HEAVY-METAL AND HYDROCARBON POLLUTION IN RECENT SEDIMENTS FROM SOUTHAMPTON WATER, SOUTHERN ENGLAND - A GEOCHEMICAL AND ISOTOPIC STUDY

A sediment core from Southampton Water, a coastal plain estuary, has been investigated and is shown to provide a record of pollution following the expansion of the Fawley oil refinery in 1949-1951. A combination of heavy metal analyses, the first appearance of hydrocarbon contamination, radiometric dating, and stable Pb isotope ratios have been used to interpret the pollution history in the core. Indications are that following dredging activities, accompanying the refinery expansion, there was a relatively rapid sedimentation rate of ca 20 mm p.a., which decreased with time to approximately 5 mm p.a. The higher accumulation rate is attributed to the response of the estuary following the major capital dredging works that occurred in 1950-1951. The accumulation rates are used to recalculate concentration profiles to reveal the heavy metal flux to the sediments. Lead isotope data indicate a significant post-1950 use of lead derived from ancient, non-U.K. (Precambrian) ores in local industry.