Adsorption of dissolved organics in lake water by aluminum oxide.  Effect of molecular weight

Davis, James A.; Gloor, R.

doi:10.1021/es00092a012

Cited by 309 publications

(176 citation statements)

References 37 publications

(88 reference statements)

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“…The observation that different size fractions of NOM exhibit very different transport behavior is consistent with observations of Davis and Gloor [1981] and Gu et al [1995] that higher molecular weight components of NOM have a greater affinity for adsorption to mineral oxides and with previous field observations of NOM transport [McCarthy et al, 1993]. Gu et al [1995] determined isotherms for adsorption of size fractions of Georgetown NOM on iron oxide because this mineral was expected to be the dominant adsorptive phase in the ironcoated sands at Georgetown.…”

Section: Resultssupporting

confidence: 88%

Field Tracer Tests on the Mobility of Natural Organic Matter in a Sandy Aquifer

McCarthy¹,

Gu²,

Liang³

et al. 1996

Water Resources Research

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Abstract. The field-scale transport of natural organic matter (NOM) was examined in a two-well forced gradient injection experiment in a sandy, coastal plain aquifer in Georgetown, South Carolina. Spatial moments described the migration of the center of mass of NOM and conservative tracer. Temporal moments were used to estimate mass loss and retardation of the NOM along a transect of six sampling locations at two depths and at the withdrawal well. Large differences were observed in transport behavior of different subcomponents of NOM. Larger and more strongly binding NOM components in the injection solution are postulated to adsorb and displace weakly binding, low-molecular weight NOM in groundwater. Conversely, NOM components that were similar to the groundwater NOM were transported almost conservatively, presumably due to ''passivation'' of the aquifer by previously adsorbed components of the groundwater NOM. NOM may thus exhibit two types of effects on contaminant dynamics in the subsurface. When the equilibria between solution and solid phase NOM is disrupted by introduction of a novel source of NOM, descriptions of the multicomponent transport process are complex and predictive modeling is problematic. Because of the differences in transport behavior of NOM subcomponents, the chemical properties and, more importantly, the functional behavior of NOM with respect to contaminant migration will vary with time and distance along a flow path. However, when groundwater NOM exists at a steady state with respect to adsorption on aquifer surfaces, the migration of NOM, and the contaminant-NOM complex, may be approximated as the transport of a conservative solute.

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Section: Resultssupporting

confidence: 88%

Field Tracer Tests on the Mobility of Natural Organic Matter in a Sandy Aquifer

McCarthy¹,

Gu²,

Liang³

et al. 1996

Water Resources Research

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“…Microcrystalline precipitate organic and inorganic solutes. The cycling or orthophosphate (13), trace metals (58,59) and dissolved organic carbon (DOC) (13,(60)(61)(62)(63) within acidic surface waters may be altered by adsorption of Al oxyhydroxides. However, few studies have addressed this specific hypothesis.…”

Section: Altering Element Cycling Within Acidic Watersmentioning

confidence: 99%

Aluminum in acidic surface waters: chemistry, transport, and effects.

Driscoll¹

1985

Environ Health Perspect

108

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Ecologically significant concentrations of Al have been reported in surface waters draining "acid-sensitive" watersheds that are receiving elevated inputs of acidic deposition. It has been hypothesized that mineral acids from atmospheric deposition have remobilized Al previously precipitated within the soil during soil development. This Al is then thought to be transported to adjacent surface waters.Dissolved mononuclear Al occurs as aquo Al, as well as OH-, F-, SO42-, and organic complexes. Although past investigations have often ignored non-hydroxide complexes of Al, it appears that organic and F complexes are the predominant forms of Al in dilute (low ionic strength) acidic surface waters. The concentration of inorganic forms of Al increases exponentially with decreases in solution pH. This response is similar to the theoretical pH dependent solubility of Al mineral phases. The concentration of organic forms of Al, however, is strongly correlated with variations in organic carbon concentration of surface waters rather than pH.Elevated concentrations of Al in dilute acidic waters are of interest because: Al is an important pH buffer; Al may influence the cycling of important elements like P, organic carbon, and trace metals; and Al is potentially toxic to aquatic organisms. An understanding of the aqueous speciation of Al is essential for an evaluation of these processes.

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“…An apparent contradiction in environmental colloidal sciences is that models invoking homoaggregation have been reasonably successful in predicting colloidal / aggregate size distributions in natural waters Newman et al 1994), despite the obvious large chemical heterogeneity of colloids in freshwaters. Such an observation is probably due in part to the fact that, in natural waters, most inorganic colloids are covered by an adsorbed layer of HS (Davis and Gloor 1981;Tipping and Higgins 1982;Tombacz et al 1999) that can modify their surface charge, resulting in an "effective" single class of compounds with similar surface properties. Homoaggregation of HS covered inorganic colloids is usually a slow process due to a low collision efficiency resulting from a significant repulsive charge of the surface bound HS.…”

Section: Homocoagulationmentioning

confidence: 99%

“…Therefore, the interaction of the HS with colloids larger than 10-20 nm corresponds to their adsorption (Sposito 1984;Gu et al 1994) and results primarily in a modification of the surface properties of the colloid (surface potential and dielectric constant). Indeed, inorganic colloids in contact with HS tend to have a similar negative surface charge (Davis and Gloor 1981;Tipping and Higgins 1982;Beckett and Le 1990;Tombacz et al 1999), irrespective of their intrinsic chemical nature. In the normal ranges of pH (5-8), ionic strength (1-50 mM) and HS concentrations (0.5 to 10 mg L -1 ) that are found in freshwaters, HS adsorption should stabilize colloidal suspensions (Tipping and Higgins 1982;Gibbs 1983;Amal et al 1992;, due to a significant electrostatic repulsion among the HS covered colloids.…”

Section: Heterocoagulation: Role Of Hsmentioning

confidence: 99%

Contrasting Roles Of Natural Organic Matter On Colloidal Stabilization And Flocculation In Freshwaters

Reinhardt¹

2004

Flocculation in Natural and Engineered Environmental Systems

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Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight

Cited by 309 publications

References 37 publications

Field Tracer Tests on the Mobility of Natural Organic Matter in a Sandy Aquifer

Field Tracer Tests on the Mobility of Natural Organic Matter in a Sandy Aquifer

Aluminum in acidic surface waters: chemistry, transport, and effects.

Contrasting Roles Of Natural Organic Matter On Colloidal Stabilization And Flocculation In Freshwaters

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