Mathilde Desprez

Vincent Freycon

Lilian Blanc

Jérôme Le Fol

Bruno Ferry

Rainforest productivity and biomass

Conclusions Conclusions

• Better physical soil properties in eastern plots.

• Parent rock is the main driver of chemical soil properties through texture:

Clay soils: higher cation exchange capacity and base saturation, but lower amount of labile phosphorus.

White sands: poor in nitrogen, intermediate for labile phosphorus, low CEC, but high base saturation. • Forest mortality by uprooting is likely to be lower in the North-East.

• Productivity could be higher in sandyclay soils (more frequent in the North-West), if labile phosphorus is considered as the main driver of fertility

  Ferry, B., Morneau, F., Bontemps, J.D., Blanc, L., & Freycon, V. (2009) Higher treefall rates on slopes and waterlogged soils result in lower stand biomass and productivity in a tropical rain forest. Journal of Ecology (in press) Madelaine, C., Pelissier, R., Vincent, G., Molino, J.-F., Sabatier, D., Prevost, M.-F., & de Namur, C. (2007) Mortality and recruitment in a lowland tropical rain forest of French Guiana: effects of soil type and species guild. Journal of Tropical Ecology, 23, 277-287. Malhi, Y., Baker, T.R., Phillips, O.L., et al. (2004) The above-ground coarse wood productivity of 104 Neotropical forest plots. Global Change Biology, 10, 563-591. Paoli, G.D., Curran, L.M., & Zak, D.R. (2005) Phosphorus efficiency of Bornean rain forest productivity: Evidence against the unimodal efficiency hypothesis. Ecology, 86, 1548-1561. Robert, A. (2003) Simulation of the effect of topography and tree falls on stand dynamics and stand structure of tropical forests. Ecological Modelling, 167, 287-303. Schuur, E.A.G. & Matson, P.A. (2001) Net primary productivity and nutrient cycling across a mesic to wet precipitation gradient in Hawaiian montane forest. Oecologia, 128, 431-442.

  from 4 to 6ha Environmental characteristics of the selected plots:

First

  key for soil organization and fertility characterization in northern French Guiana CIRAD -November 2009 -Mathilde DESPREZ, Vincent FREYCON, Lilian BLANC, Jérôme LE FOL,


J M Auger

S Martin

F Gruy

Wettability-enabling coating on oxide particles through controlled milling

Keywords: Liquid metal, Wetting, Silica, Mechanical coating, Milling, Tin alloy

The purpose of this paper is to describe a metal deposition process which aims at getting a wettability-enhancing tin coating on silica particles. This original mechano-synthesis protocol allows the deposition of thin (nm) metal layer on oxide, while maintaining particles integrity. Macroscopic wettability tests in liquid tin/bismuth alloy confirm the efficiency of this approach for the production of metal matrix/oxide inclusions composites, while microscopic imaging have shown that individual wetting of particles can easily be attained with the appropriate mixing conditions.

Introduction

The insertion of oxide particles in liquid metal meets different applications like production of metal-ceramic composites ( by infiltration process [START_REF] Kennedy | The wetting and spontaneous infiltration of ceramics by molten copper[END_REF] or mixing oxide particles within molten metal [START_REF] Kennedy | The incorporation of ceramic particles in molten aluminium and the relationship to contact angle data[END_REF] ). Such a system can also be used as a starting point to study the agglomeration of oxide inclusions within liquid metal [START_REF] Cournil | Modelling of solid particle aggregation dynamics in non-wetting liquid medium[END_REF]. However, the difference in chemical nature between metal and oxide leads to high surface energy which means poor wettability [START_REF] Eustathopoulos | Wettability at high temperatures[END_REF].

Hence, several methods have been developed to modify wetting properties and more specifically enhance wetting in liquid metals :

• surfactant addition: introduction of magnesium in molten aluminium to allow alumina, silicon carbide, or graphite particles wetting ( [START_REF] Ramani | Stability of non-wetting dispersoid suspensions in metallic melts[END_REF], [START_REF] Pai | Role of magnesium in cast aluminium alloy matrix composites[END_REF], [START_REF] Schultz | Microstructure and hardness of al2o3 nanoparticle reinforced al-mg composites fabricated by reactive wetting and stir mixing[END_REF], [START_REF] Pai | Fabrication of aluminiumalumina (magnesia) particulate composites in foundries using magnesium additions to the melts[END_REF]),

• physical/chemical alteration ([9]-thermal treatment case) of particles surface,

• mixing with a metallic alloy ( [START_REF] Tahamtan | Fabrication of al/a206al2o3 nano/micro composite by combining ball milling and stir casting technology[END_REF], [START_REF] Pai | Production of cast aluminium-graphite particle composites using a pellet method[END_REF], [START_REF] Amirkhanlou | Fabrication and characterization of al356/sicp semisolid composites by injecting sicp containing composite powders[END_REF]),

• in-situ coating through chemical reaction during liquid/solid contact (called reactive wetting [START_REF] Saiz | Reactive spreading in ceramic/metal systems[END_REF])

• metallic pre-coating [START_REF] Badia | Dispersion of graphite particles in aluminum castings through injection of the melt[END_REF] of powders, which is the less material-specific of these approaches, and which is the purpose of this paper.

Although technologies such as sputtering or chemical deposition [START_REF] Matijevic | Characterization of the stannous chloride/palladium chloride catalysts for electroless plating[END_REF] are widely used in coating processes, they suffer from some drawbacks (slow production rate and chemical contamination for example), and from a lack of generality. They are indeed designed for specific materials and valid within a limited range of properties, such as melting point or chemical reactivity.

Thus, the aim of this study is to assess the potential of milling process, which is closed to the silica-stearate dry coating process [START_REF] Ouabbas | Surface modification of silica particles by dry coating: Characterization and powder ageing[END_REF], to get a soft metal coating and allow the dispersion of ceramic particles into liquid metal. This paper first presents the materials used for the study and introduce the original mechanical-synthesis process which allows the coating of hard oxide particles with soft metals. The surface layer is then analyzed. Finally, the coated particles are dispersed within liquid alloy to confirm the potential of this method for the production of metal/ceramic composites. The procedure will be shown with the Sn/Bi/SiO 2 composite. This physico-chemical system has been selected as it will be subsequently used for the study of particle agglomeration dynamics at high temperature.

Materials

The oxide powder is a Geltech silica powder. It is composed of monodisperse silica spheres of 1.5µm diameter Figure 1. This powder meets the requirements to ensure both sufficient hardness to avoid damage during milling, and very low chemical reactivity at the considered temperatures. Coating metal is pure tin (99.99%). It was chosen for its chemical similarity with the alloy used for wetting tests and its ductility. The selected tin source consists of Alfa Aesar 5mm granules. The alloy, used for dispersion experiments of coated particles, is the tin/bismuth eutectic (commercial name CERROTRU from Metaconcept, 43w% Sn, henceforth noted Sn/Bi), its main advantage being its low melting point (412K).

Coating process

Coating was carried out with a planetary mill (PM400 from Retsch). A small alumina jar (50 mm diameter) was used as a container. The milling load was composed of 50 g of alumina balls: two large spheres (20 mm diameter) and smaller ones (10 mm). A static atmosphere of pure argon was used to limit tin oxidation during the whole process.

Jar and balls were carefully cleaned between each experiment, using the following procedure:

• separate rinsing of balls and jar with distilled water,

• ultrasonic bath cleaning (5 min) ,

• distilled water rinsing and tissue wiping,

• ethanol final rinsing.

The coating process is shown at Figure 2. It is divided into two steps:

1. Tin milling step, with 5 g tin granules (1/10 granules/milling balls ratio) inside the jar, carried out at 300 rpm for 1 hour. Following this high energy milling, it appears that jar and balls are covered by a visible tin layer, and tin granules are highly strained (up to become spherical). 3 nm. This result was further confirmed by XPS analysis, which leads to an estimation (using simple models for flat layers instead of spheres) of the tin layer thickness smaller than 5 nm. Thus, this result confirms the assumption that the tin layer is not visible on SEM images because of its very small thickness.

Wettability testing

Considering the final aim of our work which was to reach a full dispersion of ceramic particles within liquid metal, it was decided to evaluate the coating effect by directly studying the ability of coated powder to be introduced within liquid metal.

Hence, 5 %vol. of coated powders were added (over a 20 min duration) to liquid metal (300 g stirred Sn/Bi alloy at 200 o C). The resulting slurry was then cast into cylindrical ingots. Ingots were then cross-sectioned and observed through electron microscopy.

For comparison purposes, coated and uncoated powders were introduced within liquid alloy at two different stirring speeds (300 and 600 rpm).

Experiments with either coated or uncoated silica, stirred at 300 rpm, led to the accumulation of powder at the liquid alloy surface, with no apparent wetting. This observation is confirmed by the absence of silica particles in the corresponding cross-sectioned ingots. On the other hand, coated silica mixed at 600 rpm resulted in complete disappearance of the powder. SEM imaging of cross-sectioned alloy samples, shown at Figure 5, indeed reveals a full wetting of silica spheres and a full contact between particles and metal matrix. The conclusion of these observations is that metallic coating of silica is a necessary condition for wetting, but is not sufficient. Hence, a direct contact between liquid metal and particles is required, and it can only be obtained with high speed stirring. It is assumed that, with this experimental setup, shearing at the surface of liquid metal is high enough to allow the breakage of the spontaneously formed oxide layer. Thus, coated silica is easily dispersed within the Sn/Bi alloy.

