Kastelle et al.: Anoplopoma fimbria age validation 



297 



Table 2 



Comparison of background (Bk) and blank (BL) activity reported in the literature for tracer spikes, Po-210 in 

 equilibrium with Pb-210, and Ra-226. NR = not reported 



Tracer spike 

 (Po-209 or Po-208) 



Po-210 



Ra-226 



This study Bk (cpm) 1.867 x 10^ ± 5.63 x 10~ 5 to 2.353 x lO^ 1 ± 6.53 x 10" 5 to 8.500 x 10" 3 ± 5.27 x 10" 4 



6.413 x 10" 4 ± 1.472 x 10" 4 5.600 x 10 4 ± 9.75 x 10" 5 



Not significant 



6.94 x 10" 4 

 Not measurable above Bk 



6.94 x 10" 4 

 5 x 10- 4 



NR' 



Not significant 



1.4 x 10- 2 to 2.8 x 10- 2 

 3.9 x 10" 2 



NR 

 NR 



1.03 x 10- 2 + 2.7 x 10" 3 1.25 x 10" 2 ± 4.3 x 10" 



6.94 x 10" 4 



1.4 x 10" 3 to 3.5 x 10" 



1.03 x 10" 2 ± 2.7 x 10" 3 2.55 x 10" 2 ± 2.3 x 10~ 3 



' Not reported specifically for this radioisotope, but this author suggested a lower value here than reported by Bennett et al. (1982). 



porated into the biota or food chain through a vari- 

 ety of sources, such as water during the osmoregu- 

 lation process, from food (Porntepkasemsan and 

 Nevissi, 1990) such as phytoplankton (Shannon and 

 Cherry, 1971) and zooplankton (Evans et al., 1938), 



and from contact with sediments (Swanson, 1985). 

 The geographic area the species inhabits, its verti- 

 cal distribution in the water column, and the effi- 

 ciency of transfer of Ra-226 through its food chain 

 could play a role in the uptake of Ra-226 (Cochran, 



