Coastal marine sediments receive intensive stress from urbanization and industrialization, which is manifested by increased contents of heavy metals and organic pollutants. Saronikos Gulf and the small embayment of Elefsis, stretch along the coast of the greater Athens and Pireaus port, the most urbanized and industrialized areas in Greece. Here we present the data of a 20-years geochemical record on grain-size, organic carbon, and major and trace elements contents of the Saronikos Gulf sediments. A total of 216 sediment samples were collected within the period of 1999 to 2018 from the four sub-sectors of the gulf, namely, the Elefsis Bay, the Inner, Outer, and Western (Megara and Epidavros basin) Saronikos Gulf. Additionally, at least one core was obtained from each sub-sector. Sediments deposited at pre-industrial periods were recognized by 14C and 210Pb datings, and served for establishing regionalized, background levels of metals. Factor analysis was conducted to reveal the inter-parametric relationships, thus their common sources, as well as transport and deposition pathways. Then, Enrichment Factors and the multi-elemental Modified Pollution Index (MPI) were calculated to assess the current environmental status of the sediments. Data of sampling sites with at least a five-year record, were assessed for temporal trends, to explore whether sustained, increasing or decreasing trends of the MPI are observed. The dataset and analyses presented here support the research article entitled Geochemistry of major and trace elements in surface sediments of the Saronikos Gulf (Greece): assessment of contamination between 1999 and 2018 by Karageorgis A.P., Botsou F., Kaberi H., and Iliakis S., https://doi.org/10.1016/j.scitotenv.2020.137046

Objectives: National water quality monitoring Area: Slovenian sea Attributes: Contaminant concentrations Data sources: ARSO Legal references: Directive 2000/60/EC (WFD), Directive 2008/56/EC (MSFD), Directive 2013/39/EC (EQS-directive) Importance of the work: National level