Mutual Flocculation of Algae and Clay: Evidence and Implications

Avnimelech, Yoram; Troeger, Bill W.; Reed, Lester W.

doi:10.1126/science.216.4541.63

Cited by 221 publications

(126 citation statements)

References 6 publications

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“…1 mm-TEP and clay have both been suggested as effective catalysts of coagulation ( [Alldredge et al 1993;Logan et al 1995] and [Avnimelech and Troeger 1982;Hamm 2002;Lee et al 2009]) and are important for the formation of the large (. 1 mm) aggregates with high sinking velocities that play a key role in the ocean's biological carbon pump.…”

Section: Discussionmentioning

confidence: 99%

“…Besides influencing sinking velocity, both TEP (Alldredge et al 1993;Passow et al 1994;Passow and Alldredge 1995a) and minerals (Avnimelech and Troeger 1982;Beaulieu et al 2005;Verspagen et al 2006) have been found to promote coagulation of particles. Thus, any changes in TEP or mineral concentrations or in their ability to catalyze coagulation of particles will most likely affect aggregate abundance.…”

mentioning

confidence: 99%

“…We suggest that decreased polarity of highly surface-active TEP (Mopper et al 1995;Verdugo and Santschi 2010) should reduce their tendency to form ion bridges and hydrogen bonds, reducing their ''stickiness,'' and thus their ability to facilitate aggregation. Moreover, clay minerals catalyze aggregation due electrostatic forces or hydrogen bonds (Avnimelech and Troeger 1982;Ding and Henrichs 2002), which are also pH dependent (Tombá cz and Szekeres 2004). We thus expected reduced participation of clay in aggregation processes with decreasing pH to also lead to reduced coagulation rates under ocean acidification conditions.…”

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Aggregation as a function of and mineral particles

Passow¹,

Rocha²,

Fairfield³

et al. 2014

Limnology & Oceanography

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A laboratory experiment was designed to investigate the effects of ocean acidification (three levels) in the presence or absence of the clay mineral illite (five concentrations) on the coagulation of organic particles. The formation of aggregates . 1 mm from marine detritus and phytoplankton, and their characteristics and sinking velocity, were monitored during the 48 h experiment. Aggregation of particulate organic carbon (POC) was independent of both partial pressure of carbon dioxide (P CO2 ) and illite addition, implying that the fraction of POC available for export is not affected by either mineral supply or ocean acidification conditions up to ambient + 52.7 Pa P CO2 (+ 520 ppm). This was true even though the illite appreciably influenced aggregate size, number, and characteristics, including the percentage of transparent exopolymer particles (TEP) incorporated in aggregates. Carbonate chemistry, in the presence of illite, did affect particle formation by clay, carbon, and TEP at the micrometer scale (allocation between dissolved and particulate pools). Our experiment did not resolve processes on this scale well and it remains to be seen if such shifts in the size spectrum of organic carbon and minerals are relevant for the biological pump. High illite content led to small aggregates with a low average sinking velocity. In the absence of biological changes to particle production or loss, coagulation of POC, which is central to the biological pump, is not influenced by ocean acidification or dust input, but sinking velocity and, hence, flux attenuation of POC are likely to be affected by changes in dust input.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Aggregation as a function of and mineral particles

Passow¹,

Rocha²,

Fairfield³

et al. 2014

Limnology & Oceanography

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“…4) is another indication for their importance in 234 Th removal from the ocean. The inferred associations of Th isotopes with major inorganic phases (e.g., Chase et al, 2002;Luo and Ku, 2004) might be, as mentioned above, the result of organic, surface active substances coating inorganic minerals (Avnimelech and Troeger, 1982;Passow et al, 2006-this issue). Th(IV) sorption to particles is classically treated as a reversible adsorption process Whitfield, 1990, 1991) and thermodynamic treatment of Th particle adsorption requires complete reversibility at the molecular level.…”

Section: This Issue and References Therein)mentioning

confidence: 99%

Thorium speciation in seawater

et al. 2006

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Since the 1960s, thorium isotopes occupy a special place in the oceanographer's toolbox as tracers for determining rates and mechanisms of oceanic scavenging, particle dynamics, and carbon fluxes. Due to their unique and constant production rates from soluble parent nuclides of uranium and radium, their disequilibrium can be used to calculate rates and time scales of sinking particles. In addition, by ratio-ing particulate 234 Th (as well, in principle, other Th-nuclides) to carbon (and other elements), and linking this ratio to the parent-daughter disequilibrium in the water column, it is possible to calculate fluxes of carbon and other elements. Most of these applications are possible with little knowledge of the dissolved chemical properties of thorium, other than its oxidation state (IV) and tendency to strongly sorb to surfaces, i.e., its bparticle-or surface-activityQ. However, the use of any tracer is hindered by a lack of knowledge of its chemical properties. Recent observations in the variability of carbon to 234 Th ratios in different particle types, as well as of associations of Th(IV) with various marine organic biomolecules has led to the need for a review of current knowledge and what future endeavors should be taken to understand the marine chemistry of thorium. D

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“…Turbid lakes have vertically compressed euphotic zones (Grobbelaar 1985;Schallenberg & Burns 1997) and phytoplankton may become light-limited by increasing turbidity (e.g., Schallenberg et al 1999). In addition, high levels of suspended clays can remove phytoplankton from the mixed layer by co-flocculation and increased sedimentation (Avnimelech et al 1982). Aquatic bacteria, on the other hand, are able to colonise ISS (Jannasch & Pritchard 1972) facilitated by the accumulation of surficial organic layers on the particles because of electrochemical potentials (Paerl 1975).…”

Section: Introductionmentioning

confidence: 99%

Postulated responses of phytoplankton and bacteria to predicted increases of inorganic suspended sediments in oligotrophic lakes

Schallenberg¹,

Friedrich

Burns

2001

New Zealand Journal of Marine and Freshwater Research

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We establish the relationships between concentrations of inorganic suspended sediments (ISS) on light, nutrients, phytoplankton, and bacteria in three oligotrophic lakes (four sites) and we use these relationships to predict the impacts of increasing concentrations of ISS on the biomass and productivity of phytoplankton and bacteria in the lakes. Increased concentrations of ISS contributed little available nutrient to the lakes. The relationships between ISS and underwater light attenuation differed among lakes because of variation in sediment size-structure, and composition. Only at the site with the highest ISS concentrations and a relatively deep mixing depth, were phytoplankton apparently lightlimited and, thus, predicted to decline with increased ISS concentrations. In contrast to previously published studies, bacterial abundance and production were not highly correlated to suspended sediment concentrations in these lakes. However, bacterial biomass, productivity, and specific productivity were more strongly correlated to phytoplankton production. As a result of light limitation and stimulation of bacterial production, increases in ISS concentrations are not predicted to significantly shift the metabolic balance in the planktonic ecosystem of three † Author for correspondence. M00077 Received 2 November 2000; accepted 20 February 2001of the sites towards greater heterotrophy. Where light limits phytoplankton production, increases in ISS are predicted to reduce the productivity of both phytoplankton and bacteria by direct inhibition of phytoplankton production, again without a large shift towards greater importance of the microbial loop. By reducing phytoplankton production and inhibiting larger cladoceran grazers, we predict that high concentrations of ISS will reduce available energy and its flow up the food chain.

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Mutual Flocculation of Algae and Clay: Evidence and Implications

Cited by 221 publications

References 6 publications

Aggregation as a function of and mineral particles

Aggregation as a function of and mineral particles

Thorium speciation in seawater

Postulated responses of phytoplankton and bacteria to predicted increases of inorganic suspended sediments in oligotrophic lakes

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