A Model to Derive Soil Criteria for Benzene Migrating from Soil to Dwelling Interior in Homes with Crawl Spaces |
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Authors: | Leonid Turczynowicz Neville Robinson |
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Institution: | 1. Environmental Health Service, Department of Human Services, Adelaide, South Australia;2. CSIRO Mathematical and Information Sciences Adelaide, South Australia |
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Abstract: | The establishment of Australian soil criteria for volatile hydrocarbons such as benzene has been limited due to the lack of a suitable transport model to predict human exposures. In a confined environment representing worst case exposure, the inhalation of volatile hydrocarbons from sub-surface regions may be used to establish health-based soil criteria. A volatilisation model is presented for the case of a crawl space home which is a common housing design in Australia. The model is used to estimate a cumulative indoor human dose (CIHD) based on one-dimensional movement from a finite subsurface source through soil to the dwelling interior. A non-homogeneous surface boundary condition is represented where the volatile is not immediately swept away from the air/soil boundary. Time-dependent differential equations established to represent transport are solved using Laplace transforms. Australian experimental field data are used in considering mixing, dilution, ventilation and sink effects and first-order soil and air degradation of the volatile incorporated. A CIHD from the model is compared to various benzene exposure standards to determine a criterion for benzene in soil. Sensitivity analysis has revealed that the dominant influencing parameters are those relating to dwelling characteristics and not soil properties or the physico-chemical properties of the volatile. Each of the group-input parameters has been found to act virtually independently in the model presenting the potential for model refinement and establishment of a generic soil criterion for benzene. |
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Keywords: | VOCs modeling exposure assessment soil criteria benzene |
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