Sediment pollutants in the Thames estuary

This study aims to identify and map pollution in the Thames estuary and understand the processes that influence pollution distribution. Why study this?

Sediment pollutants in the Thames estuary, Kensington, London, UK. Manual core sampling for organic pollutants such as total petroleum hydrocarbons (TOCs), polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs).

The Thames

The tidal portion of the River Thames, in south-east England, covers a distance of 104 km and extends from Teddington Locks in the east to Shoeburyness/Isle of Grain in the west where it meets the southern North Sea. The Thames flows through London, the UK's most populous city, which has been permanently inhabited for over 2000 years.

Location map of the River Thames, UK, showing the tidal limit at Teddington. CLICK TO ENLARGE

The estuary has been subject to many pollution discharges from a succession of industries and domestic sources located along the banks of the Thames and also from the wider catchment area. Although the water quality of the Thames has been reported to have improved dramatically over the past 50 years, relatively little is known about the environmental quality of the near surface sediments and, in particular, the muds which are vulnerable to physical disturbance and erosion.

Ongoing programme of work

Short sediment cores of up to 1.2 m depth and surface sediments (0–10 cm) are currently being collected from the intertidal foreshore of the Thames (see video above).

Hammering core into the soft mud sediment. CLICK TO ENLARGE

Core collected to be taken to freezing facilities on the boat. CLICK TO ENLARGE

Collecting sediment samples on the bank of the Thames.

These are frozen within hours of extraction to preserve the contamination prior to being analysed in the BGS laboratories. A wide range of analyses are carried out at the bulk and molecular level:

total organic carbon (TOC) and δ¹³C values
total petroleum hydrocarbon (TPH)
polyaromatic hydrocarbon (PAH)
polychlorinated biphenyl (PCB)
polybrominated biphenyls flame retardants (PBDE)
total mercury (Hg)
137 caesium (Cs) radionuclides
207/206 lead (Pb) isotopes
selected trace metals
arsenic (As) pollution

Sampling the core for stable carbon isotopes. CLICK TO ENLARGE

Open core from the Thames. CLICK TO ENLARGE

Why study the sediment in the Thames Estuary?

Sediment profiles can contain a record of historic pollution which can be linked to:

the urbanisation and industrialisation of the Thames Basin
risk to human health and ecosystems

This project will provide an understanding of the distribution, accumulation and possibly the provenance (source) of selected pollutants in the section of the tidal Thames stretching from Richmond to the Isle of Grain.

This information will also be used to map dispersal paths, identify pollutant sinks and understand the risk should the sediments be remobilised by climate events such as the combined effects of spring tides and storm events as well as sea level rise.

Overall, this study aims to both identify and map pollution in the estuary and understand the processes that influence pollution distribution and therefore contribute to improved management of the Thames Estuary as well as comply with international treaties, such as OSPAR, which requires the separation of natural background and anthropogenic inputs.

Publications

Papers on the organic and inorganic chemistry of the sediment in the Thames will be coming soon.

Contact

Contact Dr Christopher Vane for more information.