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  • 1
    Electronic Resource
    Electronic Resource
    Comparative study of the trophic transfer of two mercury compounds—HgCl2 and CH3HgCl—BetweenChlorella vulgaris andDaphnia magna. Influence of temperature (1981)
    Springer
    Bulletin of environmental contamination and toxicology 27 (1981), S. 624-629 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Conclusion If we try to transfer these experimental results to phenomena which occur in the natural environment the phytoplanktonic biomasses, which have a high turnover rate during periods of growth, would show a very considerable facility to accumulate mercury, since the capacity to accumulate is similar for both compounds. But the first trophic transfers between these producers and the herbivores (Zooplankton for example) would show a marked inbalance in accumulation levels, in favour of methylmercury. However, in this study we must take into consideration the very great diversity of biocoenoses and the interspecific differences which can manifest themselves with regard to processes of bioaccumulation and transfer. There is, moreover, continuous competition between the inert particles in suspension and the living organisms to absorb the mercury compounds which are in a free state in the aquatic environment. According to HAVLIK & al. (1979), certain phytoplanktonic species have a tendency to transform the bioaccumulated organic compounds: in this case the eff icacity of the transfer processes would depend on the extent to which the phenomenon occurs and the speed with which it begins. With the results we have so far collected it is possible to suppose that the large quantities of the methylated form of mercury to be found in the terminal aquatic consumers — especially carnivorous fish II or III — can be accounted for by the mechanisms of bioaccumulation and transfer of the mercury compounds at the lower end of the trophic chains. At this stage in our research we are interested in knowing how transfers between the primary consumer level and the secondary consumer lever occur. Is it the same process as that observed between the first two links in the chain, or is it slightly modified ? By using our experimental trophic chain —Chlorella vulgaris→Daphnia magna→Salmo gairdneri(newlyhatched) we should be able to answer this question, provided that it proves possible to quantify the transfer and bioaccumulation processes according to the two contamination routes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01611073
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  • 2
    Electronic Resource
    Electronic Resource
    Bioaccumulation and bioamplification of mercury compounds in a second level consumer,Gambusia affinis-temperature effects (1979)
    Springer
    Bulletin of environmental contamination and toxicology 22 (1979), S. 813-818 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Conclusion These results underline the importance of setting up experimental models in ecotoxicology. The use of trophic chains, in conditions that are perfectly controlled and quantified, makes it possible to determine, from a fundamental and applied point of view, the mechanisms responsible for the contamination of natural systems. Nonetheless, such models should be progressively complexified in order to approach the conditions found “in situ”. We are pursuing our research at the moment on two higher trophic levels, represented by a second level carnivore Salmo gairdneri and a terrestrial mammal at the end of the chain, Rattus norvegicus. The ecotoxicological effects on the level “trout” are being investigated through research on the tissular distribution of the contaminant and modifications caused to the liver (optic and electronic microscopies, quantitative enzyme and protein analysis) and blood (circulating proteins and enzymes). Using the rat as terminal consumer enables us to simulate the trophic position of man and to measure precisely the degree of contamination in conditions close to those found in the natural environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02027030
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature and pH effects on cadmium and methylmercury bioaccumulation by nymphs of the burrowing mayfly Hexagenia rigida, from water column or sediment source (1996)
    Springer
    Archives of environmental contamination and toxicology 31 (1996), S. 339-349 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract An experimental approach, based on a complete experimental design, was set up in order to carry out a comparative analysis of cadmium (Cd) and methylmercury (MeHg) bioaccumulation in the burrowing mayfly nymphs of Hexagenia rigida (Ephemeridae) after 15 days' exposure to water column or sediment compartment as initial contamination sources. Combinations of two modalities of temperature—15 and 25°C— and pH—5.0 and 7.5—enabled us to quantify the actions of these two abiotic factors and also their interactions on the metal bioaccumulation. Whatever the initial contamination source, a high level of metal bioaccumulation was observed after exposure to MeHg; Cd transfers, on the other hand, were very low. For similar theoretical exposure conditions, differences between the bioaccumulation capacities of the two metals were between 20 and 30, in favor of MeHg. Multiple regression did not reveal significant interactions between MeHg and Cd