M.S. Johnson

Distribution of antimony in contaminated grassland: 1--Vegetation and soils.

Antimony concentrations in surface soils were found to decrease with increasing distance from an antimony smelter. This pattern was also found in moss bags exposed in the same area. At three sites close to the smelter, antimony concentrations in soil and vegetation were much higher than at a rural control site and published background levels. Maximum soil and plant concentrations on a dry weight basis of 1489 mg kg(-1) and 336 mg kg(-1), respectively, were found, compared to background levels of <1 mg kg(-1). Field exposure of grass in pots of uncontaminated soil and a laboratory experiment using soils from near the smelter suggested that the antimony in vegetation was largely due to continued aerial deposition and not to uptake from soil.

Lead, zinc, cadmium and fluoride in small mammals from contaminated grassland established on fluorspar tailings

The total body concentrations of Pb, Cd, and fluoride were higher at the contaminated grassland site established on fluorspar tailings compared to an uncontaminated control site for all three species of small mammal, Apodemus sylvaticus, Microtus agrestis and Sorex araneus. Zn was also higher in M. agrestis and S. araneus but in A. sylvaticus it significantly decreased and, overall, there was good evidence of homeostatic control of Zn in all three species even at the high dietary intakes at the tailings dam. Accumulation in kidney, liver and bone(femur) showed the expected pattern with Pb and fluoride highest in bone and Cd in the kidney for both the control and the contaminated sites. The only exception was S. araneus at the contaminated site were Cd was highest in the liver rather than the kidney. The accumulation of Pb, Cd and fluoride at the contaminated site was in the decreasing species order S. araneus > M. agrestis > A. sylvaticus in terms of total body concentration or target organ concentration. This order probably reflected the decreasing dietary intake rates of the three species although physiological interspecific differences may be of significance. For example, S. araneus showed considerable capability for bioconcentrating Cd to much higher total body than dietary concentrations at the high dietary intake rates at the contaminated site.

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.

Distribution of trace element pollutants in a contaminated grassland ecosystem established on metalliferous fluorspar tailings. 1: lead.

Concentrations of lead in vegetation, invertebrates and small mammals in a grassland ecosystem evolved from a mine waste revegetation scheme indicated the high concentration of lead in the original tailings. Lead levels in invertebrates reflected dietary concentrations and feeding strategy, a pattern also true of the indigenous small mammals. Total body and tissue concentrations of lead in the herbivorous Microtus agrestis L. (field vole) and insectivorous Sorex araneus L. (common shrew) were significantly higher in the contaminated grassland than in an uncontaminated area, but concentration ratios (body:diet) were less than unity and there was no evidence of age-dependent accumulation of lead.

Cadmium in small mammals from grassland established on metalliferous mine waste

Abstract Total body concentrations of cadmium in two small mammal species from a revegetated metalliferous mine site were significantly higher than those from an uncontaminated control site. Total body and tissue concentrations of the herbivorous Microtus agrestis L. and the insectivorous Sorex araneus L. were related to the cadmium concentrations of their estimated diets. The environmental mobility and bioaccumulation potential of cadmium have been demonstrated by the highly elevated cadmium concentrations of soft tissues in S. araneus and its estimated diet at the mine site. The principal target organ for cadmium accumulation was kidney in M. agrestis at both sites and S. araneus at the control site, but the liver adopted this role with the higher body concentrations in S. araneus from the mine site. Possible ecological consequences for animal populations of chronic exposure to elevated environmental levels of cadmium on contaminated sites are discussed.

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. ©

BIOLOGICAL SIGNIFICANCE OF ANTIMONY IN CONTAMINATED GRASSLAND

Highly elevated levels of Sb occurred in grassland soils near the only British Sb smelter. This soil Sb was found largely in immobile forms. Antimony in plant shoots was derived almost exclusively from the atmosphere with little from the soil. Elevated organ concentrations occurred in wild mammalian herbivores but were low compared to their estimated dietary concentrations. In short-term laboratory feeding experiments with Sb2O3, this low accumulation rate was confirmed in mice and voles and although elevated organ concentrations occurred they were not obviously harmful. Thus Sb in these smelter grasslands would seem to have low mobility but at present there is insufficient evidence to be confident in this assessment.

Distribution of antimony in contaminated grassland: 2— small mammals and invertebrates

Concentrations of antimony in invertebrates and small mammals from grasslands in the vicinity of an antimony smelter were significantly elevated compared to a control site. Higher concentrations of antimony were recorded in liver, lung and kidney tissue of herbivorous and insectivorous mammals from the contaminated sites. However, there is little evidence of bioaccumulation of antimony in food chains represented by the soil-vegetation-invertebrate-insectivore pathway of the grasslands, and little indication of significant accumulation by herbivorous mammals despite marked contamination of their diet.

Fluoride accumulation and toxicity in wild small mammals

Populations of two species of small mammal, the field vole (Microtus agrestis L.) and the bank vole (Clethrionomys glareolus L.), inhabiting grasslands contaminated by industrial sources of fluoride were examined for fluoride concentrations in skeletal tissue and for morphological changes in the teeth. Concentrations of fluoride in teeth and bones were higher for C. glareolus than for M. agrestis at the chemical works and smelter sites. Severe dental lesions were recorded on the incisor and molar teeth of both species at the chemical works and smelter sites, with less marked damage at the mine tailings dam. This is attributed to inter-site differences in fluoride speciation and the consequent effects on the availability of fluoride in the diet for bioassimilation.

Radionuclide behaviour and transport in a coniferous woodland ecosystem:vegetation, invertebrates and wood mice, Apodemus sylvaticus

Activity concentrations of radionuclides (134Cs, 137Cs, 238Pu, 239 + 240Pu and 241Am) were measured in vegetation, invertebrates and wood mice, Apodemus sylvaticus, collected in Lady Wood, a coniferous woodland in the vicinity of the British Nuclear Fuels reprocessing plant at Sellafield, Cumbria, UK. Vegetation was of low diversity and biomass with activity concentrations ranging from 1 to 5 Bq kg-1 (134Cs), 0.3-0.5 Bq kg-1 (238Pu), 0.8-8 Bq kg-1 (239 + 240Pu), and 0.6-16 Bq kg-1 (241Am), dry wt. Caesium-137 activity concentrations were high compared to the reference site in Cheshire, varying between 65 and 280 Bq kg-1. Marked inter-specific and temporal differences in radionuclide activity concentrations were recorded for invertebrate populations. Caesium-137, 238Pu, 239 + 240Pu and 241Am activity concentrations in detritivorous invertebrates were consistently higher than in all other invertebrate groups reflecting contamination of the leaf litter. The activity concentrations in detritivores increased during the autumn and winter, reflecting changes in diet as food sources varied throughout the year. Activity concentrations in invertebrates caught in Lady Wood were generally an order of magnitude higher than for the reference site. Activity concentrations in wood mice varied between 7 and 150 Bq kg-1 (137Cs), 0.1-0.3 Bq kg-1 (238Pu), 0.1-0.6 Bq kg-1 (239 + 240Pu) and 0.2-0.4 Bq kg-1 (241Am). There were clear differences in the activity concentration of 137Cs (P < 0.01), 239 + 240Pu (P < 0.05) and 241Am (P < 0.05) in animals caught in Lady Wood compared to the reference site. However, the activity concentrations for 238Pu were similar at both sites, reflecting a low gastrointestinal transfer. Seasonal variation in activity concentrations was observed for 137Cs, 238Pu and 241Am. This variation is attributed to changes in the age structure of the population and diet throughout the year.