Diffusion Coefficient Estimation

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This page provides a description and a link to a "Diffusion Coefficient Estimation" modeling tool that can be used for modeling exposure levels or information needed in exposure assessment.

Short Description

Diffusion coefficients are required inputs to some environmental transport or risk assessment models. Literature values are sometimes available for these parameters, although, often the literture values are determined at 25 oC. When parameter values are otherwise unavailable, either for an unusual chemical, or for a temperature not reported in the literature, a calculated value may be useful. EPA's two versions of on-line calculator for estimating water and air phase diffusion coefficients are availab. The first contains preset inputs for benzene, toluene, ethylbenzene, and xylenes (BTEX) and oxygenated additives of gasoline. The second version requires generation of input parameters for the chemicals of interest.



Key Words

diffusion coefficients, water, air