Records and sources of metal pollutants in a dated loch lomond scotland uk sediment core

Farmer J. G.; Swan D. S.; Baxter M. S.

Pb, Zn, Cu, Cr, As and Cd were measured in a sediment core from southern Loch Lomond [UK] for which 210Pb dating indicated a sedimentation rate of 22 .+-. 2 mg/cm2 per yr corresponding to a mean accumulation rate of 0.36 mm/yr. While Cu and Cr were enriched to only a minor extent, Pb, Zn, As and Cd concentrations were enhanced in upper sections. Increasing anthropogenic input associated with industrial activity centered on Glasgow [UK] was responsible for the vertical distribution of Pb, Zn and Cd but a high 0-1 cm level of As (474 .mu.g/g), strongly correlated with enhanced Fe content in surface oxidizing layer of sediment, attributable to post-depositional diagenetic mobilization and upward migration in the reducing zone of the sediment column. Leaching, using CH3CO2H/NH2OH .cntdot. HCl, released over 90% and 80% of common metal pollutants, Pb and Zn, from surface sediment. Onset of an approximately 10-fold increase in Pb and Zn concentrations above background levels of 13 .+-. 2 .mu.g/g and 47 .+-. 13 .mu.g/g to upper section levels of 140-170 .mu.g/g and 450-460 .mu.g/g, respectively, was placed at late-18th century, in accord with records of the commencement of significant industrial activity in Glasgow area. Current anthropogenic fluxes (.mu.g/cm2 per yr) of Pb (2.51 .+-. 0.34) and Zn (8.84 .+-. 1.20) to the sediment were in agreement with recent atmospheric deposition data for adjoining Clyde Sea area. General concordance between anthropogenic metal fluxes to Loch Lomond sediment and atmospheric deposition fluxes endorsed the potential usefulness of Loch Lomond sediment data to the resolution of pollution sources in adjoining sea lochs and firth of Clyde Sea area, illustrated through consideration of the comparative distribution of Cr in relation to its historical use.