Ecomare

To get an impression of the presence of PAHs, measurements are usually directed at a selection of the total group. The 'six of Borneff' are the most often measured PAHs, and are considered representative of the whole group.
A large number of PAHs are poorly degradable. Many attach easily to silt particles, and therefore can be transported over large distances via the particles and cause pollution in the bottom.
PAHs are found everywhere in the bottom of the North Sea. High concentrations (more than 9 micrograms per kilo bottom material) have been measured along the Dutch coast and in the region of the Frisian Front. Furthermore, the concentration fluctuates predominantly between 3 and 9 micrograms PAH per kilo bottom material. In the Wadden Sea bottom, the PAH level fluctuates between 10 and 200 micrograms per kilogram bottom material.

Lugworms, cockles and Baltic tellins that have been exposed to PAH-polluted bottoms appeared less fertile than their brothers living on clean mud. This effect was strong in fresh mud and decreased in mud that had been polluted by PAHs for a longer period of time, even though the levels were higher than in the fresh mud.
Two scientists from NIOZ, Boon and Wethaak, found an unusual number of (liver) tumours in flatfish (such as flounder and dab) in areas where higher concentrations of PAHs were measured, as well as in experiments in which the PAH concentration was artificially increased. Effects on reproduction in birds in the form of deformed embryos and embryo poisoning were also diagnosed after being exposed to PAHs.

A number of industrial processes in particular can lead to a large emission of PAHs, such as the production of cokes and aluminium or the processing of coal tars. Creosote oil, often used in earlier times for impregnating soft types of wood, also contains many PAHs. Much creosote-wood is used for revetments, jetties etc in hydraulic works. The tar with which many ships are treated below the water surface line for preventing growth and rust is also a source of PAHs. Furthermore, fireplaces and wood-burning stoves, tar-bearing asphalt (road construction) and tar products for roofing are also sources of PAH-pollution.

To get an impression of the presence of PAHs, measurements are usually directed at a selection of the total group. The 'six of Borneff' are the most often measured PAHs, and are considered representative of the whole group.
A large number of PAHs are poorly degradable. Many attach easily to silt particles, and therefore can be transported over large distances via the particles and cause pollution in the bottom.
PAHs are found everywhere in the bottom of the North Sea. High concentrations (more than 9 micrograms per kilo bottom material) have been measured along the Dutch coast and in the region of the Frisian Front. Furthermore, the concentration fluctuates predominantly between 3 and 9 micrograms PAH per kilo bottom material. In the Wadden Sea bottom, the PAH level fluctuates between 10 and 200 micrograms per kilogram bottom material.

Lugworms, cockles and Baltic tellins that have been exposed to PAH-polluted bottoms appeared less fertile than their brothers living on clean mud. This effect was strong in fresh mud and decreased in mud that had been polluted by PAHs for a longer period of time, even though the levels were higher than in the fresh mud.
Two scientists from NIOZ, Boon and Wethaak, found an unusual number of (liver) tumours in flatfish (such as flounder and dab) in areas where higher concentrations of PAHs were measured, as well as in experiments in which the PAH concentration was artificially increased. Effects on reproduction in birds in the form of deformed embryos and embryo poisoning were also diagnosed after being exposed to PAHs.