[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]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]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.

Emissions in East Asia for 1993 by administrative units and source types are estimated to support regional emission assessments and transport modeling studies. Total emission of SOₓ, NOₓ, soil NOₓ, N₂O, and NH₃are 24 150, 12 610, 1963, 908, and 8263 kton yr⁻¹, respectively.China's emission contribution is the highest for every species.The area sources are the most significant source type for SOₓand NOₓ, but the fraction due to mobile source is highest for NOₓ. Major LPSs are located from the middle to the east part of China, south and middle-west part of South Korea, and the east part of Japan. The area sources of SOₓshow a pattern similar to population density, whereas NH₃shows a strong landuse dependency. Detail emissions analysis reveals higher SOₓemission `cores' within each province. The estimated emissions are used to estimate sulfur deposition in the regions. The seasonal average sulfur distribution amounts are estimated from the ATMOS2 chemical transport model. The results showed anti-correlation with temperature for sulfur (SO₂+ SO₄⁻²) concentrations and a positive correlation with rainfall for deposition.

This paper reports on magnetic and magnetomineralogical studies of forest soils from Krkonoše (Giant Mountains) National Park in the Czech Republic. Low-field magnetic susceptibility was measured in 32 soil profiles using a field probe. Thermomagnetic analysis, acquisition of remanent magnetization, alternating-field demagnetization of saturation remanence and frequency-dependent magnetic susceptibility were measured in laboratory samples from individual soil horizons as well as on their magnetic extracts. X-ray diffraction and SEM were used to identify ferrimagnetic fractions. The uppermost layer, which is dominated by magnetically soft magnetite of presumably anthropogenic origin, can be reliably identified in soil profiles over the whole region of concern. Subsoil horizons are characterised by significantly different magnetic properties.

The hydrochemistry of mountain lakes is highly conditioned by the chemicalcomposition of atmospheric deposition and by climate characteristics. Consequently these ecosystems have proved to be sensitive to long-term changes in both factors. Climate warming seems to be particularly pronounced in the Alpine region. A reduction of snow cover in space and time, due to less precipitation and higher temperatures, means a greater exposure of rocks and soils in the watersheds, which enhances weathering processes. In this paper we aim to evaluate the possible effect of these processes on long-term changes in the chemistry of alpine lakes. Recent climate changes affecting the study area were investigated through a data series referring to temperature, precipitation, snow depth and duration at some stations in the Ossola Valley. Chemical data of 35 lakes located in the Ossola and Sesia Valleys (Central Alps) were used. Lakes were sampled both in the late summer of 2000 and 2001 in the framework of two European Projects and the results compared with previous data (1984–1987). Two lakes (Boden Superiore and Inferiore, 2343 and 2334 m a.s.l., respectively), located in the northern part of the study area, have been sampled more or less continuously since the late 70s, enabling us to evaluate the trends of the main chemical variables. For lakes lying in catchments with highly soluble rocks, a comparison between the two data sets shows an increase of solute contents in the last few years. This result could be attributed to increased weathering rates due to climate warming.

In Zacatecas, Mexico, four plants are operating to extract Ag, Au, and Hg using CaS₂O₃solution from surface soil containing tailings from the amalgamation method used during 1550–1900. The metal ions extracted are cemented by scrap Cu wires. Hg is separated by evaporation from the cemented amalgam and Ag and Au are obtained from the residue. A part of the soil to be leached was separated and leached as in the industrial process. Only 121 ppm of Hg was freed from 168 ppm of extractable Hg. About a half of the remaining Hg in the soil evaporated during 18 months. This confirms that the Hg in the soil is metallic. Pb and As are also freed in the same process. It is estimated that 13 000–34 000 t of Hg had been discarded in the extraction of Ag.

The contributions of different acidifying processes to the total protonload (TPL) of the soil in control plots (C) and ammonium sulphate treatedplots (NS) were studied in a Norway spruce stand in Southwest Sweden during 1988–1998. The annual deposition of inorganic nitrogen and sulphate was on average 18 kg N and 20 kg S ha⁻¹. In addition the NS treated plots received 100 kg N and 114 kg S ha⁻¹annually. The amounts of nutrients added to the ecosystem by wet and dry deposition and the leaching at 50 cm depth were calculated. The net atmosphericproton load, the proton load by nitrogen transformations in the soil, the sulphate sorption/desorption in the soil and the excess base cation accumulation in biomass were calculated. There was no leaching of inorganic nitrogen from control plots during the study period. The net atmospheric proton deposition, originating from sulphuric and nitric acid deposition, was the main contributor to TPL in control plots. The addition of ammonium sulphate increased the leaching of ammonium, nitrate, sulphate, magnesium and calcium but not of potassium. The TPL in NS plots was about ten times that in control plots. The nitrogen transformation processes were the main contributors to TPL to NS soil, in the beginning by ammonium uptake and later also by nitrification. The pH decreased by 0.4 units in the mineral soil. The between-year variation in TPL during the eleven year period in C plots (200–1500 molcha⁻¹yr⁻¹) and in NS plots (1000–13000 molcha⁻¹yr⁻¹) was mainly dependent on the sorption or release of sulphate. Both in C and NS, the TPL was buffered mainly by dissolving solid aluminium compounds, most probably some Al(OH)₃phase.