A three dimensional time‐dependent approach to calibrating sediment trap fluxes

We conducted an experiment to test explicitly the accuracy of upper ocean sediment trap fluxes using the particle-reactive radionuclide 234Th (t1/2 = 24.1 days). Two independent VERTEX-style multitrap arrays were used for collection of sinking particles at 95 m and 97 m depths over a four-day period in May 1992 at the U.S. Joint Global Ocean Flux Study Bermuda Atlantic Time-series Study (BATS) site. Samples for total 234Th were collected every 8 m between the surface and 96 m and immediately combined for analysis to obtain the vertically integrated activity of 234Th. We collected a total of 27 samples over the four-day period. The234Th samples were collected daily at each of the two traps and every other day on a 6 × 6 km grid to characterize the entire source region for particles collected in the traps. In situ flow sensors at one trap array indicated low horizontal shear at the trap mouth (5-10 cm/s) compared to normal values at BATS. The predicted 234Th flux from the watercolumn profiles was not significantly different from zero (−30 ± 140 disintegrations per minute/m2/d). The measured trap 234Th flux at both arrays was significantly higher (290 ± 15 dpm/m2/d). We hypothesize that upper ocean traps at Bermuda may overcollect during low-flux periods and undercollect during high-flux periods, thus recording a biased signal of the true particle flux.

[1]  Robert R. Bidigare,et al.  Seasonal patterns of ocean biogeochemistry at the U.S. JGOFS Bermuda Atlantic time-series study site , 1994 .

[2]  S. J. Tanner,et al.  Iron, primary production and carbon-nitrogen flux studies during the JGOFS North Atlantic bloom experiment , 1993 .

[3]  S. B. Moran,et al.  Short residence time of colloids in the upper ocean estimated from 238U–234Th disequilibria , 1992, Nature.

[4]  A. Knap,et al.  Seasonal variability in primary production and particle flux in the northwestern Sargasso Sea: U.S. JGOFS Bermuda Atlantic time-series study , 1992 .

[5]  R. Byrne,et al.  Particles fluxes and moving fluids: experience from synchronous trap collection in the Sargassso sea , 1992 .

[6]  K. Buesseler,et al.  Carbon and nitrogen export during the JGOFS North Atlantic Bloom experiment estimated from 234Th: 238U disequilibria , 1992 .

[7]  M. Hartman,et al.  Determination of thorium isotopes in seawater by nondestructive and radiochemical procedures , 1992 .

[8]  Ching-ling Wei,et al.  Temporal variations of 234Th activity in the water column of Dabob Bay: Particle scavenging , 1992 .

[9]  P. Hill.  Reconciling aggregation theory with observed vertical fluxes following phytoplankton blooms , 1992 .

[10]  K. Buesseler.  Do upper-ocean sediment traps provide an accurate record of particle flux? , 1991, Nature.

[11]  B. Tilbrook,et al.  Seasonal coupling of organic matter production and particle flux in the western Bransfield Strait, Antartica , 1991 .

[12]  D. Olson,et al.  Horizontal diffusion and new production in the Sargasso Sea , 1990 .

[13]  M. Silver,et al.  Cryptic zooplankton “swimmers” in upper ocean sediment traps , 1990 .

[14]  George A. Jackson,et al.  A model of the formation of marine algal flocs by physical coagulation processes , 1990 .

[15]  D. Karl,et al.  New Production at the Vertex Time-Series Site , 1990 .

[16]  J. White.  The use of sediment traps in high-energy environments , 1990 .

[17]  D. Siegel,et al.  Mesoscale eddy diffusion, particle sinking, and the interpretation of sediment trap data , 1990 .

[18]  K. Buesseler,et al.  Scavenging and particle deposition in the southwestern Black Sea - evidence from Chernobyl radiotracers. Technical report , 1990 .

[19]  K. Farley.  Predicting Organic Accumulation in Sediments Near Marine Outfalls , 1990 .

[20]  C. Lambert,et al.  Non-steady-state biological removal of atmospheric particles from Mediterranean surface waters , 1989, Nature.

[21]  E. Baker,et al.  Field assessment of sediment trap efficiency under varying flow conditions , 1988 .

[22]  F. Muller‐Karger,et al.  Temporal variations of particle fluxes in the deep subtropical and tropical North Atlantic: Eulerian versus Lagrangian effects , 1988 .

[23]  A. Longhurst,et al.  Vertical nitrogen flux from the oceanic photic zone by diel migrant zooplankton and nekton , 1988 .

[24]  W. Jenkins,et al.  Nitrate flux into the euphotic zone near Bermuda , 1988, Nature.

[25]  David M. Karl,et al.  VERTEX: carbon cycling in the northeast Pacific , 1987 .

[26]  K. Bruland,et al.  Oceanic stratified euphotic zone as elucidated by 234Th: 238U disequilibria1 , 1987 .

[27]  G. Wasserburg,et al.  238 U, 234 U and 232 Th in seawater , 1986 .

[28]  K. Stolzenbach,et al.  Predictions of sediment trap biases in turbulent flows: A theoretical analysis based on observations from the literature , 1986 .

[29]  K. Harada,et al.  Seasonal variation in the difference between observed and calculated particulate fluxes of Th-234 in Funka Bay, Japan , 1986 .

[30]  W. G. Deuser.  Seasonal and interannual variations in deep-water particle fluxes in the Sargasso Sea and their relation to surface hydrography , 1986 .

[31]  S. Fowler,et al.  Role of large particles in the transport of elements and organic compounds through the oceanic water column , 1986 .

[32]  W. J. Jenkins,et al.  Seasonal oxygen cycling and primary production in the Sargasso Sea , 1985 .

[33]  W. G. Deuser,et al.  Seasonality in the flux of natural radionuclides and plutonium in the deep Sargasso Sea. Technical report , 1985 .

[34]  W. Gardner.  The effect of tilt on sediment trap efficiency , 1985 .

[35]  K. Bruland,et al.  234Th:238U disequilibria within the California Current1: 234Th:238U disequilibria , 1985 .

[36]  David M. Karl,et al.  In situ effects of selected preservatives on total carbon, nitrogen and metals collected in sediment traps , 1984 .

[37]  I. N. McCave.  Size spectra and aggregation of suspended particles in the deep ocean , 1984 .

[38]  John H. Martin,et al.  VERTEX: manganese transport through oxygen minima , 1984 .

[39]  R. Anderson,et al.  Large particle transport of plutonium and other fallout radionuclides to the deep ocean , 1983, Nature.

[40]  R. Eppley,et al.  The residence time of particulate organic carbon in the surface layer of the ocean , 1983 .

[41]  W. Moore,et al.  Fluxes of uranium and thorium series isotopes in the Santa Barbara Basin , 1981 .

[42]  B. Peterson,et al.  Particulate organic matter flux and planktonic new production in the deep ocean , 1979, Nature.

[43]  Kenneth W. Bruland,et al.  Fluxes of particulate carbon, nitrogen, and phosphorus in the upper water column of the northeast Pacific , 1979 .

[44]  Akira Okubo,et al.  Oceanic diffusion diagrams , 1971 .

[45]  V. Noshkin,et al.  LOW BACKGROUND BETA DETECTOR FOR SOLID SAMPLE ASSAY , 1966 .

[46]  A. Carey,et al.  Acceleration of Sinking Rates of Radionuclides in the Ocean , 1963, Nature.