What are Contaminated Hydrocarbons?
Hydrocarbons in whatever form are by and large the most common contaminant that requires remediation because of their far reaching occurrence and the dangers they pose to human health and controlled waters.
Total Petroleum Hydrocarbons (TPH) is a term used to depict hydrocarbon mixes got from Petroleum Sources. Common fuels, for example, Petrol, Diesel and Kerosene and Lubricating Oils/Greases all fall within the TPH banner. Because of the diversity compounds that contain TPH and the environmental and human health risks they present, the remedial methods used to address them should be considered on a site-specific basis.
Despite the fact that hydrocarbons are simple natural substances (including just carbon and hydrogen) there are countless different compounds, each displaying distinctive chemical and physical properties. To rationalize the behaviour of TPH once discharged into the environment it is most effortless to look at the structure and size of particular compounds. TPH compounds that have an aliphatic structure (i.e. straight or branched chains of carbon molecules) will behave differently to aromatic mixes (ringed chains of carbons). Likewise TPH compounds that have less carbon molecules will likewise act differently.
Lighter end TPH mixes (i.e. under 16 carbon atoms) have a tendency to be more mobile because of their greater solubility, more prominent volatility and lower natural partitioning coefficients. Lightweight aromatic compounds, such as, benzene, are likewise more toxic making them of greater concern if discharged into the environment.
Heavier TPH mixes typically have contradicting properties, having a tendency to adsorb into the natural portion of soil. Heavier aromatic compounds, referred to as Polycyclic Aromatic Compounds (PAH), can also have higher toxicity and are commonly more persistent in the environment. PAH’s are normally found in coal tar, heavy oils and creosotes.
Normally the majority of TPH mass will be partitioned within the soil phase. In some occurrences TPH can likewise be encountered as a phase separated liquid, which due to its buoyancy results in them floating on the surface of the water-table. Commonly phase separated TPH is referred to as Light Non-Aqueous Phase Liquid (LNAPL). A percentage of TPH will also be dissolved into the groundwater or trapped as a vapour within the soil ‘pore-space’ in the unsaturated zone.
The exact split between phases is linked to the original composition of the source, geological and hydrogeological conditions and the age since the spillage happened.