Role of Humic Carrier Substances in DDT Movement through Forest Soil

Ballard, T. M.

doi:10.2136/sssaj1971.03615995003500010041x

Cited by 74 publications

(35 citation statements)

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“…The earliest studies on colloid-facilitated transport focused on the mobility of hydrophobic pesticides and herbicides. The presence of natural organic matter (NOM), such as humic and fulvic acids, increased the solubility and mobility of DDT, phenanthrene, naphthalene, and napropamide (Kan and Tomson 1990, McDowell-Boyer et al 1986, Means and Wijayarante 1982, Ballard 1971. McCarthy and Jimenez (1985) found that there was a direct relationship between the chemical hydrophobicity and its affinity for humic acids.…”

Section: Non-radioactive Contaminant Transport With Colloidsmentioning

confidence: 99%

Colloid suspension stability and transport through unsaturated porous media

McGraw¹,

Kaplan²

1997

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Executive SummaryContaminant transport is traditionally modeled in a two-phase system: a mobile aqueous phase and an immobile solid phase. Over the last 15 years, there has been an increasing awareness of a third, mobile solid phase. This mobile solid phase, or mobile colloids, are organic or inorganic submicron-sized particles that move with groundwater flow. When colloids are present, the net effect on radionuclide transport is that radionuclides can move faster through the system. It is not known whether mobile colloids exist in the subsurface environment of the Hanford Site. Furthermore, it is not known if mobile colloids would likely exist in a plume emanating from a Low Level Waste (LLW) disposal site. No attempt was made in this study to ascertain whether colloids would form. Instead, experiments and calculations were conducted to evaluate the likelihood that colloids, if formed, would remain in suspension and move through saturated and unsaturated sediments.The objectives of this study were to evaluate three aspects of colloid-facilitated transport of radionuclides as they specifically relate to the LLW Performance Assessment. These objectives were: 1) determine if the chemical conditions likely to exist in the near and far field of the proposed disposal site are prone to induce flocculation (settling of colloids from suspension) or dispersion of naturally occurring Hanford colloids, 2) identify the important mechanisms likely involved in the removal of colloids from a Hanford sediment, and 3) determine if colloids can move through unsaturated porous media.Mobile colloid formation is commonly described as a three-step process: genesis, stabilization, and transport. Colloid genesis describes how the micron-sized particles are formed in groundwater. Stabilization describes how the colloids are brought into suspension, which is a function of the colloid and groundwater chemical composition and water flow (kinetic) forces. Transport describes how the suspended colloid move through the porous media or are retained by the porous media by physical forces (such as diffusion, straining, or gravitation settling) or physicochemical attraction of the colloid to the matrix.As the second step in mobile colloid formation indicates, colloids must remain in suspension, i.e., not flocculate, in order to be transported with groundwater flow. A series of batch experiments was conducted to identify the chemical conditions where dispersion and flocculation (settling out of suspension) of Hanford sediment colloids (

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Section: Non-radioactive Contaminant Transport With Colloidsmentioning

confidence: 99%

Colloid suspension stability and transport through unsaturated porous media

McGraw¹,

Kaplan²

1997

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“…The association of many organic pollutants including DDT (Ballard 1971;Pierce et al 1974;Carter & Suffet 1982;Chiou et al 1986;Lee & Farmer 1989), with humic material is well documented. Much of this work has focused on the increase in solubility that results from the association of DDT with the soluble humic fractions.…”

Section: Weakly Bound Residuesmentioning

confidence: 99%

“…They are divided into humic acids (which are acidprecipitated from basic soil extracts), fulvic acids (which are soluble in both acid and base), and the insoluble humin fraction. Ballard (1971) examined the amount of DDT that leached from samples of a forest soil freshly treated with DDT. Leaching was low unless the soil was treated with urea, and then substantial DDT recovery was obtained.…”

Section: Weakly Bound Residuesmentioning

confidence: 99%

“…For a site with an annual rainfall of 1000 mm/year a maximum of 13 g DDT/ha per year could potentially be leached as a saturated solution (DDT solubility of 1.3 |ag/l) assuming no evapotranspiration. The solubility and hence movement of residues may, however, be enhanced by association with organic matter (Ballard 1971;Poirrier et al 1972). Some downward movement of DDT sorbed to paniculate matter through soil pores and cracks is also possible.…”

Section: Leaching Run-off and Erosionmentioning

confidence: 99%

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DDT residues in the environment—A review with a New Zealand perspective

Boul¹

1995

New Zealand Journal of Agricultural Research

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“…Naturally occurring organic matter is present in both particulate and dissolved states. Whill~ the interaction between hydrophobic compounds and dissolved organic matter is poorly understood, chlorinated hydrocarbons in aqueous systems have been shown to associate strongly with the organic matter of soils (37,(61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71), sediments (37,(71)(72)(73),…”

Section: Introductionmentioning

confidence: 99%

Investigation of the contribution of aquatic humus to the transport of DDT in the environment

Blunk

2000

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1982 ABSTRACTThe fate and transport of insoluble, hydrophobic organic pollutants in the aquatic environment constitutes a prominent area of concern. It is thought that pollutants of this nature may exist in association with organic carbon, which is predominantly aquatic humus. This type of association could significantly affect the kinetics of such transformation processes as volatilization or chemical and biological degradation of the pollutant. While dissolved organic matter (DOM) comprises the bulk of organic carbon (or aquatic humus) in natural waters, the interact·io',\ between naturally occurring DOM and insoluble organic pollutants has not been quantified.The work presented in thi s di ssertation is an effort to quantify the, effect of dissolved organic matter on the solubility in water and, hence, the transport of hydrophobic organic compounds (specifically, DDT) in the environment.Saturated aqueous solutions of DDT were generated by a method that is different from those used by other workers. Within a closed system, an excess of sol id DDT was allowed to vaporize and enter an aqueous solution through the gas phase. The concentraction of DDT in solution increased with time, 1 eve 1 i ng off when equil i bri urn and a saturated solution was established.The solubility of p,p'-DDT in distilled water was determined to be 1.87 ± .01 ppb. The solubility of the o,p'-DDT isomer in distilled water was determined to be 4.88 ± .03 ppb. The concentrations of p,pl-3 DDT and o,pl-DDT in distilled water solutions containing dissolved organic matter were definitely higher than the aqueous solubilities of these compounds. A minimum value for the DDT/DOM partition coefficient (Kp) in water was determined. This partition coefficient, when normalized to organic carbon, is referred to as Koc (K oc = Kp/fraction organic carbon). A minimum log Koc for both p,pl-DDT and o,pl-DDT was determined to be 4.7 ± .2 log units. Under environmental conditions, this partition coefficient indicates that the majority of DDT present in aqueous systems will be associated with dissolved organic matter.

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Role of Humic Carrier Substances in DDT Movement through Forest Soil

Cited by 74 publications

References 0 publications

Colloid suspension stability and transport through unsaturated porous media

Colloid suspension stability and transport through unsaturated porous media

DDT residues in the environment—A review with a New Zealand perspective

Investigation of the contribution of aquatic humus to the transport of DDT in the environment

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