What is Diesel?
A distillate of oil, diesel is a mixture of hydrocarbons with a boiling point range from around 200 to 350°C. In reality, it is more accurate to describe diesel with vapor pressure rather than boiling point, but the distinction is similar. For the compounds that diesel contains, the diesel mixture generally equates to a range from nC10 to nC22, where n signifies straight chain alkane (n=normal) and the number represents the number of carbons in the chain. Therefore, diesel contains all the compounds between decane (10) and docosane (22). All of the hydrocarbons from the oil source within this range are contained within this diesel cut, thus making diesel a large, complex mixture of hydrocarbons.
Diesel is most commonly used as a fuel for vehicles and home heating, but also finds use for its solvent properties and is used in drilling mud in the oil and gas industry. These uses tell us what to expect for types of diesel impacts in the environment.
The addition of fatty acid methyl esters or FAME, into diesel produces a biodiesel product that is still suitable for standard diesel combustion engines. FAME is derived from esterification of fatty acids, themselves most often coming from vegetable oils. The presence of FAME in diesel is readily observed using relatively standard analytical techniques and can be a useful distinction for specific investigations as it is an age-related marker, and also may be attributable to a particular source if multiple sources are suspected.
Diesel contains only low concentrations of benzene, toluene, ethylbenzene and xylenes (BTEX), which are more concentrated in a lighter distillation cut used for gasoline. However, even though they are only present in low concentrations in diesel, groundwater plumes of BTEX can originate from diesel.
Diesel contains polycyclic aromatic hydrocarbons (PAHs), a chemical class often used to assess risk and is used as the remedial benchmark for diesel spills and releases in the environment. PAHs can thus be used as source indicators and for fate and transport studies for diesel or mixed contamination sites where diesel is a suspected impact.
Where do we find diesel in the environment?
Most often environmental investigations relating to diesel will fall into two categories:
- Releases from storage tanks and pipework,
- Impacts relating to drilling waste.
In addition, spills relating to transport, for example via tanker trucks may be an emergency response action relating to diesel.
Thus, diesel impacts at gas stations, as well as heating fuel tanks make this a distinctly urban contaminant with moderate mobility in the subsurface.
- Legal Sampling
- Chain of Custody
- Study Design
- Data Analysis and Visualization
- Data Wrangling
- Multivariate Statistical Analysis
- Principal Component (PCA); Hierarchical Cluster (HCA)
- Science Communication
- Data Science/Big Data
- Multidimensional Gas Chromatography (GC×GC)
- Source Apportionment
- Chemical Fingerprinting
- Diagnostic Ratios
- Fate and Transport
- Soil gas sampling
- Surface casing vent sampling
- Arsonous Wildfires