Sellafield waste radionuclides in Irish sea intertidal and salt marsh sediments

Low level liquid radioactive waste discharges from the Sellafield nuclear fuel reprocessing plant in north west England had generated environmental inventories of about 3 × 10¹⁶ Bq of¹³⁷Cs, 6.8 × 10¹⁴ Bq of^239,240Pu and 8.9 × 10¹⁴ Bq of²⁴¹Am by 1990. Most of the^239,240Pu and²⁴¹Am and about 10% of the¹³⁷Cs has been retained in a deposit of fine marine sediment close to the discharge point. The quantities of radionuclides discharged annually from Sellafield decreased by two orders of magnitude from the mid-1970s to 1990 but estimated critical group internal and external exposure decreased by less than one order of magnitude over this period. This indicates that during the period of reduced discharges, radionuclides already in the environment from previous releases continued to contribute to the critical group exposure and highlights the need to understand processes controlling the environmental distribution of the radionuclides. Redistribution of the contaminated marine sediment is potentially of major significance in this context, in particular if it results in transport of radionuclides to intertidal areas, where contact with the human population is relatively likely. A review is presented of published work relating to Sellafield waste radionuclides in Irish Sea sediments. Data on temporal and spatial trends in radionuclide concentrations and activity ratios are collated from a number of sources to show that the dominant mechanism of radionuclide supply to intertidal areas is by redistribution of the contaminated marine sediment. The implications of this mechanism of supply for trends in critical group radiation exposure are considered.     

Cap-and-trade, taxes, and distributional conflict

Enacting market-based environmental regulation, such as emissions taxes and cap-and-trade programs, often create rents that are contested by agents. In this paper, we create a framework that compares social welfare from alternative market-based environmental policy instruments under the presence of rent seeking. We show that, contrary to the commonly held view, non-revenue-raising instruments (NRRIs) are in many cases preferable over revenue-raising instruments (RRIs). We find that the choice of instrument depends on the size of a potential revenue-recycling effect and the level of preassigned rents.     

Distribution and behaviour of radiocaesium in Scottish freshwater loch sediments

The distribution and behaviour of radiocaesium have been studied in the sediments of two contrasting freshwater lochs: Round Loch of Glenhead, an acidified loch in south-west Scotland, with organic-rich sediments (≈20%C) and Loch Lomond, 35 km north-west of Glasgow, where sediments are low in organic matter (1–6%C, southern basin), but with a relatively high clay content. In the sediments of Scottish freshwater lochs,¹³⁷Cs [half life (t_1/2) = 30.23 yr] originates from fallout from nuclear weapons’ testing (1950s and 1960s) and from the Chernobyl reactor accident in 1986, which is also the source of the shorter-lived¹³⁴Cs [half life (t_1/2) = 2.05 yr]. Use of the characteristic¹³⁴Cs/¹³⁷Cs activity ratio of radiocaesium emitted from Chernobyl enables resolution of sedimentary radiocaesium profiles into the two component sources. In the organic-rich sediment of Round Loch, downward diffusion of radiocaesium in porewaters obscures its pattern of input to the loch. In the more clay-rich sediments of Loch Lomond, separate radiocaesium concentration peaks, related to atmospheric deposition maxima, are clearly discernible, although an influence of partial mixing is apparent. While the derived Chernobyl fallout inventory of radiocaesium in Round Loch sediments is broadly comparable with that for Loch Lomond, the corresponding weapons testing inventory is an order of magnitude lower than in Loch Lomond. Although Round Loch is situated in an area of known elevated Chernobyl deposition, the inventory is much lower than literature values of atmospheric deposition, indicating significant loss of radiocaesium from this loch. The weapons testing inventory in Round Loch is also lower than reported estimates, whereas in Loch Lomond the established inventories from both sources are similar to, or greater than, fallout deposition. The differences between the distribution and inventories in the two lakes confirms that radiocaesium is much less efficiently bound and is correspondingly much more mobile in the organic sediments of Round Loch of Glenhead than in the more clay-rich sediments of Loch Lomond.     

Effect of grinding and heating on Ni2+ uptake properties of waste paper sludge

Uptake properties of Ni2+ were examined for unmilled and milled paper sludge calcined at various temperatures to develop a new usage of waste paper sludge. Since paper sludge mainly consists of cellulose ([C6H(10)O5]n) fibers, calcite (CaCO3), kaolinite (Al2Si2O5(OH)4) and talc (Mg3Si(4)O(10)(OH)2), amorphous and crystalline CaO(MgO)-Al(2)O(3)-SiO(2) compounds are formed by calcining paper sludge. Wet and dry milling treatments were performed to accelerate solid-state reaction to form the above mentioned target compounds. The crystalline phases originally present decompose at increasing calcining temperature (up to 800 degrees C) in the order cellulose 相似文献   

Levels of intra-host and temporal sequence variation in a large <Emphasis Type="Italic">CO</Emphasis>1 sub-units from <Emphasis Type="Italic">Anisakis simplex sensu stricto</Emphasis> (Rudolphi 1809) (Nematoda: Anisakisdae): implications for fisheries management

