"Phosphorus (P) is potentially a very important environmental
proxy in speleothem palaeoclimate ... more "Phosphorus (P) is potentially a very important environmental
proxy in speleothem palaeoclimate reconstructions.
However, the transfer of P to a speleothem seems to
vary between cave sites. Therefore, it is important to investigate
the source of P and the way it is incorporated into a
speleothem on a site-by-site basis before it can be used as a
robust palaeoclimate proxy.
In this paper, the distribution of P in one modern and
two Early Pliocene speleothems formed in coastal caves on
Christmas Island (Indian Ocean) and the Nullarbor Plain
(southern Australia) is investigated using microscopy and
ultra-high resolution chemical mapping.
Phosphorus has been found to be both incorporated in
the lattice and present as diverse P-rich phases. Monitoring
data from Christmas Island suggest that co-precipitation of
P-rich phases occurs when ‘prior calcite precipitation’ decreases
following recharge, even if the drip rate decreases.
Microbial mediation may also play a role, which complicates
a direct climate relationship between P and hydrology. We
find that some P-enriched layers contain dissolution features,
with possible involvement of microbial mats which colonise
pores during reduced drip rates associated with prolonged
dry spells.
In the two Early Pliocene speleothems the relationship between
P and microbial laminae is clearer. Both petrographic
and chemical data suggest that phosphorus-rich phases in the
microbial laminae mark intervals of reduced drip rates, which
may indicate dry intervals during the otherwise wet palaeoclimate
of the Early Pliocene.
We develop a speleothem distribution coefficient for phosphorus
(SKP) rather than the thermodynamic partition coefficient
(KP) to account for the presence of crystalline phosphate
inclusions. SKP describes P enrichment in speleothems
regardless of the process, as similar mechanisms of phosphate
co-precipitation may be in operation in biotic and abiotic
conditions.
The most important implication of our study is that variability
in P concentration may be related to diverse processes
which can be recognized through petrographic observations
and chemical mapping. In particular, there may not be a direct
relation between an increase in P concentration and seasonal
infiltration as has been found in some previous studies,
especially if the source of this element is not the labile phosphate
released through leaching during seasonal vegetation
dieback in temperate climates."
ABSTRACT Metals have a number of important roles within the brain. We used laser ablation-inducti... more ABSTRACT Metals have a number of important roles within the brain. We used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to map the three-dimensional concentrations and distributions of transition metals, in particular iron (Fe), copper (Cu) and zinc (Zn) within the murine brain. LA-ICP-MS is one of the leading analytical tools for measuring metals in tissue samples. Here, we present a complete data reduction protocol for measuring metals in biological samples, including the application of a pyramidal voxel registration technique to reproducibly align tissue sections. We used gold (Au) nanoparticle and ytterbium (Yb)-tagged tyrosine hydroxylase antibodies to assess the co-localisation of Fe and dopamine throughout the entire mouse brain. We also examined the natural clustering of metal concentrations within the murine brain to elucidate areas of similar composition. This clustering technique uses a mathematical approach to identify multiple elementals, avoiding user bias and showing that metal composition follows a hierarchical organisation of neuroanatomical structures. This work provides new insight into the distinct compartmentalisation of metals in the brain, and presents new avenues of exploration with regard to region-specific, metal-associated neurodegeneration observed in several chronic neurodegenerative diseases.
The double-spike approach for correction of instrumental mass bias in mass spectrometry data is w... more The double-spike approach for correction of instrumental mass bias in mass spectrometry data is well established. However, there is very little consistency within the scientific community in terms of double-spike data reduction. Double-spike solutions require computer calculation, using either geometric or algebraic approaches, and are often performed using spreadsheet calculations that vary from group to group and between isotope systems. Here, we present IsoSpike, a generalised computer procedure for the processing of double-spike mass spectrometry data, built as an add-on for the Iolite data-reduction package (www.iolite.org.au). Use of this software permits visualisation of mass spectrometry data in a time window, and rigorous treatment and screening of data. Additionally, IsoSpike uses an integration-by-integration approach where the double-spike calculations are performed on every integration within an analysis, providing straightforward quantification of uncertainties on doublespike-corrected isotope ratios. The advantages of this approach over traditional methods are discussed here. Platinum stable isotope data are presented as an example data set, although the procedure is applicable to any double-spike system. IsoSpike is freely available from www.isospike.org.
