[Annual distribution of bacterial indicators generated by the domestic wastes from the landfill of Etueffont (France)]. / Distribution annuelle de bacteries indicatrices au niveau de la decharge d'ordures menageres d'Etueffont (France).

We assessed over 15 months the distribution of total coliforms concentrations of Escherichia coli, Enterococci, Pseudomonas aeruginosa, Salmonella and Staphylococcus aureus in three monitoring points in the Etueffont landfill (Belfort, France). We selected the piezometer (PZ30) which is located downstream from the dump and two leachate collectors from the old dump and the new casing. The results showed that the leachate was free from both Salmonella and Staphylococcus aureus. The absence of Salmonella was most likely due to the small occupation of the landfill environment by vertebrates, especially rodents, birds and reptiles, which are known to be principal vectors of Salmonella. S. aureu, is generally hosted on skins and mucus of animals. The mean densities of E. coli and Enterococcus in the leachates were low. In contrast, P. aeruginosa abundance was high and closely related to precipitations. Coliform bacteria concentrations in the leachate averaged UFC.100 CFU x ml(-1). In the contaminated groundwaters, the coliforms, E. coli and Enterococci were always present at concentrations 10 to 100 fold higher than those reported from septic tank effluents. P. aeruginosa concentrations were low (mean: 11 CFU.100 ml(-1)) and inferior to those quoted in the leachate. This may be explained by the anoxic conditions which prevailed in the shistous aquifer. The absence of Salmonella in groundwaters may be due to its sensitivity to disinfectants and that of S. aureus linked to the fact that it is not a common host of the human intestine. Finally, our study clearly indicates the role played by E. coli and Enterococci as biomarkers of recent faecal contamination.

Coupling of abiotic and biotic parameters to evaluate performance of combining natural lagooning and use of two sand filters in the treatment of landfill leachates.

A study in the Etueffont landfill, located in Belfort (France), was conducted to evaluate the performance of combining natural lagooning and use of two sand filters for treating leachates through the coupling estimation of several abiotic and biotic parameters. Two gravel filters were installed in the upstream of the first basin which communicates with the remaing 2, 3 and 4 basins. The distribution of physical-chemical (T, pH, Eh, EC, O2, SM, SO4(2-), Cl-, Zn, Fe, Mg, Ni, Al, As, Ba, Cu, Sn, Zn, BOD, COD, KN, NH4+, NO2+ ,TP, AOX: absorbable organic halides, VFA: volatile fatty acids, and atrazine) and biological (bacteria, protozoa, phytoplankton) parameters was assessed in the leachate entering in basin 1, and downstream of the filters. The results showed slight variations in the physical-chemical composition of the leachate between 1999 and 2000, most likely ascribed to the maturation of the landfill but a very significant removal of SM (suspended matter) by the sand filters. This, applied to the majority of the studied parameters. Thus, the sand filter treatment of the leachates combined with natural lagooning was efficient in the improvement of water clarification.

Coupling of the biochemical composition and calorific content of zooplankters with the Microcystis aeruginosa proliferation in a highly eutrophic reservoir.

The impact of the Cyanobacteria Microcystis aeruginosa on zooplankton dynamics was studied in the hypertrophic Villerest Reservoir (France). Samples were collected and their biochemical composition and calorific content examined. Three most abundant zooplankton species in the reservoir were considered: the cladoceran Daphnia longispina and the copepods Cyclops vicinus and Eudiaptomus gracilis. The three species were differently affected by the Microcystis aeruginosa blooms. Daphnia longispina did not seem to suffer from the proliferation of the M. acruginosa, although its biomass decreased concomitantly to the bloom. This collapse would be attributable to the lack of nutritional value of algae. Cyclops vicinus seemed to move away when Microcystis invaded the superficial layers of the reservoir. Because this zooplankter had migratory abilities, it reached the littoral zone where food was available. The energetic costs linked to this migration were clearly pointed out when the species recovered the pelagial zone in early fall. The behaviour of Eudiaptomus gracilis was not clear. This species underwent diapause as M. aeruginosa proliferated. This suggests that Eudiaptomnus gracilis moved away from the pelagial zone over the cyanobacterial blooms. In most cases, the cyanobacterial toxins affected the growth of zooplankton and the potential to use herbivorous zooplankton as a means to combat Microcystis proliferation in the Villerest reservoir seems limited.

The bacteria in the sediment of the Sahela reservoir (Morocco): potential impacts on phosphorus budget.

Temporal variations of phosphorus concentrations, bacterial abundance and activity of fractionated (i.e: size fractions: 0.22 to 0.65 microm; 0.65 to 100 microm and 0.22 to 100 microm) alkaline phosphatase (APA) were studied in situ in a benthic chamber placed in a station near urban inputs in the Sahela reservoir (Morocco) on September and October 98. Results show that low oxygen concentrations induced enhanced concentrations of orthophosphates, and bacterial numbers and APA activity reached their highest values. Anoxic conditions and the decrease of pH favour the dissolution of particulate phosphorus and the release of soluble reactive phosphorus. This release is accompanied simultaneously by an increase in the abundance of anaerobic bacteria and a progressive reduction in APA. Lastly, the release of phosphorus together with urban inputs from the city of Taounate should be considered as potential inducers of the eutrophication of the reservoir.

[Contribution of several physico-chemical tracers to the study of groundwater contamination by landfill leachates]. / Apport de certains traceurs physico-chimiques a l'étude de la contamination des eaux sosuterraines par les lixiviats de décharges.

