PIXE measurements of heavy metals of Tsunami sediment samples

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PIXE measurements of heavy metals of Tsunami
sediment samples

• John V Kennedy, Bernard Barry and Andreas
  Markwitz
• National Isotope Centre, Lower Hutt, New Zealand

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Outline

• Overview Experimental
• Tsunami sediment samples from Thailand
• Tsunami sediment samples from Malaysia
• Water and sediment analysis for future Marine
  project Sequel
• External beam scanning of complete core samples
• Summary

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1. GNSs ion beam analysis facility
3 MV accelerator
Water/Air particulate analysis beam line
External PIXE beam line
MicroPIXE beam line
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1. Analysis of performance of different methods
for metal measurement
Imaging capability is an additional advantage for
PIXE
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2. Experimental

• 2.5 MeV protons for accelerator
• Characteristic PIXE X-rays generated by the
  sample detected by a Si (Li) detector
• Simultaneous detection of K X-rays of elements
  such as Ba, La with a HPGe detector
• PIXE spectra were analysed with GUPIX software to
  determine the elemental concentration values
• To detect light elements such as F, Na, and Al we
  have also performed PIGE analysis at the same time

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2. Tsunami sediment samples from Thailand

• Sediment samples collected by Ms.Kanitha
  Srisuksawad
• C1 - series of sample from moderate impact site
• C2 series of sample from low impact site
• Samples seived to collect clay only
• Pellets prepared of 10 samples of each series
  along with NIST sediment standards.

Done
Not yet
Done
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2. Results
Low impact

• Ti was detected at 1000-2000 ppm level in both
  series with no discernable depth trends.
• Ti concentration in the AOP series was about
  twice that in the PMBC series
• Mn concentration in the PMBC series was around
  2-3 times lower than AOP

Moderate impact
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2. Results
Low impact

• Fe is detected in all samples, and was found at
  higher concentration in the AOP series with a
  trend to higher concentration at greater depth.
• Ni varies with depth

Moderate impact
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2. Results
Low impact

• Zn in generally at similar concentration except
  close to the surface
• Sr is much higher in PMBC than AOP from both
  standard and HPGe PIXE results

Moderate impact
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3. Tsunami sediment samples from Malaysia

• 24 sediment samples collected in Kuala Mude by
  Malaysian Colleagues (Mr.Abdul Kadir b. Ishak)
• The core code is KM25A
• KM00 is core section 2 from another core, KM24B.
• Sample code KM46 is replicate of KM42.
• Sample code KM44 is SRM IAEA-405
• We have prepared 3 pellets of each samples along
  with NIST sediment standards.
• All the pellet samples were carbon coated in
  order to avoid charging during the PIXE
  measurement

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3. Results
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3. Results Depth information
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3. Results Depth information
As
Ba
Pb
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4. Water and sediment analysis for future Marine
project - Sequel
Example Waiwhetu stream, Lower Hutt, New Zealand

• Samples filtered through Nuclepore polycarbaonate
  filter papers for few minutes and dried with UV
• Filter papers weighed before and after filtering
  the samples to determine the weight of the
  filtered particles
• Almost all elements detected were present in the
  level of 10-100 ppm in the samples collected
• Heavy metals such as Cr, Ni, Cu, Zn, Pb were
  found at high level of concentrations at the
  locations where most of the industries were
  present. This indicates that these heavy metals
  are being washed out from the sediments slowly to
  surface waters
• Few studies were carried out earlier in the
  sediment samples indicated that there is a high
  level of heavy metals (Al, Cd, Cr, Cu, Pb, Zn,
  Mn, Fe) present in the sediments

V. J. Kennedy and A. Markwitz, International
Journal of PIXE Vol 12, (2002)189
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4. Water and sediment analysis for future Marine
project - Sequel
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5. External beam scanning of complete core samples

• Samples are often taken from geological cores and
  analysed destructively for trace elements.
• The effectiveness of this would be enhanced with
  a technique which enabled cores to be
  pre-screened quickly and non-destructively for a
  range of elements at low concentrations.
• Particle induced X-ray emission (PIXE) using a
  proton beam is a candidate technique to fulfil
  this need.
• Because of the size of cores, typically in the
  order of a meter long and 100 mm wide, scanning
  under vacuum is impractical. Thus use of an
  external beam is necessary.

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5. External beam scanning of complete core samples

• Stepper motor driven slider shown without
  detectors and with core in protective wrapping in
  position on the slider.

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5. Scanning an example core

• A sample core from the seabed near the Brothers
  volcano north of the Bay of Plenty was scanned
  over a distance of 200 mm at 10 mm intervals for
  approximately 5 minutes per point.

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5. Scanning an example core

• Core measurements for Si, Fe, Ti.

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Summary

• Some Tsunami sediment samples from Thailand and
  Malaysia were analysed with PIXE. Interesting
  depth information was obtained for heavy
  elements. Further analysis is required on highly
  effected Tsunami sites from Thailand
• NAA results from Malaysia are in good agreement
  with the PIXE results (see talk from Malaysia)
• Ideas for water, sediment and complete core
  analysis have been presented.

End.