Papers by François Delmas
Hydrobiologia, 2005
A relational database linking benthic diatom records, taxonomic nomenclature including synonyms, ... more A relational database linking benthic diatom records, taxonomic nomenclature including synonyms, and corresponding environmental data has been built in MS Access. It allowed flexible and long-term use of a relatively important amount of data (∼3000 records) gathered in the framework of the EC-funded PAEQANN project, gathering precise and documented information both about benthic diatoms and quantitative or semi-quantitative environmental data. Such a database has been shown to be a useful tool for the definition of benthic diatom typology at a multi-regional scale, the prediction of the impact of environmental characteristics on the structure of diatom communities, and additionally for a new insight on the auto-ecology of some taxa. This database could serve as a template for further work on diatoms and, after some implementation, on other freshwater communities. It could also be the basis for wider typology of stream diatoms, extended to other regions.
A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemic... more A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemical bases.
This study reports field and laboratory experiments in which the impact of cadmium on the growth ... more This study reports field and laboratory experiments in which the impact of cadmium on the growth characteristics of several diatom taxa from multispecific natural biofilms was assessed under non-limiting nutrient availability. The diatom community structures were determined for each time and each treatment, and coinertia analysis with the physicochemical characteristics of the water revealed the strong influence of many “uncontrolled” factors (differentiating field assemblages and microcosms), but also of metal contamination and duration of exposure. Under non-contaminated conditions, the inverse relationship between specific growth rates (μmax) and cell sizes was in accordance with the allometry studies reported by several authors. Metal contamination influenced the growth responses of the diatoms but, under these toxic conditions, the growth rates were not necessarily correlated with biovolumes. Microcosm and in situ results showed marked differences; examination of the standardiz...
Le glyphosate et son principal produit de dégradation acide aminométhylphosphonique (AMPA) sont d... more Le glyphosate et son principal produit de dégradation acide aminométhylphosphonique (AMPA) sont dérivés avec le 9-fluorenylméthyl chloroformate (FMOC-Cl). L'échantillon dérivé est purifié par extraction liquide/liquide puis concentré grâce à une extraction sur phase solide. La combinaison d'extractions liquide-liquide et sur phase solide permet de purifier les extraits et d'éliminer les éventuels effets matrice. L'analyse est réalisée avec une technique de chomatographie liquide haute performance couplée à la spectrométrie de masse en tandem via une source electrospray (HPLC-ESI-MS/MS). La séparation est obtenue avec une colonne de polarité de phase inversée particulière (phase stationnaire C18 hybride). La limite de quantification de 0,05 µg.L-1 a été obtenue pour le glyphosate et l'AMPA.
Fresenius Environmental Bulletin
Periphytic diatoms are an important phototrophic component of river biofilm and are used in situ ... more Periphytic diatoms are an important phototrophic component of river biofilm and are used in situ for the bioindication of pollution as well as in laboratory ecotoxicological tests to assess the toxicity of contaminants. In spring 2009, phototrophic biofilm samples mostly composed of diatoms were collected in a small river and their sensitivity to the herbicide diuron was estimated via photosynthesis bioassays. A large difference in tolerance to diuron was demonstrated between two periphytic communities from an upstream unpolluted site and a downstream site subjected to high seasonal contamination by pesticides. The comparison of diatom community structure between sites revealed important variations of the relative abundance of some species which could explain this difference. Consequently, some of these species were isolated from the river in autumn when toxic pressure was low, and kept in culture for more than six months in uncontaminated water. Acute toxicity tests of diuron based...
Journal of Chromatography A
The aim of this study is to propose an analytical method for determining different classes of pes... more The aim of this study is to propose an analytical method for determining different classes of pesticides in water using LC-ESI-MS/MS. Two techniques of field-sampling and analyte extraction were used: solid phase extraction (SPE) of water samples from active sampling and field exposure of Polar Organic Chemical Integrative Samplers (POCIS). We have worked with thirty-three molecules representing eight pesticide classes: carbamates, chloroacetanilides, dicarboximides, morpholines, organophosphorous, phenylureas, strobilurines and triazines. First, liquid chromatography separation protocols and the optimization of the ESI-MS/MS parameters were developed. Then, the SPE step was optimized to obtain acceptable levels of recovery for the various classes of molecules. The matrix effect that may significantly lower the ionization efficiency with ESI interfaces was evaluated and minimized. The performances (limits of quantification, accuracy and precision) of the SPE and POCIS techniques wer...
Environmental science and pollution research international, Jan 12, 2014
Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate communi... more Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level structural responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial supports placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatisation phase of 7 days were exposed to alachlor at 10 and 30 μg L(-1) for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash-free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The s...
