ISBN-13: 9789048150625 / Angielski / Miękka / 2010 / 167 str.
ISBN-13: 9789048150625 / Angielski / Miękka / 2010 / 167 str.
Oceans and lakes are characterized by large residence times and can thus be considered as being in an equilibrium or quasi-equilibrium state. In contrast, estuaries, which constitute the interface between the fresh water and marine ecosystems, are biogeochemically and physically very dynamic. Strong gradients in physical and chemical variables such as temperature, pH, salinity, dissolved oxygen, nutrients, amount and composition of particulates result from the mixing of fresh water and saline end members. These gradients provoke increased biogeochemical processes, generally resulting in a geochemical filter (the area of high turbidity, showing enhanced adsorption-desorption processes) and a biological filter (the area of high plankton activity showing, besides a high uptake of nutrients, a high accumulation of trace metals). Both filters disturb the conservative mixing pattern of the trace metals in an estuary.
In addition, four aspects make the Scheldt estuary very unusual and different from other estuaries: