[Departement_IRSTEA]GMA [TR1_IRSTEA]11 - VERSEAU / TRANSPOL | Assessment of main contamination causes in each situation is required to settle action planes that are aimed at decreasing water contamination by. Hence, diagnosis consists in assessing risk of phytosanitary products transfer into an area and finding factors that favour it (CORPEN 2001). Action plane will consist in settling corrective solutions as well as defining priorities according to technique criteria and social, economic and local policies obligations. This document presents some technical aspects of different actions that can limit water contamination after diagnosis. | Malgré l'ampleur des investigations exigées pour leur homologation, les produits phytosanitaires sont susceptibles d'être retrouvés dans les milieux aquatiques, ce qui met en évidence à la fois la difficulté de cerner les risques de transfert de ces molécules et la nécessité de mener conjointement des actions sur le terrain pour limiter la contamination de la ressource en eau. La forte interaction qui existe entre les propriétés de ces substances et les conditions dans lesquelles elles sont employées explique cette difficulté et rend indispensable d'estimer, dans chaque situation, quelles sont les causes dominantes de la contamination. C'est l'objectif du diagnostic qui, dans la perspective qui nous intéresse ici, a pour seul objectif de mettre en place des plans d'actions visant à réduire la contamination de la ressource en eau par les produits phytosanitaires. Il consistera ainsi à estimer les risques de transfert de ces substances dans une zone géographique donnée et à caractériser les facteurs qui le favorisent (CORPEN 2001). Le plan d'action, quant à lui, consistera non seulement à mettre en oeuvre des solutions correctives, mais aussi à définir des priorités, en fonction de critères techniques et des impératifs socio-économiques et politiques locaux. Dans le cadre de cet exposé, nous nous en tiendrons aux seules considérations techniques, destinées à servir de base de décision aux acteurs locaux, seuls à même de prendre en considération les impératifs ci-dessus. Le diagnostic étant orienté par les solutions correctives puisqu'il s'agit d'en évaluer la pertinence et d'en optimiser la mise en oeuvre, nous présenterons tout d'abord les différentes actions possibles pour limiter la contamination des eaux.

[Departement_IRSTEA]EEE [Departement_IRSTEA]GMA [TR1_IRSTEA]11 - VERSEAU / TRANSPOL | This program is part of the common research action AQUAE (2000-2003) between Cemagref and INRA. It aims at understanding and quantifying the mechanisms of retention, degradation and transport of pesticides at the field and the catchment scales. The study relates in particular to man-made impact causing hydrological discontinuities such as ditches network and grass and wooded cover zones. Experiments were undertaken on two catchments with different geomorphological and climatic characteristics, La Jaillière (44) and Roujan (34), in order to analyse the contamination of water by pesticides. The factors determining the efficiency of these man-made hydrological discontinuities are extensively studied : hydrometeorological conditions, geomorphological position, soil characteristics; land-use, vegetation cover classes, and the oxydo-reduction conditions. A typology of these various types of discontinuities is established on a great range of catchments, in order to characterise the various experimental situations and to ensure the applicability of the results on un-gauged catchments. Finally, a distributed hydrological modelling approach (the model MHYDAS : Modélisation Hydrologique Distribuée des AgroSystèmes = Distributed Hydrological Modelling of AgroSystems) of water and pollutant transfer, integrating the principal mechanisms observed on hydrological discontinuities in farmed catchments, is conceived and is in an advanced phase of development. The first tests of the model at the catchment scale enable the simulation of hydrograph and pesticides concentrations at various locations of ditches network. Furthermore, it enables the testing of various scenarios of land management and the impact of man-made planning on water and pesticides fluxes. | Ce programme fait partie de l'action structurante AQUAE (2000-2003) entre le Cemagref et l'INRA et a pour objectif de comprendre et quantifier les phénomènes de rétention, de dégradation ou de transfert subis par les produits phytosanitaires entre la parcelle agricole et le milieu aquatique. L'étude porte notamment sur les discontinuités hydrologiques que constituent les fossés et les dispositifs enherbés ou boisés. Ces structures font l'objet de suivis en continu et d'expériences spécifiques, afin d'analyser le devenir des produits phytosanitaires en leur sein, sur deux bassins versants aux caractéristiques différentes : La Jaillière (44) et Roujan (34). Les facteurs déterminant leur efficacité tampon sont étudiés, qu'il s'agisse des conditions hydrométéorologiques, de leurs positions géomorphologiques, des caractéristiques du sol ou de la végétation, et de l'alternance des conditions d'oxydo-réduction. Une typologie de ces différents types de discontinuités est établie sur une grande gamme de bassins versants sur lesquels les équipes participantes travaillent ou ont déjà travaillé. Cette typologie a permis de caractériser les principales situations existantes ou envisageables, afin d'assurer (la généralisation ou l'extrapolation) des résultats obtenus sur les bassins versants expérimentaux. Enfin, une approche de modélisation hydrologique distribuée (le modèle MHYDAS : Modélisation Hydrologique Distribuée des AgroSystèmes) des transferts d'eau et de polluants à l'échelle du versant, intégrant les principaux mécanismes observés sur les discontinuités hydrologiques, est en phase avancée de développement. Les premiers tests du modèle ont permis de simuler les hydrogrammes de crue en différents points du réseau de fossés et les ordres de grandeur des flux de pesticides à l'exutoire du bassin versant.

