Beschreibung:
<jats:title>Abstract</jats:title><jats:p>When modeling the fate and transport of chemicals in ground water, a common assumption is that sorption equilibrium is achieved rapidly. This local equilibrium assumption is valid when the rate of chemical sorption to soil particles is more rapid than the rate of aqueous chemical change by other processes. However, for some chemicals (e.g., weathered hydrocarbons) this assumption is not necessarily correct. As a result, an increasing body of knowledge related to the extent and rate of release (ROR) of hydrocarbons from soil has been generated.</jats:p><jats:p>When evaluating site remediation options, it is important to know when nonequilibrium sorption conditions may have a significant impact on such decisions. In this study, a tiered procedure was developed to consistently evaluate the importance of ROR information at a site. The procedure consists of three tiers, each requiring more information and computational effort than the previous one. The first tier employs three power‐law relationships between site parameters and the importance of ROR kinetics to quickly and easily estimate the importance of ROR information at a site. The second tier involves running and evaluating the deterministic component of a ground water fate and transport model. The third tier involves running and evaluating the probabilistic component of the ground water model. Given the sequential nature of the procedure, it is not necessary to perform Tier II (or Tier III) unless the Tier I (or Tier II) evaluation indicates that ROR kinetics may be important at the specific site under consideration. An example of applying the Tier I analysis to a specific site is provided. The results illustrate the influence of the chemical removal processes (e.g., advection and biodegradation) on the predicted importance of ROR kinetics. For the site considered, ROR kinetics had an important impact on model predictions when the biodegradation rate was high.</jats:p>