Sporstoffer til benzin, diesel og fyringsolie, - indledende screening

Summary and conclusions

In Denmark, the change in the legislation regarding soil pollution means that future soil pollution shall be removed by the polluter and in special cases by the owner of the polluting company or the affected land. To segregate future from previous pollution, the Danish EPA has initiated a project to evaluate a possible addition of a tracer/marker to crude oil products such as gasoline, diesel and heating fuel.

Oil products are a complex solution of many chemical substances of which the most are hydrocarbons. The individual products are manufactured by distillation at a refinery and characterised based on their temperature distillation intervals. For their different purposes, further additives are added to the oil products. The additives vary among gasoline, diesel and heating fuels, not only within the different products but also among the manufacturers. Due to the huge variation within products, season etc., it has, thus, been concluded not to be in these groups that a marker should be sought.

Potential markers have been looked for within the groups of alcohol and ethers, dyes, radioisotopes, organometals and non-natural substances. The types of alcohol and ethers are involved in a constant change and also regulated by other legislation. Thus, types of alcohol and ethers have been excluded as possible markers. Dyes are already added to oil products for other reasons e.g. duty purposes and visual recognition. A few dyes are already mentioned as markers in international legislation. Radioisotopes are a potential possibility since they can be used in very small amounts and still be detected. The problem with a radioactive substance is the public opinion and legislators wish to reduce anthropogenic releases of radioactive substances. The use of stable-activable radioisotopes has been considered possible; but evaded because the analyses are expensive and require access to a nuclear reactor. Non-natural substances may be possible but require assessment of fate and effect of the potential substances on the environment and health besides the effect on fuel quality.

It is concluded that the dyes present the best opportunities for finding a marker. The dyes are already added to gasoline, diesel and heating fuel for identification of their use and to detect misuse of tax exempt fuels. These uses require a visual colour.

Unlike dye, a marker does not need to reveal its presence until the fuel into which it has been introduced is subjected to a special test. A marker can therefore be added at considerably lower dosage than a visual dye. The marker may be looked for within already known dye groups. The text refers to dyes from the azo-, anthraquinone- and coumarin groups. These groups all have possible representatives, which are excellent for the purpose of a marker. Perhaps a minor change in molecular structure to avoid confusion with other dyes in the same group used in other countries or for other purposes should be considered.