[Departement_IRSTEA]EEE [Departement_IRSTEA]GT [TR1_IRSTEA]31 - RURAMEN / TERREAU | A comparison between different existing or simulated BMPs has been carried out through a cost/effectiveness assessment along with the study of their acceptability by farmers on eight European watersheds in a multidisciplinary framework involving eleven research teams. Water quality problems encountered and dealt with in this project for all eight watersheds include: high nitrate loads and concentrations at the outlet of the two western French watersheds associated with dairy production, high loads of phosphorus into lake Vico (Italy) associated with hazelnut plantations, high nitrate concentration in groundwater for two watersheds in Austria and Italy, high sediment loads at the outlet of a second Austrian watershed, acid water associated with artificial drainage of moraine soils in Finland, pesticide contamination in Norway.The comparison of different BMPs for a given watershed is built as a 6 steps framework :step 1 : describing the watershed, the general problematic (including the objective of the different actors) and of the main water quality problems. .step 2 : describing and computing the hydrology. Description of the model used, calibration and validation of the model, definition of critical areas and risky practices, assessment of their impact on total fluxes or concentrations, deduction of proposed BMPs, assessment of the ex ante effectiveness of each BMP.step 3 : describing the economics. Description of the diversity of farms, choice of the model to represent this diversity, results of model implementation (does this model provide an acute description of the statu quo situation ?), assessment of the consequences on introducing BMPs and ex ante cost of this introduction.step 4 : assessing the results of steps 2 and 3 to a cost/efficiency ratio for each BMP.step 5 : interviewing the farmers to assess the acceptability for each BMP.step 6 : comparing of the cost/efficiency ratio and the acceptability to build a selection grid.

A photochemical puff-trajectory model (Fotoplume) has been applied to simulate emissions, atmospheric transport and chemical transformations of pollutants from offshore oil and gas production in the North Sea. The above model was used in conjunction with the European Monitoring and Evaluation Programme (EMEP) regional Lagrangian oxidant model. The Fotoplume and EMEP models were used to evaluate the effects of the atmospheric emissions from the oil and gas exploration activity in the Norwegian sector of the North Sea. Deposition of nitrogen and formation of boundary level ozone in Southern Norway due to North Sea emissions of nitrogen oxides (NOₓ), carbon monoxide (CO) and volatile organic compounds (VOC) have been studied. The petroleum activity in the North Sea is calculated to contribute approximately 20% of the nitrogen deposition in the coastal areas of Norway in 1992. In addition, the models were used to estimate the AOT40 ozone exposure levels. The results indicate that emissions from British and Norwegian oil and gas exploitation sector separately contribute to less than 5% each of the AOT40 values for coniferous forests and meadows. Comparison of model calculations with experimental measurements is quite satisfactory and the models show realistic results for both the nitrogen deposition and AOT40 values.

Small- and medium-scale mining operations in Guyana have increased significantly since the late 1980s. The majority of these gold mining operations utilize mercury (Hg) amalgamation methods in the recovery process, raising the question as to the significance of Hg inputs to the environment from mining activities. In March and April, 2001, 168 samples were collected from floodplain, sand bar, and channel bed deposits along a 350 km reach of the Mazaruni River and a 160 km reach of the Essequibo River. Distinct trends in the geochemical data suggest that much of the Hg found in the alluvial deposits is related to anthropogenic sources, including (1) Hg concentrations in floodplain, channel bed and sand bar deposits locally exceed background values defined by ferralitic soils; (2) core data reveal that Hg concentrations within floodplain deposits have increased in recent years; and (3) high Hg concentrations along the channels can be attributed to the influx of material from tributaries affected by mining operations, or to mining activities along the rivers. Recent investigations in Amazonia have argued that Hg from amalgamation mining represents a small portion of the total Hg load to riverine systems, the majority coming from the erosion of Hg enriched upland soils within deforested terrain. Geochemical data from the Essequibo and Mazaruni Rivers suggest that Hg from mining may be a more significant source in Guyana where large-scale deforestation is limited. However, it is unclear whether the increased Hg represents the direct input associated with the amalgamation process, or Hg associated with the erosion of soils and sediments that results from activities that accompany mining.

