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High levels of metal concentrations in soils constitute a threat to terrestrial organisms leading possibly to a loss of biodiversity and/or soil functions. This is why most European countries have adopted soil protection policies each containing soil threshold values representing a limit above which remediation interventions will be possibly required. The toxicity of metals in soils has been assessed with the Predicted No Effect Concentration (PNEC) calculator methodology. This approach relies on chronic toxicity data for terrestrial organisms and Ageing/Leaching factors which take into account soil parameters such as organic matter content, clay content, pH and cation exchange capacity. The aim of this study is to map the PNEC in European countries in order to compare their soil threshold values with the observed PNEC values. The soil parameter dataset used for computing the PNEC is the Lucas Topsoil Dataset, which includes 20 000 soils parameter analyses similarly spatially sampled across Europe. Here we present maps and comparison results for Cu and Zn. The resulting maps show that the PNEC exhibits strong variations across Europe. This map allows to compare the level of the soil threshold values for each country with the observed distribution of PNEC. This approach highlights differences in soil environmental conservation level among the compared countries. Although it takes into account only the soil ecosystem receptors, this work provides a first approach toward consistent soil threshold values across Europe.

As in many parts of the world, land application of organic amendements such as sewage sludge known to contain trace metal elements motivated the walloon administration (Belgium) to establish a regulation to limit the spreading on soils with high contents of trace metal elements. This regulation requires to perform a soil analysis prior to application to check if the parcel meets the policy thresholds for trace metal elements. As most of the soil metal content analyses were below the policy thresholds, the walloon administration conducted a study leading to the establishment of a map recommending the necessity to impose a soil analysis before application. This paper presents an algorithm to determine for each agricultural parcel in Wallonia if it is able to receive spreading sludge according to soil metal content policy thresholds basing on the soil analyses performed in the frame of the implementation of the regulation. The principles of this algorithm combine both geostatistical methods, expert judgement and constraints imposed by the Administration. As a result more than 50% of agricultural parcels are located in zones where a soil analysis is not recommended, reducing thus costs for both the the administration and owners of agricultural parcels.

High levels of metal concentrations in soils constitute a threat to terrestrial organisms leading possibly to a loss of biodiversity and/or soil functions. Ageing/Leaching factors and soil parameters such as organic matter content, clay content, pH and clay content are known to in uence the toxicity of the soil metal content. For years Wallonia has collected a large amount of georeferenced soil analyses and was able to constitute a database that covers the whole region with high spatial resolution. The rst aim of this study is to map the eect of metals on terrestrial organisms taking into account soil parameters as well as Ageing/Leaching factors. This is done by computing the species sensitivity distribution on each point of a grid of 70 000 points using the PNEC Calculator methodology, which relies on chronic toxicity data for terrestrial organisms and Ageing/Leaching factors derived from EU REACH reports. The second aim of this study is to compare the sensitivity distribution function to the predicted concentration of metals at each point of the grid to compute the potentially aected fraction (PAF) of organisms. The PAF due to zinc and copper concen- trations have been computed. For copper, the PAF is below 5% everywhere in Wallonia. For zinc, the PAF is higher than 10% in the Liege area

Des niveaux élevés de concentrations en métaux dans les sols constituent une menace pour les organismes terrestres pouvant éventuellement mener à une perte de biodiversité et/ou une diminution de la capacité du sol à remplir ses fonctions. Dans ce contexte, les paramètres pédologiques tels que la teneur en matière organique, la teneur en argile, le pH et la capacité d’échange cationique sont connus pour influencer la toxicité de la teneur en métal présente dans le sol. De plus, les seuils de toxicité des métaux dans le sol tels qu’ils sont déterminés par les expériences en laboratoire de marquage de sols de référence à l’aide de solution de sels de métaux sont généralement différents de ceux qui se présentent effectivement sur le terrain. Ces différences sont prises en compte par les facteurs de « vieillissement/lessivage ». Pendant des années, la Wallonie a recueilli une grande quantité d’analyses de sol géoréférencées et a été en mesure de constituer une base de données qui couvre tout son territoire avec une résolution spatiale élevée. Le premier objectif de la présente étude a été de cartographier l'effet des métaux sur les organismes terrestres en tenant compte des paramètres du sol ainsi que les facteurs de « vieillissement/ lessivage ». Ceci a été réalisé en calculant la courbe de sensibilité des espèces pour chaque point d'une grille de 70 000 mailles en utilisant la méthodologie du PNEC Calculator (Predicted No Effect Concentration), qui prend en compte des données de toxicité chronique pour les organismes terrestres et les facteurs de «vieillissement/lessivage » provenant des rapports européens rédigés dans le cadre de l’application de la législation REACH. Le second objectif de cette étude est de comparer la courbe de sensibilité des espèces à la concentration en métaux prédite en chaque point de la grille pour calculer la fraction des organismes potentiellement affectée (FPA). Les FPA dues aux concentrations prédites de zinc et de cuivre ont été calculée

