Trace metals transport and behaviour in the Mediterranean estuary of Acheloos river

The concentration levels and the chemical behaviour of trace metals during their transport, were studied in the estuary of the Acheloos river, in western Greece. It is a typical, non tidal and stratified Mediterranean estuary which, although is not heavily polluted, is affected by a lot of human activities (dams, agriculture, fishing, etc.) that, in combination with its hydrological and morphological characteristics, affect also the distribution of trace metals. The concentration levels of metals in the estuary are lower than in polluted Greek gulfs and rivers. In the Acheloos case, in contrast to polluted estuaries, the dissolved metal concentrations are increased seawards whereas the particulate metal concentrations and the metal content of the particles are decreased. Suspended particulate matter and especially particles having diameter < 8 μm were found to play an important role in the processes related to trace metal mobility. These processes include desorption of particulate metals seawards, adsorption of dissolved metals on increased particulate loads, non conservative behaviour of both dissolved and particulate metals and association of particulate metals with particulate Al, Fe and Mn. The behaviour of metals show that Cu, Pb and Mn are possible dangerous pollutants for the system.