The aim of this present research is to improve the containment properties of clayey soil by the use of bentonite and polymers as the additives. Clayey soils are generally used for the control of soil and water pollutions as they are inexpensive material. However, their applications are limited when it comes to durability of such liners in the field condition. Addition of additives to increase their efficiency by reducing the hydraulic conductivity can overcome this limitation. Generally, bentonite is used as the effective barrier additives because of their ability to render high swell and reduced hydraulic conductivity to the soil-bentonite mixtures. Due to high specific surface area and large cation exchange capacity, bentonite is always preferred for containment application. Despite their wide applicability in containment barrier, the problem with bentonite is its reduction of swell when the contaminant of interest consists of multivalent ions. Higher valency ions attach to the exchange site of bentonite and thus reduce its efficiency. To overcome these constraints the bentonite has, polymers are being used for containment applications. Normally, anionic polymers are used for such containment applications which help in increase negative charge concentration of the clayey soils. Previous studies have also proved the effectiveness of polymer in increasing the retardation factor of the soil which is due to the adsorption of contaminants to the negatively charged surface of clay. Hence attempt is also made in this thesis to study the effectiveness of super absorbent polymers when used as additive to the clayey soil. In this thesis, effectiveness of the local Bangalore soil for its use as barrier material is studied. Tests are done on the compacted sample to determine its contaminant transport properties. Because of their low hydraulic conductivities, advective flux through the barriers is negligible. In such cases, contaminant migration takes place due to the difference in concentration and this transport mechanism is known as diffusion. Laboratory test have been done to determine the diffusion coefficient of soil when the soil is saturated. For barriers and liner systems which are not fully saturated, suction adds to the hydraulic head. For unsaturated samples, although the liquid phase diffusion have been found to be nominal, head difference caused due to suction facilitates the migration of contaminants. Hence, effects of initial degree of saturation and density in contaminant transport process through soils have been examined. An attempt has been made to study unsaturated transport properties by using saturated transport parameters and unsaturated soil parameters obtained from soil-water characteristics curve. Another focus of this thesis has been towards enhancing the containment property of local soil by using additives. Effects of addition of bentonite and polymer on contaminant transport parameters of the soil have been studied. An attempt has been made to reduce the hydraulic conductivity of soil by using additives like bentonite. In addition, use of super-absorbent polymer as a novel material for barrier application has been studied to determine its suitability for local conditions. Experiments have been conducted to determine free swell, hydraulic conductivity and diffusion coefficient of soil-bentonite and soil-polymer mixes and compare them to those of local soil. To determine the effectiveness of soil-bentonite and soil-polymer mixes under the attack of concentrated solution over a long duration, chemical compatibility tests have been carried out. Micro-structural changes in the soil on addition of bentonite and polymer have been studied with the help of scanning electron microscope (SEM) images. Mineralogical changes occurring in the soil due to the additives have been studied using X-Ray Diffraction (XRD) plots. Effects of salt solution on soil-bentonite and soil-polymer mixes have also been studied by the help of SEM images and XRD plots. The final section of this thesis is on analysis of barrier performance for different conditions of densities, compaction and saturation by using numerical software CODE_BRIGHT. Transport parameters obtained from the experiments conducted in previous sections have been used as input for the analysis. A field condition of Bingipura landfill site in South Bangalore, Bangalore city has been simulated as a case study for this thesis. Time taken for contaminants to migrate from landfill to the nearby water body which is at a distance of about 122 meters is calculated for no barrier case. When barrier is provided, concentration variations of contaminant through the barrier with time are plotted and the results are compared for soil barrier, soil-bentonite barrier and soil-polymer barrier. v

