatments is found in the literature for a wide range of applications going from mineralogy to diagenesis. Additionally, stable carbon and oxygen isotopes in bioapatite carbonates are often measured after pre-treatment to study ancient diets and reconstruct past environments. It is common to pre-treat the samples to remove contributions from competing sources associated to organic material and secondary carbonates. Several chemical methods are described in the literature to pre-treat archaeological and fossil bioapatites (bone and teeth) for isotopic measurements with no consistency on their efficiency. Infrared and elemental analyses are combined in this study to highlight the effects of the different pre-treatments on the structure and chemistry of bioapatite. The different pre-treatments can variably affect the organic and carbonate contents of bioapatites, with some, such as sodium hypochlorite, apparently adding carbonate to the system. This may lead to a change in the biological isotopic signature of bioapatite carbonate, with effects on the correct interpretation of the results. According to the findings of our study, hydrazine hydrate seems to be the best chemical to remove organic matter without affecting the carbonate content of bioapatites, while the use of acetate buffered acetic acid solutions is recommended for removing adsorbed carbonates, when necessary. Sodium hypochlorite, instead, induces the adsorption of exogenous carbonates, while hydrogen peroxide does not remove organic matter efficiently even at high temperatures. These two chemicals should not be used to remove organic matter, especially from bone and dentine.
A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p) in Britain is p... more A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as 'non-local' to the areas where they were buried (spatial outliers). A marked variation in δ 18 O p is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ 18 O values–a process known to be problematic. Understanding and reconstructing the mobility of past populations and individuals is important in archaeological and forensic studies. One of the ways to address this topic is through the chemical analysis of skeletal remains, for the life history of an individual is recorded in the chemistry and isotopes of his or her body tissues. The use of isotope geochemistry techniques to trace mobility of individuals 1–7 relies on the fact that the chemical composition of human (and animal) tissues is acquired principally through ingested food and drink, and the isotopic composition of these items is in turn determined by local climate and environmental conditions. Isotope ratios such as 18 O/ 16 O and 87 Sr/ 86 Sr are employed in soft and hard tissues to investigate origins and mobility of past populations. The relationship between the isotopic composition of local environments and the different biological tissues varies with the type of element and isotopes investigated, the tissue, and often the type of animal species 8,9. The partitioning of isotopes in the environment is, in turn, contingent on many factors, including the geological nature of the substrate, environmental conditions, soil type, hydrological circulation, amount of precipitation, plant species and their distribution 2,8,9. Oxygen isotopes in human hard tissues are commonly used in archaeological and forensic science to study residential changes between childhood and adulthood 10–13. Here, and for the rest of the paper, oxygen isotope ratios (18 O/ 16 O) are expressed with the delta (δ) notation as δ 18 O per mil (‰), where δ = R sa /R st –1, R being the isotopic ratio, sa the sample and st the reference standard. In obligate drinkers, such as is the case for humans, oxygen isotope values (δ 18 O) in bones and teeth are related to those of local water (rain-and groundwater). Longinelli and Peretti Padalino 14 demonstrated that a direct relationship exists between the δ 18 O of drinking water and the δ 18 O of blood water in mice and humans. Following these observations, Longinelli 15 and Luz et al. 16 found that a linear correlation also exists between the δ 18 O of human skeletal bone phosphate (δ 18 O p) and the mean annual precipitation (δ 18 O w) characteristic of the area where the individual lived. This correlation is explained by the fact that the mean annual isotopic value of the precipitation falling on a certain area is similar to that of plant food and water available to individuals dwelling in the area. If the nutrients are locally sourced, their isotopic composition is reflected in that of the body water. Since biological apatite precipitates in near equilibrium with body water, it
Proceedings of the Prehistoric Society, 2010
Rapid Communications in Mass Spectrometry, 2008
