Shahul Hameed K.P , Sadashiva Murthy B.M
Volatile Organic Compounds (VOCs) are the most common subsurface environment contaminants usually in the form of Non-Aqueous Phase Liquids (NAPL) through Leaking Underground Storage Tanks (LUSTs) and pipelines, accidental spills, land disposal sites, and industrial waste impoundments. VOCs are toxic, mutagenic and carcinogenic. Hence, VOCs in subsoil pose a serious threat of groundwater contamination. Organic compounds, owing to their persistence and volatility, present unique environmental problems in the vadose zone of soils. The uncertainty in transport mechanisms and subsoil environment pose a serious challenge in developing transport model for VOC compounds. Apart from advection and dispersion, VOC also undergo several complex chemical reactions such as adsorption, degradation, volatilization and ionic exchange. The transport mechanisms and transport modeling studies for VOCs are largely based on extensive field studies and relevant laboratory experiments. The focus here is to review the role of transport mechanisms and modeling aspects of organic compounds in petroleum fuels and other such liquids and liquid wastes that have the potential to migrate through subsoil to groundwater and also to atmosphere by vapor diffusion.