It is recognised through current literature that contaminantin trusion is a primary threat leading to degradation of water quality and threat to human health. The problem is more serious in developing countries where the water supply is intermittent and water distribution system crisscross with sanitary systems. Therefore there is a need to develop the methodology that enables the decision makers and engineers to undertake actions to minimise the risk of contamination of water. The researchs tudy presentedin this thesis addresses these water quality issues by developing the appropriate modelling tools to minimize the risk of contaminant intrusion. The conceptual framework proposed in this study consists of a risk based approach where the process of contaminant intrusion into the systems is traced to know the hazards of contaminant intrusion and vulnerability of the system. The risk of contaminant intrusion into the pipes of a water distribution system is then estimated as the function of hazards and vulnerability. A suit of four models is developed based on this framework. The first model is a water distribution pipe condition assessment model that simulates the potential pathway for contaminant ingress into water pipes by relating it to the deterioration/condition of the pipes. The condition of each pipe is assessed by means of numerous factors related to physical, environmental and operational aspects of the water distribution system. These factors are grouped into different indicators at three levels, depending on the nature of influence of each factor on the deterioration process of the pipe. The uncertainties inherent in these pipe condition indicators are described with fuzzy set theory. A distance based multi-criteria decision making method-fuzzy composite programming has been applied to combine the multilevel pipe condition indicators to form a single indicator to rank the condition of the pipes. The second model is a water flow and contaminant transport modelling tool. This model predicts the envelope of pollution emanating from pollution sources (contaminant zone) and simulates the seepage and contaminant transport in this zone. It is assumed that the seepage of contaminant from pollution sources such as unlined canal/drains and surface water bodies follow saturated flow while from pollution sources such as sewer pipelines, lined canals/drains follow unsaturated flow. Accordingly Richard/Green Ampt equations (unsaturated flow) and Darcy's equation (saturatedf lows) are coupled with advection-diffusion equations that account for water flow and contaminant transport respectively. The third model, the contaminant ingress model, identifies sections of pipe of water distribution system within contaminant zone by combining the outputs from the contaminant seepage model with spatial analysis. The fourth model, the risk assessment model, identifies the risk of contaminant intrusion into a water distribution system from the outputs of the above three models, namely the vulnerability of the water distribution pipe (pipe condition assessment model), the contaminant concentration(contaminant seepage model) and section of pipe in contaminant zone (contaminant ingress model). All these models have been integrated into ArcView GIS to form a decision support system (Improved Risk Assessment of Water Distribution System) and applied to a real water distribution system in Guntur, India for which water pipe network data and data for pollution sources were collected. The modelling results are presented as risk maps that show the potential areas that are under threat of contamination with relative risk scores. It is envisaged that the developed modelling tools will be used by water utilities in developing countries to improve the water quality management by identifying vulnerable areas and understanding threats that exist to the water distribution systems.

Au vu de l'omniprésence des oxydes de fer dans le milieu naturel, et en particulier la goethite et l'hématite qui sont les formes les plus stables, mais aussi de la prolifération des contaminants émergents dans l'environnement, comme les fluoroquinolones, notre objectif a été d'étudier leur réactivité et de définir les mécanismes de sorption et d'oxydoréduction à l'interface oxyde/solution dans des conditions statiques (batch) et hydrodynamiques contrôlées (colonne) en couplant une étude macroscopique (techniques chromatographiques, LC/MS, LC/UV) avec une approche microscopique (spectroscopie vibrationnelle et XPS) et de modélisation mécanistique (TPM et CD-MUSIC). Ces travaux mettent en évidence les principaux mécanismes responsables de la transformation des molécules organiques à la surface d'un oxyde de fer, et donc fournissent des informations nécessaires à la compréhension du devenir des contaminants émergents dans l'environnement. / Given the ubiquity of iron oxides in environmental settings, particularly goethite and hematite, the most stable forms, but also the proliferation of emerging contaminants, such as fluoroquinolones, in the environment, our goal was to study their reactivity and describe mechanisms of sorption and redox at oxide /solution interfaces in static batch) and hydrodynamic conditions (column) by coupling a macroscopic study (LC/MS, LC/UV) with a microscopic/molecular approach (vibrational spectroscopy and XPS) and mechanistic modeling (TPM and CD-MUSIC).. These works highlight the main mechanisms responsible of the transformation of organic molecules on iron oxide surfaces and thus provide valuable information necessary for the understanding of the fate of emerging contaminants in the environment.

