Accumulation de quelques metaux lourds (Cd,Cu, Pb et Zn) chez l'eperlan (Osmerus mordax) preleve sur la rive Nord de l'Estuaire du Saint-LaurentHeavy metal accumulation (Cd,Cu, Pb and Zn) by smelt (Osmerus mordax) from the North shore of the St Lawrence estuary

Heavy metals in trace amounts are normal constituents of marine organisms. At sufficiently high concentrations, heavy metals are toxic to living organisms and so it is important to know by how much their concentration may be increased before effects on marine or estuarine populations can be detected or commercial species become unsuitable as food. A method of removing metals is by storage in a particular tissue. Several different sites for storing metals were investigated and concentrations of Cd, Cu, Pb and Zn were examined in muscle, liver and gonads of the smelt (Osmerus mordax) from the North shore of the St Lawrence estuary. Copper and zinc are constituents of several enzymes and are absolutely essential for normal growth and development, while cadmium and lead are not known to have necessary physiological function. A modified wet digestion procedure was used to prepare biological samples for the determination of trace elements by flameless atomic absorption spectrophotometry procedure, using calibration standards made up in a matrix of similar acidity (Table 1). NBS reference material bovine liver was analyzed along with the samples and the results were within the specified tolerance (Table 2). Analyses were reported on a dry weight basis (Table 3) and the correlations with total body weight were determined by regression analysis. Copper (range 0.3–3.3 μg g^?1) and zinc (range 19–38 μg g^?1) in muscle fillets were found to be negatively correlated with total body weight (Fig. 1). Apparent decreasing concentrations in these two metal levels in muscle sample with increasing body weight were possibly due to factor such as dilution with growth. Growth may dilute metal concentrations in an organism if tissue is added faster than metal. Livers and gonads contained greater levels of the four metals than somatic muscle. Liver metal concentrations of Zn (range 29–108 μg g^?1) and Cd (range 0.06–0.37 μg g^?1) increased with total body weight. All equations fit data at P < 0.01 (Fig. 2). Positive correlations between size and metal concentrations suggest that net uptake may occur. Inessential, slowly exchanging metals such as Cd appear to reflect an uptake which tend to become a cumulative process (age dependence of concentrations). The occurrence of insignificant correlation between liver concentrations of Cu (mean value: 4 μg g^?1) and environmental concentrations of this metal was consistent with equilibration. Since fish are known to possess the metal binding protein metallothionein, a sequestering agent, detoxification of these metals in fish liver may be by sequestration rather than elimination. Increasing metal concentrations in liver may represent storage of sequestered products in that organ. In the gonads, no significant relationship exists between total body weight and trace metal contents. Results of t-test indicated that females had significantly greater Cu and Zn concentrations, but no significant difference existed between males and females for Cd concentrations (Figs 3 and 4). Thus, the relation between concentration and total body weight appears to be specific as to the species, tissues analyzed and environmental conditions. The comparison of metal concentrations in fish to assess variations in contamination levels requires understanding the relationship between metal concentration and body size within each population.     

Capteur de resine chelatante pour le prelevement la preconcentration et la determination de metaux traces toxiques (Zn, Cd, Hg, Pb) dans les eaux

The subject of this article is the elaboration of a catcher of toxic metals (Zn, Cd, Hg, Pb) which enables them to be determined at μg 1⁻¹ level.It is known that, at these low concentrations, it is advisable to prevent the sample from being altered in any way between the time of taking and the time of analysis; moreover, it is necessary to proceed, on the one hand, to the pre-concentration of the wanted elements and, on the other hand, to the elimination of the main elements present in water and likely to interfere at the time of analytical determination.We therefore made a catcher which makes it possible to achieve these two desired effects by chromatographic separation and to carry out the conditioning of the sample, in the field, in a well-defined, chemical form, stable in time as a small volume in a solid state, easy to carry and to store.The catcher is in the shape of a small, cylindrical capsule (diameter = 29 mm, thickness = 10 mm) in Makrolon (Lexan) whose bases are made of a nylon cloth and which contains a chelating resin load (Chelex-100, 100–200 mesh).At the time of use, the catcher is put into a dismountable filtering-apparatus which permits percolation of the solution containing the wanted metal traces.Then, to proceed to the analytical determination of the elements it is possible to use two methods: analysis in solution after elution;X-ray fluorescence spectrometry, or else activation analysis on the catcher dried and then pelletized when hot in an hydraulic press.The experimentation has included the following points:

1. 1. Determination of the conditions of chromatographic separation on Chelex-100 resin which permits optimal fixation of Zn, Cd, Hg and Pb and the elution of the main elements Ca, Mg and Fe. We chose soda-citrate medium 7.1 · 10⁻² M at pH = 7.00;

2. 2. Determination of the conditions of use of the catcher and its efficiency according to the main elements in the sample of water.