In many parts of the world, multiple geochemical datasets are available for cartographers when mapping a region. Using multiple datasets for regional geochemical mapping can be highly beneficial for establishing geochemical maps with increased resolution and/or coverage area. This practice involves assessing the equivalence between datasets and, if needed, applying data leveling to correct possible biases between datasets. Here we present two original methods for assessing equivalence and for leveling data when datasets contain records that are located within the same perimeter. The first method is designed for datasets similarly spatially distributed and is based on the Kolmogorov-Smirnov test and quantile regression. The second method does not require datasets to be similarly spatially distributed and is based on the prior knowledge about the factors explaining the geochemical concentrations and on Bivariate Least Squares regression. The scope of application, pros, cons and detailed practical recommendations are presented for each method. Both methods were then applied to a case study involving Fe, V and Y datasets originating from two European geochemical mapping projects: the Geochemical Mapping of Agricultural Soils of Europe (GEMAS) and the Baltic Soil Survey (BSS). The two methods yielded similar results thereby suggesting that they are both reliable and effective enough to take advantage of the steadily increasing number of geochemical datasets available for mapping a region

Biases between geochemical survey datasets and procedures for dataset leveling are issues that have been discussed for a long time. Methods proposed in the literature are generally based on common sense, but their performance are not discussed with statistics and indicators figures. Here we propose a general procedure for randomly generating geochemical datasets and assessing the performance of methods applied in geochemical mapping by computer simulation. This procedure is illustrated by the performance comparison between two methods for testing the equivalence between geochemical datasets and for data leveling. The first compared method is based on the Kolmogorov-Smirnov test and quantile regression. The second method is based on BLS (Bivariate Least Squares) regression. Each simulation run consists in randomly generating a reference dataset and a biased dataset and applying the methods to test the equivalence between these two datasets and to level the bias between datasets. After completing 10 000 simulations, we compute several performance indicators aimed at answering the following questions: are the methods efficient to detect the bias introduced into the biased datasets? Are both methods efficient to remove the bias? What is the best method depending on the bias? The results of this study show that computer simulation is a useful tool to identify the particular benefits and limitations of each method, and provide practical recommendations for prudent use of these methods in geochemical mapping.

Geochemical mapping projects carried out in the last fifty years both in Europe and around the world have successfully met a range of needs from mineral exploration to environmental management. New databases have been created for each of these projects, representing an equal number of additional geochemical data sources. Combining data from several existing databases can be highly profitable for obtaining geochemical maps that offer greater precision and/or that cover larger areas. However, the data quality of the datasets can be highly variable and, in many instances, the biases between the geochemical data must be removed in order to optimally combine the different sources of data. The present thesis examines these issues by taking into account the characteristics specific to geochemical data, and by defining the relevant concepts, such as the link between a geochemical value and its position in space or the notion of geochemical data equivalence. This study resulted in the formulation of a general method defining a specific set of procedures that make it possible to effectively combine multiple data sources. This general method first consists in performing four data quality checks: georeferencing, temporal variability, spatial structure and presence of censored values. It then includes two procedures, each having a specific scope, which serve to detect the biases between data and to correct them through linear transformation. The feasibility and the advantages of the proposed procedures are demonstrated using several case studies focusing on soil geochemical mapping both in Wallonia (Belgium) and in Europe. The scope, benefits and limitations of the proposed procedures are discussed, and the performance of the bias detection and the correction procedures are evaluated using Monte Carlo simulations., (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2016

