engleski

Behaviour of aromatic surfactants in estuarine environments – comparison of microtidal and macrotidal estuaries

Detergent derived chemicals are among the most common pollutants of estuarine and coastal waters. Input and distribution of two major classes of aromatic surfactants, alkylphenol polyethoxylates (APnEO) and linear alkylbenzene sulphonates (LAS) were studied to assess the impact of estuarine master variables, such as salinity gradients and particle load, on their behaviour and fate. The studies presented in this paper comprised the determination of the surfactant input via municipal wastewaters and their subsequent distribution in estuarine waters for two basically different types of estuaries, the highly stratified Krka River estuary and the macrotidal Tamar estuary. Both LAS and APnEO were found in all investigated wastewater effluents in relatively high concentrations. Following a rapid exponential decrease of the concentrations with increasing distance from sewage outlets, the behaviour and fate of investigated surfactants in estuarine waters strongly depends on basic hydrographic properties of a given estuary. As a consequence, there are some profound differences between the predominant distribution and transformation patterns in macrotidal and microtidal estuaries. The concentration maxima in both systems were determined at the air-freshwater and freshwater-seawater boundaries, the later being particularly important place for physicochemical partitioning and biotransformation reactions. Our results suggest that the biotransformation capacity of microtidal estuaries, characteristic of the Mediterranean Sea, to cope with increasing load of aromatic surfactants, is considerably reduced as compared to macrotidal systems.

aromatic surfactants; behaviour; estuaries; LAS; APnEO

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