Urban ecology: assessment of the pollutants accumulation in sediments from the Colentina lakes in Bucharest

In Bucharest, capital of the Romania, the artificial lakes on the river Colentina have an operation period of decades. The functionality of these lakes is: the flood regularization and for recreation. Over time were deposited on the bottom of lakes a large amounts of the alluvial deposits (sediments) carried by the waters of the river and its tributaries, and rainfall run-off out of the vicinity. A first consequence of the alluvial deposits consist in lowering the initial depth of the lakes, which facilitated excessive growth of the aquatic vegetation, and, in summer, the effects that affect the ichthyofauna and the recreation activities. Another consequence of the alluvium deposits located immediately upstream of discharge points is the diminuation of the transport capacity of the Colentina river. This paper presents a synthesis that brings together both specific elements: the conceptual model of the lakes and a series of the analytical results obtained from implementing an experimental field: 11 sampling points in order to investigate water quality, respectively the monitoring and control. The results regarding the quality of the sediments highlight the unequivocal role of deposition of
the pollutants in a long periods of time.