6. 239,240 Pu in aerosol (TSP) samples shows a strong seasonal cycle
7. A seasonal cycle in 239,240 Pu has been previously observed.* But the causes for the seasonal cycles in the current vs. historical data are different. *Perkins & Thomas, 1980
8. Current data suggests an association of 239,240 Pu with aluminum, an indicator of mineral dust
9. 239,240 Pu activities are correlated with aluminum, and the 239,240 Pu/Al relationships are similar at all sites
11. Current 239,240 Pu Levels in Soils (courtesy H. Beck) Beck, H. L., and B. G. Bennett, Historical overview of atmospheric nuclear weapons testing and estimates of fallout in the continental United States, Health Physics , 82, 591-608. Carlsbad is not a Pu hotspot—the Pu is probably associated with resuspended global fallout Carlsbad
12. … but about half of the 239,240 Pu activity is in the PM 10 fraction, implying contributions from local sources Intercept = -1.2 E-10 Slope = 0.58 R 2 = 0.57
15. Recent trends of plutonium fallout observed in Japan: plutonium as a proxy for desertification K. Hirose , Y. Igarashi , Michio Aoyama , C. K. Kim , C. S. Kim and B. W. Chang Abstract: Plutonium in monthly deposition samples collected in Tsukuba (the Meteorological Research Institute), Japan from 1990 to end of 2001 is reported, together with monthly plutonium deposition in Nagasaki and Yonaguni in 2000. The annual deposition of 239,240 Pu during the period from 1990 to 2001 shows no systematic inter-annual variation. However, monthly 239,240 Pu depositions show a typical seasonal variation with a maximum in spring season (March to April), which corresponds to seasonal cycle of soil dusts originating from the East Asian arid area. Plutonium isotopic ratios in the deposition samples suggest that significant amounts of the recent 239,240 Pu deposition observed in Japan are attributed to the resuspension of plutonium-bearing surface soil particles ; resuspended plutonium originates from the East Asian arid areas. The recent increased tendency of 239,240 Pu content in residues in deposition samples may reflect desertification in the East Asian continent. J. Environ. Monit. , 2003, 5 (2), 302 - 307 A recent study indicates that Asian dust also is contaminated with plutonium!
16. Chemical Composition of Atmospheric Aerosols from Zhenbeitai, People’s Republic of China, and Gosan, South Korea, during ACE-Asia R. Arimoto, X. Zhang, B. J. Huebert, C.H. Kang, J. M. Prospero, D. Savoie, S. Sage, C. A. Schloesslin, and H. Khaing
17. Rishiri Sado Hachijo Chichijima Seoul Gosan Amami 30 o N 40 o N 20 o N 10 o N 50 o N 60 o N 160 o E 100 o E 140 o E 120 o E 180 o Midway ACE-Asia Ground Station Network Fukue Tango Lan-yu Hong Kong Beijing Qingdao Linan Zhenbeita i Dunhuang Wan-li
18. Sampling & Analyses Zhenbeitai IMPROVE-type sampler (PM 2.5 ) IC & ICP-MS at CEMRC TSP sampler IC at UH, PIXE at IEE/BNU Gosan High-volume bulk sampler IC & ICP/MS at CEMRC (Same sampler used for PEM-West)
19. Water Soluble (WS) Cations in Aerosol Samples from Zhenbeitai (ZBT): Concentrations and Relationships to Aluminum Cations are correlated with aluminum At Zhenbeitai ACE-Asia
20. Correlations (r-values) Bold, p < 0.01 Plain, p < 0.05, Blanks , ns. At Gosan Alkali/alkaline earths, major cations and Al are generally correlated Correlation Matrix Numbers of sample pairs ACE-Asia
21. water-soluble calcium is about equal to total calcium At Zhenbeitai both WS and total Ca are correlated with aluminum
22. Ca & Al concentrations are lower At Gosan (compared with Zhenbeitai) a smaller percentage of Ca is water soluble both WS and total Ca are correlated with Al, but the ratios to Al are lower
23. TSP, North Winds TSP, South Winds PM 2.5 Zhenbeitai: large particle sulfate sometimes accompanies the dust Aluminum vs Sulfate 50 0.67 8 0.11 N r TSP (North) PM 2.5 Al & sulfate are correlated in TSP samples, but not PM 2.5
24. Sulfate/WS Ca 2+ molar ratio averages 0.090 ± 0.035 Nitrate/WS Ca 2+ molar ratio averages 0.015 ± 0.005 At Zhenbeitai during high dust events (> 40 µg m ‑3 soluble Ca) Sulfate and nitrate in dust prior to mixing? TSP, North Winds TSP, South Winds PM 2.5
25. the sulfate/WS Ca 2+ molar ratio is about 5 to 10X higher than at ZBT the correlation between sulfate and Al is lower than at ZBT (r = 0.35), but still significant Daily Multi-day At Gosan ACE-Asia
26. Observations and Possible Explanations The sources for dust at ZBT and GOS are different Calcium and especially WS Ca 2+ are preferentially removed relative to Al during transport Pollution sources mix non-crustal proportions of Ca, Al and sulfate with the dust Differences in Ca and WS(Ca 2+ ) concentrations at ZBT & GOS Higher percentage of WS(Ca 2+ ) at ZBT Higher sulfate/WS(Ca 2+ ) ratio at GOS Sulfate/Al correlation lower at GOS
27. Summary: There’s (probably) dirt on that dust! Dust from Carlsbad, NM is contaminated with transuranic radionuclides Asian dust/major ion relationships Al vs. cation relationships demonstrated Al & sulfate tend to be correlated, but there’s a need to better constrain element/ion relationships in source materials Ca results are perplexing--need to evaluate source differences vs. differential removal vs. weathering reactions
28. Wind threshold-distance (W t,d ) is the sum of the products of the wind velocities (V) above the threshold (t) and duration (T) W t,d measures wind travel and has units of meters Relationship between 239,240 Pu and wind speed
29. Relationships between wind threshold-distance and 239,240 Pu activity vary as a function of threshold velocity