La convention CAPASOL 4 a cherché à répondre à deux questions de recherche d'intérêt général en matière de gestion de la contamination diffuse des sols par les métaux. La première thématique de recherche a permis de montrer que la mesure des métaux dans les sols wallons par fluorescence des rayons X portable représentait une bonne manière de prédire/évaluer la concentration mesurée par eau régale pour la plupart des métaux en particulier lorsque les sols étaient tamisés et séchés. Quatre appareils portables de quatre fabricants différents ont été testés et fournissent des résultats comparables, en faisant abstraction des différences dues à des problèmes de calibration des appareils. La mesure des métaux sur le terrain sur sol humide a donné également des résultats confirmant son utilisation exploitable dans un contexte de screening, en particulier pour le plomb. La seconde thématique a permis d'aboutir à une cartographie de l'évaluation de l'effet des concentrations en métaux sur les organismes en contact avec le sol (toxicité primaire) en tenant compte des facteurs de "vieillissement/lessivage" dérivés de REACH et mis en forme par la société ARCHE Consulting via le PNEC Calculator. Les résultats de cette cartographie pour Cu et Zn montrent que les quantités de métaux que peuvent contenir les sols wallons avant d'avoir un effet délétère important sur les organismes du sol varient beaucoup selon les propriétés du sol, et sont en général bien supérieures aux valeurs limites spécifiées dans le texte légal wallon visant à la protection des sols.

Wallonia (South Belgium) has had an intense industrial activity during the 19th century including iron mills, steelmaking blast furnaces and non-ferrous metals smelting plants (Pb,Zn), which durably impacted soils pollutant concentrations on large areas. Here we outline the results of the modeling of the impact of the major former industrial plants on metal soil concentration at a regional scale. The methodology established for assessing the impact of each industrial plant involves three steps. In the first step, the pollutant dispersion from 89 former industrial plants each considered individually is modeled by a finite volume method. In the second step, the enrichment of atmospheric pollutants in 508 control points spatially distributed over Wallonia is estimated. In the last step the amount emitted by each of the industrial plants is calculated by fitting the 508 control points using a non-negative linear least squares model. For Cd, the results indicate that its presence in Wallonia soils is mainly due to atmospheric deposition originating from former base metal smelters. The methodology allow us to determine at any point of Wallonia the soil industrial plant(s)responsible for the soil Cd concentration. In the same way the total amount of Cd emitted by each industrial plant has been estimated. The results are based on strong assumptions and thereby contain uncertainties, but illustrate a promising methodology that can be used to trace the environmental impact of former industrial activities based on soil geochemical data.

Tephra particles in physically and chemically evolving volcanic plumes and clouds carry soluble sulphate and halide salts to the Earth’s surface, ultimately depositing volcanogenic compounds into terrestrial or aquatic environments. Upon leaching of tephra in water, these salts dissolve rapidly. Previous studies have investigated the spatial and temporal variability of tephra leachate compositions during an eruption in order to gain insight into the mechanisms of gas-tephra interaction which emplace those salts. However, the leachate datasets analysed are typically small and may poorly represent the natural variability and complexity of tephra deposits. Here, we have conducted a retrospective analysis of published leachate analyses from the 18 May 1980 eruption of Mount St. Helens, Washington, analysing the spatial structure of the concentrations and relative abundances of soluble Ca, Cl, Na and S across the deposits. We have identified two spatial features: (1) concentrated tephra leachate compositions in blast deposits to the north of the volcano and (2) low S/Cl and Na/Cl ratios around the Washington-Idaho border. By reference to the bulk chemistry and granulometry of the deposit and to current knowledge of gas-tephra interactions, we suggest that the proximal enrichments are the product of pre-eruptive gas uptake during cryptodome emplacement. We speculate that the low S/Cl and Na/Cl ratios reflect a combination of compositional dependences on high-temperature SO2 uptake and preferential HCl uptake by hydrometeor-tephra aggregates, manifested in terrestrial deposits by tephra sedimentation and fallout patterns. However, despite our interrogation of the most exhaustive tephra leachate dataset available, it has become clear in this effort that more detailed insights into gas-tephra interaction mechanisms are prevented by the prevalent poor temporal and spatial representativeness of the collated data and the limited characterisation of the tephra deposits. Future l

In Wallonia, as in many other regions of the world, government agencies rely on soil maps of trace metal background concentrations to implement soil protection policies. Here we present the result of a study funded by the Walloon Public Service which aims to establish trace metal background concentration maps in Walloon soils. Two databases containing georeferenced soil analyzes providing data on soil background concentrations were used for this study: the CAPASOL database (17,000 sampled agricultural soils) and the permanent inventory of woody resources (about 700 sampled forest soils). The methodology used for drawing the maps involves three steps. In the first step, we divided Wallonia (17,000 km²) into soil pedogeochemical units based on (1) the soil map of the Wallonia (1:20,000), (2) geological maps (1:40,000 and 1:25,000), and (3) literature data and survey results about soils and geology of Wallonia. In the second step, we produced a single reliable dataset by compiling the two available soil databases by a data selection and data leveling method which we designed for this purpose. On the last step, we drew the maps by using a geostatistical model based on the pedogeochemical soil units and the reliable dataset of soil analyzes produced in the previous step. The resulting maps reveal large variations in local background concentrations over short distances, mainly due to the high diversity of soil parent materials, and to the atmospheric deposition of pollutants around former base metal smelters. Wallonia has higher Ni background concentration in soil than average values in Europe (according to the values of Geochemical Atlas of Europe), principally because of high geogenic background levels. Also, higher Zn and Cd values are found, principally due to atmospheric deposition of pollutants originating from former base metal smelters.

Merging several already existing geochemical datasets can be highly profitable for obtaining geochemical maps with increased resolution and/or coverage area. However, this practice can lead to potential problems due to varying quality of the datasets and biases between datasets. In this paper, we present a general method which addresses these issues thereby making it possible to pool together multiple pre-existing datasets to produce one reliable dataset for geochemical mapping. The method first consists in performing four data quality checks that evaluate the relevance of existing data for the intended geochemical map. The checks pertain to georeferencing, temporal variability, spatial structure and presence of censored values. Next, a procedure is applied to detect biases between datasets and, where needed, to level the data using linear transformation. We then applied this method to a case study in Wallonia (Southern Belgium) involving the mapping of nickel in agricultural soils and create a new dataset based on multiple pre-existing geochemical datasets. We conclude by quantifying the new dataset’s improved reliability for geochemical mapping thereby demonstrating the potential benefits of applying this proposed method to real-life situations.

En Wallonie (Belgique), comme dans beaucoup d'autres régions du monde, la mise en œuvre des politiques de protection des sols nécessite une connaissance précise de la concentration de fond en polluants dans les sols, et notamment en éléments traces métalliques (ETM). Une étude a été financée par l'administration (Service Public de Wallonie) et réalisée par une équipe de recherche de l’UCL afin d'établir des cartes de concentrations de fond en ETM dans les sols wallons. Deux bases de données contenant des analyses en ETM géoréférencées ont été utilisées pour réaliser les cartes de concentrations de fond : la base de données CAPASOL (18.000 sols agricoles échantillonnés) et l'Inventaire permanent des ressources ligneuses (environ 700 sols forestiers échantillonnés). Un modèle géostatistique qui prend en comptes les propriétés pédogéochimiques des sols de Wallonie a été mis au point afin de prédire les concentrations de fond en tout point de la Wallonie. Les cartes montrent qu'en Wallonie, pour certains ETM comme Cr et Ni, les niveaux de concentration de fond dépendent principalement du fond pédogéochimique naturel. Pour d'autres ETM, comme Cd, Pb et Zn, les concentrations de fond sont fortement influencées par les retombées atmosphériques de polluants, comme en témoignent les niveaux plus élevés de concentration de fond autour des zones industrielles liées à la métallurgie des non-ferreux.

Background concentrations of pollutants in soil can play different roles in soil protection policies. They can be used for instance to detect a local pollution or to calculate the cleaning targets if a site has to be remediate. However, soils from urban and industrial areas generally present high concentration of pollutants, since they usually are disturbed by urbanization, mixed with technogenic material and affected by smoke and dust fallout. In these zones, background concentrations can be very high and fluctuating across short distances. It is therefore difficult to calculate them precisely, and use them properly for the roles they must fulfill. Dealing with this notion in soil protection policy can therefore be complicated. We present seven western European approaches for the consideration of background concentrations in soil protection policies: Flanders, Wallonia, Grand Duchy of Luxembourg, Germany, France, England and the Netherlands. The definition of the concept of background concentrations of pollutants in soils, the way to calculate them and their roles are presented between these different systems that have various pedogeological and industrial contexts. The advantages and disadvantages of these systems are presented and discussed especially with regards to soils from urban and industrial areas. It appears from this survey that neighboring states use background concentrations to diverse goals. Background concentrations are used to calculate cleaning targets in the case of soil remediation (France, Flanders, Wallonia and Grand Duchy of Luxembourg) and to detect local pollution (England, Grand-Duchy of Luxembourg and Wallonia). In the Netherlands and Germany, background concentrations are used for other purposes regarding soil protection (reuse of soil, spreading of sludge from wastewater treatment plants, etc).

Soils from peri-industrial areas are usually disturbed by urbanization, mixed with technogenic material and affected by smoke and dust fallout. A precise knowledge of the local baseline content of pollutants in soil is needed by the government agencies in order to implement the environmental protection policies. However, in peri-industrial areas, pollutant concentrations often exhibit a high spatial variability which requires an appropriate investigation methodology. Here, we outline the key results obtained from a survey on baseline soil concentrations of trace metal elements (TME) and polycyclic aromatic hydrocarbons (PAH) in peri-industrial soils from the Walloon region (Belgium). For the survey, 8 areas were selected in order to represent the range of current and historical industrial activities of the region. These include chemical plant, steelmaking blast furnace, collieries, coal agglomeration and coke production plants and nonferrous metals smelting plants (Pb, Zn). The sampling points (70 to 200 in each area) were spatially distributed and were representative of the various land uses that occur in peri-industrial area: vegetable gardens, urban parks, farmland and forest. At each sampling point, we collected a sample of the topsoil and, when possible, a sample from a deeper horizon (between 60cm and 1m depth). Concentrations were measured for 5 major elements, 14 TME and 16 PAH (EPA). This sampling and analyzing scheme made it possible to distinguish the effects of the four main factors that affected the concentrations of TME and PAH in the topsoil: (1) the pedogeological soil type (2) the predominant industrial activities responsible for the atmospheric fallout of pollutants (3) the amount and the nature of the technogenic materials and (4) the type of land use. In the peri-industrial areas of Wallonia, we found that the presence of As, Co, Cr, Ni, Be, Ni and Mo was predominantly linked with the pedogeological soil type and was not related to atmospheric fa

L’application du décret du Parlement wallon du 5 décembre 2008 relatif à la gestion des sols (Décret « sols ») pour un terrain donné requiert l’exécution par l’expert d’une étape qui est l’établissement des concentrations de fond. Cette étape intervient soit lorsque l’on souhaite vérifier si les concentrations mesurées sur un sol relèvent des concentrations de fond, soit lorsque l’on souhaite déterminer les concentrations de fond pour fixer les objectifs d’assainissement. L’objectif de ce guide est de présenter les éléments sur lesquels l’expert peut s’appuyer pour proposer des valeurs de concentrations de fonds. Ce sont également les éléments qui serviront à l’Administration pour juger du bien-fondé des propositions de l’expert.

When undertaking a mapping of trace metal concentrations in the soil at the regional level, it is often found that several databases already exist. These databases, usually quite large, were obtained for instance because of an environmental protection regulation which requested to perform soil analyses or in the course of geochemical characterization surveys. The use of all the available databases is often a necessity if one has to provide high resolution maps of the pedogeochemical background. However, analyses from these geochemical databases were generally carried out by different laboratories at different periods of time. Although these laboratories are required to follow strict protocols and quality control procedures, the precision and the accuracy of a particular laboratory can vary in time. This can be due to modifications regarding the analytical equipment, the analytical procedure or the analyst. In addition, there may also be interlaboratory biases. Exploiting multi-laboratory geochemical databases can therefore be a tricky task. Here we outline a generic procedure and caution rules that proved to be useful for this purpose. The procedure consists in two sets of checks: (1) relevance checks, and (2) accuracy checks. The latter also comprises the correction of the dataset, if needed. The checks for relevance pertain to the analytical protocol, the georeferencing, the temporal variability, the spatial structure and the presence of censored values. The checks for accuracy involve testing the existence of interlaboratory bias by a method that takes into account to the geochemical characteristics of the study area. An interlaboratory bias correction method is proposed and discussed. The procedure is illustrated with a soil geochemical database of about 17.000 georeferenced analyses of trace metal elements carried out by 13 different laboratories in Wallonia (South Belgium). The cases of Cd (atmospheric deposition), Ni (geogenic origin) and Zn (both origins) ar

