Évaluation de l'efficacité d'une couche de recouvrement par modélisation numérique : application au cas du Fjord du Saguenay

Suite au déluge qui a marqué la région du Saguenay en 1996, une couche de nouveaux sédiments a recouvert les sédiments du secteur amont du fjord du Saguenay. Avant le déluge cette zone était caractérisée par la présence de sédiments contaminés, associés au déversement incontrôlé d’effluents liquides, pratiqué dans le passé par les industries de la région. La couche de sédiments déposés en 1996 a enfoui les sédiments contaminés et constitue donc une barrière isolante composée de matériaux plus propres. Afin d'estimer l'efficacité à long terme de la couche, un nouveau modèle numérique (TRANSCAP-1D) a été développé. Ce modèle simule la migration de composantes dissoutes dans une colonne de sédiments et considère l'advection, la diffusion/dispersion, et l'effet de la bio-irrigation. La formulation mathématique représente un milieu à double porosité, composé de pores et de trous ou tubes de vers. Le modèle a été calé avec les profils de concentration de l'arsenic dissous qui ont été mesurés à deux stations du fjord du Saguenay, après la déposition de la couche de recouvrement naturelle. Par la suite, une analyse de sensibilité a été réalisée afin d'évaluer l'impact de certains paramètres caractérisés par une variabilité ou incertitude importante aux sites à l'étude. Les résultats montrent que les paramètres associés à la bio-irrigation ont un impact significatif sur la migration des contaminants dissous vers la colonne d'eau. Par la suite, nous avons réalisé une analyse d'incertitude en utilisant la méthode Monte Carlo et les résultats ont été intégrés dans une analyse de décision pour le design d'une couche de recouvrement potentielle. Le cas présenté est hypothétique et concerne la réhabilitation d'un site contaminé qui est fréquenté régulièrement par la population de bélugas du Saint Laurent. L'exemple illustre les avantages de l'application de l'analyse de décision pour trouver l'alternative correspondante au coût total plus bas, en considérant les coûts et les risques d'échec associés au projet de réhabilitation.In 1996 two days of intense rainfalls caused severe flooding in the Saguenay region and a new sediment layer was deposited on the upstream area of the Saguenay fjord. In the past, this area was exposed to the uncontrolled discharge of industrial effluents and the sediments were contaminated. The new sediment layer buried the contaminated sediments and constitutes a natural barrier of cleaner material, which isolates the contaminants from the water column. A new numerical model (TRANSCAP-1D) was developed in order to estimate the effectiveness of the natural barrier in isolating the contaminated sediments from the overlying water column. The model simulates the migration of dissolved compounds in a sediment column and includes advection, diffusion/dispersion and the effect of bio-irrigation. The mathematical formulation represents a double porosity medium, composed of sediment pores and tubes or burrows dug by worms. The model was calibrated using the concentration profiles of dissolved arsenic measured at two stations of the Saguenay fjord, after the capping event. Thereafter, a sensitivity analysis was performed in order to evaluate the impact of certain parameters showing a great variability and uncertainty at the studied sites. The results indicate that the parameters associated to bio-irrigation have a significant impact on the migration of dissolved contaminants towards the water column. Thereafter, we performed an uncertainty analysis, using the Monte Carlo method. The results were integrated in a decision analysis for the design of a capping layer in a hypothetical case of sediment remediation. The presented case considers a contaminated site regularly frequented by the beluga population of the St. Lawrence Estuary. The example illustrates the advantages of the application of the decision analysis method, which is used to find the least cost option, considering the costs and failure risks associated to the remediation project

Dynamic Modelling of the Fate of DDT in Lake Maggiore: Preliminary Results

Release of chemical substances significantly impacts European waters. Impacts are both direct and indirect, through degradation products, acute and/or chronic toxicity, and/or long-term effects via bioaccumulation in aquatic food chains. As the number of substances is large and measures to reduce emission are costly and time demanding, there is a necessary prioritisation of the efforts through risk assessment studies requiring exposure data, which are both scarce and difficult to obtain. This is complicated by the fact that contaminants may reach the aquatic environment and hence biota and sediments, through several routes ranging from atmospheric deposition (airshed), diffuse and/or point sources in the watershed. Furthermore, a contaminant may arrive constantly during the year or in a pulse due to an accidental release or periodically driven by environmental fluctuations. For these reasons, as a first step, we have developed a model to simulate the fate of DDT family, i.e. pp’DDT, pp’DDD, pp’DDE, op’DDT, op’DDD, op’DDE, in Lake Maggiore. The model is 0D and consists on a dynamic mass balance that includes a time-variable chemical transport and fate model for calculating DDT concentrations in the water column as well as and in sedimentsJRC.H.5-Rural, water and ecosystem resource