Conclusion

The 2-steps coating process presented in this study is shown to be an efficient process to obtain a metallic tin layer on silica powder, with minimal damage incurred by the particles. In spite of its very low (nanometer scale) thickness, this layer is able to allow a complete wetting of oxide particles by between unoxidized metal and coated particles are also provided. Obvious advantages over existing coating methods resides in protocol simplicity (no need for specialized equipment), scalability and generality (no dependency on specific chemical reactivity). Since this study was only dedicated to SiO 2 /Sn, further works will be carried out to study the adaptability of this process to others oxide/metal couples, but it can be assumed that the main condition is the difference in hardness between oxide and metal. Potential applications range from laboratory experiments with oxide/metal couples, to cleaner and more environment friendly large scale industrial production, since this process do not involve any unwanted by-products, contrary, for example, to the chemical coating route.

Figure 1 :

 1 Figure 1: Silica powder before coating (SEM)

2 .

 2 The coating step: 5 g of silica powder is added to the jar, and milled at 150 rpm during 15 min. At the end of this step, the balls and the jar surface are partially cleaned, while the color of silica powder have changed from white to grey. The aim of this low energy milling is to coat the powder without damaging (breakage) silica particles.

Figure 2 :

 2 Figure 2: Coating process

Figure 3 :

 3 Figure 3: Silica powder after coating (SEM)

Figure 4 :

 4 Figure 4: Diffractograms of pure amorphous silica (orange) and coated silica (black)

Figure 5 :

 5 Figure 5: SEM images of ingots for uncoated (a, b) and coated (c, d) silica introduced at 300 (a, c) and 600 rpm (b, d)

  This research work was carried out in the context of French/German FLOTINC project (ref. ANR-15-CE08-0040), funded by ANR (Agence Nationale de la Recherche) and DFG (Deutsche Forschungsgemeinschaft).


Yves Perrodin
email: perrodin@entpe.fr

Gilles Donguy

Christine Bazin

Laurence Volatier

Claude Durrieu

Sylvie Bony

Alain Devaux

Mohammed Abdelghafour

Robert Moretto

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments

The dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the "substances" approach derived from the European methodology for assessing new substances placed on the market, and the "matrix" approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, …). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments "1" and "2" presented a low risk for the peripheral aquatic ecosystems while sediment "3" presented a high risk.

Introduction

Over the last 20 years, dredged seaport sediments have been subject to increasingly severe management procedures due to their contamination by the industrial, commercial, urban and tourist activities carried out in and around seaports [START_REF] Andersen | Environmental risk assessment of surface water and sediments in Copenhagen harbour[END_REF][START_REF] Lau | A strategy for the management of contaminated dredged sediment in Hong Kong[END_REF][START_REF] Meeddat | Circulaire du 04/07/08 relative à la procédure concernant la gestion des sédiments lors de travaux ou d'opérations impliquant des dragages ou curages maritimes et fluviaux[END_REF]. The main families of pollutants concerned are heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs) and Tributyltin (TBT), to which must be added a high chloride content leading to problems when these sediments are stored on land. The bioassays performed on these seaport sediments often reveal high ecotoxicity [START_REF] Clément | Effects of a physico-chemical treatment of a dredged sediment on its ecotoxicity after discharge in laboratory gravel pit microcosms[END_REF]Davoren et al., 2005a;[START_REF] Mamindy-Pajany | Ecotoxicological evaluation of Mediterranean dredged sediment ports based on elutriates with oyster embryotoxicity tests after composting process[END_REF][START_REF] Wong | The toxicity of marine sediments in Victoria Harbour, Hong Kong[END_REF]. Rarer studies also mention genotoxicity [START_REF] Kocan | Cytotoxicity/genotoxicity: the application of cell culture techniques to the measurement of marine sediment pollution[END_REF][START_REF] Srut | Genotoxicity of marine sediments in the fish hepatoma cell line PLHC-1 as assessed by the Comet assay[END_REF]. The current figure for contaminated sediments located in seaports in France is high (about 10 million tonnes) and they cannot be dredged due to recent legislation prohibiting their discharge at sea (IFREMER, 2001). This leads to a new source of polluted materials for which no industrial method of treatment exists, since traditional treatment methods (incineration, landfilling, etc.) are poorly adapted to this type of material in both economic terms and those of absorbable volumes. In view to finding viable solutions for these materials, works have begun in many countries and in France in particular [START_REF] Grosdemange | The SEDIMARD project: presentation and results[END_REF]. Different methods of reuse, e.g. use as aggregate/construction material, or use for artificial recharge of beaches or salt marshes, have been studied. Among them, one of the most promising alternative solutions under consideration is that of filling quarries located in coastal areas, as it is one of the best adapted both technically and economically, and it also provides sufficient capacities for managing the large quantities involved. Nonetheless, it was necessary to subject this solution to a research programme aimed at offering a specific ecological risk assessment methodology for validating the compatibility of each quarry fill project with its neighbouring inland ecosystems (terrestrial and aquatic) (SEDIGEST, 2011).

In this article, we first present the specific characteristics of dredged seaport sediments and the general approach to performing ecological risk assessments at international level, in view to formulating a specific method dedicated to the problem of filling coastal quarries with seaport sediments, and implementing it for three sediments taken from seaports in southern and western France.

Specific characteristics of dredged seaport sediments

The physicochemical composition of dredged seaport sediments is now becoming clearer due to the different characterisation campaigns carried out around the world. The main families of pollutants identified in these materials are heavy metals [START_REF] Colacicco | Enhanced electrokinetic treatment of marine sediments contaminated by heavy metals and PAHs[END_REF][START_REF] Lepland | Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway[END_REF][START_REF] Romano | Marine sediment contamination of an industrial site at Port of Bagnoli, Gulf of Naples, Southern Italy[END_REF], PAHs [START_REF]Polycyclic aromatic hydrocarbons in marine sediments from the Rijeka Bay area, Northern Adriatic, Croatia[END_REF][START_REF] Gschwend | Fluxes of polycyclic aromatic hydrocarbons to marine and lacustrine sediments in the northeastern United States[END_REF][START_REF] Romano | Marine sediment contamination of an industrial site at Port of Bagnoli, Gulf of Naples, Southern Italy[END_REF][START_REF] Simpson | Composition and distribution of polycyclic aromatic hydrocarbon contamination in surficial marine sediments from Kitimat Harbor, Canada[END_REF], and TBTs [START_REF] Bhosle | Butyltins in the sediments of Kochi and Mumbai harbours, west coast of India[END_REF][START_REF] Blanca | Environmental levels, toxicity and human exposure to tributyltin (TBT)contaminated marine environment. A review[END_REF][START_REF] Langston | Tin and organotin in water, sediments, and benthic organisms of Poole Harbour[END_REF][START_REF] Saeki | The stability of butyltin compounds in a dredged heavily-contaminated sediment[END_REF]. However, reports of the fate and behaviour of these sediments when deposited on land, subject in particular to the action of rainwater, remain scarce and many grey areas persist [START_REF] Chatain | Assessment of the potential mobilization of inorganic contaminants in a French harbor sediment[END_REF][START_REF] Saeki | The stability of butyltin compounds in a dredged heavily-contaminated sediment[END_REF]. These areas include: (i) the effect of oxidation on sediments when they are transported on land; (ii) the effect of chlorides on the solubility of the mineral and organic pollutants present; (iii) the behaviour of the percolates seeping from the sediments into the soil located under the deposit, especially in the case of heterogeneous soils; (iv) the role of plants located on the surface of the deposit on pollutant transfers; (v) the bioavailability of sediment pollutants and its longterm evolution during storage; (vi) its toxicity for inland terrestrial and aquatic organisms under the exposure conditions concerned, the mixture of the pollutants present in mixture in the "marine sediment" matrix and in its emissions (percolates). In what follows, it will be necessary to take into account all these elements during the formulation of the ecological risk assessment methodology dedicated to managing the seaport sediments, in order to produce a reliable and robust tool.

Methodological approach for the ecological risk assessment

The first Ecological Risk Assessment (ERA) methodologies emerged at the beginning of the 1990s with dawning awareness of the risks liable to impact ecosystems exposed to substances of anthropic origin. In 1992, the United States EPA proposed a framework for the ecological risk assessment of contaminated industrial sites (US-EPA, 1992). Following a certain number of works, especially those of [START_REF] Suter | Environmental risk assessment[END_REF], this guide was improved to become "The Guidelines for Ecological Risk Assessment" (US EPA, 1998) and has become the reference regarding ERA [START_REF] Hayet | Variabilité des méthodologies d'évaluation des risques écologiques : conséquences et perspectives d'améliorations[END_REF][START_REF] Perrodin | Ecological risk assessment of urban and industrial systems: a review[END_REF][START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF]. Since then, this guide has been revised by many countries and adapted to manage their polluted sites [START_REF] Ceaeq | Procédure d'évaluation des risques écotoxicologiques pour la réhabilitation des terrains contaminés[END_REF]Environment Agency of United Kingdoms, 2003;Liliburne and Phillips, 2011). In addition, methodologies have been formulated to evaluate ecological risks linked to other problems. Mention can be made of the methodology drawn up by the European Union to evaluate risks relating to chemical substances placed on the market (ECB, 2003;Environment Agency of United Kingdoms, 2003), of French studies on the assessment of ecotoxicological risks linked to dumping inland dredged sediments [START_REF] Cetmef | Évaluation écotoxicologique de sédiments contaminés ou de matériaux de dragage[END_REF] and the assessment of the ecocompatibility of using wastes [START_REF] Perrodin | Assessment of the ecocompatibility of waste disposal or waste use scenarios: towards the elaboration and implementation of a comprehensive methodology[END_REF], and of the assessment of ecotoxicological risks linked to hospital effluents [START_REF] Boillot | Ecotoxicological risk assessment of hospital wastewater discharge: characterization of combined effect due to binary mixtures of three surfactants and three disinfectants towards Daphnia magna[END_REF][START_REF] Emmanuel | Ecotoxicological risk assessment of hospital wastewater: a proposed framework for raw effluents discharging into urban sewer network[END_REF]. Most ERA methods are implemented with four main phases: (1) the formulation of the problem, (2) the characterisation of exposures (3) the characterisation of effects, and lastly, (4) the characterisation of the risk itself (Fig. 1). It is noteworthy that the characterisation of exposures and that of effects are performed in parallel; however they are in constant interaction [START_REF] Babut | Évaluation écotoxicologique de matériaux de dragage -(1) présentation et justification de la démarche. Cemagref, ENTPE, VNF[END_REF][START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF].

