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230 Th in the Andaman Sea: Rapid deep‐sea renewal
Author(s) -
Okubo Ayako,
Obata Hajime,
Nozaki Yoshiyuki,
Yamamoto Yoshiyuki,
Minami Hideki
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl020226
Subject(s) - bay , bengal , oceanography , scavenging , seawater , geology , ridge , structural basin , deep sea , deep water , oceanic basin , paleontology , biochemistry , chemistry , antioxidant
230 Th activities were determined in seawater collected from the Bay of Bengal and the Andaman Sea. The Andaman Sea is a semi‐closed basin that is isolated from the Bay of Bengal by the Andaman‐Nicobar Ridge. The noticeable trend in the vertical distribution of 230 Th activity in the Andaman Sea is its uniformity below 1250 m depth. We applied the scavenging‐mixing model to this vertical profile in the Andaman Sea, and estimated the upper limit of renewal time to be 6 yr. We compared 210 Pb/ 226 Ra ratios among deep waters of various oceanic basins to constrain the application of 230 Th as a tracer of deep‐water renewal. The 210 Pb/ 226 Ra ratios were almost identical for the deep‐water of the Andaman Sea and the inflow water from the Bay of Bengal, suggesting that the deep water in the Andaman Sea is replaced rapidly without bottom scavenging effects on the 210 Pb/ 226 Ra ratio.