Reply to comment by Chin-Chang Hung et al on 'How accurate are Th-234 measurements in seawater based on the MnO2-impregnated cartridge technique?‘‘

• Main Authors: Cai, PH, Dai, MH, Lv, DW, Chen, WF, 戴民汉
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER GEOPHYSICAL UNION 2008
• Subjects: PARTICULATE ORGANIC-CARBON; GULF-OF-MEXICO; SMALL-VOLUME TECHNIQUE; UPPER OCEAN EXPORT; THORIUM ISOTOPES; SEASONAL-CHANGES; SEDIMENT TRAPS; ARCTIC-OCEAN; POC EXPORT; FLUX; Arctic; Arctic Ocean
• Online Access: http://dspace.xmu.edu.cn/handle/2288/88310

We disagree that the comparison of the small-volume MnO2coprecipitation method and the MnO2，cartridge method of Hung et al.[2008] is adequate. This is because at least some of the small-volume234Th data used for their compar-ison relied on an early protocol of the small- volume method that did not include a recovery correction. Thus results are potentially biased. New data from the South China Sea onfirmour earlier conclusion that the extraction efficiency for 234，Th is substantially overestimated by the cartridge method. We therefore restate that the small-volume234，Thmethod that includes a recovery correction is advantageous over the cartridge tech-nique and is recommended to more acurately quantify234，Th activities used to constrain the export of particulate organic carbon in the upper ocean.