The process we chose involves a sample of 1 l. of water which is acidified at pH 1 by concentrated HNO₃ and then filtered through a membrane (0.45 μm).The solid residue is examined by X-ray fluorescence spectrometry.To the filtrate are added 100 ml of soda-citrate buffer 7.1 · 10⁻¹ M and the pH is set to seven by addition of NaOH. Then the filtrate is percolated through the Chelex-100 resin catcher (flux = 1.5 ml min⁻¹).Then, it is possible to proceed: either to the elution of toxic metals by HNO₂ 2M to determine them in solution (atomic absorption spectrophotometry, anodic stripping voltammetry); or to pelletizing of the catcher and to the analytical determination by X-ray fluorescence spectromy or activation analysis.The results of these methods are compared with different water: (1) spring warer: (2) over waters and (3) sea-water. The elution method as well as direct analysis of the pelletized catcher gave satisfactory agreement.     

Etude du transfert de Cd, Pb, Cu et Zn dans les chaines trophiques neritiques et estuariennes—II. Accumulation biologique chez les poissons planctonophages

Plankton-feeder fish and their preys (mainly Copepods and Mysids) were obtained from the Loire estuary (France). Trace elements (Cd, Pb, Cu, Zn) concentrations in organisms from different steps in the food chain were compared using the transfer factor:It is generally lower than 1 for Cd, Pb and Cu but often higher than 1 for Zn. Before interpreting this last data as a consequence of biomagnification of Zn in food chain, we have to emphasize that the level of Zn in the predator, used for the calculation of f.t., results of accumulation from both food and water.During the digestion, we often observed a light decrease of metal concentrations between prey and stomach content followed by an increase of the metal levels in intestine content compared to stomach.     

Etude du transfert DE Cd, Pb, Cu ET Zn dans les chaines trophiques neritiques et estuariennes—I. Etat dans l'estuaire interne de la loire (France) au cours de l'ete 1978

In order to determine the behaviour of some trace elements (Cd, Pb, Cu, Zn) in estuarine biota, different species of crustaceans and fishes were taken up from the Loire estuary. The concentrations of metals were determined by atomic absorption.Except for Zn, the accumulation of metals is higher in crustaceans than in fishes and the phenomenon is particularly important for copper, a constituent of crustaceans respiratory pigment. The concentrations of metals are no more important for bottom-feeders than for other fishes. The highest levels are encountered for Zn followed by Cu, Pb and Cd. The Loire organisms are not so contaminated than those of the same species taken up from heavily polluted estuaries (Severn and Medway, G.-B.).Transfers in food chains were quantified with the transfer factor: f.t. = Concentration in the consumer/Concentration in the prey.For Cd, Pb and Cu, the transfer factor is generally inferior to 1, attaining exceptionally 2.01. Except in one case, it is higher than 1 for Zn. The concentration of trace elements in intestine content is higher than in stomach content, probably as a consequence of faeces enrichment by unassimilated metals. So, there is probably no biomagnification in estuarine food chain for Cd, Pb and Cu, the case of Zn being more ambiguous.     

Etude de la retention du 65Zn absorbe par voie trophique chez Cyprinus carpio L. influence du rythme d'ingestion et de la teneur en radiozinc de la nourriture

