Polycyclic Aromatic Hydrocarbons

PAH

Group of organic compounds with at least three condensed six-membered rings

PAH (Polycyclic aromatic hydrocarbons) denominates a class of several hundreds of compounds which share a common structure of at least three condensed aromatic rings. The number of rings strongly influences the physico-chemical properties of the respective PAH. Increasing ring numbers are associated with decreasing volatility and solubility whereas toxicity mostly increases.
PAH almost always occur as mixtures. The composition of these mixtures depends on the respective generation process.
PAH occur naturally in crude oil, peat, lignite, and coal. Moreover, they are formed by heating or combustion of organic material under anoxic conditions. They can be found in fried or grilled meat and tobacco smoke as well as in tar- and pitch-containing adhesives and coatings, in bitumen compounds and asphalt.

PAH are ubiquitous in the environment. In the atmosphere, compounds with 3 aromatic rings are mostly found in the gaseous phase whereas PAH with 4 and more rings adhere to particles. They enter waters and soils by wet and dry deposition.
In air and water, PAH can undergo photodegradation when exposed to ultraviolet light. Microbial degradation in soil and sediment is much slower.

They are of environmental concern due to their persistence and bioaccumulation potential. Many of the compounds are toxic, carcinogenic, mutagenic, teratogenic and reproductive toxic.

The U.S. EPA included 16 PAH in the so called EPA-list of Priority Pollutants. These 16 ‘EPA-PAH’ are frequently used as representatives of the whole class of PAH. The EU has included 16 partly different compounds in its list of PAH recommended for analysis (EU-list).

Substances

  • Polycyclic aromatic hydrocarbon with three connected six-membered rings
  • Polycyclic aromatic hydrocarbon with three six-membered rings and one five-membered ring
  • Polycyclic aromatic hydrocarbon with four connected six-membered rings
  • Polycyclic aromatic hydrocarbon with three six-membered rings and one five-membered ring with a single sulphur atom
  • Polycyclic aromatic hydrocarbon with four connected six-membered rings
  • Polycyclic aromatic hydrocarbon with four connected six-membered rings
  • Polycyclic aromatic hydrocarbon with five connected six-membered rings
  • Polycyclic aromatic hydrocarbon with five connected six-membered rings
  • Polycyclic aromatic hydrocarbon with five six-membered rings and one five-membered ring
  • Polycyclic aromatic hydrocarbon with six connected six-membered rings
  • Polycyclic aromatic hydrocarbon with seven connected six-membered rings

Specimen

  • Common mussel species as invasive animal in rivers and lakes with high information level for water pollution
  • Fine insoluble mineral or organic particles in the water phase
  • One of the most important edible mussel species common in the North and Baltic Sea
  • A major primary producer in semi-natural and anthropogenic affected ecosystems.
  • A major primary producer in semi-natural and anthropogenic affected ecosystems.
  • A deciduous tree typical of ecosystems close to dense conurbations and an indicator for the characterisation of the immission situation during the vegetation period.
  • As the most dominant deciduous tree species in Central Europe, it plays a significant role in most nearly natural and also anthropogenically influenced forest ecosystems up to an altitude of 1100 m.
  • As an organism living at ground level, it is a major driver of the decomposition of organic material (e.g. plant litter).
  • As an organism living at ground level, it is a major driver of the decomposition of organic material (e.g. plant litter).
  • Soil is livelihood and biosphere for humans, animals, plants and soil organisms. All the substances brought in are transported, transformed and/or accumulated in the soil.

Sampling area

Sampling period

1985 - 2019