Kenneth Pye Associates Ltd. - www.kpal.co.uk Kenneth Pye Associates Ltd.
 Scientific Research, Consultancy and Investigations

              
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Chemical Analysis
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Major and Trace Element Analysis

A wide range of solid samples can be digested and analysed by both atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) to quantify major, minor and trace elements.  This technique is able to measure the abundance of a broad suite of elements (typically up to 50) in very low concentrations and for small samples (c. 0.1 g). Where sample size is not limited, the composition can be determined by x-ray fluorescence (XRF) analysis. Data can be processed to meet specific requirements or analysed in-house using proprietary software.  Over a number of years several databases of chemical data have been compiled. including soils and sediments from a wide range of environments and geographical coverage.

Examples using ICP data

    
Example bivariate plots comparing concentrations of elements and ratios of elements for mud taken from
a suspect's boots and control soil samples taken at a crime scene 

 

    
Spider diagrams comparing elemental concentrations (log scales) in mud taken from a suspect's boots and control
soil samples taken at a crime scene: (left) full suite of 49 elements, with the main differences arrowed;
(right) chondrite-normalized rare earth elements

 

    
Example cumulative frequency plots of the aluminium oxide concentration and cerium/lanthanum
ratio in a database of nearly 2000 UK soil samples analysed by ICP.


Locations of sediment samples collected from sand dune
sites in England and Wales.

 



Average SiO2 content in the 63-250 µm fraction of over 500 sediment samples collected
from dune sites in England and Wales: (top) east coast; and (bottom) west coast.

 


Bivariate plot of the Al2O3/K2O ratio versus the SiO2/Al2O3 ratio in the 63-250 µm
fraction of over 500 sediment samples collected from dune sites in England and Wales.
The samples from Studland Bay (circled) are chemically very distinct.

 

Examples using XRF data


Map showing the location of sand dune sediment samples
collected along the coast of Denmark.

 

    
Frequency histograms of SiO2/Al2O3 ratio and Al2O3/Fe2O3 ratio for the 63-250 µm size
fractions of sand dune sediment samples collected along the coast of Denmark.

 


Cluster analysis dendrogram, performed using Ward's method, for Denmark sand
dune samples, based on data for 29 elements determined by XRF.

 


Plots of the first two axes of the principal component analysis, performed using Ward's
method, for Denmark sand dune samples, based on data for 29 elements determined
by XRF.

 

Stable Isotope Analysis

Hydrogen, carbon, nitrogen, oxygen and sulphur possess two or more stable isotopes, which do not undergo radioactive decay. The stable isotopic ratios of these elements have been demonstrated to be useful indicators of many geological and biological processes. Ratios are determined by isotope ratio mass spectrometry (IRMS), either continuous helium flow (CF-IRMS) or combustion-gas chromatography (C-GC-IRMS).

    

                                                       

Bivariate plots of δ13C (per mil) relative to VPDB against δ15N (per mil) relative to atmospheric N2 for:
(left) the <150 mm, and (right) the >150 mm size fractions of soil samples taken from one metre square
grids in two different locations in Berkshire, UK.

 

pH, Eh, Electrical Conductivity and Anion Analysis

Simple determination of pH, Eh and electrical conductivity (total dissolved solids) can be an indication of temporal and spatial variations in environmental conditions. Analyses can be performed in the field and laboratory using a range of instrumentation ion-selective electrodes. Anion determination by ion chromatography can also be a useful and rapid method of detecting variations in water and sediment quality.


Variations in the electrical conductivity of river water along approximately 40 km of the Bristol Avon,
UK.

Publications

Pye, K., Blott, S.J., Croft, D.J. and Witton, S.J. (2007). Discrimination between sediment and soil samples for forensic purposes using elemental data: An investigation of particle size effects. Forensic Science International 167, 30-42.
(click to view the abstract of this paper)

Pye, K., Blott, S.J., Croft, D.J. and Carter, J.F. (2006). Forensic comparison of soil samples: assessment of small-scale spatial variability in elemental composition, carbon and nitrogen isotope ratios, colour, and particle size distribution. Forensic Science International 163, 59-80.
(click to view the abstract of this paper)

Pye, K., Blott, S.J. and Wray, D.S. (2006). Elemental analysis of soil samples for forensic purposes by Inductively Coupled Plasma Spectrometry – precision considerations. Forensic Science International 160, 178-192.
(click to view the abstract of this paper)

Saye, S.E., Pye, K. and Clemmensen, L.B. (2006) Development of a cliff-top dune indicated by particle size and geochemical characteristics: Rubjerg Knude, Denmark. Sedimentology 53, 1-21.
(click to view the abstract of this paper)

Saye, S.E. and Pye, K. (2006). Variations in chemical composition and particle size of dune sediments along the west coast of Jutland, Denmark. Sedimentary Geology 183, 217-242.
(click to view the abstract of this paper)

Pye, K. and Blott, S.J. (2004). Comparison of soils and sediments using major and trace element data. In: Pye, K. and Croft, D. (Eds.) Forensic Geoscience - Principles, Techniques and Applications. Geological Society Special Publication No. 232, Geological Society Publishing House, Bath, pp. 183-196.
(click to view the abstract of this paper)

Saye, S.E. and Pye, K. (2004) Development of a coastal dune sediment database for England and Wales: forensic applications. In: Pye, K. and Croft, D. (Eds.) Forensic Geoscience - Principles, Techniques and Applications. Geological Society Special Publication No. 232, Geological Society Publishing House, Bath, pp. 75-96.
(click to view the abstract of this paper)

Croft, D.J. and Pye, K. (2004) Stable carbon and nitrogen isotope variations in soils: forensic applications. In: Pye, K. and Croft, D. (Eds.) Forensic Geoscience - Principles, Techniques and Applications. Geological Society Special Publication No. 232, Geological Society Publishing House, Bath, pp. 257-267.
(click to view the abstract of this paper)

Croft, D.J. and Pye, K. (2003) The potential use of continuous-flow isotope-ratio mass spectrometry as a tool in forensic soil analysis: a preliminary report. Rapid Communications in Mass Spectrometry 17, 2581-2584.
(click to view the abstract of this paper)


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Page last modified: July 11, 2007