In many countries, government agencies rely on soil maps of trace metal background concentrations to implement soil protection policies. In Wallonia (South Belgium), regional regulation requires extremely detailed background concentration maps. The main obstacle to obtain these maps are the large variations in local background concentrations over short distances, mainly due to the high diversity of soil parent materials, and the atmospheric deposition of pollutants around former base metal smelters. Here we outline the developed methodology and we present an example of the achieved geochemical maps at land parcel scale. The methodology established for the geochemical mapping of soils involves three steps. In the first step, we divided the Wallonia (17,000 km²) in pedogeochemical units of soil based on (1) the soil map of the Wallonia (1:20,000), (2) geological maps (1:40,000 and 1:25,000), and (3) literature data and surveys results about soils and geology of Wallonia. In the second step, we gathered about 17,500 georeferenced soil geochemical data from environmental surveys (that we carried out) or from regulatory analyses (required for agricultural use of sludge from sewage plants). On the last step, we drew the maps by using geostatistical model based on the map of the pedogeochemical soil units and the georeferenced trace metals analyses. The resulting maps show that Wallonia has higher Ni background concentration in soil than average values in Europe (according to the values of Geochemical Atlas of Europe), principally because of elevated geogenic background levels. Also, higher Zn and Cd values are found, principally due to atmospheric deposition of pollutants originating from former base metal smelters. Thanks to their resolution, the maps make it possible to predict, for instance, the risk of exceeding threshold metal concentrations in any particular land parcel in Wallonia.

INTRODUCTION Oral bioaccessibility - the fraction of soil contaminant that dissolves in the human gastrointestinal tract - can be evaluated using various chemical extraction tests, some of which are designed to mimic biochemical conditions. As for any other partial extraction tests, bioaccessibility can be expected to be influenced not only by the soil parameters, but also by the characteristics of the contamination, such as the metal speciation, the contamination aging, etc. Here, we try to relate bioaccessibility measurements to factors that can only be obtained when the sampled soils are surveyed and mapped at a regional scale. The factors we consider are the type of industrial activity responsible for soil contamination in industrialized areas, the land-use, and the regional level of contaminant concentrations. The question which we address is whether a fixed bioaccessibility value can be proposed for risk-based approach of contaminated land or a variable bioaccessibility value must be considered in order to take into account regional differences. To substantiate our conclusions about the influence of these factors on bioaccessibility measurements, chemical sequential extraction tests were also performed on the same soil samples. MATERIALS AND METHODS In the course of the POLLUSOL 2 survey, 237 topsoil samples have been collected in urban parks, vegetable gardens and forests within several industrial areas of Wallonia (South Belgium). The in-vitro oral bioaccessibility test used in this study is Unified BARGE Method (UBM). We looked at the ‘stomach’ compartment of the test for the 237 samples, and at the ‘stomach and intestine’ compartment for a subset of 178 samples. Analysis of the extracts for eight trace metal elements (As, Cd, Co, Cr, Cu, Ni, Pb, Zn) was carried out by ICP-AES. Total metal contents were measured by aqua regia extraction and ICP-AES. The sequential extraction was performed on a subset of 103 samples out of the 237 using the modified three-st

Since 2007, SPAQuE, with the collaboration of four universities in Belgium (UCL-ELIE, UMONS, Ulg-GxABT and Ulg-Aquapôle), has investigated urban areas near industry in Wallonia (Belgium), collecting data in residential gardens, woodland and cultivated or grazing areas. The objectives of the project were to define urban background soil quality values and to investigate soil-to-plant and soil-to-human exposition pathways. 1126 soil samples, 1341 vegetables and 435 groundwater samples were collected and analyzed. Seventeen inorganic pollutants, 33 organic pollutants, 6 soil parameters and 5 major elements were analyzed in soil, 16 inorganic and 16 organic pollutants in vegetables and 20 inorganic pollutants and 74 organic compounds in groundwater. Furthermore, several laboratory experiments were carried out by the universities: - To study human bioaccessibility via the gastrointestinal tract, the Unified BARGE (Bioaccessibility Research Group of Europe) Method was applied to 307 soils samples for 8 inorganic pollutants; - To estimate the soil-to-plant transfer, several chemical extractives were tested: 480 soil samples with CaCl2 and 126 samples with EDTA, DPTA and Mehlich 3 method; - To develop an identification key, 96 samples of slag were analyzed by x-ray. The collected data were used to: - Map pollutants background concentrations in soils and groundwater ; - Develop tools designed to provide a better estimation of soil-to-plant, soil-to-human and soil-to-water transfers ; - Assess the human health exposure level. The POLLUSOL 2 results will be an important asset for the Walloon administration when implementing the legislation about potentially contaminated sites. The presentation will focus on the POLLUSOL 2 results regarding the soil-to-plant and soil-to-human transfers, and their impact on risk assessment studies.