It is widely acknowledged that olivine-hosted melt inclusions retain compositional information un... more It is widely acknowledged that olivine-hosted melt inclusions retain compositional information unavailable from the study of bulk-rock samples alone. Whether or not the compositions of melt inclusions are truly representative of geologically significant melt bodies has, however, been called into question; isotopic data are critical to resolving this debate but the rare existing data are contradictory. Previous studies of Pb
Speleothem proxy records, coupled with UeTh chronologies, are widely used in studies of palaeocli... more Speleothem proxy records, coupled with UeTh chronologies, are widely used in studies of palaeoclimate, landscape and faunal evolution. The prospect of extending such studies beyond w500 ka has fuelled considerable interest in the UePb dating method. While theoretical mechanisms for the transport and incorporation of both U and Pb in speleothem calcite remains a matter of debate, it is clear that natural samples span a broad spectrum of compositional variation, and likely contain Pb components with multiple origins and/or transport pathways. Based upon these observations, optimal methods for sample selection are proposed and a variety of techniques for age estimation are explored. Laser ablation ICPMS and autoradiography are ideal rapid screening methods for reconnaissance studies. Common Pb isotopic variability is a key parameter in the choice of analytical strategy for age determination. In large UePb studies where invariant common Pb can be established, common Pb corrected ages can be produced for individual sample aliquots promoting rapid throughput and permitting the establishment of detailed age-depth models. Even with these technologies, however, age resolution becomes an issue beyond a few million years, at which time alternative strategies for developing internal speleothem chronologies, such as lamina counting, must be considered in unison with UePb dating.
We present a novel approach to creating compositional images using a module created for use with ... more We present a novel approach to creating compositional images using a module created for use with the freely distributed software package Iolite. The module creates images by synchronising the state of the laser (eg, whether the laser is firing or not) and the position on the sample, which are recorded in laser log files, with concurrently collected mass spectrometer data. When these two data sources are synchronised, mass spectrometer data which are recorded temporally can then be displayed versus ablation position (ie, spatially ...
Iolite is a non-commercial software package developed to aid in the processing of inorganic mass ... more Iolite is a non-commercial software package developed to aid in the processing of inorganic mass spectrometric data, with a strong emphasis on visualisation versus time of acquisition. The goal of the software is to provide a powerful framework for data processing and interpretation, while giving users the ability to implement their own data reduction protocols. It is intended to be highly interactive, providing the user with a complete overview of the data at all stages of processing, and allowing the freedom to change parameters and reprocess data at any point. The program presents a variety of windows for the selection and viewing of data versus time, as well as features for the generation of X-Y plots, summary reports and export of data. In addition, it is capable of generating X-Y images from laser ablation rasters, and combining information from up to four separate elemental concentrations (intensities of red, green and blue, and the z-axis) in a false-colour three-dimensional image. By virtue of its underlying computing environment-Igor Pro-Iolite is capable of processing very large datasets (i.e., millions of timeslices) rapidly, and is thus ideal for the interrogation of multi-hour sessions of laser ablation data that can not be easily manipulated in conventional spreadsheet applications, for example. It is also well suited to multi-day sessions of solution-mode inductively-coupled plasma mass spectrometer (ICPMS) or thermal ionisation mass spectrometer (TIMS) data. A strong emphasis is placed on the interpolation of parameters that vary with time by a variety of user selectable methods including smoothed cubic splines. Data are processed on a timeslice-by-timeslice basis, allowing outlier rejection and calculation of statistics to be employed directly on calculated results. This approach can reduce the risk of processing biases associated with the manipulation of integrated datasets, while also allowing the implementation of more complex data reduction methods.
It is widely acknowledged that olivine-hosted melt inclusions retain compositional information un... more It is widely acknowledged that olivine-hosted melt inclusions retain compositional information unavailable from the study of bulk-rock samples alone. Whether or not the compositions of melt inclusions are truly representative of geologically significant melt bodies has, however, been called into question; isotopic data are critical to resolving this debate but the rare existing data are contradictory. Previous studies of Pb
J. Anal. At. Spectrom., 2005, 20, 1350-1357 DOI:10.1039/B507647A (Paper). Improved in situ isotop... more J. Anal. At. Spectrom., 2005, 20, 1350-1357 DOI:10.1039/B507647A (Paper). Improved in situ isotope analysis of low-Pb materials using LA-MC-ICP-MS with parallel ion counter and Faraday detection. Bence Paul*, Jon D. Woodhead ...
