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(38-37) Preliminary study of PAHs and diatom remains in the sediments of Esmoriz/Paramos coastal lagoon. Teixeira, Catarina*,1, Carvalho, Laurence2, Cortez, Amelia1, Salgado, Maria1,3, 1 Instituto de Ciencias Biomedicas de Abel Salazar, Largo do Prof. Abel Salazar, 2, Porto, Portugal2 Centre for Ecology & Hydrology, Edinburgh, Huntingdon Cambs, U.K.3 Centre of Marine and Environmental Research, Porto, Portugal ABSTRACT- The Esmoriz/Paramos lagoon is located on the northern coast of Portugal, is classified as CORINE BIOTOP and is a part of the National Ecological Reserve covering an area of 56 ha. The local industry includes textile, paper and bark industries. The lagoon receives untreated sewage water from industry and from about 49 thousand inhabitants in the surrounding area. Organic pollution and siltation are the major threats faced by the lagoon leading to eutrophication and in-filling. Dredging the sediments of Esmoriz/Paramos lagoon is the strategy planned by the local authorities to reverse these natural and anthropogenic effects. The aim of this study is to quantify the contamination of the sediments by polycyclic aromatic hydrocarbons (PAHs) in order to assess the risk of their disposal and resuspension at the time of dredging. In addition, assessment of the history of water quality in the lagoon using diatom analysis will give indication of the timing and extent of both salinity and hidrological changes. Diatoms are very sensitive to changes in water quality, particularly salinity and to sewage pollution. Sediment samples have been collected along the main hydrological gradient of the lagoon using a Glew corer. Thirty centimetres cores are being sliced into 1-2 cm and analysed for PAHs and diatom remains on a spatial and temporal scale. Quantification of PAHs has been carried out by HPLC-UV and GC-FID using deuterated compounds as internal standards. Pyrene and fluoranthene were found at 24-29 cm depth. Estimates of the siltation rate and age of the sediments will be conducted. Key words: coastal lagoons, sediments, PAHs, diatoms |
