Abstract
Dissolved and particulate 234Th were determined on several surface transects within the Pacific Ocean. These transects, spanning major oceanographic regimes, ranged from oligotrophic subtropical gyres to eutrophic eastern boundary and equatorial divergence zones. Modeling of the disequilibria between 234Th and 238U within the surface waters provides estimates for the residence time of dissolved thorium with respect to particle scavenging, the residence time of particulate 234Th, and the particulate 234Th flux from the surface layer. The results provide a broad spatial view of the intensity and temporal variability of these scavenging processes. Within the oceanic surface waters dissolved 234Th residence times vary from 6 to 220 days and the scavenging rate of dissolved 234Th onto particles appears to be proportional to primary production. The scavenging intensity of dissolved 234Th is strongly correlated with particulate organic carbon flux throughout a wide range of marine environments ranging from estuaries to the deep sea. Including these environments, which represent end-members for 234Th scavenging intensity, the residence time for dissolved 234Th is shown to vary from 0.3 days to 2 years depending on the particle flux. Particulate 234Th residence times in oceanic surface waters are of the order of weeks and appear to be governed by the rate of zooplankton grazing. Model-derived particulate 234Th fluxes can be used to constrain estimates based upon surface sediment trap collections.
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References
Bacon, M.P., and Anderson, F., 1982, Distribution of thorium isotopes between dissolved and particulate forms in the deep sea, J. Geophys. Res., 87:2045.
Bacon, M.P., Spencer, D.W., and Brewer, P.G., 1976, 210pb/226Ra and 210po/210Pb disequilibria in seawater and suspended particulate matter, Earth Planet. Sci. Lett., 32:277.
Betzer, P.R., Showers, W.J., Laws, E.A., Winn, C.D., DiTullio, G.R., and Kroopnick, P.M., 1984, Primary productivity and particle fluxes on a transect of the equator at 153°W in the Pacific Ocean, Deep-Sea Res., 31:1.
Bhat, S.G., Krishnaswami, S., Lal, D., Rama, and Moore, W.S., 1969, Th-234/U-238 ratios in the ocean, Earth Planet. Sci. Lett., 5:483.
Bishop, J.K.B., Edmond, J.M., Ketten, D.R., Bacon, M.P., and Silker, W.B., 1977, The chemistry, biology, and vertical flux of particulate matter from the upper 400 m of the equatorial Atlantic Ocean, Deep-Sea Res., 24:511.
Broecker, W.A., Kaufman, A., and Trier, R.M., 1973, The residence time of thorium in surface sea water and its implications regarding the fate of reactive pollutants, Earth Planet. Sci. Lett., 20:35.
Coale, K.H., and Bruland, K.W., 1985, 234Th/238U disequilibrium within the California Current, Limnol. Oceanogr., 30:22.
Eppley, R.W., and Peterson, B.J., 1979, Particulate organic matter flux and planktonic new production in the deep ocean, Nature, Lond., 282:677.
Eppley, R.W., Renger, E.H., and Harrison, W.G., 1979, Nitrate and phytoplankton production in the Southern California coastal waters and its role in the growth of phytoplankton, Limnol. Oceanogr., 24:483.
Eppley, R.W., Renger, E.H., and Setzer, P.R., 1983, The residence time of particulate organic carbon in the surface layer of the ocean, Deep-Sea Res., 30:311.
Feely, H.W., 1981, Natural radionuclides in waters of the New York Bight, Earth Planet. Sci. Lett., 55:217.
Feely, H.W., Kipphut, G.W., Trier, R.M., and Kent, C., 1980, 228Ra and 228Th in coastal waters, Estuarine Coastal Mar. Sci., 11:179
Goldberg, E.D., 1954, Marine Geochemistry, Chemical Scavengers of the Sea, J. Geol., 62:249.
Honjo, S., 1978, Sedimentation of materials in the Sargasso Sea at 5367 m deep station, J. Mar. Res., 36:469.
Kaufman, A., Li, Y.-H., and Turekian, K.K., 1981, The removal rates of 234Th and 228Th from waters of the New York Bight, Earth Planet. Sci. Lett., 54:385.
Knauer, G.A., and Martin, J.H., 1981, Primary production and carbon-nitrogen fluxes in the upper 1500 m of the northeast Pacific, Limnol. Oceanogr., 26:181.
Knauer, G.A., Martin, J.H., and Bruland, K.W., 1979, Fluxes of particulate carbon, nitrogen and phosphorus in the upper water column of the Northeast Pacific, Deep-Sea Res., 26:97.