This work deals with the estimation of the water content of several physico-chemical parameters in a landfill (Etueffont, Belfort, France), and their impact on the quality of the underground water. Samples were collected monthly from May 1998 to May 1999 with a vertical bottle, from the output of the landfill and from eight wells. The results showed high concentrations of most parameters in the well PZ30 and PZ3, situated near the landfill. The spatio-temporal distribution of the physico-chemical parameters (T, pH, EC, Eh, O2, Cl-, NO3-, SO4(2-), Na+, Ca2+, Mg2+, K+, Cu2+, Ni2+, Mn2+, Zn2+ and total iron) in the 8 wells was governed by geological, hydrogeogical, physical and chemical, and climatic factors. In addition, the concentrations of contaminants decreased in the last well (1 km from the landfill), indicating a purification and dilution effect. Nevertheless, we suspect short-term degradation of the groundwater in the Etueffont site.

[Effects of nitrogen nutritional deficiency on the distribution of particular lipids in a eutrophic lake milieu]. / Effets de la déficience nutritionnelle en azote minéral sur la distribution des lipides particulaires en milieu lacustre eutrophe.

The seasonal distribution of particulate lipids coupled with N-nutrient availability was studied in eutrophic Lake Aydat (Massif Central, France). The concentrations of lipids ranged between 196.9 and 2971.5 micrograms.l-1 (mean +/- s.d. = 1090.1 +/- 705.5 micrograms.l-1. Lipids were abundant in summer and fall when nitrates were insufficient reflecting thus an orientation of cell metabolism towards an accumulation of storage products. In such conditions, the heterocystous Cyanobacteria were found to develop due to their competitive advantage of exploiting atmospheric nitrogen. Their lipid metabolism did not seem to be affected at least partially by NO3- exhaustion.

Evidence for the contribution of ciliates to denitrification in a eutrophic lake.

High levels of nitrate reductase (NR) activity were found during a field survey in the epilimnion and metalimnion of a temperate lake (Lake Aydat, France) during summer stratification, when nitrates were analytically undetectable (< 0.5 mg L(-1)). We hypothesized that the NR activities were due to phytoplankton in the epilimnion, due to the ciliate Loxodes at the mid-depth oxic/anoxic interface and preferentially due to bacteria in the anoxic hypolimnion of the lake. In support of the hypothesis, a significant negative correlation was detected in the metalimnion between the abundance of Loxodes and nitrate concentrations, indicating nitrate use by the ciliate, and significant positive correlations were found between bacteria and nitrite concentrations at depth. The correlations are corroborated by additional evidence from chlorophyll a/NRA ratios, nitrite dynamics, and lake circulation patterns. Other ciliates besides Loxodes did not appear to significantly contribute to NRA potential. The data suggest that facultatively anaerobic ciliates such as Loxodes may be significant contributors to denitrification in eutrophic planktonic ecosystems.

[The theory of ecosystems: new views for a better understanding of the distribution of matter and energy within a viable system]. / Réflexions sur la théorie des écosystèmes: nouvelles vues pour une meilleure compréhension de la distribution de matière et d'énergie au sein d'un système viable.

Seasonal periodicity of phytoplankton was studied in a eutrophic lake (Lake Aydat, Massif Central, France), from March to November 1985. Weekly samples were taken from both the euphotic and dysphotic zones (245 samples). An attempt is made to check the general concepts of the theory of ecological succession using the H-diversity index of Shannon and Weaver. The population community of Lake Aydat appears to be constantly juvenile and permanently immature confirming the bias introduced by calculation of H, whose values are strongly influenced by the number of species present. In evaluating correlations between specific diversity (H) and several biotic parameters, some of our results approach the theoretic statements of Frontier. However some results contradict the ecological succession theory when specific biomasses H-based were considered. These findings imply that this concept should be further " rethought".

[Not Available]. / Couplage saisonnier entre nucléotides adényliques et activité photosynthétique de diverses fractions de taille phytoplanctoniques en milieu lacustre eutrophe.

As part of the study of the eutrophic lake Aydat (Massif Central, France), the energy charge (CE = ATP + 1/2 ADP/ATP + ADP + AMP) and photosynthetic activity of size fractionated phytoplankton (0,2-160 µn; 0,2-45 µm and 12-160 µm) were assessed from April to November (1985). Weekly samples were gathered from several depths in both the euphotic and dysphotic zones. The fraction 0,2-45 µm showed elevated primary production and weak energy charge percentages confirming the generally accepted idea about the increase of metabolical cell processes with lower cell size. We have also looked for the ecophysiological significance of the energy charge through its seasonal coupling with primary production. The highly significant negative correlations obtained between CE and primary production for the three fractions indicate that the pool of adenine nucleotides evolves towards forms less charged with a high energy phosphate bond. However, some exceptions to this rule were noticed in April and June (both CE and photosynthetic activity were high). This observation derived from in situ studies showed the difficulties encountered in natural environments when we try to check the ecophysiological significance of the energy charge.

Usefulness of simultaneous use of several methods for the estimation of phytoplanktonic biomass.

The annual cycle of phytoplankton biomass was followed in a eutrophic lake (Lake Aydat, Massif Central, France), using classic descriptors (biovolumes and chlorophyll a) as well as adenosine-5'-phosphate (ATP) levels. ATP is the metabolite indicating living biomass. ATP/Cell count and ATP/Chlorophyll a ratios were elevated due to the presence of heterotrophic organisms, such as several species of ciliates. The first ratio is greater than the second. The difference can be explained either by an underestimation of the nanoplankton fraction through the cell count method, or by a lack of sedimentation in the settling chambers used for counting cells.