The formulation of the problem

The problem formulation phase is fundamental. It comprises investigation and technical options, following which a highly precise plan of actions has to be established (identification of the data to be collected, the measurement and assessment techniques to be used, as well as the framework of interpretation) to carry out the subsequent phases of the ERA [START_REF] Perrodin | Ecological risk assessment of urban and industrial systems: a review[END_REF][START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF]US EPA, 1998).

The characterisation of exposures

Exposure characterisation aims at determining the spatial-temporal contact between pollutants and target populations (US EPA, 1998). It includes the analysis of sources of pollutants, the transfer of the latter from their sources, and the distribution of pollutants in the environment. Exposure depends on both the concentrations of pollutants in the environment and the characteristics and behaviour of the target organisms. Finally, it takes into account the doses absorbed by target populations. This analysis can be performed by using theoretical models of pollutant transfer and/or pollutants and/or on the basis of experimental results [START_REF] Perrodin | Ecological risk assessment of urban and industrial systems: a review[END_REF].

This phase results in the determination of one or more values characterising exposure. In the case of a "substance-based" approach, the term "Predicted Environmental Concentration" (PEC) is used. It corresponds to the concentration to which organisms are exposed (in mg/l, for example). In the case of a "matrix" approach, the notion of percentage of polluted source matrix in the environment of the organisms is employed (the PEC is then expressed in %). In both cases the parameter concerned is the concentration that can be expected in the environment following different inputs. Determining these values can prove complex, since account must be taken of a considerable number of phenomena liable to occur during transit via different pathways: dilution, evaporation, biodegradation, bio-accumulation, change of speciation of substances, the characteristics of the ecosystem, etc. Exposure can also be direct or indirect, short or long-term, or variable or invariable through time [START_REF] Record | Évaluation et acceptabilité des risques environnementaux[END_REF][START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF].

Planning

The characterization of effects

This phase entails defining to what extent the organisms of the target ecosystem are significantly sensitive to the pollutants to which they are exposed [START_REF] Perrodin | Ecological risk assessment of urban and industrial systems: a review[END_REF]. This step is mainly based on biological approaches that include batteries of bioassays. A large number of batteries of bioassays have been proposed in the literature for different fields of study and matrixes. Mention can be made of those relating to: (1) substances [START_REF] Davoren | A test battery for the ecotoxicological evaluation of the agrichemical Environ[END_REF][START_REF] Kim | Aquatic toxicity of acetaminophen, carbamazepine, cimetidine, diltiazem and six major sulfonamides, and their potential ecological risks in Korea[END_REF][START_REF] Radix | Comparison of four chronic toxicity tests using algae, bacteria, and invertebrates assessed with sixteen chemicals[END_REF]; (2) effluents [START_REF] Andrén | A multivariate biological and chemical characterization of industrial effluents connected to municipal sewage treatment plants[END_REF][START_REF] Naudin | Influence of the sample preservation mode to assess the chronic toxicity of an industrial effluent[END_REF][START_REF] Persoone | A practical and user-friendly toxicity classification system with microbiotests for natural waters and wastewaters[END_REF][START_REF] Ren | Use of multidimensional scaling in the selection of wastewater toxicity test battery components[END_REF]; (3) sediments (Davoren et al., 2005b); (4) wastes [START_REF] Clément | Estimation of the hazard of landfills through toxicity testing of leachates. I. Determination of leachate toxicity with a battery of acute tests[END_REF][START_REF] Isidori | Toxicity identification evaluation of leachates from municipal solid waste landfills: a multispecies approach[END_REF][START_REF] Pandard | Selecting a battery of bioassays for ecotoxicological characterization of wastes[END_REF][START_REF] Rojícková-Padrtová | Evaluation of alternative and standard toxicity assays for screening of environmental samples: selection of an optimal test battery[END_REF]; and (5) soils, sludges and composts [START_REF] Juvonen | A battery of toxicity tests as indicators of decontamination in composting oily waste[END_REF][START_REF] Schaefer | Assessing 2,4,6-trinitrotoluene (TNT)-contaminated soil using three different earthworm test methods[END_REF]. It results in the acquisition of different values of ecotoxicological effects as NOEC (No Observable Effect Concentration) or CE20 (Efficient Concentration on 20% of the population), making it possible to calculate, after applying an extrapolation factor, the value of absence of significant effect on the whole of the target ecosystem. This value is commonly known as the PNEC (Predicted No Effect Concentration). Although the toxicity of a chemical mixture may be greater or lesser than predicted from toxicities of individual constituents of the mixture, a quotient addition approach assumes that toxicities are additive or approximately additive (US EPA, 1998). This assumption may be most applicable when the modes of actions of chemicals in a mixture are similar, but there is evidence that even with chemicals having dissimilar modes of action, additive or near-additive interactions are common [START_REF] Altenburger | Predictability of the toxicity of multiple chemical mixtures to Vibrio fischeri: mixtures composed of similarly acting chemicals[END_REF][START_REF] Bliss | The toxicity of poisons applied jointly[END_REF][START_REF] Boillot | Joint-action ecotoxicity of binary mixtures of glutaraldehyde and surfactants used in hospital: use of TI model and isoblogram representation[END_REF][START_REF] Feron | Toxicological evaluation of chemical mixtures[END_REF][START_REF] Hermens | Quantitative structure-activity relationships and toxicity studies of mixtures of chemicals with anaesthetic potency: acute lethal and sublethal toxicity to Daphnia magna[END_REF][START_REF] Lin | Mechanism of concentration addition toxicity: they are different for nonpolar narcotic chemicals, polar narcotic chemicals and reactive chemicals[END_REF].

The characterization of the risk itself

To carry out this final phase of ecological risk assessment, there is a range of possible methods of variable complexity [START_REF] Babut | Évaluation des risques écologiques causés par des matériaux de dragage: proposition d'une approche adaptée aux dépôts en gravière en eau[END_REF]. The choice depends on the operational constraints and the available data. [START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF] notes "the ecological risk can be expressed in various manners: qualitative (absence or not of risk), semi-quantitative (weak, average and high risk), and in probabilistic terms (the risk is x%)". The method known as "the quotient" is the most widespread method for the semi-quantitative characterization of risks. This method consists in calculating the quotient which is equal to the "Predicted Environmental Concentration" (PEC) divided by the "Predicted No Effect Concentration" (PNEC). When the quotient value "Q" is greater than 1, the risk is considered as significant, and increasingly so as the quotient rises. Conversely, the further the quotient is below 1, the more the risk is regarded as weak. The "probable non concentration effect" on an organism is, in practice, generally represented by NOEC or EC20 divided by an extrapolation factor (e.g. 10).

Formulation of the specific risk assessment methodology

Formulation of the problem

Description of the scenario

The aim of this description is to present the different ecosystems potentially in the vicinity of the seaport sediment deposit and the different exposure pathways concerned as exhaustively as possible to provide a full vision of the scenario (Fig. 2).

Regarding source S1, three samples of treated maritime sediments were selected to perform the programme. To do this, we first chose to work with relatively polluted sediments [START_REF] Chatain | Assessment of the potential mobilization of inorganic contaminants in a French harbor sediment[END_REF] in order to obtain a response during the bioassays. In view to using the methodology in the future to validate landfill projects, less polluted sediments will be considered. The three sediments chosen taken from an Atlantic seaboard site (Port of Guilvinec) and from a Mediterranean seaboard site (Port of Toulon), were as follows:

• Sediment from the port of Toulon, dried and aired for 4 months (sediment 1), • The fine fraction of the sediment from the port of Toulon, dried and aired for 4 months (sediment 2), • Sediment from the port of Guilvinec limed and crushed (sediment 3).

Table 1 presents the substances chosen as risk tracers, given current knowledge of seaport sediments and their potential ecotoxicity.

Regarding the environmental targets to be taken into account, in the framework of the present article, it was first considered that runoff from the surface of the deposit was negligible (surface slope oriented inwards, peripheral drainage, etc.). It was then considered that the landfill project did not include a deposit surface vegetation project and that the local groundwater was not subject to risk, notably with respect to the production of drinking water. These choices led to narrowing the target environment to be studied to only that of C4 (aquatic environment) (other variants of the scenario will be the subject of further publications). The river (C4) located near the deposit therefore receives part of the deposit percolate flowing laterally on the peripheral soil. On the basis of a conservative assumption, we considered that the flow on the soil did not change the concentration of the substances transported in the percolate. Lateral flow (T3) was therefore the main pathway of pollution transfer to the river. The trophic levels and potential biological targets to be taken into account were primary producers (green algae, etc.), detritivores (bacteria, etc.), primary consumers (rotifers, crustaceans, etc.), and secondary consumers (fish, etc.).

