Constraints on deep water age and particle flux in the Equatorial and South Atlantic Ocean based on seawater Pa-231 and Th-230 data
High-precision measurements of Pa-231 and Th-230 in filtered seawater and suspended particulate matter samples are reported for the Equatorial and South Atlantic, Distributions of Pa-231 and Th-230 clearly indicate the influence of advection, as evidenced by departures from scavenging models that pr...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Geophysical Union (AGU)
2001
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| Subjects: | |
| Online Access: | http://ir.lib.ncku.edu.tw/handle/987654321/59746 |
| Summary: | High-precision measurements of Pa-231 and Th-230 in filtered seawater and suspended particulate matter samples are reported for the Equatorial and South Atlantic, Distributions of Pa-231 and Th-230 clearly indicate the influence of advection, as evidenced by departures from scavenging models that predict a linear increase with depth for these tracers. Application of a scavenging-mixing model implies a deep water transit time of similar to 60-100 years from the northern source water regions. The average particulate Pa-231 /Th-230 activity ratio is 0.0498 +/- 0.0160, a factor of similar to2 lower than the Pa-231 /Th-230 production ratio of 0.093 and in agreement with reported excess Pa-231/Th-230 ratios of 0.06 +/- 0.004 in Holocene sediments north of 50 degreesS in the Atlantic. These water column data further suggest that lateral eddy diffusive transport combined with enhanced scavenging in high-particle flux marginal regions (boundary scavenging) is weakly expressed in the Atlantic. Particle fractionation of these tracers is also indicated by the elevated fractionation factors F-Th/Pa = 4.32-24.04 (ave. = 9.97 +/- 4.98) compared to values of similar to1-4 in the Southern Ocean. |
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