Published results on the relative contribution of food and water in the accumulation of ⁶⁵Zn by freshwater fish are contradictory and it is observed that the retention rate of radiozinc absorbed from food varies over a wide range (from 5 to 70%) depending on the authors (Chipman et al., 1958; Nakatani and Liu, 1964; Pentreath, 1973, 1975; Berg and Brazzelli, 1975; Merlini et al., 1976; Baudin, 1981). The present paper aims to highlight the variability of the retention rate of the radionuclide absorbed from contaminated food.Two experiments were carried out using the soft tissue of previously contaminated lymnaea as food. The first experiment was conducted over a 9 week period on three groups of carp, each receiving food of identical composition, the only difference concerning the splitting up of the weekly food intake. The second experiment was carried out over a 40 day period on a group of 15 carps which received 26 daily meals (Table I).In the first experiment, the pattern of contamination is similar in the three cases, but the carps in groups A and B were more contaminated than those in group C (Table 2, Fig. 1). The same observations apply to the trophic transfer factor (Fig. 2). These differences are explained by a lower retention of ⁶⁵Zn absorbed with each of the 9 weekly food intakes for the carps in group C than for those in groups A and B (Table 3). The global rate of retention of radiozinc develops in accordance with an exponential model (Fig. 3), reaching maximum value of approx. 14% (group C) to 25% (groups A and B). The similarity of the results for groups A and B can be explained by the fact that the difference in the distribution frequency of the food constituting the weekly intake (2 and 4 days) is insufficient to bring about a significant difference in either the transit rate or the digestibility of the food (Grayton and Bremish, 1977; Luquet et al., 1981; Hudon and De la Noue, 1984). In the case of group C, the lower value of the global retention rate can be explained by an incomplete absorption of the nutriments due to a faster food transit rate in the digestive tract (Possompes et al., 1975; Hudon and De la Noue, 1984).In the second experiment, correlatively with the strong contamination of the ingested food, an increased accumulation of ⁶⁵Zn is observed in the carp. However, contrary to what was observed in the first experiment, the global rate of retention decreases as a function of time (Table 5). The differences which can be observed between the results of the two experiments do not only concern the level but also the development of the parameters. Thus, for the concentration (Fig. 4a) and the trophic transfer factor (Fig. 4b) the evolution corresponds to power functions, but the slope of the curves indicates that the kinetics are different. This is the consequence of the conflicting evolution of the retention rate ⁶⁵Zn by the carp in the two experiments (Fig. 4c). The homeostatic regulation of zinc, proposed by Berg and Brazzelli (1975), cannot justify the observed difference in retention of ⁶⁵Zn. The hypothesis concerning the influence of the nature of the food proposed by several authors (Pentreath, 1975; Berg and Brazzelli, 1975; Merlini et al., 1976) can hardly explain such differences. According to an analysis of results obtained during several experiments (Table 6), it can be also hypothesized that the rate of retention of radiozinc by the carp is inversely proportional to the quantity of radionuclide absorbed with the food, due to a slow turnover of zinc.The faeces are a very important pathway of the radionuclide excretion (Table 4). This fact agrees with high radioactivity levels measured in the digestive tract of fish contaminated from water or placed in decontamination for several days or weeks (Hibiya and Oguri, 1961; Joyner, 1962; Pentreath, 1975; Aprosi, 1978; Suzuki et al., 1979; Baudin, 1977, 1981).     

Influence de sediments argileux incorpores au milieu d'insemination sur le succes de la fecondation chez la truite arc-en-ciel (Salmo Gairdneri)

The aim of this paper is to determine whether clay sediments suspended in water can prevent trout eggs from being fertilized. Kaolinite-rich clays (granulometric fraction: <2μm) (Fig. 1) were suspended in an artificial insemination diluent in doses ranging between 0 and 20 g l⁻¹. The eggs were exposed for 1, 10 or 20 min (experiment A) or inseminated (experiment B) in the diluent-sediment mixture. In experiment (C), the eggs were exposed to this mixture at three different temperatures (10, 15, 20°C). After insemination, the eggs were incubated for 10 days at 10°C and the percentage of eyed-eggs was used as an approximation of the fertility rate. The presence of clay sediments in the medium in which artificial insemination was carried out did not affect fertilization rate after the ovules had been exposed during 1 min to clay suspensions, at any of the temperatures used (8°C: Fig. 3; 10–15 or 20°C: Fig. 5) or at any of the sperm dilution rates (10⁻², 10⁻³, 10⁻⁴) (Fig. 3). On the contrary, there was a significant decline (P < 0.01) in the fertilization rate after the eggs had been exposed for 10 min at 8°C to doses of sediment exceeding 1.2 g l⁻¹ (Fig. 2). The fertilization rate also decreased significantly (P < 0.05) when the dose of sediment in the medium increased after 20 min at 20°C and 40 min at 15°C (Fig. 4). The 15 and 20°C temperatures were unfavourable for the eggs anyway. It is probable that fertility decreased due to micropyle clogging when the eggs were exposed longer than 10 min to the sediments. It is concluded that presence of sediments in the medium in which the gametes meet does not prevent fertilization.     