"Phosphorus (P) is potentially a very important environmental
proxy in speleothem palaeoclimate ... more "Phosphorus (P) is potentially a very important environmental
proxy in speleothem palaeoclimate reconstructions.
However, the transfer of P to a speleothem seems to
vary between cave sites. Therefore, it is important to investigate
the source of P and the way it is incorporated into a
speleothem on a site-by-site basis before it can be used as a
robust palaeoclimate proxy.
In this paper, the distribution of P in one modern and
two Early Pliocene speleothems formed in coastal caves on
Christmas Island (Indian Ocean) and the Nullarbor Plain
(southern Australia) is investigated using microscopy and
ultra-high resolution chemical mapping.
Phosphorus has been found to be both incorporated in
the lattice and present as diverse P-rich phases. Monitoring
data from Christmas Island suggest that co-precipitation of
P-rich phases occurs when ‘prior calcite precipitation’ decreases
following recharge, even if the drip rate decreases.
Microbial mediation may also play a role, which complicates
a direct climate relationship between P and hydrology. We
find that some P-enriched layers contain dissolution features,
with possible involvement of microbial mats which colonise
pores during reduced drip rates associated with prolonged
dry spells.
In the two Early Pliocene speleothems the relationship between
P and microbial laminae is clearer. Both petrographic
and chemical data suggest that phosphorus-rich phases in the
microbial laminae mark intervals of reduced drip rates, which
may indicate dry intervals during the otherwise wet palaeoclimate
of the Early Pliocene.
We develop a speleothem distribution coefficient for phosphorus
(SKP) rather than the thermodynamic partition coefficient
(KP) to account for the presence of crystalline phosphate
inclusions. SKP describes P enrichment in speleothems
regardless of the process, as similar mechanisms of phosphate
co-precipitation may be in operation in biotic and abiotic
conditions.
The most important implication of our study is that variability
in P concentration may be related to diverse processes
which can be recognized through petrographic observations
and chemical mapping. In particular, there may not be a direct
relation between an increase in P concentration and seasonal
infiltration as has been found in some previous studies,
especially if the source of this element is not the labile phosphate
released through leaching during seasonal vegetation
dieback in temperate climates."
ABSTRACT Metals have a number of important roles within the brain. We used laser ablation-inducti... more ABSTRACT Metals have a number of important roles within the brain. We used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to map the three-dimensional concentrations and distributions of transition metals, in particular iron (Fe), copper (Cu) and zinc (Zn) within the murine brain. LA-ICP-MS is one of the leading analytical tools for measuring metals in tissue samples. Here, we present a complete data reduction protocol for measuring metals in biological samples, including the application of a pyramidal voxel registration technique to reproducibly align tissue sections. We used gold (Au) nanoparticle and ytterbium (Yb)-tagged tyrosine hydroxylase antibodies to assess the co-localisation of Fe and dopamine throughout the entire mouse brain. We also examined the natural clustering of metal concentrations within the murine brain to elucidate areas of similar composition. This clustering technique uses a mathematical approach to identify multiple elementals, avoiding user bias and showing that metal composition follows a hierarchical organisation of neuroanatomical structures. This work provides new insight into the distinct compartmentalisation of metals in the brain, and presents new avenues of exploration with regard to region-specific, metal-associated neurodegeneration observed in several chronic neurodegenerative diseases.
The double-spike approach for correction of instrumental mass bias in mass spectrometry data is w... more The double-spike approach for correction of instrumental mass bias in mass spectrometry data is well established. However, there is very little consistency within the scientific community in terms of double-spike data reduction. Double-spike solutions require computer calculation, using either geometric or algebraic approaches, and are often performed using spreadsheet calculations that vary from group to group and between isotope systems. Here, we present IsoSpike, a generalised computer procedure for the processing of double-spike mass spectrometry data, built as an add-on for the Iolite data-reduction package (www.iolite.org.au). Use of this software permits visualisation of mass spectrometry data in a time window, and rigorous treatment and screening of data. Additionally, IsoSpike uses an integration-by-integration approach where the double-spike calculations are performed on every integration within an analysis, providing straightforward quantification of uncertainties on doublespike-corrected isotope ratios. The advantages of this approach over traditional methods are discussed here. Platinum stable isotope data are presented as an example data set, although the procedure is applicable to any double-spike system. IsoSpike is freely available from www.isospike.org.