Philosophiae Doctor - PhD / The primary aim of these coal fired industries for co-disposing fly ash and brine was to use the fly ash as a sustainable salt sink. It is therefore important to study the interaction chemistry of the fly ash-brine systems to fully understand the leaching and mobility of the contaminant species, and to determine the possibility of capturing the salts from the brine solution when fly ash and brine are co-disposed. In order to achieve the aims and objectives of this study, several leaching procedures such as batch reaction tests, long-term fly ash-brine interaction tests, acid neutralization capacity (ANC) tests, up-flow percolation tests and sequential extraction tests were employed. The geochemical modeling software was applied to predict the formation of secondary mineral phases controlling the release of species in the fly ash-brine systems. Several analytical techniques such as x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), inductively coupled plasma-mass spectroscopy (ICP-MS) and ion chromatography (IC) were applied to characterize the fresh fly ashes, solid residues recovered from the fly ash-brine interaction tests, the brine sample used in this study and the leachate samples in order to determine the chemical and mineralogical compositions and speciation of the waste materials. / South Africa

There are rural residents of Central Appalachia that collect their drinking water from roadside springs despite having access to in-home piped point-of-use (POU) water. Residents have cited perceptions about water availability/quality as primary motivators for collecting drinking water from roadside springs. Water from roadside springs has been found to contain total coliform and E. coli, suggesting that consumers may be at an increased risk of contracting gastrointestinal illnesses. This research effort seeks to better understand roadside spring usage in Central Appalachia, by exploring motivations influencing potable water source selection and comparing household and spring water quality to Safe Drinking Water Act recommendations. Households were recruited from communities surrounding springs in three states (Kentucky, Virginia, and West Virginia). 24 tap water samples were collected from participating households and paired with samples from six roadside springs. Samples were analyzed for fecal indicator bacteria and inorganic ions. Study participants also completed short surveys to inventory their perceptions of their household drinking water. The majority of participants did not trust their home tap water, indicating water aesthetics as primary motivators for distrust of their homer water source. Statistical comparisons indicated that 10 water quality constituents (Cd, F, NO3-, Cu, Pb, Ag, Mn, Zn, Na, and Sr) were significantly higher in tap water samples and four constituents (total coliform, U, Al, and SO2-4) were significantly higher in spring samples. These results suggest that residents might be exposed to different risks based on their drinking water source and that water quality solutions must be devised case-by-case. / Master of Science / Some rural residents of Central Appalachia collect their drinking water from roadside springs, despite having access to piped drinking water at their homes. Water collected from roadside springs can contain harmful bacteria, suggesting that people may risk exposure to illness when consuming spring water. Through a household water quality study, this research effort aims to compare roadside spring and in-home tap water quality in order to determine what contaminants are present at each source, and why residents are choosing spring water over tap water. Households were recruited from communities surrounding roadside springs in three states (Kentucky, Virginia, and West Virginia). A total of 24 tap water samples were collected from participating households, and compared with samples from six nearby roadside springs. Samples were analyzed for bacteria, metals, and nutrients. Study participants were also asked to complete short surveys to better understand their perceptions of their drinking water sources. The majority of participants did not trust their home tap water, citing aesthetic concerns as the primary reason behind their distrust. When comparing roadside spring and home samples, 10 contaminants (Cd, F, NO3-, Cu, Pb, Ag, Mn, Zn, Na, and Sr) had greater concentrations in home tap water samples and four (total coliform, U, Al, and SO2- 4) had greater concentrations in spring samples. While home water samples had higher levels of metals, roadside spring samples had higher levels of bacteria, suggesting that residents might be exposed to different risks based on water source and that water quality solutions must be developed case-by-case.