Application de la spectrometrie d'absorption atomique zeeman aux dosages de huit elements traces (Ag, Cd, Cr, Cu, Mn, Ni, Pb et Se) dans des matrices biologiques solides

The use of biological indicators in studies of aquatic pollution (in fresh, estuarine or sea waters), as well as research about the metal transfers in food chains, need a great accuracy of the trace element determination. Therefore, as shown by the results of international intercalibration exercises, the mastery of analytical techniques is far from being perfect in all the laboratories.One of the main sources of error in atomic absorption results from non-specific absorptions due to the presence of important organic and mineral matrixes in biological materials and especially in aquatic and marine organisms. In this case, the correction of unspecific absorption by using deuterium lamp was insufficient and the determination of trace elements had to be preceded by a pre-instrumental stage which allowed the elimination of the organic matter by mineralization and of a large part of the mineral matrix by extraction. The previous separation was long and induced contamination risks. The use of the Zeeman effect background correction allows the transfer of most processes from the pre-instrumental to the instrumental stage. Moreover, the Zeeman effect has three advantages: (1) the background correction is effective up to 2 units of absorbance; (2) the correction is effective from 190 to 900 nm; (3) the method of the double beam is optimalized.The aim of this study was to apply the Zeeman effect to the determination of eight trace elements (Ag, Cd, Cr, Cu, Mn, Ni, Pb, Se) in three different biological solid samples, two originated from the marine environment (lobster hepatopancreas TORT-1, standard reference material from the National Research Council Canada; oyster tissues SRM 1566 from the US National Bureau of Standards) and one from the vegetable kingdom (tomato leaves, SRM 1573 from the US NBS).The experimental procedure is reduced to a minimum since it consists in the digestion of an aliquot of 100 mg of the powdered sample with 1 ml of concentrated nitric acid at 95°C for 1 h. Then the volume is adjusted to 4 ml with deionized water. The metal analysis is carried out using a graphite furnace coated with tantalum carbide.This analysis is achieved according to the method of standard addition. The three added concentrations used for each element are listed in Table 1. The analytical conditions and graphite atomizer program are indicated in Table 2. The temperature program has to be modified according to the type of equipment.The internal quality control of the suggested method related to four criteria: sensitivity, repeatability, accuracy, practicability. The results are shown in Table 3. The threshold of sensitivity (3 times the SD of a series of eight results obtained for a blank of digestion) are low: < 1 μg kg⁻¹ for Ag, Cd and Mn; 1 μg kg⁻¹ for Cr and Pb; 5 μg kg⁻¹ for Cu and Ni and 15 μg kg⁻¹ for Se. The variation coefficients, calculated for both two series of six determinations each, are generally included between 5 and 10%. The trace element concentrations determined by using this method are in perfect agreement with the certified values of the US NBS and NRC Canada (Table 3.)The quality of the results establishes the possibility of using a very easy and fast method to determine the level of eight trace elements in materials with high mineral and organic matter content.     

Influence de la duree d'exposition sur la bioaccumulation par voie directe de deux derives du mercure par Salmo gairdneri (alevins) et relation “poids des organismes-concentration en mercure”

