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J Garnier-Laplace

Publications and source records attributed to J Garnier-Laplace.

10 recordsLinked to original sources
PubMed2006

Effects of chronic internal alpha irradiation on physiology, growth and reproductive success of Daphnia magna.

Daphnids were chronically exposed to waterborne Am-241, an alpha-emitting radionuclide, ranging in concentration from 0.4 to 40 Bq ml(-1). Am-241 amounts were monitored in the medium, daphnid tissues and cuticles. Corresponding average dose rates of 0.02, 0.11 and 0.99 mGy h(-1) were calculated for whole organisms with internal alpha-radiation contributing 99% of total dose rates. Effects of internal alpha irradiation on respiration and ingestion rates, adult, egg and neonate individual dry masses, fecundity and larval resistance to starvation were examined in 23-day experiments. Daphnids showed increased respiratory demand after 23 days at the highest dose rate, suggesting increased metabolic cost of maintenance due to coping with alpha radiological stress. Although no effect was detected on ingestion rates between contaminated and control daphnids, exposure to dose rates of 0.11 mGy h(-1) or higher, resulted in a significant 15% reduction in body mass. Fecundity remained unchanged over the 23-day period, but individual masses of eggs and neonates were significantly smaller compared to the control. This suggested that increased metabolic expenditure in chronically alpha-radiated daphnids came at the expense of their energy investment per offspring. As a consequence, neonates showed significantly reduced resistance to starvation at every dose rate compared to the control. Our observations are discussed in comparison with literature results reported for cadmium, a chemical toxicant which affects feeding activity and strongly reduces individual energy uptake.

Age Factors↗
PubMed2006

Modeling radiological dose in non-human species: principles, computerization, and application.

Due to the increasing interest in environmental protection against ionizing radiation on the international scene, the need for operational tools for radiological environmental risk assessment is becoming critical. Within this framework, this paper puts forward a fast and user-friendly computerized method to allow the transformation from exposure (expressed in Bq per unit of mass or volume) to dose (i.e., the energy deposited in the organism, expressed in Gy) received from any radionuclide by any non-human species, for a unit of time and a unit of "concentration" of radionuclide in the radiation source. The calculation principles used to determine this dose coefficient, expressed in Gy/unit of time per Bq/unit of volume or mass, are described for gamma, beta, and alpha radiation. Both internal and external exposure situations are considered. The domain of validity of the proposed model is specified, as is the way in which it has been computerized. The paper concludes by verifying the numerical accuracy of the tool and making initial comparisons between results from the described method and those developed at the European level.

Algorithms↗
PubMed2002

Effects of Cd and Zn waterborne exposure on the uptake and depuration of 57Co, 110mAg and 134Cs by the Asiatic clam (Corbicula fluminea) and the zebra mussel (Dreissena polymorpha)--whole organism study.

Groups of zebra mussels (Dreissena polymorpha) and asiatic clams (Corbicula fluminea) were exposed to cadmium and zinc with the aim of studying the effect of these metals on the 57Co, 110Ag and 134Cs uptake and depuration by these freshwater bivalves. In the presence of zinc, the 57Co concentration factor for the whole organism of the two species was halved, notably because of a decrease of the uptake parameter. Conversely, Zinc and the Cd + Zn mixture increased the 110mAg uptake process by clams and mussels. The two metals also increased the depuration of this radionuclide in mussels, whereas this phenomenon was only observed in clams exposed to cadmium. In comparison with 57Co and 110mAg, the 134Cs bioconcentration was 5-10 times lower in D. polymorpha and not detected in C. fluminea. This weak contamination by this radionuclide resulted from a lower uptake and a higher depuration parameters.

Animals↗
PubMed2002

CASTEAUR: a simple tool to assess the transfer of radionuclides in waterways.