It is widely acknowledged that olivine-hosted melt inclusions retain compositional information un... more It is widely acknowledged that olivine-hosted melt inclusions retain compositional information unavailable from the study of bulk-rock samples alone. Whether or not the compositions of melt inclusions are truly representative of geologically significant melt bodies has, however, been called into question; isotopic data are critical to resolving this debate but the rare existing data are contradictory. Previous studies of Pb
Speleothem proxy records, coupled with UeTh chronologies, are widely used in studies of palaeocli... more Speleothem proxy records, coupled with UeTh chronologies, are widely used in studies of palaeoclimate, landscape and faunal evolution. The prospect of extending such studies beyond w500 ka has fuelled considerable interest in the UePb dating method. While theoretical mechanisms for the transport and incorporation of both U and Pb in speleothem calcite remains a matter of debate, it is clear that natural samples span a broad spectrum of compositional variation, and likely contain Pb components with multiple origins and/or transport pathways. Based upon these observations, optimal methods for sample selection are proposed and a variety of techniques for age estimation are explored. Laser ablation ICPMS and autoradiography are ideal rapid screening methods for reconnaissance studies. Common Pb isotopic variability is a key parameter in the choice of analytical strategy for age determination. In large UePb studies where invariant common Pb can be established, common Pb corrected ages can be produced for individual sample aliquots promoting rapid throughput and permitting the establishment of detailed age-depth models. Even with these technologies, however, age resolution becomes an issue beyond a few million years, at which time alternative strategies for developing internal speleothem chronologies, such as lamina counting, must be considered in unison with UePb dating.
We present a novel approach to creating compositional images using a module created for use with ... more We present a novel approach to creating compositional images using a module created for use with the freely distributed software package Iolite. The module creates images by synchronising the state of the laser (eg, whether the laser is firing or not) and the position on the sample, which are recorded in laser log files, with concurrently collected mass spectrometer data. When these two data sources are synchronised, mass spectrometer data which are recorded temporally can then be displayed versus ablation position (ie, spatially ...
Iolite is a non-commercial software package developed to aid in the processing of inorganic mass ... more Iolite is a non-commercial software package developed to aid in the processing of inorganic mass spectrometric data, with a strong emphasis on visualisation versus time of acquisition. The goal of the software is to provide a powerful framework for data processing and interpretation, while giving users the ability to implement their own data reduction protocols. It is intended to be highly interactive, providing the user with a complete overview of the data at all stages of processing, and allowing the freedom to change parameters and reprocess data at any point. The program presents a variety of windows for the selection and viewing of data versus time, as well as features for the generation of X-Y plots, summary reports and export of data. In addition, it is capable of generating X-Y images from laser ablation rasters, and combining information from up to four separate elemental concentrations (intensities of red, green and blue, and the z-axis) in a false-colour three-dimensional image. By virtue of its underlying computing environment-Igor Pro-Iolite is capable of processing very large datasets (i.e., millions of timeslices) rapidly, and is thus ideal for the interrogation of multi-hour sessions of laser ablation data that can not be easily manipulated in conventional spreadsheet applications, for example. It is also well suited to multi-day sessions of solution-mode inductively-coupled plasma mass spectrometer (ICPMS) or thermal ionisation mass spectrometer (TIMS) data. A strong emphasis is placed on the interpolation of parameters that vary with time by a variety of user selectable methods including smoothed cubic splines. Data are processed on a timeslice-by-timeslice basis, allowing outlier rejection and calculation of statistics to be employed directly on calculated results. This approach can reduce the risk of processing biases associated with the manipulation of integrated datasets, while also allowing the implementation of more complex data reduction methods.
It is widely acknowledged that olivine-hosted melt inclusions retain compositional information un... more It is widely acknowledged that olivine-hosted melt inclusions retain compositional information unavailable from the study of bulk-rock samples alone. Whether or not the compositions of melt inclusions are truly representative of geologically significant melt bodies has, however, been called into question; isotopic data are critical to resolving this debate but the rare existing data are contradictory. Previous studies of Pb
J. Anal. At. Spectrom., 2005, 20, 1350-1357 DOI:10.1039/B507647A (Paper). Improved in situ isotop... more J. Anal. At. Spectrom., 2005, 20, 1350-1357 DOI:10.1039/B507647A (Paper). Improved in situ isotope analysis of low-Pb materials using LA-MC-ICP-MS with parallel ion counter and Faraday detection. Bence Paul*, Jon D. Woodhead ...