In the context of ecotoxicological research on the contamination of continental aquatic systems by mercury compounds, the analysis of bioaccumulation at different consumer levels (especially fish) shows that the weight of the organism affects the concentration factors measured. However, after a bibliographic synthesis it is not possible to define precisely what this effect might be, since published results show either an absence of any relationship, or a positive or negative correlation, depending on the authors and on the conditions of intoxication.Our research is based on the direct contamination of newly hatched rainbow trout (weight when time factor = zero : 0.20 g); concentration of mercury in the water was 1 μg l⁻¹ (1 ± 0.1 ppb for the duration of the experiment). Two compounds were studied : HgCl₂ and CH₃HgCl. By using automated contamination modules we were able to maintain constant biotic conditions (number of fish per tank) and abiotic conditions (temperature: 15 ± 0.5°C; photoperiod; 16h/8h; concentration of Hg in the water) for the two contaminants.An analysis of the mercury bioaccumulated was carried out after 15, 30, 60 and 83 days of exposure. For each experimental condition—e.g. HgCl₂, 15 days—25 fish were kept at time factor zero. The mercury concentration was determined by flameless atomic absorption spectrophotometry (VARIAN AA 475). A polynomial regression method, with or without transgeneration of the dependent variable, was used in order to demonstrate a possible relationship between the “weight of organism” and “concentration of mercury” parameters.A comparison of the development in weight of the organisms in all the different populations contaminated by HgCl₂ and CH₃HgCl (Fig. 1) shows that this is identical up to 30 days. Between 30 and 83 days it may be seen that methylmercury has a very strong influence on this parameter which is coupled with a reduction in food intake and a considerable increase in mortality.The dynamics of the average mercury content—μg per organism—and the corresponding concentrations (μg g⁻¹ fresh weight) over the 83 days exposure period (Fig. 2) show that the mercury content and concentration in the fish are much higher for methylmercury than for mercuric chloride and this does not depend on the length of exposure period, e.g. at 60 days the ratio between CH₃HgCl and HgCl₂ concentrations is about 7.Although the concentration of the two contaminants in the environment was kept constant (1 ppb), the curves representing mercury accumulation—expressed as a concentration—are not linear and show a fairly pronounced plateau.The relationship between “organism weight” and “concentration of mercury” was studied for both two mercury compounds during each experimental exposure period (Figs 3 and 4).The noticeable grouping of points corresponding to each population studied indicates a relationship between the weight and concentration parameters; in both contaminants the concentration factor develops in relation with the exposure period. Although it is rather simple and approximate, the linear model displays quite satisfactorily the phenomenon we are studying and its development (Table 1). However a logarithmic relationship gives a better adjustment of the results.Analysis of the results shows:A negative correlation between the weight of the organisms and their mercury concentration for both compounds. This correlation decreased as the exposure period increased. In the case of HgCl₂, after 83 days exposure, the weight no longer seemed to have an influence on the amounts of metal bioaccumulated by the fish.A difference between the adjusted straight lines for HgCl₂ and CH₃HgCl, the organism weight has a greater influence on concentration in the case of contamination by the organic compound.Observations conducted in a natural environment usually show a positive relationship between concentration and the weight of the organisms. When compared with these, our experimental results cannot be said to be contradictory since they deal with different biotic conditions: contamination methods, growth rate and age of individuals.An assessment of the level of contamination in aquatic ecosystems is usually based on an estimation of concentration levels found in the organisms, and, especially for fish, in the skeletal muscles. Our results however, show the necessity of taking organism weight into consideration; the influence of this parameter on the processes of bioaccumulation is particularly important in the case of mercury contamination in the newly hatched stage, and probably in other species with a rapid growth rate. In the case of experimental research into these processes influence of organism weight is considerable and therefore necessitates its examination especially when the object of the study is the development of a standardised toxicological test.     

Influence sur la survie jusqu'a eclosion des embryons de carpe commune (cyprinus carpio l.) apres traitement, pendant la fecondation et le developpement precoce, par le carbendazime, un fongicide antimitotique de synthese

The toxicity of the systemic antimitotic fungicide carbendazim, a benzimidazol compound, was studied both by trout and common carp insemination, as well as on the early development of the common carp.The toxicity is several grades of magnitude higher for these stages of the vital cycle compared with the effect on the adult stages: whereas The Pesticide Manual states that for the adult Carp, an LC₁₀₀ (24 h) > 1000 mg 1⁻¹ we find, during insemination at pH 9: LC₁₀₀ (30 min) < 5 mg l⁻¹ and during insemination at pH 7: LC₁₀₀ (30 min) <2.5 min l⁻¹.During early development we find, for instance, LC₁₀₀ (30 min) < 5 mg 1⁻¹ before the end of activation and LC₁₀₀ (24 h) < 1 mg l⁻¹ before the end of epiboly.In the course of insemination, the egg is more sensitive to carbendazim at pH 7 than at pH 9: this difference may be attributed to a greater solubility of the non ionic form of the molecule in the biological membranes.The resistance of the embryo to short treatment grows at the end of activation. This may be attributed to the decrease of the shell permeability during activation.Before the end of activation, the resistance to short intoxication seems to be able to fluctuate, which perhaps corresponds to the existence of sensitive stages in the mitotic cycle.The resistance to an over 24-h exposure increases abruptly at the end of epiboly, which could correspond to a protective part played by the enveloping layer.We suggest the possibility of classifying aquatic pollutants by correlating their physiological mode of action to the resistance profile of the fish embryo.The carp egg seems to be a favourable biological model for studying the effects of aquatic pollutants.     