The CASTEAUR project proposes a simplified tool to assess the transfer of radionuclides between and in the main biotic and abiotic components of the freshwater ecosystem. Applied to phenomenological modeling, various hypotheses simplify the transfer equations, which, when programmed under Excel, can be readily dispatched and used. CASTEAUR can be used as an assessment tool for impact studies of accidental release as well as "routine" release. This code is currently being tested on the Rhone River, downstream from a nuclear reprocessing plant. The first results are reported to illustrate the possibilities offered by CASTEAUR.

Algorithms↗
PubMed2000

Experimental kinetic rates of food-chain and waterborne radionuclide transfer to freshwater fish: a basis for the construction of fish contamination charts.

A standardized procedure is proposed to obtain from laboratory experiments the kinetic accumulation and release rates necessary to calibrate dynamic models to quantify radionuclide direct and trophic transfer in fish. The model takes into account the food-chain effect, the feeding rate, and the growth of organisms. It takes as examples (54)Mn, (60)Co, and (137)Cs transfer dynamics through a simple pelagic food-chain (phytoplankton, zooplankton, prey fish, and predator fish). The estimated kinetic rates used in quantifying all the transfers of the three radioactive pollutants through the pelagic food chain are compared from the radioecological point of view. For fish, comparison was based on the calculation of concentration factors referring to direct transfer from water and trophic transfer factors. For the prey fish and the predator fish, direct transfer gave the following order for accumulation (60)Co < (137)Cs < (54)Mn. Values reached at equilibrium in L/kg WW were respectively for the prey fish and the predator fish: 8.7 < 27.4 < 107 and 4.14 < 6.59 < 13.4. For the trophic route, (137)Cs is the most accumulated (TTF(eq) = 0.485 in 291 days for the prey fish and TTF(eq) = 1.45 in 17 years for the predator fish). A sensitivity analysis adapted to the case of a chronic contamination scenario of a watercourse was run. It showed that the phytoplankton biomass, the contact time of these drifting particles from a release point to the station where they are ingested and the feeding rates of the fish are the most influential parameter with regard to the concentration in fish, whatever the trophic level. Contamination charts are constructed for the predator fish to illustrate the relationship between the most influential ecological parameters and the radionuclide concentration in fish for simple contamination scenarios. They are shown to be effective tools for helping in the choice of the most relevant value of aggregated concentration factors (ACFs: radionuclide concentration ratio between the organism and the water, referred to steady-state and to all possible transfer pathways) for a given key ecological situation in a given ecosystem. An example is given of a simple chronic release scenario of 1 Bq/L and a phytoplanktonic bloom period. For (137)Cs, the ACF increases with increasing contact time and increasing feeding rate, to nearly 550 L/kg WW at equilibrium. For (54)Mn, ACF reaches 65 L/kg WW. For (60)Co, the general pattern of the relationship is due to the rapid kinetic rates governing the distribution of the radionuclide between dissolved and solid (phytoplankton) phases with a maximum value for ACF of 7.2 L/kg WW for the case study. Analysis of these charts provides a basis for overall guidelines for chronic releases in a given watercourse.

Animals↗
PubMed1997

60Co transfer from water to the rainbow trout (Oncorhynchus mikiss Walbaum).

60Co uptake from natural water, release and tissue distribution were investigated in the rainbow trout (Oncorhynchus mikiss), which is representative of the third order consumers of the freshwater trophic chains. The experiments were carried out on two groups of fingerling trout placed in 0.45 microm filtered river water, maintained at 12 +/- 0.5 degrees C, contaminated with about 30 Bq ml-1 of 60Co and renewed three times a week. After a 8-week exposure phase, the fish of one group were dissected to determine the contamination of the tissues and organs and the distribution of the accumulated 60Co. The fish of the other group were placed in non-contaminated water, renewed daily, to monitor radionuclide release. After a 42-day depuration phase, the specimens were dissected to study the tissue distribution of the residual 60Co.60Co accumulation from water by trout can be described by a one-compartment exponential model. The concentration factor, calculated from the ratio of the radionuclide concentration in filtered water and in the fish, reached a maximum value of 4.6 (w.w.) after 30 days exposure. After the 42-day depuration phase, the fish retained about 29% of the accumulated radionuclide. A single-compartment exponential model was fitted to the 60Co elimination data, and the corresponding radionuclide half-life was 21 days. At the end of the exposure phase, tissue contamination study showed 60Co accumulation by the gills, viscera (air bladder, heart and spleen) and kidneys, to be the highest. At the end of the depuration phase, the kidney was the most contaminated organ, followed by the viscera, head, gills, and liver. In both cases, 60Co concentration was by far the lowest in the muscle, which accounted for about 45% of the total body weight and only 20% of the total radionuclide body load.