Des études de sorption/désorption ont été effectuées pour neuf contaminants émergents sélectionnés (caféine, sulfaméthoxazole, déséthylatrazine, carbamazépine, atrazine, estradiol, éthinylestradiol, noréthindrone et diclofénac) dans les boues usées provenant de trois systèmes différents. Les contaminants incluent une variété de classes de composés (pesticides, hormones et pharmaceutiques) qui possèdent des propriétés physicochimiques différentes. L’objectif de ces travaux est de modéliser leur comportement dans une station d’épuration, en présence d’une phase particulaire et d’une phase aqueuse, et du même coup, de mieux comprendre leur devenir lors de leur rejet dans l’environnement. Le coefficient octanol-eau (log Kow) permet de bien interpréter les résultats et nous permet de classer les composés selon deux types de comportements observés : les composés avec un log Kow inférieur à 3 montrent peu ou pas de sorption alors que les composés avec un log Kow supérieur à 3 montrent une sorption variant de 30 à 90 % durant les premières minutes, suivi d’une sorption lente durant les heures suivantes. Une augmentation du contenu organique favorise la sorption des composés hydrophobes alors qu’un changement de pH peut modifier la charge à la surface des particules et également la charge des analytes. Les résultats ont montré que seul le diclofénac était sensible aux variations de pH étudiés. Dans une telle situation, il est nécessaire d’utiliser le facteur d’hydrophobicité corrigé en fonction du pH (log Dow). Le coefficient de distribution solide-eau (log Kd) a été déterminé pour chaque composé à la fin de chaque expérience de sorption et se situe entre -0.3 et 2.6. Avec l’augmentation de l’hydrophobicité, la désorption diminue avec le temps et avec l’étape de rinçage. Pour simuler le relargage dans les systèmes aquatiques, les facteurs de rinçage ont été déterminés pour estimer le nombre de rinçages qui seraient nécessaire pour désorber 50 et 99 % de la concentration initialement sorbée. Les bilans de masse ont été effectués après chaque expérience dans le but de ne pas surestimer les capacités de sorption d’un composé et se situent entre 7 et 25 % pour l’estradiol, la noréthindrone et le sulfaméthoxazole et entre 44 et 103 % pour l’éthinylestradiol, l’atrazine, la déséthylatrazine, la carbamazépine, la caféine et le diclofénac. / Sorption/desorption studies were performed for nine selected emerging contaminants (caffeine, sulfamethoxazole, desethylatrazine, carbamazepine, atrazine, estradiol, ethinylestradiol, norethindrone and diclofenac) in sewage sludge from three different systems. Contaminants include a variety of compound classes (pesticides, hormones and pharmaceuticals) with different physicochemical properties. The objective of this work is to model their behavior in a treatment plant in the presence of a particulate phase and an aqueous phase, and at the same time, understanding their fate upon their release into the environment. The octanol-water partition coefficient (log Kow) allowed a good understanding of the results and allowed us to classify the compounds according to the two types of behavior observed: compounds with log Kow below 3 showed little or no sorption while compounds with log Kow over 3 showed a 30 to 90% sorption within the first few minutes, followed by a slow sorption during the next hours. An increase of the organic content promotes the sorption of hydrophobic compounds while a change in the pH can modify the charge on the surface of the particles and also the charge of the analytes. Only diclofenac was found to be sensitive to the different pH studied. In such a situation, it is necessary to use the pH-corrected hydrophobicity factor (log Dow). The solid-water distribution coefficient (log Kd) were determined for each compound at the end of each sorption experiment and ranged from 0.2 to 2.9. With increasing compounds hydrophobicity, desorption decreased with time and rinsing step. To simulate releases into aquatic systems, rinsing factors were determined to estimate the number of rinsing that would be needed to desorb 50 and 100 % of the sorbed concentration. Mass balances were performed after each experiment in order to not overestimate the sorption capacity of the compound and ranged from 7 to 25 % for estradiol, norethindrone and sulfamethoxazole and from 44 to 103 % for ethinylestradiol, atrazine, desethylatrazine, carbamazepine, caffeine and diclofenac.

L'utilisation de pesticides sur les surfaces agricoles conduit à une contamination généralisée des eaux de surface et de subsurface en France. Dans l'attente d'une évolution profonde des pratiques agricoles et d'une baisse durable de l'utilisation des pesticides, il est intéressant de chercher à limiter des transferts des zones agricoles aux zones aquatiques. Pour mieux agir sur les voies de transfert, il est nécessaire d'approfondir les connaissances des processus en jeu et de leurs interactions éventuelles et de tirer au mieux partie des observations du terrain.L'objectif de cette thèse est l'intégration de processus de transferts réactif dans le modèle hydrologique à base physique CATHY (CATchment HYdrology), capable de simuler en 3 dimensions les écoulements de l'eau de façon couplée surface-subsurface et le transport advectif dans des situations variablement saturées. En subsurface, les processus d'adsorption linéaire et de dégradation du premier ordre sont implémentés. Un module de mélange des solutés entre la lame ruisselante et la première couche de sol est ajouté, qui permet de simuler la remobilisation des solutés de la subsurface dans le ruissellement. Le couplage surface-subsurface des écoulement est très efficace dans ce modèle, et le couplage du transport de soluté adoptant la même stratégie a été amélioré pour mieux respecter la conservation de la masse.Le modèle est en premier lieu testé sur des données issues d'expérimentations de transfert de subsurface sur une maquette de laboratoire à petite échelle (2 m de long, o.5 m de large, 1 m de profondeur). Les résultats sont confrontés aux chroniques de flux massiques observées et une analyse de sensibilité de type Morris est menée. Le modèle est capable de reproduire de façon satisfaisante