The conceptual model for the soil-atmosphere exchange of a model compound, phenanthrene, in shown in Figure 1, wherein there are several defined layers within the profile (bulk air and near-surface air, and sorptive soil layers). Using this conceptual model, this work aims to implement a 2-D numerical simulation of soil-atmosphere exchange using the geochemical model MIN3P, and including factors like sorption, biodegradation, volatilization, temperature variation, recharge rate, eddy diffusion and molecular diffusion which are estimated from literature data.
Special interest for the soil-atmosphere exchange of organic compounds includes: (1) understanding the physical and biogeochemical processes controlling the long-term fate of organic pollutants; and (2) estimating cross compartmental concentration gradients and flux rates under future scenarios of emissions or climate change. Future work aspires to link the model to field observations of this exchange process. In addition, the model developed could be extended to simulate the dynamics of carbon turnover (CO2, O2, etc) and weathering processes.