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| SHORT RESIDENCE TIME OF COLLOIDS IN THE UPPER OCEAN ESTIMATED FROM U-238 TH-234 DISEQUILIBRIA |
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| Author(s): MORAN SB, BUESSELER KO |
| Source: NATURE Volume: 359 Issue: 6392 Pages: 221-223 Published: SEP 17 1992 |
| Times Cited: 87 References: 34 |
| Abstract: RECENT observations of abundant, nonliving, submicrometre particles in the upper ocean1-3 and new measurements of 'dissolved' organic carbon4-7 have fuelled speculation concerning the role of colloidal matter in ocean chemistry and biology. Colloids may act as reactive intermediates in the marine geochemistry of trace metals8-12, and a biologically labile pool of colloidal matter would affect models of ocean carbon cycling13-16. Here we report the use of naturally occurring Th-234 as an in situ tracer to estimate the residence time of colloidal matter in the surface waters near Bermuda. The Th-234 activity of colloidal matter (size range 10,000 nominal molecular weight to 0.2-mu-m) is similar to that of small particles (0.2-53-mu-m). Modelling of our results indicates a mean residence time of colloidal Th-234 with respect to aggregation into small particles of 10 days, which is roughly the same as for small-particle Th-234, yet a factor of approximately 6 less than for the dissolved pool. These results suggest that, more generally, macromolecular colloidal matter has a short residence time and hence a rapid turnover rate in the upper open ocean. |
| Document Type: Article |
| Language: English |
| Reprint Address: MORAN, SB (reprint author), WOODS HOLE OCEANOG INST, WOODS HOLE, MA 02543 USA |
| Publisher: MACMILLAN MAGAZINES LTD, PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW |
| Subject Category: Multidisciplinary Sciences |
| IDS Number: JN944 |
| ISSN: 0028-0836 |
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