1. PIXE measurements of heavy metals of Tsunami sediment samples
John V Kennedy, Bernard Barry and Andreas Markwitz
National Isotope Centre, Lower Hutt, New Zealand

2. 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

3. 1. GNS’s ion beam analysis facility
3 MV accelerator
Water/Air particulate analysis beam line
External PIXE beam line
MicroPIXE beam line

4. 1. Analysis of performance of different methods for metal measurement
PIXE
Detection limits
Excellent for most elements
Z>12
Sample throughput
All elements in 10 min
Dynamic range
Precision
0.1-1%
Interferences
None
Sample medium
Any type
Sample volume mg
Ease of use
Easy
Capital costs
Very high
Running costs
Low
Cost per elemental analysis
Medium
Imaging capability is an additional advantage for PIXE

5. 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

6. 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

7. 2. Results Low impact Moderate impact
Ti was detected at 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

8. 2. Results Low impact Moderate 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

9. 2. Results Low impact Moderate 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

10. 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

11. 3. Results

12. 3. Results – Depth information

13. 3. Results – Depth informationAs Ba Pb

14. 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 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

15. 4. Water and sediment analysis for future Marine project - Sequel

16. 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.

17. 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.

18. 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.

19. 5. Scanning an example core
Core measurements for Si, Fe, Ti.

20. 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.