Quantification,identification et propriétés physiques des sédiments de la retenue du barrage Sidi Saad (centre de la Tunisie)

Silting of impounding Sidi Saâd lake seriously threatens the reservoir. The total watershed is 8 650 km² practically devoid of vegetal cover. The erodable formation extends on about 300 000 ha. The rate of silting increases during exceptional hydrological years from 2,24 hm³ to 3,54 hm³. Superficial sampling, sediment cores in the lake and drawing off material are collected for gain size analysis, mineralogy and geotechnical studies. The gamma-density curves of sediment cores reveal the presence of several deposit sequences. The latter are attributed to the turbidity sequences of Bouma type with a predominance of a, b, d and e divisions. However, the superficial sampling shows a granular sorting from the alluvial fans to the dam. This sorting is confirmed by a geotechnical study (water content, plasticity, density, cohesion, etc.). The mineralogical composition shows a detritic origin from the erodible formation in the watershed. The laboratory consolidation tests on mixtures of different solid charges show five stages of deposition. The consolidation speed depends on the initial charge of the mixture and on the drainage conditions. The increase of the sediments cohesion along the time flow follows an exponential law.     

The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)

Fresh floodplain deposits (FD), from 11 key stations, covering the Seine mainstem and its major tributaries (Yonne, Marne and Oise Rivers), were sampled from 1994 to 2000. Background levels for Cd, Cu, Hg, Pb, and Zn were established using prehistoric FD and actual bed sediments collected in small forested sub-basins in the most upstream part of the basin. Throughout the Seine River Basin, FD contain elevated concentrations of Cd, Cu, Hg, Pb and Zn compared to local background values (by factors>twofold). In the Seine River Basin, trace element concentrations display substantial downstream increases as a result of increasing population densities, particularly from Greater Paris (10 million inhabitants), and reach their maxima at the river mouth (Poses). These elevated levels make the Seine one of the most heavily impacted rivers in the world. On the other hand, floodplain-associated trace element levels have declined over the past 7 years. This mirrors results from contemporaneous suspended sediment surveys at the river mouth for the 1984-1999 period. Most of these temporal declines appear to reflect reductions in industrial and domestic solid wastes discharged from the main Parisian sewage plant (Seine Aval).     

Assessment and biomonitoring of aquatic pollution by heavy metals (Cd,Cr, Cu,Pb and Zn) in Hammam Grouz Dam of Mila (Algeria)

Concentrations of Cd, Cr, Cu, Pb and Zn were determined in water, sediment and tissues of fish (Cyprinus carpio and Barbus setivimensis) from November 2014 to August 2015, in order to estimate the aquatic pollution in Hammam Grouz dam, by the technique of atomic absorption spectrophotometry. The concentrations of heavy metals in the water and sediment were higher than the WHO standards. The calculation of Bioconcentration factor showed that all fish species studied have accumulated heavy metals in their tissues (gill, liver, muscle and kidney). The concentrations of metals in B. setivimensis were higher than those in C. carpio. The highest concentration of heavy metals was recorded in the gill while the lowest was recorded in the muscle and kidney. Our study reveals that these fish species can be used as bioindicators in the biomonitoring of metallic pollution in aquatic ecosystem.     

Geochemical signals and source contributions to heavy metal (Cd, Zn, Pb, Cu) fluxes into the Gironde Estuary via its major tributaries

