Historical Contaminant Fluxes in the Tees Estuary, UK: Geochemical, Magnetic and Radionuclide Evidence

摘要

Geochemical, magnetic and radionuclide analyses were undertaken on deep and shallow cores from the Tees estuary in an investigation of sediment flux during the historical past, using the record of contamination from mining and industrial activity to link Holocene coastal change with present-day sedimentary processes. The extent of contamination can be identified from XRF and environmental magnetism data, and is variable in magnitude and thickness. Concentrations of Pb and Zn are particularly effective in the identification of far-field mining contamination, whilst As concentration and the concentration of magnetic minerals (χ, magnetic susceptibility) are used to characterise near-field industrial contamination. Radionuclide chronologies (~(210)Pb and ~(137)Cs) confirm limited post-depositional disturbance of the shallow sedimentary record and place the onset of industrial contamination at c. 1925, with a peak level in the mid-1950s. Although contamination has decreased since the early-1980s, the marked spatial and vertical variation in the extent of this contamination adds a significant level of complexity to any future assessment programme where sediment erosion and redistribution are important concerns.