Quantification of petroleum hydrocarbon mass removal by geochemical changes in groundwater chemistry

Quantification of mass removal is a key issue for application of natural attenuation as a remediation strategy. Both distribution of organic contaminants geochemical observations can provide indications of mass loss. Significant changes in total inorganic carbon from produced carbon dioxide can be observed in petroleum hydrocarbon plumes undergoing aerobic or anaerobic degradation. These data can be used in combination with total alkalinity observations, the consumption of electron acceptors and production of reduced species (e.g. Fe2+, CH4) to evaluate and quantify mineralisation of petroleum hydrocarbons. The data indicates anaerobic degradation of petroleum hydrocarbon and that gas transport (oxygen, methane) between the unsaturated zone and the groundwater is important