Science of The Total Environment, 2014
In this study, the main current limitations in the application of the Polar Organic Chemical Inte... more In this study, the main current limitations in the application of the Polar Organic Chemical Integrative Sampler (POCIS) in regulatory monitoring programmes were evaluated. POCIS were exposed from March to December by successive periods of 14 days in the River Trec (Lot et Garonne, France) and analysed for 34 pesticides. The study of the uncertainty related to the POCIS data was performed and we concluded that it might be up to 138%, which is higher than European Union requirements but this issue was adequately counterbalanced by the gain of temporal representativeness. Comparison with data from the official monitoring programme from the French Water Agency showed that the POCIS is already suitable for both operational and investigative monitoring. The sampled fraction issue, and then compliance with Environmental Quality Standards, was also addressed. It was confirmed that POCIS samples only the dissolved fraction of dimethenamid and showed that for compounds like atrazine, desethylatrazine and metolachlor, the POCIS concentration is equivalent to the whole water concentration. For dimethenamid, which exhibited a tendency to adsorb on suspended matter, a method was suggested to assess the raw water concentration from the POCIS measure. Finally, an innovative procedure for using passive sampler data for compliance checks in the framework of surveillance monitoring is proposed.
Water Research, 2012
Diatom Cadmium Metal Quantitative real-time PCR a b s t r a c t
Water Research, 2005
Nous mettons ce document à disposition sous cette forme dans le but d'assurer la plus grande diff... more Nous mettons ce document à disposition sous cette forme dans le but d'assurer la plus grande diffusion de nos travaux scientifiques et techniques, en particulier auprès des étudiants. Le copyright et tous les droits restent la propriété des auteurs et des éditeurs. Nous prions chaque personne utilisant ces informations de respecter les droits et copyright des auteurs et éditeurs. Dans la plupart des cas, ces travaux ne peuvent être réexpédiés sans la permission explicite du détenteur des droits.
Science of The Total Environment, 2014
Four diatom methods were compared using the Intercalibration Common Metric (ICM).
Science of The Total Environment, 2012
This study focuses on an industrial contamination site subjected to remediation processes since 2... more This study focuses on an industrial contamination site subjected to remediation processes since 2007 in the Riou-Mort watershed (southwest France). The purpose was to assess the first impacts of remediation on periphytic biofilms, and was performed during two years of biomonitoring. Periphytic biofilms were collected on glass slides immersed 24 days at different sites along the contamination gradient for 12 colonisation cycles. Metal contaminations (Cd and Zn) were analysed in biofilms and the evolution of diatom communities was assessed, integrating teratology quantifications. Despite remediation work initiated at the industrial site, this study demonstrated the persistence of metal contamination in water, as well as in biofilms. In addition, our data, showed that the remediation process was initially marked by an increase in metal contamination in the river, with increasing diatom community shifts. Metal-contaminated biofilms presented decreasing species diversities and were dominated by metal-resistant species such as Eolimna minima, whom abundances increased in 2010 reaching 57.2±10%. No significant decrease in metal accumulation was observed and total Cd content in biofilms collected downstream the industrial site ranged from 772.7±88 in July 2009 to 636.9±20 μg/gDW in July 2010. Results obtained on artificial substrates were compared with those of natural substrates and showed similar diatom communities and abundances of deformed diatoms but lower diversities. This ensured that glass slide subtrates gave a good representation of periphytic biofilm health. Finally, results were compared to studies performed before the remediation process and this did not reveal a decrease of metal accumulation in biofilms nor shifts in taxonomic composition of the communities, rather the remaining dominance of metal resistant species such as E. minima was confirmed.
Science of The Total Environment, 2009
The aim of the present study was to understand the effect of reservoir configurations on sediment... more The aim of the present study was to understand the effect of reservoir configurations on sediment pesticide fate. Two dams were selected on the River Garonne, in southwest France: Carbonne and Golfech, both with reservoirs subject to accumulation of herbicide-contaminated sediment. They are situated upstream and downstream respectively of an agricultural and urban area: the Mid-Garonne. The results presented include pesticide concentrations and C/N ratios in the smaller sediment particles (b2 mm) and values of oxygenation and herbicide concentrations in the water. The dynamic behaviour of sediment in the reservoirs is discussed. The present study shows that the theoretical lifespan (weak remanence in vitro) and the results actually observed in the sediment are conflicting. Pesticide contamination in Carbonne indicates conservation, even accumulation, of herbicide molecules while in Golfech transformation processes clearly dominate. The hydromorphological position of Golfech reservoir, i.e. located at the junction of two rivers with contrasting hydrological regimes and very different oxygenation conditions, leads to accelerated pesticide desorption or degradation. Unfortunately, this configuration is rare.
