Publication Abstract

The Behaviour of ²¹⁰Pb and ²²⁶Ra in the Eastern Irish Sea

M. McCartney, P.J. Kershaw and D.J. Allington

The sedimentary inventory of excess ²¹⁰Pb in the eastern Irish Sea is higher than can be supported by atmospheric deposition plus its in-situ production from ²²⁶Ra in the overlying water column. The depositional fluxes (30-500 Bq m^-2 y^-1) necessary to maintain the inventories increase towards the coast. Enhanced concentrations of dissolved ²²⁶R_a found in this area cannot account for the excess ²¹⁰Pb production but evidence suggests that both these nuclides may have a common local source. Similarly, very high concentrations of unsupported ²³⁰Th are found in the surface sediments (1-60 Bq kg^-1), the distribution of which mirrors that of ^21OPb. The source of these natural radionuclides appears to be liquid waste discharged from a chemical factory involved in phosphate production. Annual variations of ²²⁶Ra and unsupported ²¹⁰Pb concentrations in sediments over the period 1959-1986 were derived from cores, of known chronology, collected from a nearby harbour (Maryport). The temporal records of these nuclides correlate well with discharge data provided by the chemical plant.

Reference:

M. McCartney, P.J. Kershaw and D.J. Allington (1990) The Behaviour of ²¹⁰Pb and ²²⁶Ra in the Eastern Irish Sea. Journal of Environmental Radioactivity, 12: 243-265.