les observations, et très satisfaisante après une légère calibration. Les conductivités à saturation horizontale et verticale, la porosité et le paramètre $n$ de la courbe de rétention influencent de façon non négligeable les résultats hydrodynamiques et de transfert de soluté. Dans un second temps, le modèle est évalué sur les données issus d'un versant viticole réel (0.6 ha) dans un contexte orageux avec de fortes interactions surface-subsurface. Une analyse de sensibilité globale est menée, et met en valeur les mêmes paramètres que la méthode de Morris. Les interactions entre les paramètres influencent fortement la variabilité des sorties hydrodynamiques et de transfert. La conservation de la masse est très correctement assurée malgré la complexité de la simulation.Le modèle auquel on aboutit correspond bien aux objectifs de départ, sa validation est solide, même si elle n'est rigoureusement valable que dans les contextes précis où elle a été réalisée. On a montré que le modèle était robuste et capable de reproduire des données observées. D'autres processus manquent encore pour représenter toutes les voies de transfert à l'échelle du versant, notamment la représentation du transfert préférentiel en subsurface et du transport sédimentaire en surface. / Pesticide use on agricultural surfaces leads to a broad surface and subsurface water contamination in France. Awaiting a deep agricultural practices evolution and a sustained fall of the pesticide use, it is of interest to limit transfers form agricultural fields to rivers. In order to constrain those transfers, a deepen knowledge of processes at stake and their potential interactions is necessary, as well as taking full advantages of fields observations.The aim of this PhD is the reactive transfer processes integration in the Hydrological physically-based model CATHY (CATchment HYdrology) which simulates surface-subsurface coupled water flow and advectiv solute transport in three dimensions and in variably saturated situations. Linear adsorption and first order decay are implemented in subsurface. A mixing modules is added, and evens the concentration between surface runoff and subsurface first layer. This module simulates the solute mobilisation from soil to surface runoff. The water flow surface-subsurface coupling procedure is very accurate in CATHY, and the transport coupling procedure is improve in order to respect the mass conservation.The model is first evaluated on subsurface transfer laboratory experimentation data at a small scale (2 m long, o.5 m wide, 1 m deep). Results are compared to mass flux evolution in time and a Morris sensitivity analysis is conducted. The model is able to acceptably reproduce observation, and properly after a slight calibration. Horizontal and vertical saturated conductivities, porosity and the $n$ parameter of retention curve significantly influence hydrodynamics and solute transport. As a second step, the model is evaluated on data from a field wine hillslope on an intense rain event, therefore in a context with a lot of surface-subsurface interactions. A global sensitivity analysis is conducted and highlights same parameters as the Morris method. Interactions between parameters highly influence the variability of hydrodynamic and solute transfer outputs. Mass conservation is accurate despite the complexity of the context.The resulting model meets the objectives, its evaluation is strong even if its theoretically only valid in the precise context in which the evaluations where conducted. The model is robust and able to reproduce observed data. Some complementary processes are still missing in the model to properly represent transfer ways at the hillslope scale, such as subsurface preferential transfers and surface sedimentary transport.

La gestion des eaux a pendant longtemps été associée à des préoccupations sanitaires afin d'éviter la dissémination de maladie hydrique. Au cours du temps, l'aspect sanitaire a été remplacé par des préoccupations environnementales. A ce jour, des questions sur les potentiels risques sanitaires dues aux ouvrages de gestion des eaux sont récurrentes. Dans ce travail, nous nous sommes intéressés au comportement d'un bassin sec de rétention de l'est lyonnais en étudiant les liens existant entre la présence de bactéries pathogènes opportunistes, le fonctionnement hydraulique et la capacité de piégeage des polluants de ce bassin. Pour cela, nous avons réalisé 6 campagnes de prélèvements sur un an et demi. Les prélèvements ont été caractérisés au niveau physico-chimique et microbiologique (A. caviae, P. aeruginosa, Nocardia, E. coli, coliformes, entérocoques). Les caractéristiques physico-chimiques trouvées sont comparables à celles obtenues dans des bassins similaires. L'ensemble du bassin est régulièrement contaminé par les bactéries suivies (0 à 1.92E+07 UFC/g sec). Des concentrations plus fortes en été et un apport par les pluies ont pu être observés. Des analyses de corrélation de type Pearson ont mis en évidence de rares liens entre la présence de bactéries et de polluants chimiques, comme par exemple entre P. aeruginosa et les HAPs. Une corrélation entre les Nocardia et des caractéristiques sédimentaires (teneur en masse organique volatile et densité) a aussi pu être observée. Une étude plus poussée sur le genre Nocardia a permis: d'isoler pour la première fois en France des N. cyriacigeorgica dans l'environnement, de mettre au point une qPCR (spécifique de cette espèce) utilisable en milieu complexe