Linking Terrestrial and Aquatic Ecosystems: Complexity, Persistence and Biodiversity in European Food Webs

In this work we have defined and analyzed the network structure, properties and composition of cohesive sub webs in two food web networks at two selected European sites: Ferto lake in Hungary and Ria Formosa lagoon in Portugal, respectively. The main objective of this work was to test and to apply a coherent methodology for the definition and analysis of trophic networks in typical European ecosystems. Persistence and cohesion of the two networks have been determined and studied. Moreover the biodiversity in terms of number of species have been measured. Several preliminary conclusions can be drawn on a basis of results obtained from application of network analysis indices and dynamical simulation. In terms of ecosystem stability the lake Ferto network (persistence 0.42) seems more stable than Ria Formosa (persistence 0.26), but if we consider the stability of the main k-core, we obtain opposite results (0.48 and 0.50 respectively). Taking into account the distribution of species in the k-core partition, the general structure of Ria Formosa network appears more complex than Ferto lake. In both networks a main core containing species taxonomically different is present, but in the Ria Formosa network (37.7%) the proportion of species inside the core is lower than in Ferto lake (60%), this can be an indication that the dimension of the main core is not related to size of the network in real ecosystems. This hypothesis is confirmed by results obtained from k-core partition of simulated networks. In both studied networks the cohesion (measured in terms of mean density and degree) of k-cores is greater than k-cores extracted from simulated networks generated by different models, this may indicate a complex and not arbitrary structure of ecological networks, not easily reproducible by models. In general the approach used appears to be able of defining the main proprieties of the trophic networks examined. The extension to other European ecosystems is needed for having a clearer and complete picture and to use data collected to simulation of different scenarios, afterwards the effects on network structure and ecosystem biodiversity as a function of different European environmental policies could be assessedJRC.H.5-Rural, water and ecosystem resource

The Use of Data and Models for Assessing the Equilibrium Partitioning Approach for Analysising Environmental Quality Standards in the Water Column and in the Sediments

An analysis of experimental and simulated data has been performed to study the relationships between EQS defined for surface waters in the Daughter Directive (COM (2006) 397) and possible EQS defined for sediments. From the above analysis of experimental and simulated data, it is clear that even though there is a coupling between water column and sediments, it is not possible to assess the chemical quality status of sediments based on water column data and viceversa. At the moment EQS have been defined for the water column and therefore these EQS will assess only the compliance with good chemical status of surface waters. If EQS were to be defined for sediments, these EQS will not reflect systematically the surface water quality and therefore they could not be used for this purpose, being the contrary is also true, i.e. compliance with EQS values for water column does not reflect sediment chemical status. However, it is clear that the good chemical quality of a water body will depend on having good chemical quality of surface water and sediments and that to assess both it is necessary to measure in both media. The same EQS developed for water could, in principle, be applied to porewater, hence, there is no need of developing another set of EQS. If porewater could not be measured, then the partitioning approach to pass to sediment concentrations should be applied. However, in this case an additional uncertainty is added to the procedure and therefore it is necessary to develop to develop new techniques and better databases since at the moment the predictions are between several orders of magnitude, which are not adequate for setting EQS. Additionally, the use of this approach would certainly require the characterization of the sediments in terms of its physical (grain size, material, temperature), chemical (organic matter content, black carbon, pH, redox, etc.) and biological (e.g. bioturbation), which at the moment are not obtained from standard environmental monitoring.JRC.H.5-Rural, water and ecosystem resource