The hunter-gatherer transhumance model presents foragers as specialised hunters of migratory ungu... more The hunter-gatherer transhumance model presents foragers as specialised hunters of migratory ungulates, which moved seasonally between coastal lowlands and interior uplands. We studied six animal teeth of horse (Equus hydruntinus) and red deer (Cervus elaphus) from four different archaeological sites: the Grotta di Vado all'Arancio, Grotta di Settecannelle, Grotta Polesini and Grotta di Pozzo, in central Italy to test whether the migratory patterns and seasonal variations recorded in their teeth were consistent with expectations of the transhumance model for this region during the late Upper Palaeolithic. Sequential sub-samples of enamel were analysed from each tooth for oxygen, carbon and strontium isotope ratios to reconstruct mobility and yearly seasonal variations. The results show little evidence that these animals were moving over different geological terrains throughout the year, although small variations in Sr isotope ratios and concentrations were detected that corresponded to probable seasonal variations as shown by variability in oxygen isotope sequences. The results do, however, demonstrate that Cervus elaphus and Equus hydruntinus had different ranging behaviours, with the former moving over wider areas than the latter. This methodology produces results appropriate to assess animal migratory behaviour and, in turn, to test the consistency of proposed models of hunter-gatherer subsistence and mobility strategies. Copyright © 2008 John Wiley & Sons, Ltd.
1.1 Cambiamenti climatici e biosfera terrestre Gli ecosistemi terrestri svolgono un ruolo rile-va... more 1.1 Cambiamenti climatici e biosfera terrestre Gli ecosistemi terrestri svolgono un ruolo rile-vante nei cicli biogeochimici (es. ciclo del car-bonio). Le emissioni antropogeniche di C sono molto maggiori dell'incremento di concentra-zione di CO 2 ([CO 2 ]) atmosferica osservato, a causa dell'assorbimento da parte degli oceani e degli ecosistemi terrestri. Tenendo conto del-l'entità del sink oceanico, i modelli individua-no un considerevole sink nella biosfera terre-stre, particolarmente ampio nell'emisfero set-tentrionale. Pertanto, lo studio del bilancio del carbonio e degli scambi vegetazione-atmosfe-ra è di primaria importanza per valutare la pro-duttività della biosfera terrestre e per compren-derne le riposte al cambiamento globale e la capacità di mitigazione dell'aumento di [CO 2 ]. Il ciclo del carbonio negli ecosistemi terrestri è spesso studiato con approcci micrometeorolo-gici come la tecnica eddy covariance. Queste metodologie consentono di quantific...
Palaeogeography, Palaeoclimatology, Palaeoecology, 2011
Proceedings of the Prehistoric Society, 2010
Journal of Geophysical Research, 2009
Mineralogical, geochemical, and melt inclusion analyses have been performed on scoria samples fro... more Mineralogical, geochemical, and melt inclusion analyses have been performed on scoria samples from a small scoria fall deposit interbedded between the Cape Riva (21 ka) pyroclastic deposits and the Minoan (3.6 ka) Plinian eruptions of Santorini volcano and located near the resort ...
A large variety of bioapatite pre-treatments is found in the literature for a wide range of appli... more A large variety of bioapatite pre-treatments is found in the literature for a wide range of applications going from mineralogy to diagenesis. Additionally, stable carbon and oxygen isotopes in bioapatite carbonates are often measured after pre-treatment to study ancient diets and reconstruct past environments. It is common to pre-treat the samples to remove contributions from competing sources associated to organic material and secondary carbonates. Several chemical methods are described in the literature to pre-treat archaeological and fossil bioapatites (bone and teeth) for isotopic measurements with no consistency on their efficiency. Infrared and elemental analyses are combined in this study to highlight the effects of the different pre-treatments on the structure and chemistry of bioapatite. The different pre-treatments can variably affect the organic and carbonate contents of bioapatites, with some, such as sodium hypochlorite, apparently adding carbonate to the system. This may lead to a change in the biological isotopic signature of bioapatite carbonate, with effects on the correct interpretation of the results. According to the findings of our study, hydrazine hydrate seems to be the best chemical to remove organic matter without affecting the carbonate content of bioapatites, while the use of acetate buffered acetic acid solutions is recommended for removing adsorbed carbonates, when necessary. Sodium hypochlorite, instead, induces the adsorption of exogenous carbonates, while hydrogen peroxide does not remove organic matter efficiently even at high temperatures. These two chemicals should not be used to remove organic matter, especially from bone and dentine.
