Azaarenes in sediments, suspended particles and aerosol associated with the River Mersey estuary

The distributions of a variety of azaarenes in suspended particulate material and sediments in the River Mersey estuary and two tributary canals are described. Azaarene concentrations in the local urban atmosphere are also provided. Total azaarene concentrations (the sum of the concentrations of 48 individual azaarenes) range from 2–364 ng · g −1 for estuarine suspended material and 128–2451 ng · g −1 for canal sediments. Atmospheric aerosol concentrations fell within the range 1 to > 9 ng · m −3. Whilst sediments and suspended matter showed concentrations similar to those previously reported, the atmospheric concentrations were considerably higher and it is hypothesised that deposition of aerosols is a major source of azaarenes to this estuarine system. Down estuary removal of the lower molecular weight azaarene species from the particulate fraction is reported and attributed to selective solubilisation of these molecules. Seasonal variations in both the total and relative azaarene concentrations occur with the greatest abundance of all species in the colder months when post-depositional alteration is least and inputs from combustion sources are greatest. A clear seasonal variation in atmospheric aerosol azaarenes is reported and this appears to be reflected in the sedimentary record.