Rapid formation and sedimentation of large aggregates is predictable from coagulation rates (half-lives) of transparent exopolymer particles (TEP)
- a Department of Chemical and Environmental Engineering, University of Arizona, Tuscon, AZ 85721, U.S.A.
- b Marine Sciences Institute, University of California, Santa Barbara, CA 93106, U.S.A.
- c Limnological Institute, University of Constance, D-78434 Konstanz, Germany
- Received 5 September 1994
- Revised 20 December 1994
- Accepted 9 January 1995
- Available online 5 May 2000
Abstract
Two hypotheses have been proposed to account for the precipitous formation of large, rapidly settling aggregates at the termination of phytoplankton blooms in nature; aggregation due primarily to cell-cell collisions, and aggregation resulting from the presence of abundant transparent exopolymer particles (TEP), a recently discovered class of particles formed from polysaccharides excreted by phytoplankton. The hypothesis of TEP-driven coagulation in three disparate systems, a freshwater lake, a coastal ocean, and a saltwater mesocosm was evaluated, by comparing TEP abundance to several related factors including phytoplankton concentrations, measured sediment fluxes, and abundances of large aggregates. The timing of large aggregate formation and sedimentation events was related to coagulation rates expressed in terms of particle half-lives, , calculated as the time for TEP or phytoplankton to decrease to half their concentration through shear coagulation. While TEP have been previously investigated only in marine systems, it is reported here that TEP also can be present in high concentrations (860 ml−1) in freshwater lakes (Lake Constance, Germany) and that high fluxes of particulate organic matter at depth coincide with the disappearance of abundant TEP from overlying waters. The half-lives of TEP in the three different systems indicate that large aggregate formation and massive sedimentation events following diatom blooms occur when the TEP half-life decreases to less than a few days. By comparing TEP and phytoplankton half-lives in these systems, it is concluded that the formation of rapidly sinking aggregates following blooms of mucous-producing diatoms is primarily controlled by concentrations of TEP, not phytoplankton.
References
- Alldredge et al., 1993
The abundance and significance of a class of large, transparent organic particles in the ocean
Deep-Sea Research I, 40 (1993), pp. 1131–1140
- | |
- Alldredge et al., 1995
Mass aggregation of diatom blooms: Insights from a mesocosm study
Deep-Sea Research II, 42 (1995), pp. 9–27
- | |
- Birkner and Morgan, 1968
Polymer flocculation kinetics of dilute colloidal suspensions
Journal of the American Water Works, 60 (1968), pp. 175–191
- Fowler and Knauer, 1986
Role of large particles in the transport of elements and organic compounds through the oceanic water column
Progress in Oceanography, 16 (1986), pp. 147–194
- | |
- Friedlander, 1977
Smoke, dust and haze: Fundamentals of aerosol behaviour
Wiley, NY, USA (1977)
- Grossart and Simon, 1993
Limnetic macroscopic organic aggregates (lake snow): Occurrence, characteristics, and microbial dynamics in Lake Constance
Limnology and Oceanography, 38 (1993), pp. 532–546
- |
- Han and Lawler, 1992
The (relative) insignificance of G in flocculation
Journal of the American Water Works Association, 85 (1992), pp. 79–91
- Hill, 1992
Reconciling aggregation theory with observed vertical fluxes following phytoplankton blooms
Geophysical Research, 97 (1992), pp. 2295–2308
- |
- Hunt, 1982
Self similar particle-size distributions during coagulation: Theory and experimental verification.
Journal of Fluid Mechanics, 122 (1982), pp. 169–185
- |
- Jackson, 1990
A model of the formation of marine algal flocs by physical coagulation processes
Deep-Sea Research, 37 (1990), pp. 1197–1211
- | |
- Jackson, 1995
Comparing observed changes in particle size spectra with those predicted using coagulation theory
Deep-Sea Research II, 42 (1995), pp. 159–184
- | |
- Jackson and Lochmann, 1993
Modeling coagulation of algae in marine ecosystems
J. Buffle, H.P. van Leeuwen (Eds.), Environmental particles, Lewis, Boca-Raton, Florida, USA (1993)
- Jiang and Logan, 1991
Fractal dimensions of aggregates determined from steady-state size distributions
Environmental Science and Technology, 25 (1991), pp. 2031–2038
- |
- Kiørboe et al., 1990
Coagulation efficiency and aggregate formation in marine phytoplankton
Marine Biology, 107 (1990), pp. 235–245
- |
- Kiørboe and Hansen, 1993
Phytoplankton aggregate formation: Observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material
Journal of Plankton Research, 15 (1993), pp. 993–1018
- Kiørboe et al., 1994
Aggregation and sedimentation processes during a spring phytoplankton bloom: A field experiment to test coagulation theory
Journal of Marine Research, 52 (1994), pp. 297–323
- |
- McCave, 1984
Size spectra and aggregation of suspended particles in the deep ocean
Deep-Sea Research, 31 (1984), pp. 329–352
- | |
- Passow
- Passow U. and A. L. Alldredge (in press) Distribution, size and bacterial colonization of transparent exopolymer particles (TEP) in the ocean. Marine Ecology Progress Series.
- Passow and Alldredge, 1995
Aggregation of a diatom bloom in a mesocosm: The role of transparent exopolymer particles (TEP)
Deep-Sea Research II, 42 (1995), pp. 9–27
- Passow et al., 1994
The role of particulate carbohydrate exudates in the flocculation of diatom blooms
Deep-Sea Research I, 41 (1994), pp. 335–357
- | |
- Riebesell, 1991
Particle aggregation during a diatom bloom, II. Physical aspects
Marine Ecology Progress Series, 69 (1991), pp. 281–291
- |
- Simon et al., 1993
Bacterial production and the sinking flux of particulate organic carbon in a large and deep lake in comparison to oceanic environments
Marine Microbial Food Webs, 7 (1993), pp. 161–176
- Smetacek, 1985
Role of sinking in diatom life-history cycles: Ecological, evolutionary and geological significance
Marine Biology, 84 (1985), pp. 239–251
- |
- Swift and Friedlander, 1964
The coagulation of hydrosols by Brownian motion and laminar shear flow
Journal of Colloid Science, 19 (1964), pp. 621–647
- | |
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