Biomonitoring of trace metal availabilities in the Thames estuary using a suite of littoral biomonitors

This study employed a suite of three biomonitors to investigate trace metal pollution in the Thames estuary, a region of significant clean-up of contaminants and the cumulative return of fauna and flora over the last two decades. The biomonitors chosen are the brown seaweed Fucus vesiculosus (bladder wrack), the barnacle Balanus improvisus and the talitrid amphipod crustacean Orchestia gammarellus, in order to obtain data on the bioavailabilities of Zn, Cu, Cd, Pb, Fe, Ag and Mn in the Thames estuary in 2001, as a basis for future comparisons as pollution is further reduced in the Thames. Accumulated metal concentrations in these organisms represent integrated records of the total bioavailabilities of the metals to that organism at that location over a previous time period, and comparisons of accumulated concentrations in a biomonitor between sites are indeed comparisons of the recent contaminant bioavailabilities to that biomonitor. All three biomonitors showed geographical differences in trace metal bioavailabilities along the Thames estuary. There was general agreement in the conclusions to be drawn from each of the three species used. Raised bioavailabilities of zinc, cadmium, lead, iron and manganese are present, particularly in the middle region of the Thames investigated, downstream of the effluent discharges of the sewage works at Beckton and Crossness.