Daily measurements of water discharges and suspended particulate matter (SPM) concentrations and monthly sampling for trace element analyses (Cd, Zn, Pb and Cu) were conducted from 1999 to 2002 on the Garonne, Dordogne and Isle Rivers, the three main tributaries of the Gironde Estuary, France. Dissolved and particulate Cd, Zn, Pb and Cu concentrations in the Isle River were generally higher than those in the Garonne River, despite the known historical polymetallic pollution affecting the Lot-Garonne River system. Even if the relatively high dissolved metal concentrations in the Isle River may be of importance for the local ecosystem, metal inputs into the estuarine and coastal zones are mainly controlled by fluvial transport via the Garonne River. Characteristic element concentration ratios (e.g., Zn/Pb) in SPM and stream sediments from the Dordogne and Isle Rivers suggest two different metal source areas with distinct geochemical signals. Low Zn/Pb ratios (<8) and low Cu/Pb ratios (<0.8) have been attributed to upstream source zones in the Massif Central, featuring various ore deposits and mining areas. High Zn/Pb ratios were assigned to downstream sources (e.g., vineyards), partly explaining high Zn and Cu concentrations and high Cu/Pb ratios (>0.8) in SPM. Although SPM derived from the upstream parts of the studied watersheds may greatly contribute to the observed fluvial metal transport (up to approximately 80% for Pb), the results suggest that intensive agriculture also considerably influences gross metal (e.g., Zn, Cu) fluxes into the Gironde Estuary. Relative contributions of upstream and downstream source zones may vary from one year to another reflecting hydrological variations and/or reservoir management. Monitoring fluxes and identifying distinct geochemical signals from source areas in heterogeneous watersheds may greatly improve understanding of contaminant transport to the coast.     

Temporal trends of Cd, Cu, Hg, Pb and Zn in mussel (Mytilus galloprovincialis) from the Spanish North-Atlantic coast 1991-1999

Temporal trends for heavy metals (Cd, Cu, Hg, Pb and Zn) in mussel (Mytilus galloprovincialis) from the Galician and Cantabrian areas in Spain, where samples were yearly collected from 1991 to 1999, are presented. This study was carried out by the Centro Oceanográfico de Vigo of the Instituto Espa?ol de Oceanografia (I.E.O.) as part of the Spanish contribution to the Joint Assessment and Monitoring Programme (JAMP) of the OSPAR Convention. The experimental work and subsequent statistical treatment, following OSPAR procedures and guidelines, are described. In order to carry out the statistical treatment of the data, median values of the different shell length classes were used for each contaminant, year and area. The Kendall T-b correlation coefficient was used with the purpose of demonstrating the existence of a downward significant temporal trend in the pollution levels, according to the advice of ICES Working Group on Statistical Aspects of Environmental Monitoring. A decrease of copper levels was detected in Vigo, Pontevedra and Arosa, of mercury in Pontevedra and A Coru?a, of lead in Vigo, Pontevedra, A Coru?a and Bilbao and of zinc in Pontevedra and A Coru?a. However, a cadmium positive trend was registered at Ria de Vigo. No significant trends were detected in the other cases.     

Sub-cellular partitioning of Zn, Cu, Cd and Pb in the digestive gland of native Octopus vulgaris exposed to different metal concentrations (Portugal)

Concentrations of Zn, Cu, Cd and Pb and their sub-cellular distributions were determined in composite samples of digestive glands of the common octopus, Octopus vulgaris caught from two areas of the Portuguese coast characterised by contrasting metal contamination. Minor contents of Zn (1%), Cu (2%), Cd (6%) and Pb (7%) were found in the insoluble fraction, consisting of nuclei, mitochondria, lysosomes and microsome operationally separated from the whole digestive gland through a sequential centrifugation. A tendency for linear relationships between metal concentrations in nuclei, mitochondria, lysosomes and whole digestive gland was observed. These relationships suggest that despite low metal content organelles responded to the increasing accumulated metals, which means that detoxifying mechanism in cytosol was incomplete. Poorer correlations between microsome and whole digestive gland did not point to metal toxicity in the analysed compartments. However, the high accumulated Cd indicated that O. vulgaris is an important vehicle of this element to its predators in the coastal environment.     

Metal concentrations (As, Cd, Cu, Pb and Zn) in shorthorn sculpins, Myoxocephalus scorpius (Linnaeus), and Arctic char, Salvelinus alpinus (Linnaeus), from the vicinity of Strathcona Sound, Northwest Territories

Concentrations of arsenic, cadmium, copper, lead and zinc were determined in muscle and liver tissues from shorthorn sculpins and landlocked Arctic char collected in the vicinity of Strathcona Sound, N.W.T., prior to industrial activity. The concentration of arsenic in both muscle and liver tissues from shorthorn sculpins displayed a positive correlation to body weight over the entire size range, and substantially exceeded the maximum recommended level for arsenic in marine animal products established by the Canadian Food and Drug Directorate. The concentrations of the other four elements were either not correlated to body weight or else the data were non-linear. No correlation between the metal concentrations and body weight was found in Arctic char.