Finally, source "S1" (maritime sediment), transfer "T3" (lateral flow) and target "C4" (river) composed the three main elements of the studied scenario. The spatial and numerical data of the latter were then set randomly for the needs of this study (Table 2), nonetheless with efforts being made to stick as closely as possible to the reality in-the-field.

It is noteworthy that the speciation of metal contaminants within the deposit can undergo modification, and that organic contaminants can be biodegraded. The biodegradation of PAHs, the main organic contaminants of the sediment, is a priori low given the probably anaerobic nature predominating within the deposit and the low dwell time during runoff on the soil. Whatever the case, this potential degradation mainly concerns compounds with low molecular weight. Furthermore, some pollutants are liable to bring about genotoxic effects [START_REF] Devaux | Monitoring of the chemical pollution of the river Rhône through measurement of DNA damage and cytochrome P4501A induction in chub (Leuciscus cephalus)[END_REF][START_REF] Theodorakis | Integration of genotoxic and population genetic endpoints in biomonitoring and risk assessment[END_REF][START_REF] Würgler | Environmental effects of genotoxins (eco-genotoxicology)[END_REF]. Although little is known at present about the additional risk this type of effect could generate, its potential consequences imply that they cannot be ignored and that they must be taken into account in risk assessment procedures applied to ecosystems.

Selection of "assessment parameters" and formulation of the conceptual model

The demands for preserving surface aquatic ecosystems can be summarised as follows: filling a terrestrial cavity with treated seaport sediments must not lead to short or long-term effects on the aquatic species of the river located nearby.

The assessment parameters are physicochemical (concentrations in sediment contaminants and percolates), physical (lateral runoff flow rates and river flow rates, dilution factor) and ecotoxicological (battery of bioassays performed for several trophic levels). Fig. 3 shows the conceptual model resulting from the choices made.

Material and methods

Exposure characterisation

The exposure level was based first on the water balance of the site, using the data of Table 2, and on the dilution of the percolate in the river during its low flow period, with the assumption that the runoff between the deposit and the river did not significantly reduce the flow of pollutants discharged by the deposit due to the nature of the soil, slope and the short distance between the deposit and the river. The ratio chosen for the distribution of the percolate, by taking into account the site data collected during the visit to several existing deposit sites, and the data available for similar scenarios [START_REF] Perrodin | Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil[END_REF], was 50% for the groundwater and 50% for the river.

In order to simulate the behaviour of the sediments deposit, and the fate of the pollutants, three lysimeters for the three treated sediments were then constituted. They were subjected to a controlled moisture regime lasting 18 months, with continued spraying (automated system) and sprinkling every 20 min. These lysimeters were formed by rectangular aluminium tanks (2.5 m × 1.75 m). A layer of sand was deposited at the bottom of the lysimeters, and a low point was installed in one of the angles of each one. It was covered with a polyolefin sealing geomembrane. A layer of draining material (gravel) 5 cm thick was deposited on the geomembrane and then covered with a protective geotextile to avoid any migration of the sediments into the drainage layer. The sediment was finally placed over these sub-layers using a vibratory tamping machine to compact the sediment to Proctor density. The percolates were collected daily with a peristaltic pump, then stored automatically in a refrigerator while awaiting analysis. Regular measurements of pH, conductivity, Redox potential and ammonium were performed.

Chemical analyses of the percolates of the 3 sediments were performed according to the following protocols: The samples (about 900 kg per sediment) were taken from experimental sediment treatment sites. After homogenisation, they were divided into 100 l drums and quickly transported to the laboratory. On arrival at the laboratory, they were subjected to sub-sampling to S1: dredged seaport sediment deposit in a terrestrial cavity T1: transfer of deposit pollutants to the surface terrestrial ecosystem C1: terrestrial ecosystem developing on the deposit T2: transfer of deposit pollutants through the soil to the groundwater C2: groundwater located beneath the sediment deposit and which receives part of percolates seeping from it T3: transfer of deposit pollutants via the lateral flow of the percolates C3: terrestrial ecosystem near the deposit and which receives the water flowing laterally from it C4: aquatic ecosystem: river located near the deposit and which receives the water flowing laterally from it PWS : Potable Water Supply. prepare the samples required for each test and analysis. These operations were all performed as rapidly as possible after sampling. The resulting samples were then conserved in a cold chamber at 4 °C.

Continent Sea

Soil

Effect characterisation

The effects were characterised according to two complementary approaches: the "substances approach" and the "matrix approach". The "substances approach" consists in seeking in international databases the concentrations of each of the "risk tracer" substances with no effect on ecosystems (PNEC mg/l). The "matrix approach" consists in exposing organisms representative of the target ecosystem (bioassays) to a range of dilutions of the "matrix" responsible for the pollution, in this case the percolate discharged by the seaport sediment, so as to determine the no effect concentration of the latter for the target ecosystem (PNEC%). For the "matrix approach", priority was given to selecting normalised (or standardised) bioassays. These bioassays are listed in Table 3. In conformity with the conclusions in the formulation of the problem, the battery of bioassays determined comprised tests representative of primary producers, detritivores, primary consumers and secondary consumers, as well as genotoxicity tests.

Risk characterisation

The "quotient method" can be applied to both the "substances approach" (pollutant concentrations) and the "matrix approach" (% dilution of a complex matrix of pollutants).

In the case of the "substances approach", the objective is to determine the aquatic PNEC for each risk tracer, by consulting international databases and by taking the following approach: (i) if the PNEC values can be obtained from reference organisations, such as the US-EPA in the USA (US-EPA, 2011) or the INERIS in France [START_REF] Ineris | Fiche de données toxicologiques et environmentales des substances chimiques[END_REF] for the substances considered, priority is given to these values, (ii) if certain PNEC values are not available, they have to be generated from ecotoxicological data available in international databases: the PNEC is then calculated according to the procedures of the TGD (ECB, 2003), which defines in particular the rules defining the extrapolation factors. In the case of the "matrix approach", the TGD can also be used to adjust the value of the extrapolation factors as a function of the type and number of available test results.

Results

The approach described above was applied to the three sediments presented in the description of the scenario.

Characterisation of exposures

The results stemming from the numerical data of the scenario permit to calculate the lateral flow debit (Dlf) and the dilution factor of the percolate in the river (Fp):

• Dlf = 0.9 m/year ⁎ 100,000 m 2 ⁎ 0.3 ⁎ 0.5 = 0.135 ⁎ 10 5 m 3 /year • Fd = 315 ⁎ 10 5 / 0.135 ⁎ 10 5 = 2333 (i.e. 0.04% percolate in the river).

Analytical monitoring of the percolates discharged from the lysimeters over the 18 months of operation showed that the percolate of the first month was almost always that most heavily loaded. Under these conditions, we considered that it corresponded to the "critical" period of the scenario and thus decided to focus our attention on it. The results of the physicochemical analyses of the percolate of the first month of each of the three sediments are presented in Table 4.

Regarding the "substances" approach, the calculation of exposure concentrations vis-à-vis aquatic organisms was performed using the results of the chemical analysis of the percolates to which the dilution factor Fp mentioned above was applied. This provided the PEC (Table 4).

For the "matrix approach", the predicted exposure concentration is expressed in percentage of percolate in the river: 0.04%.

Characterisation of effects and risks

The effects measured by the "Predicted No Effect Concentration" on organisms were characterised as a function of the "substances approach" (PNECmg/l) and the "matrix approach" (PNEC%). The risk can be characterised by comparing the results with the "Predicted Environmental Concentration" (PEC).

Characterisation of the effects and risks as a function of the "substances approach"

The results of this procedure, and that of the risk quotient of the calculated (Q) for each substances and each of the 3 sediments are presented in Table 5.

For sediment 3, the ecotoxicological risk was very high for the aquatic ecosystem mainly due to the strong concentrations of copper and TBT in the percolate, and then in the river. For the two other sediments, no ecotoxicological risk was observed under the conditions of the scenario, the substances monitored. For these two sediments, copper was the pollutant for which the safety margin was lowest (Q = 0.55 and 0.68).

5.2.2. Characterisation of effects and risks according to the "matrix approach" 5.2.2.1. Effect characterisation. Table 6 groups the results of the different bioassays performed on the percolates studied. After analysing the rules recommended by the ECB (European Chemicals Bureau) in the TGD (Technical Guidance Document for new notified substances), and given the wealth and type of bioassays selected (chronicity, trophic levels), the value of the extrapolation factor applied to the result of the most unfavourable ecotoxicity test for establishing the PNEC of the ecosystem concerned was set at "10". On this base, the PNEC obtained for each sediment tested was as follows:

-Sediment 1: PNEC = 1.0/10) = 0.10% -Sediment 2: PNEC = 0.6/10) = 0.06% -Sediment 3: PNEC = 0.13/10) = 0.013% 5.2.2.2. Risk characterisation. The risk quotient calculated for each of the three sediments tested was as follows:

-Sediment 1: Q = PEC/PNEC = 0.04/0.1 = 0.4 -Sediment 2: Q = PEC/PNEC = 0.04/0.06 = 0.3 -Sediment 3: Q = PEC/PNEC = 0.04/0.013 = 3.1.