River Research and Applications, 2003
A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemic... more A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemical bases.
Journal of the North American Benthological Society, 2007
... In the riffles studied, the dominant substratum types are pebbles (90%) and clayey rock (10%)... more ... In the riffles studied, the dominant substratum types are pebbles (90%) and clayey rock (10%), allowing development of extensive epilithic biomass (Améziane et al. ... The mean epilithic biomass during summer low flow in the Garonne River is 22 g AFDM/m 2 (Améziane et al. ...
Journal of Environmental Monitoring, 2011
Despite a significant decrease in the metallic waste emissions from an industrial site and a reme... more Despite a significant decrease in the metallic waste emissions from an industrial site and a remediation process initiated in 2007, the Riou-Mort watershed (southwest France) still exhibits high Cd and Zn concentrations. Metal wastes have long been proven to significantly disturb aquatic communities. In this study, bioaccumulation capacities and responses to the chemical improvement of the hydrosystem were assessed for a year along the contamination gradient through the comparison of two biological models: Corbicula fluminea and periphytic biofilms, both considered as good bioindicators. Bioaccumulation results confirmed the persistence of water contamination in Corbicula fluminea and biofilms with, respectively, maximum Cd concentrations reaching 80.6 and 861.2 μg gDW(-1), and Zn concentrations 2.0 and 21.3 mg gDW(-1). Biofilms exhibited bioaccumulation in close correlation with water contamination, while Corbicula fluminea presented Cd bioaccumulation clearly regulated by water temperature and metal concentrations, affecting the ventilatory activity, as revealed by condition indices measurements. Also, a linear regression using Cd bioaccumulation and temperature () showed that below approximately 6 °C Corbicula fluminea did not appear to accumulate metals. Bioconcentration factors (BCFs) were higher in biofilms in comparison with Corbicula fluminea and showed the great accumulation capacity of suspended particulate matter in biofilms. However, bioaccumulation capacities are known to be influenced by many factors other than metal concentrations, such as temperature, water oxygenation or plankton and nutrient concentrations. Thus, this study demonstrates the power of a combined assessment using both Corbicula fluminea and biofilms as bioindicators to give a more integrated view of water quality assessment. Finally, when comparing our results with previous studies, the start of hydrosystem restoration could be shown by decreasing bioaccumulation in organisms.
Journal of Environmental Monitoring, 2009
In this work, the effects of matrix interferences on the analytical performance of a new multires... more In this work, the effects of matrix interferences on the analytical performance of a new multiresidue method based on off-line solid phase extraction followed by reversed-phase liquid chromatographic separation and electrospray triple quadrupole mass spectrometric detection were investigated. This technique allows the simultaneous determination of 30 triazines, phenylureas and chloroacetanilides, extracted from freshwaters, in 40 minutes. Quantifications were performed with the use of appropriate internal standards (i.e. atrazine D5, diuron D6 and metolachlor D6). The limits of quantification were from 1 to 32 ng L -1 for the triazines, from 5 to 59 ng L -1 for the phenylureas and from 13 to 54 ng L -1 for the chloroacetanilides. The matrix effects were studied by spiking various waters (i.e. tap, river, pond and sea waters) with the chemicals of interest. The results showed that the samples with the highest conductivity (i.e. seawater) and the most abundant dissolved organic matter content (i.e. pond water) exhibited important matrix effects with signal suppressions and high imprecision, respectively. These matrix effects were strongly minimized by performing appropriate internal standardizations. Afterward, this analytical method was applied for analyzing environmental samples from either river or estuarine waters and for monitoring herbicide input in a freshwater-seawater interface.
Journal of Chromatography A, 2007
This work set out the laboratory calibration of the passive samplers such as polar organic chemic... more This work set out the laboratory calibration of the passive samplers such as polar organic chemical integrative samplers (POCISs) which preconcentrate hydrophilic organic contaminants in aqueous medium. We compared the two different configurations available (i.e. pesticide and pharmaceutical POCISs) for sampling different classes of herbicides representative of a wide range of polarity (5.34 ≥ log K ow ≥ −1.70). The results showed that pharmaceutical configuration was probably more convenient for sampling basic, neutral or acidic herbicides. Afterward, we performed a kinetic study with the pharmaceutical POCIS only. This calibration revealed linear and integrative uptakes of several herbicides for 21 days. For some compounds like sulcotrione, mesotrione, deisopropylatrazine (DIA) and deethylatrazine (DEA), the linear uptake model was only valid for 10 days. Lastly, we observed an increase of the sampling rates with the hydrophobicity of the herbicides. (N. Mazzella). devices were developed by Alvarez et al. and enable TWA concentration estimates.
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Papers by François Delmas