In M. O'Sullivan, C. Scarre and M. Doyle (eds.), Tara - From the Past to the Future, 165-190., 2013
Journal of Archaeological Science
Anomalously 13C-depleted carbon stable isotope values from closed forest ecosystems have been ter... more Anomalously 13C-depleted carbon stable isotope values from closed forest ecosystems have been termed the ‘canopy effect’. Originally this was ascribed to recycling of depleted carbon from forest floor decomposition of organic material, although others have suggested that it is equally likely to be due to variations in leaf-level processes in response to increased shade. This depletion in the heavier carbon isotope is passed on to woodland herbivores feeding within the forest environments. A similar isotopic depletion has also been reported in the archaeological literature from more open temperate woodland settings, but no measurements have been made on the plants at the base of the food chain in order to quantify the effect. In this study we attempt this by examining the carbon and nitrogen stable isotopic values of different species of grasses from a range of open to closed habitat settings within Wytham Wood, Oxfordshire, UK. We find a strong relationship between carbon isotopic depletion of plant tissue and lowered light intensity with an up to 5‰ shift between grass grown in open and closed locations. In order to follow this up the food chain, we also report data on wool from sheep grazing in open pastures near the Wood, and on fallow deer living within the woodland, but which turn out not to show a strong canopy effect, probably related to their feeding strategies. We conclude that there is indeed a strong ‘canopy effect’ in temperate woodland, probably related to differential light levels, but that not all apparently woodland-dwelling mammals show such an effect. We also show considerable isotopic variation at the base of the food chain, which should counsel caution when attempting to interpret dietary isotopes using mixing models.
Rapid Communication in Mass Spectrometry
RATIONALEThe integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be... more RATIONALEThe integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be contingent upon the complete removal of competing sources of oxygen such as associated organic matter. A range of pretreatment methods to purify phosphate material from competing sources of oxygen has been reported, with contradictory evidence on the usefulness and efficiency of one or another. Yet, a systematic comparison of these techniques for bioapatite phosphate has not been conducted.The integrity of the biological phosphate oxygen isotope (δ18Op) signal is thought to be contingent upon the complete removal of competing sources of oxygen such as associated organic matter. A range of pretreatment methods to purify phosphate material from competing sources of oxygen has been reported, with contradictory evidence on the usefulness and efficiency of one or another. Yet, a systematic comparison of these techniques for bioapatite phosphate has not been conducted.METHODSChemical and thermal pretreatment techniques were tested for their effectiveness at removing organic matter and the likelihood that they modify original δ18O values. The test was performed in inorganic (synthetic apatite and a phosphorite rock) and organic (bone and tooth tissues) phosphate materials for which we had an expectation of the actual original δ18Op value. Analysis of nitrogen content (wt.%), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed.Chemical and thermal pretreatment techniques were tested for their effectiveness at removing organic matter and the likelihood that they modify original δ18O values. The test was performed in inorganic (synthetic apatite and a phosphorite rock) and organic (bone and tooth tissues) phosphate materials for which we had an expectation of the actual original δ18Op value. Analysis of nitrogen content (wt.%), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed.RESULTSWe detected variable efficiency at removing organic matter between pretreatment methods with no correlation to any specific structural change. The δ18Op results showed considerable variation between samples pretreated with the different methods and the untreated samples, with a compositional range of up to 4.5 ‰ in the bone samples. Variations of the δ18Op values within error were found for tooth enamel, phosphorite rock and inorganic apatite.We detected variable efficiency at removing organic matter between pretreatment methods with no correlation to any specific structural change. The δ18Op results showed considerable variation between samples pretreated with the different methods and the untreated samples, with a compositional range of up to 4.5 ‰ in the bone samples. Variations of the δ18Op values within error were found for tooth enamel, phosphorite rock and inorganic apatite.CONCLUSIONSWe recommend a cautious approach when interpreting and comparing δ18Op data from bone samples treated with different pretreatment protocols. In general, the untreated samples seem to show δ18Op values closer to the expected ones. According to our results, pretreatment is completely unnecessary in highly mineralized tissues. Copyright © 2012 John Wiley & Sons, Ltd.We recommend a cautious approach when interpreting and comparing δ18Op data from bone samples treated with different pretreatment protocols. In general, the untreated samples seem to show δ18Op values closer to the expected ones. According to our results, pretreatment is completely unnecessary in highly mineralized tissues. Copyright © 2012 John Wiley & Sons, Ltd.
