Vertical variations of radionuclides, trace metals, and major elements were determined in two sediment cores, which were collected in the marine environment of Ierissos Gulf near Stratoni's mining area. The enrichment factors (EFs) were also estimated and provided moderately severe to extremely severe enrichment for most trace elements and Mn, describing the anthropogenic influence in the gulf during the previous century. According to the applied dating models based on 210Pb and 137Cs, the effect in the marine sediment due to the exploitation of pyrite for the production of sulfuric acid during 1912-1920 was observed. Additionally, the decrease of mining activity during 1935-1945 due to the Second World War and the type of ore exploitation, the alteration of the exploited ores, and the construction and operation of Olympiada's floatation plant during 1950-1970 were identified. The end of tailing discharging into the marine environment during 1980-2010 was also noted.
Keywords: Enrichment factor; Ierissos Gulf; Marine sediment; Radiometric dating; Radionuclides and heavy metals.