Modelling Mesocosm Experiments

In this report, an integrated model including fate of and effects of contaminants on an ecological model is presented. The aim is to simulate the dynamic behaviour of the mesocosm experiments carried out at NERI (see D431-D433) to elucidate the combined effects of nutrients and contaminants at ecosystem level.The outcome of the simulation highlighted some strengths and weaknesses of the methodology. On the one hand it is shown that it is possible to represent the main dynamics observed in a mesocosm experiment over a relatively short time (11 days) with a rather simplified food-web model. This confirms that the model contains the features necessary to represent the system correctly even on a small scale. On the other hand some of the parameters, e.g. the shape of the dose-response curve for phytoplankton and zooplankton, had to be fitted with a very limited amount of experimental data. More research would be necessary to elucidate this. The difference between the enriched and non enriched communities was not that obvious to represent in the model, since the data on and concentrations in the enriched and non-enriched systems are similar. If the nutrient concentration could be kept higher during the experiment, e.g. by means of more additions, it would be easier to see a difference in the simulations.JRC.H.5-Rural, water and ecosystem resource

Integrated Modeling of Fate and Effects of Persistent Organic Pollutants in Marine Ecosystems

In this report, an integrated model including fate of contaminants and ecological models it is presented. The model has been developed in the framework of the Thresholds project for analysing the effects of contaminants at ecosystem level. The fate model was already presented in D2.6.2 where the major families of POPs (PCDD/Fs, PCBs, PAHs and PBDEs) were implemented. In this work a simple ecological model has been incorporated in the fate model and coupled with it in terms of organic matter. The model allows estimating the environmental concentrations of POPs and the main fluxes between compartments, i.e. air/water/sediments and organisms. In addition the model has been validated for PAHs based on experimental data available in literature and it is now used to analyse NERI’s mesocosm experiments where combined effects of nutrients and contaminants are assessed. Furthermore, the model is being validated with other contaminants families as the experimental results from Thresholds campaigns are starting to be available.JRC.H.5-Rural, water and ecosystem resource

Thresholds of Contaminants: A Synthesis

A fundamental problem in ecotoxicology is the prediction of long term population and ecosystem-level effects of contaminant exposure based on dose response data of few individuals obtained over a short time period. In addition, environmental fluctuations will always affect significantly the population/ecosystem resilience. However, these fluctuations are not taken into account under dose-response experiments on individuals. In the Thresholds project we have analyzed some of these questions by using experiments, data analysis tools and modelling approaches. Several important finding may be summarized as follows: 1 Molecular level effects are detected even at concentrations that did not affect the macroscopic end point studied, i.e. growth rate. 2 Natural populations are more sensitive that populations in cultures. 3 There are differences for the same species at different environments, e.g. Mediterranean, Black Seas and Atlantic Ocean. 4 The environmental conditions and the time of release of the contaminant cause a variability of the response at ecosystem level that can reach 50%. 5 At the actual level of knowledge it is difficult to assess if the legal approach, based on the precautionary principle, is over or under conservative, when considering molecular and its long term effects, the combined effects of mixtures and the environmental fluctuations that affect all ecosystems. 6 A similar colour code to the one adopted for biological quality elements should be adopted for the definition of EQS, with values higher than the EQS as orange (poor). This will allow assessing contamination trends and an early detection of a chemical contamination problems. 7 In aquatic environments ecosystem experience the combined effects of mixtures. Ecotoxicological risk assessment should be performed taking this aspect into account. However, with the amount of new chemicals being produced and the detection limits required it is clear that new integrated indicators are necessary. Limiting the levels of certain chemicals in the environment is one step to improve ecosystem health but alone it will not prevent further deterioration. 8 Due to practical limitations, knowledge on ecotoxicology is only available for a small fraction of the anthropogenic chemical pressure. The importance of this simplification has not been comprehensibly assessed and introduce uncertainty in the appropriate outcome of current legislation and managing practices.JRC.H.5-Rural, water and ecosystem resource

Joint effects of nutrients and contaminants on the dynamics of a food chain in marine ecosystems

