THE USE OF MOLECULAR ORGANIC MARKERS TO INVESTIGATE POLLUTANT BEHAVIOR AT THE FRESHWATER SEAWATER INTERFACE (FSI) OF ESTUARIES

The freshwater seawater interface (FSI) of an estuary is unique in that reaction mechanisms, microbial regimes, flocculation/depositional characteristics and ecology radically change. Concentrations and distribution of sterols, synthetic musk fragrances and hydrocarbons in sediments through an axial transect are reported. High concentrations of coprostanol and B sitosterol (1.11-8.03 μg g-1 and 1.19-15.73 μg g-1 respectively) were recorded in the region of the turbidity maximum of the Tamar Estuary. High concentrations of synthetic musk fragrances Galaxolide® (HHCB) and Tonalide® (AHTN) (0.01-0.42 μg g-1 and 0.04-0.52 μg g-1) were observed in freshwater stations above the turbidity maximum. PAH (2.6-10.2 μg g-1), UCM (466.3-1271 μg g-1), saturated hydrocarbons (14.38-40.84 μg g-1) and C27,29,31,33 (6.04-14.65 μg g-1) showed similar distribution patterns to organic carbon, with no distinct sink at the turbidity maximum. High negative co-variability between musks and PAHs was observed, with a correlation coefficient of r2 = 0.86, possibly reflecting diversity in sources. No correlation was observed between the saturated hydrocarbons and UCM (r2 = 0.0001), probably reflecting the lubricity of the saturated compounds and major contribution of odd numbered alkanes derived from biogenic organics contrasting the petrogenic sources of the UCM. Capsule: Concentrations, distributions and co-variance of sterols, synthetic musk fragrances and hydrocarbons through an axial transect of the Tamar Estuary where determined, to investigate the freshwater seawater interface as a sink for catchment derived contaminants.Faculty of Science; Plymouth Marine Laborator