Polycyclic Aromatic Hydrocarbons in Dated Freshwater and Marine Sediments Along the Norwegian Coast

Polycyclic aromatic hydrocarbons (PAH) have been identified and quantified in dated layers of freshwater and marine sediments in Norway. Furthermore, profiles of the individual PAH (22 different) have been used to evaluate possible PAH sources. There is a significant increase in total PAH levels (sum of the 22 PAH) in freshwater sediments from the south-western part of Norway representing the 1800-1950 period, whereas the concentrations have decreased with a factor of approximately four since the 1950s. This pronounced trend was observed in two independent surveys. In northern Norway, the PAH levels in lake sediments have increased slightly during the past decades. In spite of this, the levels are considerably lower than in lake sediments from the south-western part of Norway. In fact, the PAH levels are decreasing northwards on the Norwegian mainland for both freshwater and marine surface sediments. Generally, the regional total PAH levels are higher (three to four times) in freshwater sites compared to the corresponding marine sites. Results of PAH source allocation indicate that pyrogenic sources are important in almost all sediment samples studied. Sediment samples were also collected at Svalbard where the local coal reserve is the major contributor to PAH.