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Papers by Bence Paul
proxy in speleothem palaeoclimate reconstructions.
However, the transfer of P to a speleothem seems to
vary between cave sites. Therefore, it is important to investigate
the source of P and the way it is incorporated into a
speleothem on a site-by-site basis before it can be used as a
robust palaeoclimate proxy.
In this paper, the distribution of P in one modern and
two Early Pliocene speleothems formed in coastal caves on
Christmas Island (Indian Ocean) and the Nullarbor Plain
(southern Australia) is investigated using microscopy and
ultra-high resolution chemical mapping.
Phosphorus has been found to be both incorporated in
the lattice and present as diverse P-rich phases. Monitoring
data from Christmas Island suggest that co-precipitation of
P-rich phases occurs when ‘prior calcite precipitation’ decreases
following recharge, even if the drip rate decreases.
Microbial mediation may also play a role, which complicates
a direct climate relationship between P and hydrology. We
find that some P-enriched layers contain dissolution features,
with possible involvement of microbial mats which colonise
pores during reduced drip rates associated with prolonged
dry spells.
In the two Early Pliocene speleothems the relationship between
P and microbial laminae is clearer. Both petrographic
and chemical data suggest that phosphorus-rich phases in the
microbial laminae mark intervals of reduced drip rates, which
may indicate dry intervals during the otherwise wet palaeoclimate
of the Early Pliocene.
We develop a speleothem distribution coefficient for phosphorus
(SKP) rather than the thermodynamic partition coefficient
(KP) to account for the presence of crystalline phosphate
inclusions. SKP describes P enrichment in speleothems
regardless of the process, as similar mechanisms of phosphate
co-precipitation may be in operation in biotic and abiotic
conditions.
The most important implication of our study is that variability
in P concentration may be related to diverse processes
which can be recognized through petrographic observations
and chemical mapping. In particular, there may not be a direct
relation between an increase in P concentration and seasonal
infiltration as has been found in some previous studies,
especially if the source of this element is not the labile phosphate
released through leaching during seasonal vegetation
dieback in temperate climates."
proxy in speleothem palaeoclimate reconstructions.
However, the transfer of P to a speleothem seems to
vary between cave sites. Therefore, it is important to investigate
the source of P and the way it is incorporated into a
speleothem on a site-by-site basis before it can be used as a
robust palaeoclimate proxy.
In this paper, the distribution of P in one modern and
two Early Pliocene speleothems formed in coastal caves on
Christmas Island (Indian Ocean) and the Nullarbor Plain
(southern Australia) is investigated using microscopy and
ultra-high resolution chemical mapping.
Phosphorus has been found to be both incorporated in
the lattice and present as diverse P-rich phases. Monitoring
data from Christmas Island suggest that co-precipitation of
P-rich phases occurs when ‘prior calcite precipitation’ decreases
following recharge, even if the drip rate decreases.
Microbial mediation may also play a role, which complicates
a direct climate relationship between P and hydrology. We
find that some P-enriched layers contain dissolution features,
with possible involvement of microbial mats which colonise
pores during reduced drip rates associated with prolonged
dry spells.
In the two Early Pliocene speleothems the relationship between
P and microbial laminae is clearer. Both petrographic
and chemical data suggest that phosphorus-rich phases in the
microbial laminae mark intervals of reduced drip rates, which
may indicate dry intervals during the otherwise wet palaeoclimate
of the Early Pliocene.
We develop a speleothem distribution coefficient for phosphorus
(SKP) rather than the thermodynamic partition coefficient
(KP) to account for the presence of crystalline phosphate
inclusions. SKP describes P enrichment in speleothems
regardless of the process, as similar mechanisms of phosphate
co-precipitation may be in operation in biotic and abiotic
conditions.
The most important implication of our study is that variability
in P concentration may be related to diverse processes
which can be recognized through petrographic observations
and chemical mapping. In particular, there may not be a direct
relation between an increase in P concentration and seasonal
infiltration as has been found in some previous studies,
especially if the source of this element is not the labile phosphate
released through leaching during seasonal vegetation
dieback in temperate climates."