towards their bioaccumulation in the nymphs. When the microcosms were contaminated via the sediment source, increasing the temperature from 15 to 25°C led to an increase in MeHg bioaccumulation and a decrease of Cd bioaccumulation. After exposure from the water source, no significant amounts of Cd were measured in the nymphs at 25°C even though significant metal concentrations were observed at 15°C. pH had no significant effect on the bioaccumulation processes when the two metals were initially added to the sediment compartment; acidification of the overlying water, however, gave rise to a decrease in MeHg and Cd concentrations in the nymphs, with marked interactions with temperature. The results are discussed from the data available on metal partitioning in the biotopes and their bioavailability, uptake routes and also the structural and functional properties of the biological barriers involved (gills, gut wall).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212672
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature and pH Effects on Cadmium and Methylmercury Bioaccumulation by Nymphs of the Burrowing Mayfly Hexagenia rigida, from Water Column or Sediment Source (1996)
    Springer
    Archives of environmental contamination and toxicology 31 (1996), S. 339-349 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. An experimental approach, based on a complete experimental design, was set up in order to carry out a comparative analysis of cadmium (Cd) and methylmercury (MeHg) bioaccumulation in the burrowing mayfly nymphs of Hexagenia rigida (Ephemeridae) after 15 days' exposure to water column or sediment compartment as initial contamination sources. Combinations of two modalities of temperature—15 and 25°C— and pH—5.0 and 7.5—enabled us to quantify the actions of these two abiotic factors and also their interactions on the metal bioaccumulation. Whatever the initial contamination source, a high level of metal bioaccumulation was observed after exposure to MeHg; Cd transfers, on the other hand, were very low. For similar theoretical exposure conditions, differences between the bioaccumulation capacities of the two metals were between 20 and 30, in favor of MeHg. Multiple regression did not reveal significant interactions between MeHg and Cd towards their bioaccumulation in the nymphs. When the microcosms were contaminated via the sediment source, increasing the temperature from 15 to 25°C led to an increase in MeHg bioaccumulation and a decrease of Cd bioaccumulation. After exposure from the water source, no significant amounts of Cd were measured in the nymphs at 25°C even though significant metal concentrations were observed at 15°C. pH had no significant effect on the bioaccumulation processes when the two metals were initially added to the sediment compartment; acidification of the overlying water, however, gave rise to a decrease in MeHg and Cd concentrations in the nymphs, with marked interactions with temperature. The results are discussed from the data available on metal partitioning in the biotopes and their bioavailability, uptake routes and also the structural and functional properties of the biological barriers involved (gills, gut wall).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900117
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  • 5
    Electronic Resource
    Electronic Resource
    Comparative Experimental Study of Cadmium and Methylmercury Trophic Transfers Between the Asiatic Clam Corbicula fluminea and the Crayfish Astacus astacus (2000)
    Springer
    Archives of environmental contamination and toxicology 38 (2000), S. 317-326 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Cadmium (Cd) and methylmercury (MeHg) trophic transfers were analyzed between the Asiatic clam Corbicula fluminea and the crayfish Astacus astacus. Metal bioaccumulation in crayfish was quantified after 5, 10, and 15 days of exposure via daily ingestion of soft bodies of C. fluminea, previously exposed during 7 days to Cd (20 μg · L−1) and MeHg (4 μg · L−1). Bioaccumulation kinetics in the predator were investigated at organ and tissue levels: hemolymph, tail muscle, hepatopancreas, gills, stomach/mesenteron, intestine, green gland, carapace. Trophic transfer rates were estimated at the whole organism level. Results showed marked differences (1) in assimilation efficiencies, mean transfer rates being 5% for Cd and 16% for MeHg; and (2) in the metal distribution within the different tissue compartments of the crayfish: for Cd, the trophic uptake leads to high concentrations in the hepatopancreas and small accumulation in the muscle tissue; for MeHg, the highest levels of bioaccumulation occur in the green gland and in the tail muscle. From an ecotoxicological point of view, these experimental data suggest a small risk of Cd transfer between the crayfish and predators, humans included; on the other hand, Hg distribution in the muscle and accumulation trends in this tissue represent an obvious risk of transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449910042
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Temperature and Exposure Duration on Transfer of Cadmium Between Naturally Contaminated Sediments and Burrowing Mayfly Nymphs (Hexagenia rigida) (1998)
    Springer