This paper is the first to address the suitability and potential of the cytochrome oxidase-1 (CO1) region of the parasitic marine nematode Anisakis simplex sensu stricto as a genetic marker. A. simplex s.s. is an ubiquitous parasite of many marine organisms and has been used as a ‘biological tag’ for population studies of pelagic fish stocks. The CO1 marker informs not only about nematode population structure but also about its hosts. The large CO1 sub-unit (∼800 bp) was analysed from third stage larvae of A. simplex s.s. from Atlantic herring, Clupea harengus L. caught off the north-west coast of Scotland. In total 161 A. simplex s.s. CO1 sequences were analysed from 37 herring that represented three spawning periods over 2 years. Overall very high haplotype and low nucleotide diversities were observed (h = 0.997 and π = 0.008, respectively). These results are in keeping with studies investigating parasitic nematodes of ungulates and are symptomatic of the high rate of substitutions accumulated by mtDNA and effective dispersal strategies of the parasite. The Tamura-Nei I + Г (Г = 1.2243) model of nucleotide substitution best suited the present data which were dominated by a high thymine bias and associated transitions. Large within population differences were highlighted by hierarchal AMOVAs with little variation related to spawning events or years which may indicate localised temporal stability. Temporal homogeneity in the CO1 gene coupled with the ubiquitous and widespread nature of the parasite indicates both the potential and limitations for its incorporation in stock-separation studies of its hosts. This work was carried out at the School of Biological Sciences, Liverpool University, Crown Street, Liverpool. L69 7ZB, UK.     

Eiseniella tetraedra (Savigny, 1826) (Oligochaeta: Lumbricidae) as a bioindicator of heavy metals

The objective of this study was to assess the potential of the earthworm Eiseniella tetraedra (Savigny, 1826) as a bioindicator for cadmium (Cd) and lead (Pb) exposure. The importance of earthworms in metal pollution monitoring is widely recognized in terrestrial ecosystems. In this study, the levels of Cd and Pb in soils and earthworm tissues were studied at two locations, Polur Falls and a riverside area located in Abali, in the Elburz Mountains in Iran. At both locations the concentration of Cd and Pb in earthworms was higher than in the surrounding soils and a significant difference was found between the two stations, the latter probably attributable to the (1) amount of pesticides that are used for crop treatment in Abali and (2) presence there of clay, which is known to be rich in Cd. Data indicate that E. tetraedra is an efficient bioaccumulator of Cd and Pb and might act thus serve as a bioindicator of exposure.     

Scottish peat bog records of atmospheric vanadium deposition over the past 150 years: comparison with other records and emission trends

Cores from four Scottish ombrotrophic peat bogs were used to reconstruct the historical record of atmospheric vanadium (V) deposition in Scotland over the last 150 years. The general similarity of V and Pb concentration profile trends in (210)Pb-dated cores from each of the sites strongly suggested that V, like Pb, is essentially immobile in ombrotrophic peat. After allowance via use of the conservative element Ti for the contribution of soil dust V, the deposition of anthropogenic V was found to be greatest (～ 1.3 to 2.0 mg m(-2) y(-1)) in the mid-20(th) century before decreasing to 0.1-0.3 mg m(-2) y(-1) in the early years of the 21(st) century. The latter values were in good agreement with directly measured atmospheric V fluxes at nearby sites, a finding also observed in the case of Pb. The decline in peat-core-derived fluxes for both V and Pb from 1970 to 2004, however, was not as large as the decline in official UK emission estimates for the two metals during this period. This, along with an order of magnitude discrepancy between the anthropogenic V/Pb ratios at the peat core surface and the higher values of the ratio for UK emissions in the early 2000s, suggests that the recently revised UK emissions data for V may perhaps still be overestimated and/or that some previously deposited Pb is being resuspended in the atmosphere.     

A comparison of antimony and lead profiles over the past 2500 years in Flanders Moss ombrotrophic peat bog, Scotland

Two cores collected in 2001 and 2004 from Flanders Moss ombrotrophic peat bog in central Scotland were dated (14C, 210Pb) and analysed (ICP-OES, ICP-MS) to derive and compare the historical atmospheric deposition records of Sb and Pb over the past 2500 years. After correction, via Sc, for contributions from soil dust, depositional fluxes of Sb and Pb peaked from ca. 1920-1960 A.D., with >95% of the anthropogenic inventories deposited post-1800 A.D. Over the past two centuries, trends in Sb and Pb deposition have been broadly similar, with fluctuations in the anthropogenic Sb/Pb ratio reflecting temporal variations in the relative input from emission sources such as the mining and smelting of Pb ores (in which Sb is commonly present, as at Leadhills/Wanlockhead in southern Scotland), combustion of coal (for which the Sb/Pb ratio is approximately an order of magnitude greater than in Pb ores) and exhaust emissions (Pb from leaded petrol) and abrasion products from the brake linings (Sb from heat-resistant Sb compounds) of automobiles. The influence of leaded petrol has been most noticeable in recent decades, firstly through the resultant minima in Sb/Pb and 206Pb/207Pb ratios (the latter arising from the use of less radiogenic Australian Pb in alkylPb additives) and then, during its phasing out and the adoption of unleaded petrol, complete by 2000 A.D., the subsequent increase in both Sb/Pb and 206Pb/207Pb ratios. The extent of the 20th century maximum anthropogenic enrichment of Sb and Pb, relative to the natural Sc-normalised levels of the Upper Continental Crust, was similar at approximately 50- to 100-fold. Prior to 1800 A.D., the influence of metallurgical activities on Sb and Pb concentrations in the peat cores during both the Mediaeval and Roman/pre-Roman periods was discernible, small Sb and Pb peaks during the latter appearing attributable, on the basis of Pb isotopic composition, to the mining/smelting of Pb ores indigenous to Britain.