The island of Sicily (central Mediterranean) has been the focus of considerable anthropogenic impact since pre-Classical times. More recently (post-1950), industrial development in SE Sicily has resulted in extensive modification of the coastline (port development) and a potential for persistent, chronic pollution (industrial development). This study examines the historical record of human influence on the Augusta / Syracusa coastal zone of south east Sicily, using the potentially high-resolution geochemical records contained in salt marsh sediments from the area. The study forms the basis of a longer-term project using high-resolution sedimentary records to examine the roles of climatic, tectonic and anthropogenic controls on coastal evolution in SE Sicily over the last 500 - 1000 years.
A short core was taken from the commercial port area near Augusta, in the estuary of the Mulinello River. The site is north of the main Augusta / Syracusa industrial zone. Sediments were dated using 137Cs and 210Pb and analysed using a combined sedimentological, geochemical, palynological and isotopic approach. Major element geochemistry indicates a 3-way mixing of sediment sources, derived from Etnean volcanics (upper river catchment and reworked alluvial fill), Pliocene/Miocene limestones (lower river catchment, surrounding coast and reworked alluvial fill), and in-situ organic production. The relative importance of each source has changed markedly over time. After the late 1960s a decrease in minerogenic sediment supply and an increase in organic input occurred. This date coincides with the rapid industrialisation and port development of the area, involving construction of port facilities and development of the land-areas immediately adjacent to the marsh. This appears to have significantly reduced the supply of river and marine-derived sediment, and caused the formation of organic-rich layers in the sediment. The observed change in sediment source is corroborated by palynological data, which imply a change in pollen input following industrial development in the late 1960s. In the period after development there is a significant reduction in the relative abundance of pollen derived from a river-catchment (dry-grassland type), regional source, and an increase in the importance of local, salt-marsh vegetation production.
Trace element analyses show that concentrations of Pb and, more recently, As (post-1990) are significantly higher than background following industrial development. The Augusta-Syracusa coastal zone is heavily industrialised, containing intensive oil refinery / petrochemical development. Concentrations of other heavy metals (i.e. Cu and Zn) likely to be present in refinery / petrochemical effluents, however, are not significantly elevated, indicating there is little input of contaminated sediments from the south. The Pb increase occurs over the period 1970 - the present day and is likely to be caused by increasing road traffic following industrialisation of the area. Pb sources are currently being assessed through the analysis of Pb isotopic abundances. The source of the As is not clear, but may result from its use as a pesticide or livestock feed additive in the surrounding agricultural area.