et de développer un test rapide sur nématode afin de connaitre la virulence d'isolats bactériens au niveau du SNC / Water management has been associated during a long time with health concerns to prevent the spread of waterborne disease. Over time, the health aspect was replaced by environmental concerns. Nowadays, questions about the potential health risks due to water management structures are recurrent. In this work, we studied the behavior of a dry retention basin at the eastern part of Lyon, in particular the links between the presence of opportunistic pathogenic bacteria, the hydraulic behaviour and the trapping capacity of pollutants in the basin. For that purpose, we carried out 6 sampling campaigns during a year and a half. The samples were characterized at a physicochemical and microbiological level (A. caviae, P. aeruginosa, Nocardia, E. coli, coliforms, enterococci). The physicochemical characteristics found are comparable to those obtained in similar basins. The entire basin is regularly contaminated by bacteria followed (0 to 1.92E +07 CFU/g dm). Higher concentrations in summer and during rain periods were observed. Pearson correlation analysis revealed some rare links between the presence of bacteria and chemical pollutants, such as between P. aeruginosa and PAHs. A correlation between Nocardia and sedimentary characteristics (volatile organic content and mass density) was also observed. For the first time in France, further study on the genus Nocardia has permitted: to isolate N. cyriacigeorgica in the environment, to develop a qPCR (specific of this species) used in complex environments and to develop a quick test on nematode in order to identify the virulence of bacterial isolates in the NSC

Master of Science / Department of Mechanical and Nuclear Engineering / Byron W. Jones / Airline cabins represent an indoor environment in which the spread of particles or contaminants is of interest due to the large number of passengers and distances they travel. In fact, hundreds of millions of passengers travel each year spending extended periods in close proximity to one another. This close proximity causes concern about the spread of disease and contaminants amongst passengers. These passengers move from region to region of the world increasing the potential for worldwide epidemics. In an effort to understand the aircraft cabin environment and the dispersion of fine particles, an experimental study was conducted. The cabin used for the experiments is a simulated Boeing 767-300 with eleven rows, each comprised of seven seats. The particles release occurred in a short burst in all the seats across the second row simultaneously. This design focused on the longitudinal dispersion of particles throughout the cabin. The particles from this release had corrected aerodynamic diameters between 0.87 and 1.70 micrometers. The collection and analysis of data took place based on five criteria. The first analysis focused on the total particle counts at 27 locations throughout the cabin. The second analysis made use of a reference location for each of the tests and presents the exposure in each of those locations as a fraction of the reference during the same test. The third analysis centers its attention on the transient behavior as the particles were counted at various locations. The forth and fifth types of data analysis focus on the time required for each tested location to reach either 100 total particle counts or ten percent of the total seen at that location during that test. The tests show the regions close to the source experience higher levels of exposure, less time to reach the time limits, and higher levels of variation from test to test. The locations farther from the source show lower exposure levels, longer times to reach the limits, and less variation from test to test. This indicates the variations close to the source stem from the chaotic nature of the airflow rather than from irregularities of the dispersion system. The data agree well with previous work and suggest further studies would improve the understanding of the aircraft cabin environment and the spread of airborne particles and contaminants.

Manmade climate change has expressed a plethora of complex effects on Earth's biogeochemical compartments. Climate change may also affect the mobilisation of natural metal sources, with potential ecological consequences beyond mountains' geographical limits; however, this question has remained largely unexplored. We investigated this by analysing a number of key climatic factors in relationship with trace metal accumulation in the sediment core of a Pyrenean lake. The sediment metal contents showed increasing accumulation trend over time, and their levels varied in step with recent climate change. The findings further revealed that a rise in the elevation of freezing level, a general increase in the frequency of drier periods, changes in the frequency of winter freezing days and a reducing snow cover since the early 1980s, together are responsible for the observed variability and augmented accumulation of trace metals. Our results provide clear evidence of increased mobilisation of natural metal sources - an overlooked effect of climate change on the environment. With further alterations in climate equilibrium predicted over the ensuing decades, it is likely that mountain catchments in metamorphic areas may become significant sources of trace metals, with potentially harmful consequences for the wider environment.