Pollution interactions with soil

The sorptive behavior of pesticides and organic pollutants can be studied from either equilibrium or kinetic viewpoints. While both are important, perhaps the time-dependent processes are least understood. As environmental concerns intensify about groundwater pollution, waste disposal, and soil detoxification, it will become increasingly important to better understand the kinetics and mechanisms of pesticide and organic pollutant interactions with soils. For comprehensive treatments on pesticides and... 

The indirect pathway by which air pollutants interact with plants is through the root system. Deposition of air pollutants on soils and surface waters can cause alteration of the nutrient content of the soil in the vicinity of the plant. This change in soil condition can lead to indirect or secondary effects of air pollutants on vegetation and plants. 

Models of chemical reactions of trace pollutants in groundwater must be based on experimental analysis of the kinetics of possible pollutant interactions with earth materials, much the same as smog chamber studies considered atmospheric photochemistry. Fundamental research could determine the surface chemistry of soil components and processes such as adsorption and desorption, pore diffusion, and biodegradation of contaminants. Hydrodynamic pollutant transport models should be upgraded to take into account chemical reactions at surfaces. 

Houot S, Benoit P, Chamay MP, Barriuso E (1997) Experimental techniques to study the fate of organic pollutants in soils in relation to their interactions with soil organic constituents. Analysis Magazine 25, 9-19. 

The models therefore reflect our level of knowledge of die soil solution and its interaction with soil solids. Since these models have the potential to predict the composition of natural waters (groundwater, lakes and streams, oceans as well as the soil solution), soil fertility, the effects of fertilizers and soil amendments, the effects of acid rain, and the attenuation and release of pollutants in soils, this important area of research should be actively pursued. The accuracy of the models, however, is still based on our understanding of the soil s chemistry and cannot be more accurate than that. 

The harmful effects of air pollutants on human beings have been the major reason for efforts to understand and control their sources. During the past two decades, research on acidic deposition on water-based ecosystems has helped to reemphasize the importance of air pollutants in other receptors, such as soil-based ecosystems (1). When discussing the impact of air pollutants on ecosystems, the matter of scale becomes important. We will discuss three examples of elements which interact with air, water, and soil media on different geographic scales. These are the carbon cycle on a global scale, the sulfur cycle on a regional scale, and the fluoride cycle on a local scale. 

The humic/organic matter coatings of different solid phases (i. e., SPm /SP0M), such as soils, sediments, suspended solids, colloids, and biocolloids/biosolids, interact with organic pollutants in aqueous systems in various ways. Adsorption is an important interaction mode. The reversibility and/or irreversibility of the adsorption processes is of major importance. The question whether the bound residues of pollutants are to be considered definitely inactivated has been the focus of extensive research. This question was posed as follows. Have the adsorbed pollutants become common components incorporated into the humic polymer coating of solid phases (i. e., being absorbed), or are they only momentarily inactivated in reversibly bound forms thus representing a possible source of pollution by a time-delayed release of toxic units ... 

Interaction with bentonite clay systems. Water Air and Soil Pollution 32 303-314. 

Senesi, N., and Miano,T. M. (1995).The role of abiotic interactions with humic substances on the environmental impact of organic pollutants. In Environmental Impact of Soil Component Interactions Land Quality, Natural and Anthropogenic Organics, Vol. 1, Huang, P. M., Berthelin, J., Bollag, J. M., and McGill, W. B., eds., CRC-Lewis, Boca Raton, FL, pp. 311-335. 

Pollutant realism Is achieved when the test system Includes sufficient diversity of components and the physical and chemical properties so that the pollutant behaves In the test system as it would In nature. Pollutant realism Is lacking because, In most test protocols, the pollutant does not Interact with any part of the environment, except the organism. A lack of pollutant realism In traditional tests may result In overestimates of risk. As an example, substantial Information Is now available about the toxicity of TCDD to numerous species when they are exposed via Injection, Incubation, diet, or dermal application. At Times Beach, Missouri, the TCDD is In the soli, and because It has apparently been there for some time, It is probably tightly bound to the soil. Little Is published about the toxicity of TCDD bound to soil, for any means of exposure. Intuitively, I suspect the TCDD Is less toxic when bound to soil than In the forms commonly used In toxicity testing. Thus, the risks of TCDD-lnduced toxicity to humans at Times Beach may be much smaller than would be suggested by the results of traditional testing which lacks this aspect of pollutant realism. 

Biggar, J.W., Doneen, L.D., Riggs, I.R. (1966) Soil interaction with organically polluted water. Summary Report, Department of Water Science and Engineering, University of California, Davis, California. 

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