For the peripheral aquatic ecosystem, sediments 1 and 2 therefore presented little risk if deposited in under the conditions of the scenario established at the beginning of the study. However, the risk quotient of sediment 3 was 3.1, leading to the conclusion of a significant ecotoxicological risk for the surrounding aquatic ecosystem if the sediment were deposited under the conditions of the scenario established at the beginning of the study.

Discussion

6.1. The results obtained

Chemical analyses of percolates

The chemical analyses of the percolates of the three dredged sediments tested are hardly comparable to existing data in the literature which, for the most part, concern only the analysis of total pollutant content [START_REF]Polycyclic aromatic hydrocarbons in marine sediments from the Rijeka Bay area, Northern Adriatic, Croatia[END_REF][START_REF] Bhosle | Butyltins in the sediments of Kochi and Mumbai harbours, west coast of India[END_REF][START_REF] Blanca | Environmental levels, toxicity and human exposure to tributyltin (TBT)contaminated marine environment. A review[END_REF][START_REF] Colacicco | Enhanced electrokinetic treatment of marine sediments contaminated by heavy metals and PAHs[END_REF][START_REF] Gschwend | Fluxes of polycyclic aromatic hydrocarbons to marine and lacustrine sediments in the northeastern United States[END_REF][START_REF] Langston | Tin and organotin in water, sediments, and benthic organisms of Poole Harbour[END_REF][START_REF] Lepland | Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway[END_REF][START_REF] Romano | Marine sediment contamination of an industrial site at Port of Bagnoli, Gulf of Naples, Southern Italy[END_REF][START_REF] Saeki | The stability of butyltin compounds in a dredged heavily-contaminated sediment[END_REF][START_REF] Simpson | Composition and distribution of polycyclic aromatic hydrocarbon contamination in surficial marine sediments from Kitimat Harbor, Canada[END_REF]. Regarding the analysis of the percolates, we mention in the paragraph dedicated to the results that the concentrations of pollutants were higher in the percolate of the first month. This type of behaviour is consistent with what has been observed in other studies on the leaching of inland sediments [START_REF] Perrodin | Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil[END_REF] and other types of polluted materials [START_REF] Delolme | Study and modeling of the stormwater pollutants transfer in urban soils: a lysimeter experiment. Ecotron and lysimeters, key tools for studying terrestrial ecosystem responses to global change, to pollutants, and the ecological engineering[END_REF][START_REF] Larmet | Facilitated transport of metals and bacteria into two infiltration basins in Lyon (France) under changing hydrological conditions: soil column study[END_REF][START_REF] Perrodin | Assessment of the ecocompatibility of waste disposal or waste use scenarios: towards the elaboration and implementation of a comprehensive methodology[END_REF][START_REF] Quina | Percolation and batch leaching tests to assess release of inorganic pollutants from municipal solid waste incinerator residues[END_REF]. The concentrations of pollutants obtained in the percolate of the first month of each of the three sediments tested are, moreover, logical given the nature of the sediments and the physicochemical properties of the pollutants concerned, i.e. (i) a very high chloride content linked to the maritime origin of the sediments, (ii) a variable heavy metal content, that can be linked in particular with the potential pH and Redox values of the sediments [START_REF] Baltpurvins | Heavy metals in wastewater: modelling the hydroxide precipitation of copper(II) from wastewater using lime as the precipitant[END_REF][START_REF] Barna | Leaching behavior of pollutants in stabilized/solidified wastes[END_REF][START_REF] Ichikawa | Amphoteric character of cadmium hydroxide and its solubility in alkaline solution[END_REF][START_REF] Quina | The influence of pH on the leaching behaviour of inorganic components from municipal solid waste APC residues[END_REF]. In the case of sediment "3", treated with hydraulic binders, and whose percolate pH exceeded 12, emphasis must be given to the very high amount of copper in solution, (iii) low content in PAHs, which are compounds hardly soluble in water, and (iv) the very marked presence of TBTs in the percolate of sediment "3". This was certainly related, once again, to the destabilisation of the sediment matrix by the hydraulic binders used to treat the sediments [START_REF] Loustau-Cazalet | Comportement et mobilisation potentielle de polluants inorganiques présents dans un sédiment marin traité à la chaux vive et aux liants hydrauliques[END_REF].

Exposure concentrations for aquatic organisms

For the "substances" approach the first observation is that the relative presence of each pollutant is the same as that of the percolates, since it was assumed that the transfer of the deposit to the river by runoff on the soil did not change the proportion of the different pollutants present. Given the dilution of the percolate in the river, the concentrations in pollutants generally appeared low, with the exception of copper and TBT in the case of sediment "3". It is noteworthy that due to this dilution the concentrations in chlorides predicted in the river (in the region of several mg/l) were quite comparable to that which can be observed for inland surface waters. Regarding the "matrix" approach, we recall that the value of 0.04% calculated for the proportion of percolate in the receiving river corresponds to the maximum, taking into account the conservative hypotheses made at the beginning of the study (value during the low flow period of the river).

Effect characterisation

Regarding the PNEC established for the "substances" approach, the value recorded for TBTs (0.1 ng Sn/l) stood out, indicating the very high toxicity of this substances for aquatic organisms [START_REF] Ineris | Fiche de données toxicologiques et environmentales des substances chimiques[END_REF]. The results of the bioassays implemented in the framework of the "matrix" approach showed that those with Brachionus calicyflorus and Pseudokirchneriella subcapitata were the most sensitive, which is consistent with the fact that they were chronic assays and also with the observations made in other studies using the same or similar batteries of bioassays [START_REF] Angerville | Évaluation des risques écotoxicologiques liés au déversement de Rejets Urbains par Temps de Pluie (RUTP) dans les cours d'eau : application à une ville française et à une ville haïtienne[END_REF]Boillot et al., 2008). The EC20, EC50, and NOEC values obtained provide a relatively similar ecotoxicity profile between sediments "1" and "2", apart from esterase activity. However, the same values are 5 to 10 times lower for the percolate of sediment "3", showing that it is far more ecotoxic. This ecotoxicity of the percolate of sediment "3" not only reflects its very high pH, but also its high copper and TBT contents, as both of the latter were present in quantities high enough to affect organisms (see previous paragraph). The ammonia present in these percolates in non ionised form (NH 3 ), due to the high pH, may also contribute to this ecotoxicity. Indeed, it is known that the toxicity of non ionised ammonia (NH 3 ) is clearly higher than that of ionised ammonia (NH 4 + ) (ATSDR, 2004).

Ecological risks

All said and done, the "substances" and "matrix" approaches both conclude in the absence of risk for the aquatic ecosystem if the quarry is filled with sediments "1" and "2" under the conditions defined for the scenario. For sediment "3", the two approaches appear to converge, as they both conclude that sediment "3" represents a high risk for the aquatic ecosystem. The "substances" approach shows that TBT and, to a lesser extent, copper, are probably the sources of the high ecotoxicity of this percolate and the ecological risk stemming from it.

Regarding the methodology

The assessment of exposure, whether by the "substances" approach or the "matrix" approach, greatly depends on the scenario's spatial and hydrological data (rainfall, surface and deposit height, orientation of the surface slope, etc.). In the case of a real project, these data must be collected with care to ensure the quality of the assessment. In the case of the present study, the initial choices regarding the definition of the scenario studied have a major impact on the result. Nonetheless, these choices were realistic in comparison to the situations that can be found in-the-field.

The assessment of the "substances" approach directly depends on the quality of the PNEC supplied by reference organisations and/or the quality of the EC20, EC50, NOEC values supplied by international databases. The assessment of effects by the "matrix" approach greatly depends on the organisms tested and the ecotoxicological parameters selected. Although the parameters in this study included growth, reproduction and genotoxic effects, they only concerned a small number of organisms which, in addition, were tested individually whereas in nature they interact with each other and with their environment. It is clear that this is a highly simplified representation of the ecosystem. Other authors have proposed more thorough batteries of bioassays to assess effects [START_REF] Charissou | Démarche optimale de sélection de batterie de bioessais pour l'évaluation écotoxicologique des milieux complexes. Synthèse bibliographique[END_REF], or worked with more representative models of ecosystems, such as microcosms and mesocosms [START_REF] Chatain | Assessment of the potential mobilization of inorganic contaminants in a French harbor sediment[END_REF][START_REF] Clément | Estimation of the hazard of landfills through toxicity testing of leachates. I. Determination of leachate toxicity with a battery of acute tests[END_REF][START_REF] Gustafsson | Benthic foraminiferal tolerance to Tri-n-butyltin (TBT) pollution in an experimental mesocosm[END_REF][START_REF] Kan | Marine microbial community response to inorganic and organic sediment amendments in laboratory mesocosms[END_REF]. Nonetheless, these approaches are far more costly and are not always "economically acceptable" when implemented in-the-field. Finally, the "real" issue is to know whether the battery of bioassays selected leads to sufficient protection of the ecosystems concerned. Furthermore, studying the integrity of DNA is interesting in the framework of risk assessment, in so far as it can forewarn of long-term effects, both for the organisms exposed and their offspring, via modifications of gene structure or expression [START_REF] Anderson | Linking genotoxic responses and reproductive success in ecotoxicology[END_REF][START_REF] Bickham | Effects of chemical contaminants on genetic diversity in natural populations: implications for biomonitoring and ecotoxicology[END_REF][START_REF] Depledge | Genetic ecotoxicology: an overview[END_REF][START_REF] Devaux | Monitoring of the chemical pollution of the river Rhône through measurement of DNA damage and cytochrome P4501A induction in chub (Leuciscus cephalus)[END_REF][START_REF] Larno | Responses of chub (Leuciscus cephalus) populations to chemical stress, assessed by genetic markers, DNA damage and cytochrome P4501A induction[END_REF][START_REF] Würgler | Environmental effects of genotoxins (eco-genotoxicology)[END_REF]. In the case of the present study, measuring the potential genotoxicity of matrixes measured using fish cell models constitutes a fairly novel approach which, despite the numerous validation steps required, could provide a simple tool in the future capable of assessing genotoxicity in a eukaryote cell model in the batteries of bioassays used to assess ecotoxicological risks.