As a result of the important role played by phosphorus (P) in surface water eutrophication, the susceptibility of soils to release P requires evaluation. The degree of phosphorus saturation, assessed by oxalate extraction (DPS(ox)), has been used as an indicator. However, most laboratories do not include DPS(ox) in routine soil tests because of cost and time. This study evaluates the suitability of the ammonium acetate extraction in the presence of EDTA (AAEDTA), the standard soil test P (STP) in Wallonia (Southern Belgium), to predict DPS(ox); we also compared it with the Mehlich 3 extraction. Ninety-three topsoil samples were collected in agricultural soils throughout Wallonia. Good correlations were found between the AAEDTA and the Mehlich 3 methods for P, Fe and Al (r = 0.85, 0.77 and 0.86, respectively). An exponential relationship was found between P(AAEDTA) and DPS(ox). Results of principal component analysis and regression demonstrated that STP can be used to predict DPS(ox) (r = 0.93) after logarithmic transformation. Soil test Al was also a good indicator of the P sorption capacity (PSC(ox)) of soils (r = 0.86). Including the clay fraction in regression equations only slightly improved the prediction of PSC(ox) (r = 0.90), while other readily available data (such as pH or organic carbon) did not significantly improve either DPS(ox) or PSC(ox) predictions.

Soils from urban and peri-industrial regions are affected by the presence of technogenic susbstrates and the fallout of smoke and dust dispersed by the winds in the vicinity of pollution sources. Pollutant levels in these soils display significantly higher variability than in soils that remained close to natural state. Identification of the factor controlling this variability is the first step toward prediction and mapping of pollutant levels in such soils. This work is aimed at characterizing the distribution of trace metal concentrations in urban and peri-industrial soils from the Walloon region (Belgium) through a descriptive model. We selected 8 areas representating different current and historical industrial activities of the region such as chemical plants, steel industry (blast furnaces, steel), coal extraction (extraction and agglomeration of coal, coke and coal chemical) and non-ferrous metallurgy (Pb, Zn). The sampling points (70 to 200 in each area) were spatially well distributed and were representative of the various land uses in peri-industrial area: gardens, parks, farmland and forest. Soils with suspected local pollution (eg.: dumps or industrial site) were not selected. At each point, we collected a topsoil sample corresponding to the first soil horizon and, when possible, a deeper horizon (between 60 cm and 1 m depth) was taken with a hydraulically powered percussion hammer. On each sample, pseudo-total concentrations (aqua regia) were measured for Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Se, Sn, Sb, Tl and Zn. Our soil typology was build with different statistical and graphical tools (boxplot, scatterplot, PCA). For highlighting soils categories with a clear signal in terms of trace metal content, we use robust statistics including robust methods for outlier identification. The typology is based on four main factors: (1) the geopedological substrate, (2) the industrial context, (3) the amount and nature of technogenic materia

Industrial stony residues were widely used for centuries as filling material in urban areas of the Walloon region (Belgium). Their composition and properties widely differ according to the industrial process which generated them. It is assumed, therefore, that the identification of such materials in the field can contribute to (1) better assess potential risks at an early stage when investigating such soil and (2) to devise remediation operations that are more appropriate. However, identification criteria for industrial residues are still poorly documented and might be affected by regional context. This study aims at establishing identification criteria for industrial stony residues of the Walloon region and linking the nature and amounts of such residues to the content of trace metal in a large population of soil samples from this area. On this purpose, we selected 75 reference samples of industrial stony residues in order to include a wide range of morphology and texture basing on hand specimen visual description. They were analyzed by ICP either after alkaline fusion (Li-borate) for major elements (Si, Ca, Fe, Al, Mn, Mg, K, Na, S and P) or after tri-acid dissolution for trace metals (Cu, Pb, Zn, Ni, Cr, As, Cd, Co). Associated industrial processes were identified (i) according to historical information on the sampling site, (ii) by comparing chemical composition to bibliographic data and (iii) by using morphologic and texture diagnostic criteria from literature, when available. Measured chemical compositions were compared to the composition of samples from literature using graphical and statistical methods. The samples were linked to 16 different industrial processes, mainly related to steel industry and coal power plants. On the basis of the 75 reference samples, we derived criteria for field hand specimen identification. They are based on both morphology and texture features (colour, shape, fracture, luster, vacuolar texture …) and simple tests commonly used i

