R.T. Leah

Metal contamination of angler-caught fish from the Mersey Estuary

Abstract A survey of angling in the Mersey Estuary was undertaken to determine geographical and seasonal patterns of angling, the dominant species and size range of retained fish, and the fate of the catch. Six core species of fish were sampled from five sites in the Mersey Estuary, Hoylake, on the north Wirral, and a reference site in the Solway Firth. Analysis of muscle tissue was undertaken for mercury, arsenic, lead, copper, zinc, chromium and cadmium. Mean mercury levels for the eel and flounder populations from most Mersey Estuary sites exceeded the limit values of 0.5 and 1.0 mg kg −1 for fishery products, as specified in EC Decision (93/351/EEC). Inner Mersey Estuary sites also showed mean concentrations of lead in eel and flounder in excess of the statutory limit of 2.0 mg kg −1 . Arsenic levels were higher than the general UK food limit of 1.0 mg kg −1 , but the toxicological significance of this is minimal. All other combinations of species-site-metals returned data consistent with expected ranges and which are of no concern to human health. Whilst the real practical risk to consumers of Mersey Estuary fish may be low, the concentrations of mercury in muscle reinforce the prudence of MAFF advice to abstain from the consumption of long-lived lipid(fat)-rich fish, especially eels, from industrialised estuaries such as the Mersey.

The use of sediment cores from stable and developing salt marshes to reconstruct historical contamination profiles in the Mersey Estuary, UK

Abstract Depth-profiled sediment cores from two marshes in the Mersey Estuary were analysed for concentrations of 137Cs, 238Pu, 239,240Pu, 241Am, As, Cr, Cu, Pb, Hg and Zn. Mersey sediments contain three diagnostic and persistent chemical species arising from either a unique, or a dominant, source – 137Cs, Hg and DDT. Dating of features in these cores has been completed using up to four benchmark events identifiable from these chemical species – the initial expansion of the chemical industry, commencement of DDT manufacture, initial appearance of radionuclides from a reprocessing site in NW England, and the introduction of new technology to reduce mercury discharges. The sediment pollutant profiles depend on the rate of sediment accumulation but clearly record the historical increase in discharges of metals to the environment between the mid-19th and 20th centuries. They also reflect recent regulatory and technological efforts to minimise estuarine contamination and the discontinuation of specific manufacturing and refining processes. ©

Assessing radiation impact at a protected coastal sand dune site: an intercomparison of models for estimating the radiological exposure of non-human biota

This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, R&D128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured (90)Sr, (99)Tc, (137)Cs, (238)Pu, (239+240)Pu and (241)Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.

Mercury in muscle tissue of lesser-spotted dogfish (Scyliorhinus caniculus L.) from the north-east Irish Sea

This paper reports concentrations of mercury in muscle tissue of lesser-spotted dogfish (Scyliorhinus caniculus L.) from various locations within Liverpool Bay and the north-east Irish Sea. Concentrations of mercury in fish muscle showed distinct spatial variation, with values from the northern sectors of the Irish Sea significantly lower than those for the southern area, particularly sites in Liverpool Bay and around the mouth of the Mersey Estuary. The data support the hypothesis that there are several major populations of lesser-spotted dogfish within the study area, each of which remains quite distinct during seasonal movements. Consequently, exposure to environmental mercury is reflected in muscle concentrations of mercury. Regressions of mercury concentration against fish length showed significant relationships for the majority of sites, with the slope relating to distance from known sources of mercury contamination. Mean mercury concentrations were higher than in corresponding populations of flatfish from the same areas.

Spatial patterns in accumulation of mercury by fish from the NE Irish Sea

Abstract This paper reports concentrations of mercury in muscle tissue of three marine species of fish; plaice (Pleuronectes platessa L.), dab (Limanda limanda L.) and lesser-spotted dogfish (Scyliorhinus caniculus L.), at various locations within Liverpool Bay and the North East Irish Sea. Mean concentrations of mercury in fish muscle within any one sampling area followed the order: lesser spotted dogfish⪢dab>plaice. Concentrations in lesser spotted dogfish were 5–10× higher than in flatfish from the same site. Regressions of mercury concentration against fish length showed significant relationships for the majority of species-site combinations, with the slope of the regression relating to distance from the Mersey Estuary.

Mercury in flounder (Platichthys flesus L.) from estuaries and coastal waters of the north-east Irish Sea

This paper reports concentrations of mercury in muscle tissue of flounder (Platichthys flesus L.) from various estuaries and coastal waters of north Wales and north-west England that encompass the north-east Irish Sea. Mercury concentrations were highest within and offshore the Ribble Estuary (0.476 +/- 0.037 mg kg(-1)) but were also high within the Mersey (0.389+/-0.042 mg kg(-1)) and Dee Estuaries (0.295+/-0.065) and at coastal sites in the vicinity. Values for all three estuaries and their near coastal sites were significantly higher than for sites in the north and central sectors of the study area. Regressions of mercury concentration against fish length showed significant relationships and age accumulation for the majority of sites, particularly within or in close proximity to the Mersey, Dee and Ribble Estuaries.