Knauss, K.G., Ku, T., and Moore, W.S., 1978, Radium and thorium isotopes in the surface waters of the east Pacific and coastal southern California, Earth Planet. Sci. Lett., 39:235.
Ku, T.L., Knauss, K.G., and Mathieu, G.G., 1977, Uranium in the open ocean: Concentration and isotopic composition, Deep-Sea Res., 24:1005.
Li, Y.H., Feely, W.H., and Santschi, P.H., 1979, 228Th/228Ra radioactive disequilibrium in the New York Bight and its implications for coastal pollution, Earth Planet. Sci. Lett., 42:13.
Li, Y.H., Feely, W.H., and Toggweiler, J.R., 1980, 228Ra and 228Th concentrations in GEOSECS Atlantic surface waters, Deep-Sea Res., 27:545.
Li, Y.H., Santschi, P.H., Kaufman, A., Benninger, L.K., and Feely, H.W., 1981, Natural radionuclides in waters of the New York Bight, Earth Planet. Sci. Lett., 55:217.
Martin, J.H., Knauer, G.A., Broenkow, W.W., Bruland, K.W., Karl, D.L., Small, L.F., Silver, M.W., and Gowing, M.M., 1984, Vertical transport and exchange of materials in the upper waters of the oceans (VERTEX): Introduction to the program, hydrographic conditions and major component fluxes during VERTEX-I, Moss Landing Technical Publication 84–1.
Matsumoto, E., 1975, 234Th-238U radioactive disequilibrium in the surface layer of the ocean, Geochim. Cosmochim. Acta, 39:205.
McKee, B.A., DeMaster, D.J., and Nittrouer, C.A., 1984, The use of 234Th/238U disequilibrium to examine the fate of particle-reactive species on the Yangtze continental shelf, Earth Planet. Sci. Lett., 68:431.
Nozaki, Y., and Horibe, Y., 1981, The water column distributions of thorium isotopes in the western North Pacific, Earth Planet. Sci. Iett., 54:203.
Nozaki, W.M., Thompson, J., and Turekian, K.K., 1976, The distribution of Pb-210 and Po-210 in the surface waters of the Pacific Ocean, Earth Planet. Sci. Lett., 32:304.
Paffenhofer, G., and Knowles, S.C., 1979, Ecological implications of fecal pellet size, production and consumption by copepods, J. Mar. Res., 37:35.
Rama, Koide, M., and Goldberg, E.D., 1961, Lead-210 in natural waters, Science, N.Y., 134:98.
Ryther, J.H., 1969, Photosynthesis and fish production in the sea, Science, N.Y., 166:72.
Santschi, P.H., 1984, Particle flux and trace metal residence time in natural waters, Limnol. Oceanogr., 29:110.
Santschi, P.H., Li, Y.H., and Bell, J., 1979, Natural radionuclides in the water of Narragansett Bay, Earth Planet. Sci. Iett., 45:201.
Shanks, A.L., and Trent, J.D., 1979, Marine Snow: Microscale nutrient patches, Limnol. Oceanogr., 24:850.
Silver, M.W., and Alldredge, A.L., 1981, Bathypelagic marine snow: Vertical transport system and deep-sea algal and detrital community, J. Mar. Res., 39:227.
Silver, M.W., and Bruland, K.W., 1981, Differential feeding and fecal pellet composition of salps and pteropods, and the possible origin of the deep-water flora and olive-green “cells”, Mar. Biol., 62:263.
Small, L.F., Fowler, S.W., and Ünlü, M.Y., 1979, Sinking rates of natural copepod fecal pellets, Mar. Biol., 51:233.
Turekian, K.K., 1977, The fate of metals in the oceans, Geochim. Cosmochim. Acta, 41:1139.
Wiebe, P.H., Madin, L.P., Haury, L.R., Harbison, G.R., and Philbin, L.M., 1979 Diel vertical migration by Salpa aspera and its potential for large-scale particulate organic matter transport to the deep-sea, Mar. Biol., 53:249.
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© 1986 Plenum Press, New York
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Bruland, K.W., Coale, K.H. (1986). Surface Water 234Th/238U Disequilibria: Spatial and Temporal Variations of Scavenging Rates within the Pacific Ocean. In: Burton, J.D., Brewer, P.G., Chesselet, R. (eds) Dynamic Processes in the Chemistry of the Upper Ocean. NATO Conference Series, vol 17. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-5215-0_13
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DOI: https://doi.org/10.1007/978-1-4684-5215-0_13
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