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

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

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

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 104-108 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

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

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

2. Results Low impact Moderate 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

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

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

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

3. Results

3. Results – Depth information

3. Results – Depth information As Ba Pb

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

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

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.

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.

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.

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

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.