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Intercalibration studies of short‐lived thorium‐234 in the water column and marine particles
Author(s) -
Maiti Kanchan,
Buesseler Ken O.,
Pike Steven M.,
BenitezNelson Claudia,
Cai Pinghe,
Chen Weifang,
Cochran Kirk,
Dai Minhan,
Dehairs Frank,
Gasser Beat,
Kelly Roger P.,
Masque Pere,
Miller Lisa A.,
Miquel Juan Carlos,
Moran S. Bradley,
Morris Paul J.,
Peine Florian,
Planchon Frederic,
Renfro Alisha A.,
van der Loeff Michiel Rutgers,
Santschi Peter H.,
Turnewitsch Robert,
Waples James T.,
Xu Chen
Publication year - 2012
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.4319/lom.2012.10.631
Subject(s) - geotraces , particulates , water column , environmental science , sorption , quartz , thorium , mineralogy , hydrology (agriculture) , geology , oceanography , seawater , chemistry , materials science , metallurgy , uranium , paleontology , geotechnical engineering , organic chemistry , adsorption
Intercomparision of 234 Th measurements in both water and particulate samples was carried out between 15 laboratories worldwide, as a part of GEOTRACES inter‐calibration program. Particulate samples from four different stations namely BATS (both shallow and deep) and shelf station (shallow) in Atlantic and SAFE (both shallow and deep) and Santa Barbara station (shallow) in Pacific were used in the effort. Particulate intercalibration results indicate good agreement between all the participating labs with data from all labs falling within the 95% confidence interval around the mean for most instances. Filter type experiments indicate no significant differences in 234 Th activities between filter types and pore sizes (0.2–0.8 µm). The only exception are the quartz filters, which are associated with 10% to 20% higher 234 Th activities attributed to sorption of dissolved 234 Th. Flow rate experiments showed a trend of decreasing 234 Th activities with increasing flow rates (2‐9 L min −1 ) for > 51 µm size particles, indicating particle loss during the pumping process. No change in 234 Th activities on small particles was observed with increasing flow‐rates. 234 Th intercalibration results from deep water samples at SAFe station indicate a variability of < 3% amongst labs while dissolved 234 Th data from surface water at Santa Barbara Station show a less robust agreement, possibly due to the loss of 234 Th from decay and large in‐growth corrections as a result of long gap between sample collection and processing.