Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, ^207/206 Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records

Abstract

The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and 207/206 Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg −1 , total PAHs from 19 to 16 163 mg kg −1 and total PCBs between less than 4.3 to 1217 mg kg −1 . Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern nonpolluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg −1 , while 207/206 Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.

Polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) in urban soils of Greater London, UK

“…A UK study reported P 22 PAH concentrations in the range of <1 to 55 mg/kg (n = 366) (Creaser et al, 2007c). Similarly, Glasgow has soils with P 15 PAH concentrations in the range of 1-52 mg/kg (n = 15) (Morillo et al, 2007;Vane et al, 2011). In contrast, lower amounts of PAH have been observed in urban soils from Wales and the Midlands/Birmingham (Butler et al, 1984;Smith et al, 2001;Wild and Jones, 1995).…”

The Anthropocene: a new epoch of geological time?

“…They note that in the past 200 years, humans in the UK alone have excavated and built up more than four times the volume of Ben Nevis, Britain's highest mountain. Vane et al [24] continue this theme, identifying a range of pollutants preserved in the sediments of the River Clyde that provide a stratigraphical record of the rise of Glasgow, one of the world's first industrial cities.…”

Stratigraphy of the Anthropocene

“…Other significant chemical perturbations include: a twofold increase in the amounts of reactive nitrogen at the Earth's surface and in the oceans, mainly as a consequence of the Haber process and the production of nitrogen-based fertilizers; increases in the amounts of particulate reactive iron (from fly ash), lead, soluble mercury and petroleum-based products as either spills or combustion residues; the introduction of a number of (largely novel) compounds associated with pesticides, flame retardants and other industrial products ( [43] and references therein; see also [44]); and radionuclides associated with fall-out from nuclear explosions.…”