Mobility of contaminants

Reduced volume and toxicity of contaminated groundwater toxicity of soil contamination in Area 2 reduced by 97% mobility of contaminants in Area 1 reduced by 10% while volume increased by 20%... 

High airflow rates may result in unintended fracturing leading to nonuniform flow or short-circuiting of injected air in the subsurface, or may result in unintended mobilization of contaminants as nonaqueous phase liquids (NAPL), dissolved in groundwater, or in soil gas. 

The role of green plants in natural attenuation is an important way of phytostabilazation of degraded areas, especially in the abandoned mine areas where well adapted and tolerant spontaneous plants grow. These plants contribute to decrease soil erosion, the mobility of contaminants in soil and to reduce or eliminate the risk to both human health and the environment. 

Stipp, S.L.S. (1994) Understanding interface processes and their role in the mobility of contaminants in the geosphere The use of surface sensitive techniques. Eclogae Geol. Helv. 87/2 335-355... 

Phytoremediation is only effective at shallow depths because root density decreases with depth. The mobility of contaminants also decreases with depth. In addition, phytoremediation is a slower process than some alternative technologies, and cleanup often requires several growing seasons. Environmental factors, including soil type, water availability, temperature, nutrients, and solar radiation can also limit the success of phytoremediation. 

Although such reactions and the consequences with respect to contaminant fate have primarily focused on soluble humic materials (Carter Suffet, 1982 Madhun et al., 1986 Traina et al., 1989 Morra et al., 1990 Puchalski et al., 1992 Engebretson von Wandruszka, 1994), the participation of microbial products in similar reactions is possible. Dohse and Lion (1994) showed that extracellular bacterial polymers enhanced the transport of phenanthrene in sand columns. The mobilization of contaminants might be beneficial to bioremediation if degradation reactions are not inhibited and substrate bioavailability is increased. Conversely, increased contaminant transport may increase the potential for contaminant movement and likewise the extent of environmental contamination. 

Vigon, B. W. Rubin, A.J. (1989). Practical considerations in the surfactant-aided mobilization of contaminants in aquifers. Journal of the Water Pollution Control Federation, 6l, 1233-40. 

To test the effectiveness of the CHEMFIX process as a treatment option, the solidified samples were subjected to the TCLP test and a comparison made with the TCLP results on a raw sample. This test was designed to determine the mobility of contaminants present in liquid, solid and multiphasic wastes. If the TCLP extract from a representative sample contained any of the listed contaminants above the regulatory levels it would be considered a hazardous waste and should adhere to the strict disposal requirements. )... 

Mobilization of contaminants in Milltown Reservoir can be explained by a model in which groundwater composition is controlled by successive diage-netic reactions during the transition to and from oxic and anoxic environments as the reservoir stage changes (12). Several important reactions govern the mobility of contaminants in this system ... 

Natural remediation Refers to allowing already existing biological, chemical, and physical processes in nature to biodegrade, precipitate, sorb, or otherwise reduce the toxicity and mobility of contaminants at a field site with little or no human intervention. 

Solidification/stabilization Refers to reducing the mobility of a contaminant in soils, other solids, or even liquid wastes by mixing them with Portland cement, lime, cement kiln dust, clays, slags, polymers, water treatment sludges, iron-rich gypsum, fly ash, and/or other binders. The process decreases the mobility of contaminants through physical encapsulation (solidification) and chemical bonding between the contaminants and the binders (stabilization). 

Surfactant enhancement is a technology used to remove contaminants from soils and water at hazardous waste sites. The application of surfactants enhances remediation by (a) increasing contaminant mobility and solubility, (b) decreasing the mobility of contaminants, and (c) increasing the rate of biodegradion of contaminants in soil. 

Figure 10.4 represents a summary of bioassays distinguishing between whole soil and elutriate tests reflecting different assessment objectives. Whilst whole soil tests may preferably be used for ecological assessments (e.g. the investigation of habitat functions of soil), testing of elutriates provides information on the mobility of contaminants and the retention capability of soil. 

The DOE Industry Profiles provide developers, local authorities and anyone else interested in contaminated land, with information on the processes, materials and wastes associated with individual industries. They also provide information on the contamination that might be associated with specific industries, factors that affect the likely presence of contamination, the effect of mobility of contaminants and guidance on potential contaminants. They are not definitive studies but they introduce some of the technical considerations that need to be borne in mind at the start of an investigation for possible contamination. 

The mobility of contaminants and their subsequent removal depend also on their sorption capacity to soil components. Therefore, soil properties, particularly those related to the presence of mineral colloids (e.g. montmorillonite, chlorite, kaolinite) and organic matter, additionally challenge the remediation of mixed contaminated soils. 

The criterion of reduction of toxicity, mobility, or volume through treatment refers to anticipated performance of the treatment technology potentially employed in a Superfund remediation. The technology reduces the volume and mobility of contaminants by the concentration or extraction of contaminants for subsequent disposal. Minimal waste is generated during the contaminant treatment process. 

The sorption to soil components is a determinant factor for the mobility of contaminants, accounting for their distribution among soil, sediment and water phases. The extent to which chemicals partition between the solid and solution phases in soil, or between water and sediment in aquatic ecosystems, determines the likelihood of the contaminants leaching through the soil or being immobile. The soil sorption hence influences the elution of compounds into groundwater bodies as well as their availability for transformation by soil microbes, their volatilization from soil surfaces and their bioavailability for exposed organisms. 

The migration of soil-borne contaminants is associated primarily with groundwater movement, and the effectiveness of groundwater to transport contaminants is dependent mainly on their solubility. The quality of water can provide an indication of the mobility of contaminants and the rate of dispersal. Liquid and gas contaminants, of course, may be mobile. 

SoUdiflcation/ stahUization Additives such as portland cement are mixed with soil in situ or in an aboveground treatment unit to limit the mobility of contaminants. Metals... 

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