Comment on "On the importance of opal, carbonate, and lithogenic clays in scavenging and fractionating Th-230, Pa-231 and Be-10 in the ocean" by S. Luo and T.-L. Ku

LDEO Publication: 
Publication Type  Journal Article
Year of Publication  2004
Authors  Chase, Z.; Anderson, R. F.
Journal Title  Earth and Planetary Science Letters
Volume  220
Issue  1-2
Pages  213-222
Journal Date  Mar 30
ISBN Number  0012-821X
Accession Number  ISI:000220556000015
LDEO Publication Number  6571
Key Words  thorium; protactinium; scavenging; particle composition; partition coefficient; anthropogenic radionuclide distributions; northwestern north pacific; particle composition; thorium isotopes; atlantic-ocean; particulate matter; sediment traps; arctic-ocean;

Luo and Ku have reanalyzed part of the data set we published in 2002 to address the question of the differential scavenging of thorium. protactinium and beryllium by different particulate phases (organic carbon, lithogenic material, opal and calcium carbonate). They conclude upon reanalysis that the data are consistent with their earlier proposal, based on sediment separation experiments, that lithogenic material possesses an affinity for Th some 500 times greater than do biogenic phases. While we welcome new analyses and fresh interpretations of our data set we have to disagree with their conclusion that the partition coefficient (K-d) for adsorption of Th onto lithogenic particles (K-d(Th)_L) is on the order of 2.3 x 10(8), and far greater than the K-d for adsorption of Th onto calcium carbonate (K-d(Th)_C). Here we show that such a high value for K-d(Th)_L is inconsistent with a large body of observations. These observations suggest K-d(Th)_L is closer to 1 x 10(7), consistent with our previous study. (C) 2004 Elsevier B.V. All rights reserved.


808FWTimes Cited:10Cited References Count:24

URL  <Go to ISI>://000220556000015
DOI  Doi 10.1016/S0012-821x(04)00028-7