The quotient method chosen to calculate and express risks is fast and well-suited for communicating results. However, it is a rather cursory means of characterising risks as it relies on several simplifications: (i) effects and exposure are both synthesised in one value, which can obscure conceptual biases; (ii) it does not readily take indirect effects into account. Other risk characterisation methods can be used in certain contexts [START_REF] Babut | Évaluation écotoxicologique de matériaux de dragage -(1) présentation et justification de la démarche. Cemagref, ENTPE, VNF[END_REF]; US EPA, 1998): (i) qualitative methods that characterise risk in two or three categories, for example, strong/weak/average, usually on the basis of expert opinion [START_REF] Rivière | Évaluation du risque écologique des sols pollués[END_REF]. They are used for comparative approaches (e.g., two types of contamination), (ii) methods incorporating the entire pollutant/response relation, making it possible to estimate the level of risk associated with a given exposure level. These methods are especially useful for testing several risk reduction options, or when different exposure (as a function of time or geographical region) and/or effect (chronic/acute) concentrations exist [START_REF] Klaine | An ecological risk assessment for the use of the biocide, dibromonitrilopropionamide (DBNPA), in industrial cooling systems[END_REF][START_REF] Solomon | Ecological risk assessment of atrazine in North American surface waters[END_REF].

Conclusion

This study showed that it is possible to assess risks for peripheral aquatic ecosystems caused by a deposit of dredged seaport sediments in a quarry, by using relatively accessible and mostly standardised ecotoxicological investigation methods. The method proposed here, which combined "substances" and "matrix" approaches, showed its efficiency for the three sediments tested: the "substances" approach showed that TBT, and to a lesser extent, copper, were probably the sources of a large proportion of the ecotoxicological risk, whereas the "matrix" approach provided a more realistic assessment, due in particular to the toxicity linked to the pH of the matrix, the inclusion of all the substances present in the percolate (including those not analysed), and the ecotoxicological interactions between substances liable to spur synergetic or antagonistic phenomena [START_REF] Altenburger | Predictability of the toxicity of multiple chemical mixtures to Vibrio fischeri: mixtures composed of similarly acting chemicals[END_REF][START_REF] Calamari | An approach to theoretical models in evaluating the effects of mixtures of toxicants in the aquatic environment[END_REF][START_REF] Deneer | Toxicity of mixtures of pesticides in aquatic systems[END_REF][START_REF] Hermens | Joint toxicity of chemicals to Guppy (Poecilia reticulata)[END_REF][START_REF] Vighi | Water quality objectives for mixtures of toxic chemicals: problems and perspectives[END_REF]Walter et al., 2002;[START_REF] Warne | A review of the ecotoxicity of mixtures, approaches to, and recommendation for, their management[END_REF][START_REF] Warne | The number of components in a mixture determines whether synergistic and antagonistic or additive toxicity predominate: the funnel hypothesis[END_REF].

Other ecological risk assessment approaches related to sediment deposits have been proposed, notably for inland sediments (USACE, 1998a(USACE, , 1998b)). The aim of our approach, adapted to marine sediments and combining two complementary approaches, was to improve understanding of the global process leading to ecotoxicological risk and the realism of the assessment in view to optimising decision-making at management level.

For all that, the methodology presented can, and must, undergo further improvement in several directions to permit its operational integration in procedures defined by organisations in charge of managing sediments. This validation will require in situ studies of aquatic communities performed simultaneously and comparatively with the chemical analyses and ecotoxicity tests included in our methodology, in order to verify the predictive nature of the assessment performed. It will also be advisable to check whether the battery of bioassays selected can be reduced or else must be completed. When considering this point, it must be borne in mind that reducing the number of biological responses by reducing the number of tests will lead to increasing the imprecision of ecotoxicity results, thereby augmenting the uncertainty relating to the characterisation of the risk due to the need to raise the number of applicable safety factors. Consequently, the gains made on the one hand could be detrimental to subsequent decision-making on the other. What is more, the works intended to improve the final phase of risk characterisation, currently based only on the quotient method, and to strengthen the expression of the results with the associated uncertainty, must be carried out to ensure optimal utilisation of the tool developed.

Lastly, it will be necessary to complete the investigations performed by studying the ecological risks linked to the two potential indirect phenomena not taken into account in the methodology presented: (i) the bioaccumulation and biomagnification of the pollutants in the organisms and trophic chains; and (ii) the potential eutrophication of rivers linked to the discharge of nutritive substances, in particular phosphates.

Fig. 1 .

 1 Fig. 1. General diagram of ecological risk assessment (US EPA, 1998).

•

  Metals: Standard NF EN ISO 11885, • Chlorides: Standard ISO 10304-1 2007, • PAHs: Standard ISO/WD/7981, • Ammonium: Standard NF T 90-015-1, • TBT: Standard ISO 17353.

Fig. 2 .

 2 Fig. 2. Presentation of the studied scenario.

Fig. 3 .

 3 Fig. 3. Conceptual model of the scenario studied.

Table 1

 1 Selected risk tracer substances-Selected criteria.

	Metals (As, Cd, Cr, Pb, Zn, Hg, Sn, Cu, Ni,..)
	Toxic at low or middle concentrations
	TBT and its derivatives DBT et MBT
	Toxic for aquatic organisms at very low concentrations
	PAHs
	Some PAHs are mutagenic and carcinogenic
	Chlorides
	Chlorides are harmful for inland organisms at strong concentrations
	Ammonium (NH 4

+ )

Toxic for aquatic organisms, especially in its non ionised form (NH3)

Table 2

 2 Spatial and numerical data of the studied scenario.

	Dimensions of the sediment deposit
	10 m high
	100,000 m² surface area
	1,000,000 m 3 volume
	River discharge
	1 m 3 /s i.e. 315 ⁎ 10 5 m 3 /year
	Climatic elements
	Annual rainfall: 900 mm
	Rate of evapotranspiration at the surface of the deposit: 70%
	Distribution of leachate flowing from the deposit
	50% to groundwater and 50% to river

Table 3

 3 Bioassays selected for the "matrix approach".

	Organisms	Duration	Effects	Parameters	Protocol	References
	Vibrio fischeri	30 min	Luminescence	EC50	Normalised	NF EN ISO 11348
	Daphnia magna	24 h	Mobility	EC50	Normalised	NF EN ISO 6341
	Brachionus calicyflorus	48 h	Reproduction	EC20	Normalised	NF T90-378
	Pseudokirchneriella subcapitata	72 h	Population growth	EC20	Normalised	NF T90-375
	Pseudokirchneriella subcapitata	24 h	Enzymatic reaction speed (esterase)	LOEC	Standard	Barthet et al. (2003)
	Trout cell-lines (RTG-W1 and RTL-W1)	24 h	Cytotoxicity	LOEC	Standard	Dayeh et al. (2003)
	Trout cell-lines (RTG-W1 and RTL-W1)	24 h	Genotoxicity	DNA Damage	Standard	Kienzler et al. (2012)
			(Comet Assay)

EC50: Effect concentration for 50% of organisms. EC20: Effect concentration for 20% of organisms. ISO: International Standard Organization.

Table 4

 4 Physicochemical analyses of percolates, and PEC of the 3 sediments.

		Sediment 1		Sediment 2		Sediment 3
		Percolate	PEC	Percolate	PEC	Percolate	PEC
	pH	7.0		7.1		12.4
	Conductivity (μS/cm)	33,500		37,700		23,600
	RedOx potential(mV)	397		367		110
	NH 4 + (μg/l)	900	0.38	200	0.086	2170	0.93
	Chlorides (mg/l)	10,890	4.67	12,310	5.27	5842	2.50
	Metals (μg/l)
	As	4	0.0017	4	0.0017	4	0.0017
	Cd	1	0.0004	1	0.0004	1	0.0004
	Cr	1	0.0004	43	0.0184	194	0.0831
	Pb	137	0.0587	22	0.0094	22	0.0094
	Zn	3510	1.5045	2270	0.9729	36	0.0154
	Sn	4	0.0017	4	0.0017	4	0.0017
	Cu	515	0.2207	642	0.2751	18,800	8.05
	Ni	64	0.0274	2	0.0008	522	0.2237
	TBT (ng Sn/l)	b 50	b0.0214	b50	b 0.0214	118,600	50.83
	PAHs (ng/l)
	Fluoranthène	5	0.0021	5	0.0021	7	0.0030
	Phénanthrène	5	0.0021	5	0.0021	36	0.0154
	Pyrène

Table 6

 6 Ecotoxicity of percolates of the 3 sediments studied.

	Organisms	Effects	Parameters	Sed 1 Sed 2 Sed 3
	Vibrio fischeri	Luminescence	CE50	15%	24%	2.2%
	Daphnia magna	Mobility	CE50	Non	Non	0.5%
				toxic	toxic
	Brachionus calicyflorus	Reproduction	CE20	1.0% 0,6% 0.14%
	Pseudokirchneriella	Population	CE20	1.0% 2%	0.13%
	subcapitata	growth
	Pseudokirchneriella	Enzymatic	Significant	1.0% No	0.4%
	subcapitata	activity	effect		effect
		(esterase)
	Trout cell lines (RTG-W1	Cytotoxicity	Significant	5%	1%	0.5%
	and RTL-W1)		effect
	Trout cell lines (RTG-W1	Génotoxicity	Significant	No effect
	and RTL-W1)	(Comet assay)	DNA damage