American Journal of Physical Anthropology, May 3, 2011
ABSTRACT It has become a widespread practice to convert d18Op values measured in human and anima... more ABSTRACT It has become a widespread practice to
convert d18Op values measured in human and animal
dental enamel to a corresponding value of d18Ow and compare
these data with mapped d18Ow groundwater or meteoric
water values to locate the region where the owner of
the tooth lived during the formation of the enamel.
Because this is a regression procedure, the errors associated
with the predicted d18Ow values will depend critically
on the correlation between the comparative data
used to perform the regression. By comparing four widely
used regression equations we demonstrate that the smallest
95% error is likely to be greater than 61% in d18Ow,
and could be as large as 63.5%. These values are significantly
higher than those quoted in some of the recent
literature, and measurements with errors at the higher
end of this range would render many of the published
geographical attributions statistically unsupportable.
We suggest that the simplest solution to this situation is
to make geographical attributions based on the direct
comparison of measured values of d18Op rather than on
predicted values of d18Ow.
Palaeogeography, …, Jan 1, 2011
Palaeogeography, Palaeoclimatology, …, Jan 1, 2008
Grotta di Pozzo is a cave site (23.000-6.500 cal. BP) at 720m asl in the Apennine range of Abruzz... more Grotta di Pozzo is a cave site (23.000-6.500 cal. BP) at 720m asl in the Apennine range of Abruzzo (central Italy). We tested the hypothesis that Epigravettian lithic elements from layers PS19 to PS1, 23.000 (unpublished)-14.000 cal. BP, were hafted with an adhesive agent, and used as projectile points to catch middle- to small-sized mammals during seasonal hunts.
The archaeozoological analysis was performed on 6863 faunal remains, most of them fragmented and sometimes burnt. Only 419 remains could be determined to species level (6.11% of the total). There are frequent cut marks and impact scars, from skinning, disarticulation and the recovery of bone marrow. The chamois was the most frequently hunted animal, followed by red deer, marmot and ibex. We hypothesize seasonality in hunting, when chamois were leaving summer grazing grounds at higher altitude.
Furthermore, after isotopic analyses on Equus hydruntinus and Cervus elaphus tooth enamel, the two species had a marked difference in ranging behavior, with cervids probably more mobile than equids.
Combining residue and use-wear analysis, 1315 lithic elements were eventually selected out of an assemblage of 5012 artefacts. The residue analysis was performed on traces detected by stereomicroscopy, and completed by Raman spectroscopy to determine the chemical composition. The use-wear analysis focused on impact fractures also detected by stereomicroscopy. Comparisons were made with similar scars described in the literature in collections from late Pleistocene European sites and experimental series. The Tip-cross sectional area (TCSA) was also calculated.
All lines of evidence point to the fact that both retouched points and unretouched bladelets were hafted using an adhesive that included ochre. The weapons were mostly used to kill caprids and cervids. The TCSA, as well as the weight and morphology of the points, further suggests that the bow could possibly have been in use during seasonal hunts.