Biological transport of radiocaesium in a semi-natural grassland ecosystem. 1. Soils, vegetation and invertebrates

An unused area of the British Nuclear Fuels plc low level waste disposal site at Drigg in Cumbria, together with a control site in Cheshire, have been used to investigate the behaviour of 137Cs in semi-natural grasslands over the period 1985–1988. Both sites showed significant inputs of 137Cs and 134Cs from the Chernobyl incident in 1986, estimated at up to 7330 Bq/m2 at Drigg and less than 230 Bq/m2 in Cheshire. The total deposit at Drigg was within the range of other observations in the area and could be explained without assuming any input from waste disposal operations on the site. Surface soil horizons showed the highest levels of 137Cs and 134Cs. During the study period, the dominant contribution to radiocaesium in soil and vegetation was from Chernobyl. Significant inter-specific variation in caesium concentrations of grasses was observed with an exponential decrease from June 1986 through to the summer of 1987, followed by a secondary peak in autumn 1987. Samples collected in the spring of 1988 showed 137Cs concentrations approaching pre-Chernobyl levels. Marked inter-specific and temporal differences in concentrations of radio-caesium were recorded for invertebrate populations. Radioactivity levels in herbivorous invertebrates were approximately proportional to levels in their diets with concentrations decreasing from the 1986 summer peak recorded after the input of Chernobyl radioactivity to the low levels observed during the summer of 1987. Herbivorous and predatory invertebrates showed similar concentrations of 137Cs but both groups were lower in radiocaesium than detritivorous species.

Radionuclide transfer to invertebrates and small mammals in a coastal sand dune ecosystem

International intercomparisons of models to assess the impact of ionising radiation on wildlife have identified radionuclide transfer assumptions as a significant source of uncertainty in the modelling process. There is a need to improve the underpinning data sets on radionuclide transfer to reduce this uncertainty, especially for poorly-studied ecosystems such as coastal sand dunes. This paper presents the results of the first published study of radionuclide transfer to invertebrates and small mammals in a coastal sand dune ecosystem. Activity concentrations of (137)Cs, (238)Pu, (239+240)Pu and (241)Am are reported for detritivorous, herbivorous, carnivorous and omnivorous biota. Differences in activity concentrations measured in the sand dune biota are related to the trophic level of the organisms and the influence of sea-to-land transfer is apparent in the food chain transfer observed at the site. There are notable differences in the concentration ratios (CRs) calculated for the sand dune biota compared to other terrestrial ecosystems, especially for the small mammals which have CRs that are two orders of magnitude lower than the generic terrestrial ecosystem CRs published by the recent EC EURATOM ERICA project. The lower CRs at the sand dunes may be due to the influence of other cations from the marine environment (e.g. K and Na) on the net radionuclide transfer observed, but further research is required to test this hypothesis.

Polychlorinated biphenyls in fish and shellfish from the Mersey Estuary and Liverpool Bay

Abstract Muscle tissue of flatfish (dab, sole, flounder and plaice) from the Mersey Estuary and inner Liverpool Bay contain concentrations of ΣPCB(ICES 6) that range from 7.7–43.4 μg kg−1. Using a derived conversion factor of 3.0 for ΣPCB (ICES 6) to ΣPCB(A1254), concentrations of ΣPCB(A1254) in flatfish from the Mersey Estuary and Liverpool Bay range from 23–130 μg kg−1, the latter of which classifies into the ‘upper’ category of contamination as defined by the Joint Monitoring Programme of the Oslo and Paris Commissions. Values of ΣPCB(A1254) in Mersey Estuary flatfish are 1.2–4× higher than data reported for outer Liverpool Bay and the Irish Sea over the last twenty years. ΣPCBs in roundfish (cod, whiting) from the Mersey Estuary are low, though higher than in Liverpool Bay by a factor of up to 3×. Congeners No. 138 and No. 153 contribute much of the ΣPCB in all flatfish, with No. 180 and No. 101 present in significant but lesser amounts. The lighter, less chlorinated congeners No. 28 and No. 52, are absent from roundfish except those from the inner estuary. ΣPCBs in Mersey Estuary fish are 20–200 times higher than for the north-west Atlantic Ocean and the Solway Firth. For some Mersey Estuary fish ΣPCB values exceed national proscriptive limits set by the Environmental Protection Agency for the USA. Caution is advocated regarding the consumption of fish from industrialised estuaries, including the Mersey, though there are no statutory limits for PCBs in fish or fishery products within the European Union.

Polychlorinated biphenyls in small mammals from contaminated landfill sites.

PCBs in small mammals living in a contaminated landfill site varied in both concentration and congener composition, reflecting both the feeding strategy of each species and the chlorination of the congeners. Body concentrations of SigmaPCB on a 1:1:1 Arochlor (1242:1254:1260) basis gave a rank order of Sorex araneus >> Apodemus sylvaticus > Microtus agrestis. Comparisons with data for other PCB-contaminated sites suggest that the SigmaPCB values in S. araneus from the landfill site may be of sufficient magnitude to inhibit reproductive capability and to cause other major organ dysfunction. There were also inter-specific differences in the whole body concentrations of the individually quantified congeners. For S. araneus, the rank order of concentrations of the selected ICES 7 marker PCB congeners was: No. 153>138>>180>118>>28>101>52. In M. agrestis the rank order was: No. 28>118>153>138>180, 52>101. The congener order for A. sylvaticus differed from both S. araneus and M. agrestis, but was more similar to the latter, being: No. 153>138>118>180>28>52, 101. The contribution of the different congeners to SigmaPCB in the mammals reflects the degree of chlorination of different congeners but varies with feeding strategy of the species. In the insectivorous S. araneus, heavily chlorinated congeners (Nos 153, 138 and 180) are most abundant, whereas the herbivore, M. agrestis showed congeners Nos 28 and 118 to be present in the highest amounts, whilst the equivalent pattern for the more omnivorous A. sylvaticus was intermediate between S. araneus and M. agrestis. The high concentrations of PCBs in S. araneus relative to the other species, suggests that it may serve as a useful biomarker of terrestrial environmental pollution by organochlorines.