Investigation of the technological enhancement of natural decay series radionuclides by the manufacture of phosphates on the Cumbrian coast

The aim of this study is to investigate the response of the aquatic environment following the cessation of discharges from a phosphate-ore processing plant, situated at Whitehaven, northwest England. A preliminary survey was carried out to determine 210Po, 210Pb and 238U activities in inter tidal biota and sediment in the vicinity of the plant in November 1992. The maximum concentrations observed in the samples are all above the reported natural ranges and are clearly indicative of technological enhancement. The highest 210Po (7749 ± 201 Bq kg−1 dry weight) and 238U (390 ± 12 Bq kg−1 dry weight) activities were found in the sediment collected from Whitehaven Harbour, the sampling site closest to the outfall pipe. At all sites, with the exception of Whitehaven itself, 210Po levels in mussels were greater than winkles, which, in turn, were greater than levels in sediments which exceeded the levels observed in seaweed. Uranium levels were found to be greatest in sediment, while the rest of the sample types exhibited similar levels of activity. Initial 210Pb results show similar levels in mussels and winkles which suggests the uptake mechanism to be different than that of 210Po. Further surveys have since been carried out at approximately 4–5-month intervals and the temporal trends obtained suggest an overall decrease in radionuclide concentrations in all sample types.