    Archives of environmental contamination and toxicology 35 (1998), S. 295-301 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Burrowing mayfly nymphs (Hexagenia rigida) were exposed to naturally contaminated sediments collected from two stations along a metallic pollution gradient on the Lot River (France) using indoor microcosms. Bioaccumulation kinetics (0, 20, 40, and 60 days) of cadmium (Cd) and the combined effects of temperature (12, 18, and 24°C) were evaluated by a complete experimental design, jointly with the analysis of growth rate of the nymphs, bioturbation, and total and dissolved Cd concentrations in the water column. Cadmium was transferred from the sediment to the organisms with uptake influenced by contamination levels of the sediments, exposure duration, and temperature. The two complementary criteria—Cd concentration and burden in the nymphs—clearly demonstrate the importance of the growth dilution on the quantification of Cd bioaccumulation at the whole organism level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900379
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  • 7
    Electronic Resource
    Electronic Resource
    Cadmium Uptake by Corbicula fluminea and Dreissena polymorpha: Effects of pH and Temperature (2000)
    Springer
    Bulletin of environmental contamination and toxicology 65 (2000), S. 638-645 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0012800171
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  • 8
    Electronic Resource
    Electronic Resource
    Temperature, pH and photoperiod effects on mercury bioaccumulation by nymphs of the burrowing mayflyHexagenia rigida (1995)
    Springer
    Water, air & soil pollution 80 (1995), S. 1003-1006 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Accumulation of HgCl2 and CH3HgCl byHexagenia rigida nymphs from contaminated sediment and water column was investigated experimentally, taking into account 3 abiotic factors (temperature, pH and photoperiod). When the contamination of the experimental units was based on sediment compartment, Hg concentrations at the whole organism level revealed very high bioaccumulation differences between the two chemical forms of Hg (ratio close to 20 in favour of MeHg). When Hg compounds were added to the water column, the highest Hg accumulation rates were observed for MeHg, but with a small difference between the 2 compounds (ratio close to 2.0–3.0). These bioaccumulation processes were very dependent on the 3 abiotic factors taken into account, especially temperature and water column pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01189754
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  • 9
    Electronic Resource
    Electronic Resource
    Mercury accumulation in delphinidae (1991)
    Springer
    Water, air & soil pollution 56 (1991), S. 187-201 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The aim of this work is an attempt to synthetize the different results of our researches on dolphin's contamination by Hg and their interpretation. It is based on the results obtained following the total Hg determination in several organs of 35 specimens of Stenella coeruleoalba stranded on French Atlantic and Mediterranean coasts and 45 Stenella attenuata captured in the Eastern tropical Pacific. Considering our present knowledge on Hg ecotoxicological processes, the trophic route, via cumulative Hg transfers through the marine trophic network, can be considered as the major contamination route for the dolphins. However, considering the influence of the geographical origin of the individuals it also seems reasonable to assume that the principal contamination source of the high Hg concentrations observed in pelagic dolphins are natural metal deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342271
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  • 10
    Electronic Resource
    Electronic Resource
    Fundamental roles of biological barriers in mercury accumulation and transfer in freshwater ecosystems (analysis at organism, organ, cell and molecular levels) (1991)
    Springer
    Water, air & soil pollution 56 (1991), S. 807-821 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In the framework of an ecotoxicological approach to the processes of bioaccumulation and transfer of Hg in freshwater systems, we present a synthesis of our experimental studies concerning the interactions between inorganic Hg and MeHg and biological barriers - at organism and organ levels : three biological models are selected: fish (Salmo gairdneri), burrowing mayfly nymphs (Hexagenia rigida) and rooted macrophytes (Elodea densa, Ludwigia natans). Results show strong specificities of the biological barriers (gills, intestine, roots, ...) towards metal fixation and absorption, closely related to the chemical form of the metal, the contamination sources (water, sediments or food) and the physico-chemical characteristics of the medium ; - at cell and molecular levels : biophysical study of Hg fixation on membrane reveals a new binding site on the phospholipids, the primary amine group on serine and ethanolamine polar heads, jointly with the SH groups of proteins ; Hg(II) induces a strong rigidification of the phospholipidic bilayers. Inorganic Hg and MeHg transports through model membranes (BLM) are essentially due to diffusion of neutral chloride species. These interactions between Hg compounds and membranes are strongly dependent on Hg chemical speciation (pH and pCl effects).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00342318
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