Table 5

 5 PNEC and "Q" of sediment percolates as a function of the "substances approach".

	Substances	Aquatic PNEC	Q	Q	Q
			Sediment 1	Sediment 2	Sediment 3
	Chlorides (mg/l)	230	0.020	0.023	0.011
	NH 4 + (μg/l)	5	0.077	0.017	0.18
	Metals (μg/l)
	As	4.40	≪1	≪1	≪ 1
	Cd	0.75	≪1	≪1	≪ 1
	Cr	4.70	≪1	≪1	≪ 1
	Pb	5.00	≪1	≪1	≪ 1
	Zn	8.60	0.17	0.11	0.17
	Sn	2.70	≪1	≪1	≪ 1
	Cu	0.40	0.55	0.68	20.1
	Ni	4.70	≪1	≪1	0.047
	TBT(ng Sn/l)	0.1	0.21	0.21	508
	PAHs (ng/l)
	Fluoranthene	120.0	≪1	≪1	≪ 1
	Phénanthrene	1340	≪1	≪1	≪ 1
	Pyrene	12.0	≪1	≪1	≪ 1
	Acénaphtene	3700	≪1	≪1	≪ 1
	Benzo(b) fluoranthene	30	≪1	≪1	≪ 1
	Benzo(g, h, i)perylene	1.6	≪1	≪1	≪ 1
	Naphtalene	12,000	≪1	≪1	≪ 1
	Indenol(1,2,3 c,d)pyrene	3.0	≪1	≪1	≪ 1
	Benzo(k)fluoranthene	36.0	≪1	≪1	≪ 1
	Anthracene	63.0	≪1	≪1	≪ 1
	Fluorene	250.0	≪1	≪1	≪ 1
	Benzo(a) anthracene	650.0	≪1	≪1	≪ 1
	Benzo(a) pyrene	50.0	≪1	≪1	≪ 1

Acknowledgements

We thank all the teams that participated in the "SEDIGEST" research programme focusing on the assessment of ecological risks linked to filling-in coastal quarries with treated, dredged seaport sediments, and which belonged to the following organisations: ENTPE, INSA de Lyon, BRGM, INSAVALOR, INERIS, IN VIVO Environment, CETMEF, CG 83, CG 29 and EEDEMS. The details of all the participants in the programme can be consulted on the internet site www.sedigest.org. We also thank the French National Research Agency (ANR) and the "AXELERA", "Mer PACA" and "Mer Bretagne" clusters respectively for their financial assistance and the labelling assigned to the SEDIGEST project.


Xinwei Chai

Tony Ribeiro

Morgan Magnin

Olivier Roux

Katsumi Inoue

Using Reachability Properties of Logic Program for Revising Biological Models

Keywords: Model Checking, Learning From Interpretation Transition, Dynamical Systems, Temporal Properties, Local Causality Graph

Learning system dynamics from the observations of state transitions has many applications in bioinformatics. It can correspond to the identification of the mutual influence of genes and can help to understand their interactions. A model can be automatically learned from time series data by using methods like Learning from interpretation transition (LFIT). This method learns an exact model if all transitions of the systems are used as input. However, in real biological data, such complete data sets are usually not accessible and we have to learn a system with partial observations. Usually, biologists also provide with a priori knowledge about the system dynamics in the form of temporal properties. When building models, keeping critical properties valid is one of the major concerns and model checking plays a role in the verification of such desired properties. Our research aims at providing a model checking approach to revise logic programs thanks to temporal properties. In this paper, as a first step, we propose a method that can exploit reachability properties to fit such a model.

Introduction

When modeling a real system, it is usually demanded to assess the correctness of a Boolean network with the concrete system by checking if the observed configurations are indeed reachable in the Boolean network. Whenever it is not the case, it typically means that the designed Boolean functions do not model the given system correctly, and thus should be revised before further model analysis. In [START_REF] Inoue | Logic programming for boolean networks[END_REF], it has been shown that Boolean networks can be represented by logic programs. In this paper, we provide a method to revise a logic program to fit temporal properties regarding reachability of partial states. Such logic program can be learned from observations of state transition using LFIT algorithm in [START_REF] Ribeiro | Learning prime implicant conditions from interpretation transition[END_REF], but the approach restricts the model to only synchronous update scheme. One of the benefits of synchronous modeling is computational tractability, while classical state space exploration algorithms fail on asynchronous ones. Yet the synchronous modeling relies on quite heavy assumptions: all genes can make a transition simultaneously and need an equivalent amount of time to change their expression level. Even if this is not realistic from a biological point of view, it is usually sufficient as the exact kinetics and order of transformations are generally unknown. However, the asynchronous semantics helps one to capture more realistic behaviors [START_REF] Bernot | Behaviour preservation of a biological regulatory network when embedded into a larger network[END_REF]. At a given time point, at most one single gene can change its expression level. Non-deterministic behaviors are often observed in biological systems, e.g. cell differentiation. From a given state, several possible behaviors can be expected as future states. Asynchronous update scheme results in a potential combinatorial explosion to the number of states. The first contribution of this paper is a simple adaptation of the LFIT algorithm for learning asynchronous dynamics. The main contribution is a method to revise a logic program in order to fit given reachability properties. Reachability problem on formal models is a critical challenge where both validation (whether the model satisfies a priori knowledge) and prediction (properties to be discovered) problems meet. From a formal point of view, numerous biological properties can be expressed in computation models as reachability properties [START_REF] Clarke | 2 5 years of model checking[END_REF]. Existing approaches usually rely on global search and thus face state space explosion problem as the state space grows exponentially with the number of components of model. Abstraction is an efficient strategy to deal with such systems. In [START_REF] Paulevé | Static analysis of biological regulatory networks dynamics using abstract interpretation[END_REF], local properties of the model are exploited based on an abstract interpretation: Local Causality Graph (LCG). [START_REF] Chai | A Heuristic for Reachability Problem in Asynchronous Binary Automata Networks[END_REF] provides a hybrid reachability analyzer based on LCG, with which one can verify the model is consistent with given reachability information with good runtime and conclusiveness. LFIT framework so far can only capture finite dynamical properties, i.e. relation at T -1 or T -k and the system has to be synchronous deterministic. In asynchronous systems, non-determinism can lead to loops for several times before taking a path to a certain state. In this paper, we adapt the algorithms of [START_REF] Ribeiro | Learning prime implicant conditions from interpretation transition[END_REF][START_REF] Martínez | Learning probabilistic action models from interpretation transitions[END_REF] to capture asynchronous dynamics and extend upon this method to propose an approach allowing to fit a logic program to reachability properties. By modifying rules of the program using logic generalization/specialization operations, we iteratively revise the program to fit a set of reachability/unreachability constraints while keeping the observation and learned rules consistent.

Formalization

Boolean asynchronous systems can be non-deterministic, thus from the same state a variable can take both value 0 or 1. To encode this dynamics, one requires to have explicit rules for each value of a variable and the modeling of [START_REF] Ribeiro | Learning prime implicant conditions from interpretation transition[END_REF] is not suitable. In [START_REF] Martínez | Learning probabilistic action models from interpretation transitions[END_REF], we proposed a modeling of multi-valued synchronous systems as annotated logic program. This modeling can be applied to repre-sent Boolean asynchronous systems and is recalled in the following section. In order to represent multi-valued variables, all atoms of a logic program are now restricted to the form var val . The intuition behind this form is that var represents some variable of the system and val represents the value of this variable. In annotated logics, the atom var is said to be annotated by the constant val. We consider a multi-valued logic program as a set of rules of the form

var val ← var val1 1 ∧ • • • ∧ var valn n (1)
where var val and var vali i 's are atoms (n ≥ 1). For any rule R of the form (1), left part of ← is called the head of R and is denoted as h(R), and the conjunction to the right of ← is called the body of R. We represent the set of literals in the body of R of the form [START_REF] Bernot | Behaviour preservation of a biological regulatory network when embedded into a larger network[END_REF]

(R) ⊆ s. A rule R subsumes a rule R when h(R) = h(R ), b(R) ⊆ b(R )
. A Boolean Asynchronous system can be represented by a multi-valued logic program. This section provides the necessary additional formalization to interpret asynchronous dynamics by such program and to learn from state transitions.

Modeling and learning of asynchronous dynamics

Due to the non-deterministic nature of asynchronous systems and its restriction to atmost one variable change per transition, the notion of consistency, realization and successor has to be adapted as follows.

