Abstract
The levels of six selected polyaromatic hydrocarbons (PAHs), anthracene, fluoranthrene, pyrene benzo(b)and(k)fluoranthenes, benza(a)pyrene and benzo(ghi)perylene, within the sediments of a 5.3 km2 urban catchment in N.W. London have been investigated over a 12 month period. The variations in levels throughout the catchment are discussed in terms of the influence of established hydrocarbon-sediment associations on both the contributions of different source inputs and on the controlling effects of on-line sedimentation ponds and the terminal receiving basin. These factors cause local variations within the overall pattern which demonstrates an increase in sedimentary PAH concentrations downstream as the percentage urban surface area increases. The PAH distribution is essentially hydrauli-cally controlled through discontinuous resuspension of the mobile surface sediment layer during turbulent storm flow conditions.