Pollutant fate

Fortunately — and not unfortunately — no one model exists as yet which simulates all of the physical, chemical, and biological processes associated with pollutant fate in soils. We say fortunately, because such a package would be very data intensive and difficult to use. Intensive research is required to accomplish the above objective and the value of the overall product may be questioned by users. Section 7.0 presents selected models. 

PATHS (30) is mainly an analytical groundwater model, that provides a rough evaluation of the spatial and temporal status of a pollutant fate. 

Analytic Easy model use limited calibration possibilities limited input data requirements desk computer use Rough averaged predictions of pollutant fate, limited application capabilities To be used as an overall fate (screening) tools... 

Bonazountas, M. J. Fiksel (1982). ENVIRO Environmental Mathematical Pollutant Fate Modeling Handbook/Catalogue, EPA Contract No. 68-01-5146, Arthur D. Little, Inc., Cambridge, MA 02140. 

Clearly, we can find exceptions to these rules molecular diffusivity is a pollutant fate property, but may control an intramedia process rainfall history is an environmental scenario characteristic, but may control an intermedia transfer. 

For a limited number of exposure pathways (primarily inhalation of air in the vicinity of sources), pollutant fate and distribution models have been adapted to estimate population exposure. Examples of such models include the SAI and SRI methodologies developed for EPA s Office of Air Quality Planning and Standards (1,2), the NAAQS Exposure Model (3), and the GEMS approach developed for EPA s Office of Toxic Substances (4). In most cases, however, fate model output will serve as an independent input to an exposure estimate. 

During pollutants and/or SWM leachate transport through the surface/subsurface environments, physical and chemical processes can result in the accumulation of pollutants on the solid phase constituents. The degree to which this accumulation renders the trapped pollutants immobile is of vital interest in considerations for modeling the proposed pollutant fate and transport. 

Exposure factors are also included in many of the more recently developed characterization factors for human toxicity. These characterization factors are obtained through more complex models that incorporate factors such as persistence, pollutant fate, and exposure pathways. Although involving greater complexity in development, end-users may simply employ the more complex characterization factors already calculated by existing impact assessment models such as TRACI. 

Bonazountas M. 1988. Mathematical pollutant fate modeling of petroleum products in soil systems. In Calabrese EJ, Kostecki, eds. Soils contaminated by petroleum Environmental and public health effects. New York, NY John Wiley and Sons, 31-97. 

Acetone, irradiation in water, 13 Anthracene, toxicity to fish, 192 Anthropogenic pollutant, fate in natural waters, 207 Argon saturation, effect on phototransients at 720 and 475 nm, I48,l49f,150... 

The primary means of obtaining an environmental concentration profile involve the use of monitoring data in combination with pollutant-fate modeling. At... 

F.M. Duimivant and E. Anders, A Basic Introduction to Pollutant Fate and Transport, p. 480, Wiley, 2006. 

A second limitation resides in the fact that we have confined pollutant losses to those that occur by evaporation to the atmosphere. This ignores the role played by bottom sediments as well as solids suspended in the water of the basin in removing solute by adsorption, and of possible biodegradation of the solute by bacterial action. These are important mechanisms that add to the loss incurred by evaporation and have to be taken into account in comprehensive models of pollutant fate. By ignoring these processes, we have in effect set an upper limit to the pollutant concentration in the water. In other words, things will not be as bad as our model predicts, at least as far as the aqueous phase is concerned, because a good deal of the pollutant may disappear as a result of adsorption and biodegradation. 

Wania, R and Mackay, D. 1999. The evolution of mass balance models of persistent organic pollutant fate in tlie environment. Environmental Pollution 100, 223-240. 

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