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The geochemistry of three urban streams in Athens was analysed and compared on the basis of major elements and heavy metals content in water and active sediment. Results indicated that rock weathering, rather than atmospheric or pollution influx is the dominant process affecting the major ion geochemistry of stream flow in the urban setting. Water samples from different streams are of a different Ca-Na-HCO3 type indicating the effect of different lithological types on water chemistry. However, Kifissos and Podoniftis samples had higher nitrate and phosphate concentrations indicating greater influence by anthropogenic activities. Heavy metals in water did not have significant concentrations. Also, heavy metal concentrations in sediment samples were generally low; samples from Pikrodafni showed relatively higher concentrations than the other two streams. In general the quality characteristics of water and sediment in the study area were found to be in a relatively good state regarding the studied parameters, capable of supporting abundant diatom populations. With appropriate management, the abiotic substrate of the studied streams could provide an opportunity for the evolution of a healthy ecosystem and development of so needed ‘green belts’ within the urban environment of Athens. Our aim is to further explore and study the geochemical regime of additional urban streams. Furthermore on going research is focusing on the chemical character of urban runoff as well as flooding sediments after storm events and their contribution to the redistribution of potentially harmful elements in the surface environment.
Link to video on stream water sampling by Hydrogeochemistry students- Uni. of Athens