XLIII, No 5 – 2635 HEAVY METALS IN STREAM SEDIMENTS AFFECTED BY A LANDFILL AND ASSOCIATED IMPACT ON GROUNDWATER QUALITY Koutsopoulou, E., Tsolis-Katagas, P. and Papoulis, D. University of Patras, Department of Geology, Section of Earth Materials, 26500 Patras, Greece, ekout- sop@upatras.gr Abstract Sanitary landfill facilities are essential to modern societies as repositories for municipal solid wastes. However, they always entrain a certain risk of environmental impact. For this reason monitoring is es- sential to their operation. In the present work, the environmental impact of such a landfill is studied. Soil samples were collected in and around the landfill and their mineralogy was studied. Top layers of stream sediments were collected to examine possible dispersion of pollutants in the environment. Chem- ical analyses showed enrichment in As, Cu, Zn, and Pb in the stream sediments compared to uncont- aminated samples. The presence of anions such as chloride, sulphate and phosphate adsorbed on clay minerals suggest the interaction of stream sediments with run-off water from the landfill. The groundwater near the landfill site was characterised as not potable and not suitable for irriga- tion purposes, because some parameters such as NO 3 - and Cl - were close or exceeded the permis- sible limits given by EE, EPA and WHO. Key words: sanitary landfill, clay minerals, groundwater, heavy metals, stream sediments. 1. Introduction Waste management policies concerning municipal landfills play an important role on preventing the emissions of contaminants, eliminating potential health hazards and preserving the environment. Landfills should hold no risks for the environment and that means that the transport of contaminants should be confined and restricted from reaching the natural environment. As stated by the Swiss Waste Management Standards of 1986 and the legislation in most European countries (Council Di- rective 99/31/EC), municipal waste deposits have to be compatible with the environment. Sanitary landfills require that a composite liner comprising a geomembrane and a clay mineral liner accord- ing to the multi-barrier system should be used at the bottom of the waste disposal site (Stief, 1986; Technical Instructions Hazardous Wastes, 1991; Hermanns Stengele and Plötze, 2000; Kalbe et al., 2002). This concept is essential for the avoidance of leachate migration from the landfill boundaries and its release into the surrounding environment, which may cause ground water pollution and other environmental impacts. Compacted clayey soils are widely used as landfill liners in order to isolate waste materials from surrounding environments, and to prevent the heavy metals commonly found in landfill leachate from migrating into groundwater (Chalermyanont et al., 2009). However, vari- ous studies have reported elevated concentrations of metals in stream sediments originating from landfill contamination sources. Studies of increased Cu, Pb, Zn, Cd, Ag, and Ba concentrations in stream sediments from landfills and water treatment facilities have been reported (Mantei and Coon- Δελτίο της Ελληνικής Γεωλογικής Εταιρίας, 2010 Bulletin of the Geological Society of Greece, 2010 Πρακτικά 12ου Διεθνούς Συνεδρίου Proceedings of the 12th International Congress Πάτρα, Μάιος 2010 Patras, May, 2010