Soil remediation by coupled phytoextraction/biogeochemical treatment

The present invention generally relates to a phytoremediation process for removing shallow subsurface contaminants in soils. More particularly, the present invention provides a process which combines surface chemical reaction (i.e., fixation and degradation) of contaminants with the phytoextraction and subsequent accumulation of contaminants in the above-ground biomass of the plants. In particular, a combination of phytoextraction and surface chemical reaction is provided which allows passive remediation over numerous plant growth cycles to occur without the expense of above-ground biomass removal and disposal. A process of phytoremediation is provided in which the above-ground surface is first amended with stabilizing additives which will react with and bind subsurface contaminants. As the contaminants are brought to the surface through the growth of phytoextracting plants, the plants' vegetation is left to die in situ. As the plant biomass decomposes, the soil contaminants brought to the surface react with and/or are bound by the soil amendments. The soil amendments may further be provided in the form of a geotextile barrier or mat having one or more additive layers present within the mat structure.