We analyze the joint effect of contaminants and nutrient loading on population dynamics of marine food chains by means of bifurcation analysis. Contaminant toxicity is assumed to alter mortality of some species with a sigmoidal dose-response relationship. A generic effect of pollutants is to delay transitions to complex dynamical states towards higher nutrient load values, but more counterintuitive consequences arising from indirect effects are described. In particular, the top predator seems to be the species more affected by pollutants, even when contaminant is toxic only to lower trophic levels

Evidence for increasing global wheat yield potential

Wheat is the most widely grown food crop, with 761 Mt produced globally in 2020. To meet the expected grain demand by mid-century, wheat breeding strategies must continue to improve upon yield-advancing physiological traits, regardless of climate change impacts. Here, the best performing doubled haploid (DH) crosses with an increased canopy photosynthesis from wheat field experiments in the literature were extrapolated to the global scale with a multi-model ensemble of process-based wheat crop models to estimate global wheat production. The DH field experiments were also used to determine a quantitative relationship between wheat production and solar radiation to estimate genetic yield potential. The multi-model ensemble projected a global annual wheat production of 1050 ± 145 Mt due to the improved canopy photosynthesis, a 37% increase, without expanding cropping area. Achieving this genetic yield potential would meet the lower estimate of the projected grain demand in 2050, albeit with considerable challenges.Fil: Guarin, Jose Rafael. National Aeronautics and Space Administration; Estados Unidos. Columbia University; Estados Unidos. Florida State University; Estados UnidosFil: Martre, Pierre. Institut Agro Montpellier SupAgro; FranciaFil: Ewert, Frank. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Webber, Heidi. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Dueri, Sibylle. Institut Agro Montpellier SupAgro; FranciaFil: Calderini, Daniel Fernando. Universidad Austral de Chile; ChileFil: Reynolds, Matthew. International Maize and Wheat Improvement Center ; MéxicoFil: Molero, Gemma. KWS; FranciaFil: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Garcia, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Slafer, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universitat de Lleida; España. Institució Catalana de Recerca i Estudis Avancats; EspañaFil: Giunta, Francesco. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Dell Atmosfera E del Clima.; ItaliaFil: Pequeno, Diego N.L.. International Maize and Wheat Improvement Center; MéxicoFil: Stella, Tommaso. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Ahmed, Mukhtar. University Of Pakistan; PakistánFil: Alderman, Phillip D.. Oklahoma State University; Estados UnidosFil: Basso, Bruno. Michigan State University; Estados UnidosFil: Berger, Andres G.. Instituto Nacional de Investigacion Agropecuaria;Fil: Bindi, Marco. Università degli Studi di Firenze; ItaliaFil: Bracho-Mujica, Gennady. Universität Göttingen; AlemaniaFil: Cammarano, Davide. Purdue University; Estados UnidosFil: Chen, Yi. Chinese Academy of Sciences; República de ChinaFil: Dumont, Benjamin. Université de Liège; BélgicaFil: Rezaei, Ehsan Eyshi. Leibniz Institute Of Plant Genetics And Crop Plant Research.; AlemaniaFil: Fereres, Elias. Universidad de Córdoba; EspañaFil: Ferrise, Roberto. Michigan State University; Estados UnidosFil: Gaiser, Thomas. Universitat Bonn; AlemaniaFil: Gao, Yujing. Florida State University; Estados UnidosFil: Garcia Vila, Margarita. Universidad de Córdoba; EspañaFil: Gayler, Sebastian. Universidad de Hohenheim; Alemani

Evidence for increasing global wheat yield potential

Wheat is the most widely grown food crop, with 761 Mt produced globally in 2020. To meet the expected grain demand by mid-century, wheat breeding strategies must continue to improve upon yield-advancing physiological traits, regardless of climate change impacts. Here, the best performing doubled haploid (DH) crosses with an increased canopy photosynthesis from wheat field experiments in the literature were extrapolated to the global scale with a multi-model ensemble of process-based wheat crop models to estimate global wheat production. The DH field experiments were also used to determine a quantitative relationship between wheat production and solar radiation to estimate genetic yield potential. The multi-model ensemble projected a global annual wheat production of 1050 +/- 145 Mt due to the improved canopy photosynthesis, a 37% increase, without expanding cropping area. Achieving this genetic yield potential would meet the lower estimate of the projected grain demand in 2050, albeit with considerable challenges