Les missions principales confiées à l’UCL par la Direction Générale Opérationnelle Agriculture, Ressources Naturelles et Environnement (DGO3, Service Public de Wallonie) dans le cadre de la convention SATUPHOS étaient de réaliser un état des lieux du degré de saturation en phosphore (P) des sols agricoles de la Région wallonne, et de proposer un outil d’évaluation et de gestion des risques environnementaux liés au P. Dans un premier temps, une synthèse bibliographique portant sur le comportement du P dans les sols, les risques de pertes en P et les outils d’évaluation et de gestion de ces risques a été réalisée. Cette partie a servi de base pour l’ensemble de l’étude qui a suivi, et notamment pour la détermination des indicateurs environnementaux utilisés pour l’état des lieux. Il était initialement prévu d’étudier uniquement le degré de saturation des sols en P calculé à partir de teneurs extraites par la méthode à l’oxalate (DSPox = Pox/CFPox, avec CFPox la capacité du sol à fixer le P, soit CFPox=0,5 * (Alox + Feox)), utilisé aux Pays-Bas comme indicateur environnemental. La revue bibliographique ayant montré que d’autres indicateurs basés sur la méthode d’extraction « Mehlich 3 » (le PM3 et le degré de saturation DSPM3 = PM3 / AlM3) étaient utilisés aux Etats-Unis et au Canada comme indicateurs agronomiques et environnementaux, ils ont également fait l’objet d’un état des lieux en Région wallonne. L’état des lieux a été effectué sur base de 231 échantillons de sols, dont 139 sols de culture et de 92 sols de prairie, répartis sur l’ensemble de la Région wallonne. Ces échantillons provenaient de la collection de sols wallons réalisée à l’occasion de l’étude POLLUSOL (SPAQuE-UCL-FUSAGx), complétée par une sélection d’échantillons acquis grâce à un partenariat avec l’ASBL REQUASUD, ainsi que par quelques échantillons prélevés pour cette étude par l’UCL. Les éléments extraits sur ces échantillons sont l’aluminium (noté Alox et AlM3), le fer (noté Feox et FeM3) – qui

La convention CAPASOL vise à la création d’un outil cartographique informatisé sur base des données « Analyse des sols agricoles » de la Direction de la Protection des Sols (DGRNE-DPS) afin de prédire et de gérer la capacité des sols à recevoir l’épandage d’amendements organiques conforme à la réglementation. La convention CAPASOL a été effectuée par l'Unité des Sciences du Sol de l’Université Catholique de Louvain pour compte de la Région wallonne. Les données et résultats sont et restent propriétés de la Région wallonne, qui a financé la convention. Le premier résultat de la convention CAPASOL est la constitution d'un ensemble fiable de données sur les teneurs en éléments traces métalliques dans les sols agricoles wallons. Cet ensemble, appelé "base de données CAPASOL", contient 6401 analyses de sols et 5657 contours de parcelles correspondant aux documents réglementaires (contenant les analyses de sols) introduits à la DPS jusqu'à la fin de l’année 2004. Sa constitution a donné lieu à un travail d'encodage, d'exploration, de structuration, de validation et de documentation des données afin de les rendre utilisables pour la réalisation des différents outils cartographiques visés par la convention. L'architecture de la base de données CAPASOL est bien documentée, et elle pourra servir de modèle de base pour l'élaboration du cahier des charges d’une interface d’encodage des données « analyses de sols » (à partir d’un site Web, par exemple). Le travail de validation et de documentation de la base de données CAPASOL devrait permettre de la rendre utilisable à l'avenir à d'autres fins, scientifiques ou de gestion, pour l'Administration. Plusieurs réflexions sur des problématiques parallèles à la convention ont été conduites par l'UCL à travers des échanges avec divers acteurs du secteur : l'ISSeP (G. Charlier, A. Warin), la FUSAGx (L. Bock, X. Legrain) et la SPAQuE (H. Halen) ; la convention CAPASOL s'est notamment intéressée aux problématiques de la traçabilité des do