Numerical study of one-dimensional site-specific contaminant pathway of vadose zone for risk assessment

Abstract:

Risk assessment is a scientific process that quantitatively measures these risks, which is defined as the possibility of adverse effect that can occur when receptors are exposed to pollutants. In this study, a finite difference concept model was established to evaluate the route of transport of pollutants in the soil and to calculate exposure concentration in the process of risk assessment. A conceptual model that can be used for evaluating the contaminant path of unsaturated pollutants was established, and numerical simulations using a one-dimensional transport equation were performed. In order to be applicable to the actual site, a range of parameters of hydrogeological and pollutant parameters in the unsaturated zone path was set, and scenarios for each pollutant were constructed and applied to the simulations. Contaminants in the unsaturated zone were considered to have a delay or a reduction in travel time due to adsorption and biodegradation, and it was also assumed that the pollutant concentration was depleted over time. Based on each prediction scenario, the output of simulated pollutant concentration was statistically analyzed. The results showed that the longer the vertical path from the source of contamination to the groundwater level, the lower the concentration range of the groundwater inflow. It showed that assuming high biodegradation rate and rapid exhaustion of pollutants, it was possible to predict the concentration of groundwater inflow in a specific range according to the type of pollutant.

Acknowledgements.

This work was supported by Korea Environment Industry & Technology Institute (KEITI) through SEM (Subsurface Environment Management) Project, funded by Korea Ministry of Environment (MOE) (Grant Number 2018002450003)