Animals↗
PubMed1997

Uptake from water, release and tissue distribution of 54Mn in the Rainbow trout (Oncorhynchus mikiss Walbaum).

As part of a research programme on the transfer of several radionuclides along a pelagic trophic chain, two groups of 12 trout were kept for 8 weeks in water contaminated with 30 Bq ml(-1) of (54)Mn. In order to simulate chronic contamination and limit alterations in the physical and chemical characteristics of the medium, the water was renewed every 2 days. The kinetics of the accumulation and elimination of the radionuclide were monitored in one group of fish. The second group was used to study the contamination of the main organs and tissues at the end of the accumulation phase. The dynamics of contamination can be described by a bi-compartmental model, taking into account the fluctuations in the concentration of (54)Mn in the water, as well as the biological dilution resulting from the growth of the fish. The theoretical value of the steady-state concentration factor for zero growth is 13 (w.w.) and the radionuclide release is characterised by two biological half-lives of 6 and 97 days. At the end of the accumulation phase, the (54)Mn is preferentially fixed in the bone, gills, skin and brain. The data obtained at the end of the depuration phase allow one to classify the organs in two groups with different elimination kinetics. The first group consists of organs of penetration or transit, such as the skin, gills, kidneys, liver, primary and secondary gut and viscera, whereas the second group is made up of the receptor and storage organs and tissues such as the bone, head, fins and muscle.

Journal Article↗
PubMedDate not supplied

Biomarker responses in juvenile rainbow trout (Oncorhynchus mykiss) after single and combined exposure to low doses of cadmium, zinc, PCB77 and 17beta-oestradiol.

The objective of this study was to examine (i) the biochemical responses of rainbow trout exposed to sublethal water concentrations of the metals cadmium (Cd) (1.5 microg l(-1)) and zinc (Zn) (150 microg l(-1)); and (ii) the potential combined effects when applied in mixture (Cd/Zn) with and without co-exposure to model organic chemicals 3,3',4,4'-tetrachlorobiphenyl (PCB77) (1 mg kg (-1)) and 17beta-oestradiol (E2) (0.5 mg kg(-1)). After 21 days of exposure, several biomarkers were assessed in the liver (enzymatic and nonenzymatic antioxidants, heat shock proteins [HSP70 and HSP60], ethoxyresorufin-O-deethylase [EROD]) and in the plasma (vitellogenin [Vtg], aminotransferases). Plasma aminotransferases were not affected, whereas the other biomarkers showed different patterns of response depending on the treatment. For example, Cd, and Zn to a lesser extent, induced an adaptive response in the liver shown by an increase in antioxidant defences (total glutathione [GSH], superoxide dismutase, Trolox equivalent antioxidant capacity [TEAC]), without any impairment of GSH redox status or induction of heat shock proteins. Antagonistic effects were observed in GSH-related biomarkers after Cd/Zn exposure. PCB77 strongly induced EROD activity, HSP70 and TEAC. Co-exposure with metals did not modulate significantly the effects of PCB77. E2 induced Vtg and inhibited liver antioxidants and basal EROD activity. These inhibitory effects were suppressed in fishes exposed to E2 + Cd/Zn, suggesting additive effects of E2 and metals. In addition, E2-induced Vtg was not altered by metals. Multivariate analyses confirmed some correlation between the biomarkers. The use of complementary biomarkers is necessary to discriminate different treatments and to highlight interactive effects.

Adaptation, Physiological↗