Definition 1 (Consistency). Let R be a rule and E be a set of state transition We now adapt the LFIT algorithm of [START_REF] Ribeiro | Learning prime implicant conditions from interpretation transition[END_REF] to the learning of asynchronous systems. In synchronous case, the rules R learned by LFIT represent a necessity: h(R) will be in the next state if R match the current state. In asynchronous case, the rules represent a possibility: h(R) can be in next state if R match the current state. It allows the modeling of non-determinism: two rules R, R can have the same head variables but different values and match the same state which occurs in these case: h(R) = var val , h(R ) = var val , val = val and

(I, J). R is consistent with E iff b(R) ⊆ I implies ∃(I, J) ∈ E, h(R) ∈ J. A logic program P is consistent with E if
var val ∈ b(R), var val ∈ b(R ) =⇒ val = val .
Like in previous versions, LFIT takes a set of state transitions E as input and outputs a logic program P that realizes E. In [START_REF] Martínez | Learning probabilistic action models from interpretation transitions[END_REF] multi-valued least specialization was used to learn multi-valued synchronous systems dynamics. Starting from the most general rules, least specialization allows to learn the minimal rules of such system iteratively from its state transition (I, J) ∈ E. For every possible var val , var val ∈ J the most specific rule that is not consistent, with the transition, i.e. an anti-rule, was generated: M SR := var val ← I. Here, for the asynchronous case, this anti-rule is generated and the revision occurs only if (I, J ) ∈ E, var val ∈ J , i.e. it is impossible to have a transition to var val from I. Each rule of the currently learned program P that subsumes such an anti-rule are specialized using least specialization. The resulting program P is consistent and realizes all previously treated transition plus (I, J). Doing so iteratively for each transitions, the algorithm output a program P which model the dynamics of the system observed in the transitions E.

Asynchronous LFIT

• INPUT: B a set of annotated atoms and E a set of transitions • Remove all the rules in P subsumed by a rule in P .

• Initialize P := {var val ← ∅ | var val ∈ B} • For each (I, J) ∈ E -For each var val ∈ B * If (I, J ) ∈ E,
• Remove all the rules in P subsumed by a rule in P .

• Add all remaining rules in P to P .

• OUTPUT: P

Reachability analysis

In the following definitions α is a state and ω a local state.

Definition 4 (LCG). Given a logic program P , an initial state α and a target state ω, LCG(P, α, ω) = (V state , V rule , Edges) is the smallest recursive structure with Edges ⊆ (V state × V rule ) ∪ (V rule × V state ) which satisfies:

ω ∈ V state a i ∈ V state ⇔ {(a i , R)|a i ∈ α, h(R) = a i } ⊆ Edges R ∈ V rule ⇔ {(R, b(R))} ⊆ Edges
where V state ⊆ LS and V rule ⊆ P are the vertices of LCG.

Definition 5 (Trajectory). Given a logic program P and s 0 = α, a trajectory t from α is a sequence of rule-state pairs t = (R 1 , s 1 ) :: . . . :: (R i , s i ) :: . . . :: (R n , s n ) s.t each i > 0, s i ∈ T as P (s i-1 , P ),

s i = (s i-1 \v val ∈ s i-1 )∪v val , h(R i ) = v val ), b(R) ⊆ s i-1 . From α, the reached state s n by t is denoted α • t.
Definition 6 (Reachability). Given a logic program P , ω is said reachable in P from α iff there exists a trajectory t s.t. α • t = ω and is denoted reachable(P, α, ω), otherwise unreachable(P, α, ω).

Definition 7 (Consistent program). Let P be a logic program, Re (resp. U n) be a set of reachability (resp. unreachability) properties. P is said to be consistent with Re (resp.

U n) iff ∀(α, ω) ∈ Re, ∃ a trajectory t in P s.t. α.t = ω and ∀(α, ω) ∈ U n, a trajectory t in P s.t. α.t = ω.
Specializing a rule is to add elements in the body of a rule, thus to make the condition of a rule more difficult to be satisfied (in a more specialized situation) as the condition of firing becomes more strict.

Definition 8 (Least Specialization of a rule). Let R be a rule, a least special-

ization of R is a rule R ∈ ls(R) := {h(R) ← b(R) ∪ {var val }, var val ∈ b(R)}.
If R contains already all the variables in its body, the only way to specialize R is to remove R.

Similarly, generalization of a rule is to remove certain elements in the body of a rule, thus to make the condition of a rule easier to be satisfied. Definition 9 (Least Generalization of a rule). Let R be a rule, a least gener-

alization of R is a rule R ∈ lg(R) := {h(R) ← b(R) \ {x}, x ∈ b(R)}.
Definition 10 (Revisable). A logic program P is said revisable w.r.t. a reachability (resp. unreachability) property if: ∃P ∈ {(P \ R P ) ∪ {R | R ∈ R P , R ∈ ls(R) ∪ lg(R)}} | R P ⊆ P }. P is revisable w.r.t. to a set of property S: if their exists an ordering S of the elements of S such that each ith revision, 0 ≤ i ≤ |S |, (P being the 0th revision) is revisable w.r.t. the i + 1th property.

From definition 10, it follows that the revision of logic program P w.r.t. a set of reachability/unreachability properties S can be found (or proved to be non-existent) by brute force enumeration of all possible ordering of S and trying all possible iterative revisions of P . In the next section we propose an algorithm exploiting the LCG structure to restrict the search to valid ordering of the properties.

Algorithm

In this section we propose an algorithm that exploits the previous formalization to fit a logic program to reachability properties. Given a set of transition E of an asynchronous system S, a logic program P is learned via the adaptation of LFIT of section 2.1. When E is partial, the learned program P does not have the exact dynamics of S. Given a set of reachability properties Re and a set of unreachability properties U n of S, we propose an algorithm to revise P so that the dynamics of P satisfy S. As discussed previously, this can be done by complete brute force but here we propose a first attempt to reduce the search space. Furthermore, our aim is to find what could be considered a metric of minimal revision of P : a revision P s.t. P , (P \ P ∩ P ) ⊆ (P \ P ∩ P ) Specialization/generalization operations aim to revise the rule nearest to the target state in the LCG. If it is not possible, they try to revise the successor, if there is no possible solution, return ∅ to show the input logic program is not revisable. Specialization operation is limited by the observation. If P after specialization can not explain all the transitions, the specialization is not admissible. Generalization is similar but without the constraint of the observation, as the observation is partial, P may describe some state transitions never observed. Specialization:

• Input: a logic program P , an unsatisfied element (α, ω), a reachable set Re, an unreachable set U n

• Output: modified logic program P or ∅ if not revisable 1. Rev ← {ω} 2. For each R s.t. h(R) = Rev, for each R ∈ {R |R ∈ ls(R) ∧ (I, J) ∈ E, s.t. R ∈ P ∪ {R } \ {R}, h(R ) ∈ J, b(R ) ∈ I} • If P ← P \ {R} ∪ {R },

Conclusion

In this paper, we strengthen the capability of LFIT framework to the learning of Boolean asynchronous systems in the form of logic programs. Asynchronicity implies non-determinism which is meaningful to the modeling of uncertain parts in biology. We propose a method revising the logic program learned by LFIT w.r.t. the knowledge on reachability properties. If the logic program is revisable, the revision is consistent with both state transitions and reachability information. However, our algorithm does not guarantee the minimal revision of the logic program. As future works, considering the metric for minimal revision and designing a related algorithm will be interesting. Adapting more dynamical properties other than reachability also remains as our future work.

  all rules of P are consistent with E. Definition 2 (Program realization). Let P be a logic program and E be a set of state transitions.P realizes E if ∀(I, J) ∈ E, ∃R, b(R) ⊆ I, (I \ J) = {h(R)}.Definition 3 (Asynchronous successors). Let I be the current state of an asynchronous system represented by a set of multi-valued rules S. Let T P (I, S) = {h(R)|R ∈ S, b(R) ⊆ I}. The successors of I according to S is T as P (I, S) = {I \ {v val } ∪ {v val }|v val ∈ I, v val ∈ T P (I, S)} ∪ {I | T P (I, S) = ∅}

  var val ∈ J * M SR := var val ← I * Extract each rule R of P that subsumes M SR: M R := {R ∈ P | h(R) = var val , b(R) ⊆ I}, P := P \ M R * For each R ∈ M R • Compute its least specialization P = ls(R, M SR, B).

  as b(R) = {var val1 1 , . . . , var valn n }. A rule R of the form (1) is interpreted as follows: the variable var takes the value val in the next state if all variables var i have the value val i in the current state. A state of a multi-valued program provides the value of each variable of the system and a transitions is a pair of states. The value of a variable in a state is called a local state. The set of all local state is denoted LS. The subset of state is called a partial state. A rule R matches a state s when b

  Rev ← {ω} 2. For each R s.t. h(R) = Rev, for each R ∈ lg(R) • If P ← P \ {R} ∪ {R },reachable(P , α, ω) and P satisfies all previous properties, return P 3. Rev ← b(R) with h(R) = Rev and back to step 2 4. There is no revision for (α, ω), return ∅

unreachable(P , α, ω) and P satisfies all previous properties, return P 3. Rev ← b(R) with h(R) = Rev and back to step 2 4. There is no revision for (α, ω), return ∅ Generalization:

• Input: a logic program P , an unsatisfied element (α, ω), a reachable set Re, an unreachable set U n

• Output: modified logic program P or ∅ if not revisable 1.

Complete revision:

• Input: a logic program P , a reachable set Re and an unreachable set U n The main algorithm starts with constructing the LCGs to verify Re and U n in order to ensure the reachability/unreachability properties to be satisfied. Then, for the unsatisfied properties, the program P has to be revised. LCG can share the elements s.t. revising one can modify the others. By starting with the LCGs with least dependencies with others, i.e. the ones with the smallest cardinality of l i , it increases the chance of partially satisfying other unsatisfied properties (step 3 and 4). Then all possible revision of P are generated using least specialization or generalization according to l i ∈ Re or l i ∈ U n (step 6 and 7). Each revision of P is checked against Re and U n to verify that all properties satisfied by P are still satisfied. If new ones are satisfied, L is updated accordingly (step 5). We update P until there is no unsatisfied properties (step 8 and 9). Finally, if a revision of P consistent with all given properties is found the algorithm terminates and output it.