To determine the importance of Al-availability for soil micro-organisms 95 forest soils from Tyrol/Austria with comparable topography, vegetation, climatic conditions, soil type and with low soil pH (median = 3.9) were investigated for their physical (percentage of stable aggregates, water holding capacity), chemical (pH, electrical conductivity, contents of organic matter, concentrations of easily extractable aluminium, calcium, potassium, magnesium and phosphorus) and microbiological characteristics (microbial biomass and respiration, metabolic quotient, content of ATP, activities of protease and CM-cellulase, cfu-values of total and Al-tolerant bacteria and fungi). A highly significant negative correlation was detected between concentrations of KCl-extractable aluminium and soil pH. By the application of multivariate statistical methods, the effect of the concentration of KCl-extractable aluminium on abundance and activities of soil micro-organisms could be revealed. Al turned out to be of great importance for micro-organisms and often outmatched the significance of other well known soil properties like organic matter, pH or water holding capacity. However, due to very healthy trees at the sites under investigation no effect of Al or soil acidification on forest decline could be detected.

Six soil samples taken from three contaminated sites have been assessed using chemical, ecotoxicological and genotoxicological methods. From two of these sites, samples were characterised after remediation. An overall assessment of the soil samples was done with a scheme consisting of two phases. Remediation of main pollutants in these samples, did in general not lead to a risk reduction of the water-extractable ecotoxic and genotoxic potential. It was concluded, that the assessment and remediation of contaminated sites without consideration of biological test systems is not sufficient. Focussing on single hazardous compounds does in many cases not lead to a reduction of the ecotoxic or genotoxic potential. Consequently, effects of accompanying hazardous compounds, which are not routinely quantified, might be underestimated. It was pointed out, that the assessment of contaminated soil samples on the basis of LID-values applying dual dilution series seems to be sufficient for the evaluation, if there is no need for a quantitative comparison of toxic potentials.

We studied the environmental effects of the mining activity of Troya Mine on the fluvial ecosystem, in the Basque Country, Spain, from 1993 to 1995. The multivariate analysis of the physicochemical conditions shows that the main abiotic factors of variation are: (i) in the water column, a significant increase in the content of heavy metals and conductivity, and (ii) an intense accumulation of heavy metals in the bottom sediments. We studied the effects of these factors on density, richness, dominance, similarity coefficient and composition of the benthic macroinvertebrate community (BMI).We observed a de-structuring of the community. Richness decreases (from 25 to 11 different number of families), but it does not suitably value the impact. Density oscillates radically (255–1548 individuals m⁻²) and reflects changes occurred in sediments. Dominance, which oscillates from 0 to 1, increase from 0.16 upstream from the mine, to 0.42 downstream, fundamentally due to oscillations of Chironomidae, Tubificidae, Baetidae and Simuliidae. The similarity coefficient indicates the physicochemical variations both in the sediment and in the water column; this index is therefore suitable for the follow-up of the evolution of the disturbance studied. The families sensitive to disturbance in the water column are: Ephemeridae, Athericidae, Sericostomatidae, Leptophlebiidae, Baetidae, Gammaridae, Perlidae, Heptageniidae, and Leptoceridae; the tolerant ones are: Coenagrionidae, Hydrobiidae, Lumbricidae, and Polycentropodidae.With regard to the metal content in sediments, the sensitive families are: Gammaridae, Ephemeridae and Ceratopogonidae; the tolerant ones are: Simuliidae, Culicidae, Hydrophilidae, Dolichopodidae, Chironomidae, Psychodidae, Tipulidae, and Chrysomelidae.We thus synthesized the complexity inherent to this type of pollution, in which large amounts of variables are normally involved.

Bleached Kraft mill effluent was treated in an activated sludgereactor followed by an allophanic soil adsorption system (ASAS). Under aerobic conditions, removal efficiencies of biological oxygen demand (BOD₅) and chemical oxygen demand (COD) varied between 57.7–96.5% and 30.3–57.0%, respectively, depending on the hydraulic retention time (HRT). On the other hand, tannin-lignin and phenolic compounds removal efficiencies attained values between 13.2–51.2 and 3.6–33.5%,respectively. An allophanic soil adsorption system was designed for color and phenolic compounds removal. Three different types of soils were used: Natural allophanic soil as the control compared, with calcinated and acidified allophanic soil. The initial removal efficiencies for phenolic compounds varied between 72 an 87% for activated soils, while color initial removal efficiencies were between 95 and 99%. Moreover, COD and tannin-lignin initial removal efficiencies reached maximum values of 74 and 87%, respectively, for calcinated soil. Design parameters show that there is an enhancement factor in adsorption capacities for both activated soils. In fact, phenolic compounds breakpoint adsorption capacity increased 5.3 times for calcinated soil and 17.6 times for acidified soil, while saturation capacity increased between 2.2 and 3.2 times. In addition, color breakpoint adsorption capacity increased 2.8 times for calcinated soil and 10.4 times for acidified soil, while saturation capacity increased between 3.2 and 5.5 times.