The consequences of the Oder flood in 1997 on the distribution of polycyclic aromatic hydrocarbons in the Oder River

Changes in the levels and spatial distribution of PAHs as a consequence of the Oder flood in the summer of 1997 were investigated in post-flood sediments from the Oder River and the Oder Lagoon. The aim of this study was to identify sources of the PAH pollution and in particular investigate polluted sites (hot spots) in the most highly suspected locations of the drainage area. Molecular indices based on isomeric PAH ratios and the ratio of the parent PAHs to methylated PAHs were used to distinguish between the pollution sources. Elevated levels of PAHs were discovered in the post-flood sediments of the Oder River in comparison to the average regional values. Elevated concentrations of PAHs were also found in fluffy layer samples taken from the Oder Lagoon and the Pomeranian Bight in late August. The highest concentrations of PAHs were observed near power plants or roads with heavy traffic. Most of the contamination originates from high temperature pyrogenic sources with some slight overlays of petrogenic sources. These increased concentrations of pyrogenic origin may be attributable to flooding of municipal and industrial waste disposal areas in the Oder River drainage.