Contrasting sewage, emerging and persistent organic pollutants in sediment cores from the River Thames estuary, London, England, UK

Sedimentary organic pollution in the urban reaches of the Thames estuary is changing from fossil fuel hydrocarbons to emerging synthetic chemicals. De-industrialisation of London was assessed in three cores from Chiswick (Ait/Eyot) mud island using pharmaceuticals, faecal sterols, hydrocarbons (TPH, PAH), Black Carbon (BC) and organotins (TBT). These ranked in the order; BC 7590-30219 mg/kg, mean 16,000 mg/kg > TPH 770-4301, mean 1316 mg/kg > (Sigma 16)PAH 6.93-107.64, mean 36.46 mg/kg > coprostanol 0.0091-0.42 mg/kg, mean of 0.146 mg/kg > pharmaceuticals 2.4-84.8 mu g/kg, mean 25 mu g/kg. Hydrocarbons co-varied down-profile revealing rise (1940s), peak (1950s - 1960s) and fall (1980s) and an overall 3 to 25-fold decrease. In contrast, antibiotics, anti-inflammatory (ibuprofen, paracetamol) and hormone (17 beta-estradiol) increased 3 to 50-fold toward surface paralleling increasing use (1970s-2018). The anti-epileptics, carbamazepine and epox-carbamazepine showed appreciable down-core mobility. Faecal sterols confirmed non-systematic incorporation of treated sewage. Comparison to UK sediment quality guidelines indicate exceedance of AL2 for PAH whereas TBT was below AL1.

Automated summary

Sedimentary organic pollution in the urban reaches of the Thames Estuary is transitioning from fossil fuel hydrocarbons to emerging synthetic chemicals. The study found a decrease of 3 to 25-fold in hydrocarbon content, while antibiotics, anti-inflammatory drugs, and hormones increased by 3 to 50-fold. Additionally, the composition of treated sewage was also incorporated into the sediments.