Résumé
L'étude de la contamination par vioe directe de Salmo gairdneri avec les dérivés du mercure (HgCl2 et CH3HgCl) fait apparaitre, au niveau de l'organisme entier, des tendances sigmoïdes dans l'augmentation des concentrations ou des teneurs du métal, au cours des 30 jours d'observation. La contamination avec le méthylmercure conduit à des valeurs de concentrations et de teneurs, environ 6 fois supériures à celles recontrées avec le chlorure mercurique, après 30 jours d'exposition. Ces évolutions logistiques trouvent leurs explications dans les comportements écotoxicologiques de certains organes, notamment le mucle squelittique et les arcs branchiaux.
A partir des différents comportements enregistrés pour les huit organes ou tissus considérés, nous avons réalisé une synthèse conduisant à quatre types essentiels de la tendance exponentielle à la tendance sigmoïde.
L'étude de la relation ‘vitesse d'accumulation (ΔC/Δt)-concentration tissulaire moyenne‘ a permis de mettre en évidence l'action régulatrice de la concentration dans les processus d'accumulation et de révéler les décalages d'amplitude des phénomńes, traduisant la spécificité des organes et la cinétique de répartition du mercure dans l'organisme.
Pour finir, la notion de bioaccumulation du mercure chez Salmo gairdneri est abordée en prenant en considération les résultats obtenus lors d'expérimentations sur les processus de décontamination après contamination par voie directe.
Summary
The kinetics of mercury accumulation in the whole fish following direct contamination of Salmo gairdneri using two mercury compounds (HgCl2 and CH3HgCl) was characterised by a sigmoid curve. Both the mercury concentrations (Figure 2) and mercury contents (Figure 3, Table I), showed this tendancy. During the 30 day experimental period the weight of the fish did not change significantly (Figure 1). Mercury accumulation in the fish was much greater when methylmercury was used (6 times greater after 30 days exposure).
The sigmoid tendancy in the accumulation of mercury for the whole fish is the result of the ecotoxicological behavior of the different compartments examined. The study of mercury concentrations in the different organs (liver, brain, gills, muscle posterior intestine, kidneys, spleen, and blood) over the experimental period was of interest as it gave an idea of the ‘ecotoxicological risk’ for each organ. These concentrations were higher following contamination with methylmercury (Table II).
The profile described by the mercury contents in the different organs are shown in Figure 4. The influence of exposure period on mercury bioaccumulation shown by sigmoid or exponential curves was apparent. These curves are more or less pronounced according to the organ in question (Table III).
The study of the 16 different profiles obtained allowed the demonstration of 4 main types of curves (Figure 5). These range from the sigmoid profile (type 1) to the exponential one (type 4).
The profile described by the mercury concentrations and contents in the whole fish is better understood following an examination of the ‘relative’ mercury contents in each organ (Table IV). In the case of HgCl2, the muscle and the gills contained no less than 55% of total mercury in the fish. In the case of methylmercury these organs contained 60% of total mercury. Other organs which showed a high mercury accumulation were: the blood, 3 to 12% total mercury content; the liver, 2 to 5%; the kidneys, 2 to 7%. The brain, posterior intestine and spleen only account for 2% of total mercury content.
The phenomena observed during the experimental period were influenced by two processes: the first called ‘cumulative’ characterized by an increase in the rate of mercury accumulation and the second one ‘limitative’, characterised by a progressive showing of mercury accumulation. The first is probably comparable to the second, but they do not occur simultaneously. For example, the case of a transitive phenomenon corresponding to a succession of mercury transfers between the different compartments of the fish.
The concentrations present in the tissues indicating the density of mercury within a specific organ seemed to play an important part in regulating mercury accumulation. As might be expected a relationship between the ‘tissue concentrations’ at 30 days and the ‘accumulation rate’ was observed during the period 20 to 30 days contamination. The high concentrations corresponded to slow accumulation rates (Figure 6).
The position occupied by the liver and kidneys at some distance from the regression line illustrating the relationship between tissue concentrations and inorganic mercury accumulation, at t.30 days (Figure 6), may be explained by the fact that mercury accumulation in these organs reached its maximum at this time. The other organs however showed a decrease or were stationary with regard to mercury accumulation.
As emphasised in the introduction of this article, the concept of bioaccumulation in the fish (for example), corresponds to the superposition of contamination (entry and stocking of mercury in the organism) and decontamination processes (transfer of the contaminant between the different organs or between the fish and the environment). Therefore, the comparative analysis of results obtained during direct contamination and the following decontamination period in Salmo gairdneri should permit a better understanding of bioaccumulation processes.
An analysis of results of this type (Figure 4) using those obtained the decontamination period Ribeyre and Boudou, 1983 — Figure 8) allowed the demonstration of two different types of ecotoxicological behavior:
-
- first those organs showing fast ratio of decontamination (‘donor’ organs) had a sigmoid profile during contamination phase.
-
- secondly, those organs whose mercury content is increased during the decontamination period (‘receivers’ organs) showed an exponential type accumulation curve during contamination.
Examination of the curves for each organ obtained during contamination by both mercury compounds and the decontamination period demonstrated 6 main exotoxicological responses, extending from type 1: organs showing a saturated accumulation curve and a fast decontamination rate to type 6: caracterised by a cumulative accumulation curve and an increase in mercury level during the decontamination phase (Figure 9).
These results are closely related to the method of contamination used (direct). Those obtained during trophic contamination are very different especially in the case of HgCl2, which crosses the intestinal epithelium with difficulty.
Article PDF
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Bibliographie
Boudou, A.: 1982, Thèse d'état N° 748 — Université de Bordeaux I, 297 pp.
Boudou, A. et Ribeyre, F.: 1983, John Wiley and Sons publishers, Chapter 3, pp. 73–116. O. Nriagu (ed.) (13).
Delarche, A. et Ribeyre, F.: 1978, Thèse de 3ème cycle N° 1436 — Université de Bordeaux I, 265 pp.
Giblin, J. F. et Massaro, E. J.: 1973, Toxicology and Applied Pharmacology 24, 81.
Randall, R. J.: 1970, W. S. Hoars et D. J. Randall (éd.), IV, 133–172.
Ribeyre, F. et Boudou, A.: 1981, Environmental Technology Letter 2, 425–432.
Ribeyre, F. et Boudou, A.: 1984, Environmental Pollution A (in press).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ribeyre, F., Boudou, A. Bioaccumulation et repartition tissulaire du mercure — HgCl2 et CH3HGCl — chez Salmo gairdneri apres contamination par voie directe. Water Air Soil Pollut 23, 169–186 (1984). https://doi.org/10.1007/BF00206974
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00206974