Persistent Organic Pollutants (POPs) in the European Atmosphere: An Updated Overview

POPs are a group of chemicals which share some specific characterictics, that make them of high international concern. Due to their semivolatility, POPs present a widespread distribution being able to reach remote locations and areas after traveling long distances in the atmosphere where they have never been produced nor used. Different chemical families are considered as POPs, such as PCBs, OCPs, PCDD/Fs, PAHs, and, PCNs. In addition, some emerging contaminants are currently considered as candidate POPs, like PBDEs and PFCs. POPs exist in the atmosphere as gases and bound to particles depending on their physico-chemical properties. This affinity to gas or particulate phase is of relevant importance in the processes of POP atmospheric global transport and degradation. POPs are delivered to aquatic and terrestrial ecosystems by atmospheric deposition, air-water interchanges and direct discharges. The general hydrophobic nature of POPs results in high affinity to organic matter and biota tissues. Consequently, organisms and sediments become final sinks of POPs, due to low metabolic activity for these compounds and slow degradation processes in the environment. A number of national and international actions have been promoted to reduce or ban their production and control their emissions to the environment. The UNEP Stockholm Convention adopted in May 2001. The Artic Monitoring and Assessment Programme (AMAP) is measuring atmospheric concentrations of POPs in the artic region since it was established in 1991. At a European scale a big effort is being carried out combining the update of existing monitoring programmes with the generation of new legislations. Such is the case of the largest monitoring network across Europe gathering concentrations of POPs in air and deposition (EMEP). On the political side, the brand new European legislation on chemicals, REACH, will regulate the production of chemicals at a European scale. In addition, other POPs monitoring programmes exist at regional or national scales and a large number of ;independent; sites measuring atmospheric concentrations of POPs are spread out in the European geography. Considering such a scenario it seems obvious that a strong effort in harmonization and communication of results and monitoring and research strategies needs to be achieved. A step to facilitate this needed interaction was the workshop on ;Persistent Organic Pollutants (POPs) in the European Atmosphere ; Concentration, Deposition and Sources in Europe; organized by the European Commission Joint Research Center held in October 17-19th, 2005 in Stresa (Italy). It was one of the objectives of the workshop to gather top experts from Europe and North America to share their expertise on POP monitoring and research in the atmospheric compartment in order to evaluate their current status in Europe. Invited experts develop their professional activities either in the existing POPs monitoring networks or in research institutions closely linked to POPs research. Other objectives of the workshop were to explore future research lines on the topic and to establish links with the existing science and new policies in Europe regarding chemicals. Twenty oral communications were presented covering relevant key issues on POPs: In this report a compilation of the extended abstracts submitted by the participants is presented, whereas the working result output of the workshop will be submitted as an article to a peer-reviewed scientific journal.JRC.H.5-Rural, water and ecosystem resource

Biogeochemical controls of the transport and cycling of persistent organic pollutants in the polar oceans

Humanity is currently using more than 200000 synthetic organic compounds in many industrial, agricultural and domestic applications. Many of these chemicals reach the environment and have a harmful effect on ecosystems and humans. Among them, the group of persistent organic pollutants (POPs) comprises several families of compounds that have physical and chemical properties that give them the ability to be distributed and impact globally (semivolatility, high persistence and bioaccumulation capacity due to their hydrophobicity). In the present thesis, the coupling of atmospheric transport and biogeochemical cycles in the Arctic and Southern Ocean has been studied for Hexachlorocyclohexanes (HCHs), Hexachlorobenzene (HCB) and Polychlorinated Biphenyls (PCBs). Three oceanographic cruises were conducted, one in the North Atlantic and the Arctic Ocean (2007) and two in the Southern Ocean surrounding the Antarctic Peninsula (2008 and 2009). During these campaigns, air (gas and particulate), water (dissolved and particulate) and biota (phytoplankton) were sampled simultaneously allowing to report a complete picture of POPs cycling in polar areas. In the case of the Southern Ocean, the largest data set available for PCBs, HCH and HCB has been generated. The atmospheric and seawater concentrations were low, among the lowest reported for the Polar Oceans, and in the case of the Southern Ocean there is a clear historical trend of decreasing concentrations, consistent with reduced emissions in source regions. Long range atmospheric transport was identified as the main POPs input to polar ecosystems agreeing with previous works. However, it has been found that secondary local sources from soil and snow influences strongly the atmospheric concentrations overland in the Antarctic region, and over the adjacent Southern ocean in the case of HCHs. Atmospheric residence times calculated from the measurements were in agreement with the prediction from environmental fate models. The atmospheric residence times were longer for the less hydrophobic PCBs and shorter for the more hydrophobic, consistent with the role of the biological pump sequestering atmospheric PCBs. Once POPs reach the Polar regions the main route of entry of these compounds to surface waters is by atmospheric deposition, mainly by diffusive exchange between the gas and dissolved phase with minor contributions from dry deposition of aerosol bound POPs. Estimated bioconcentration factors revealed that concentration of POPs in phytoplankton were correlated with the chemical hydrophobicity, but some discrepancies with model predictions were observed. The biological and degradative pumps are identified as the two main processes that control the fate and occurrence of POPs in the surface water column, and also are able to modulate the atmospheric transport of POPs to remote areas. POPs such HCHs are prone to be efficiently degraded by bacterial communities in surface waters, depleting the seawater concentrations and increasing the diffusive air-water exchange to the Arctic and Southern Ocean. Conversely, the biological pump decreases the dissolved phase concentrations of the more hydrophobic PCB congeners increasing the air to water fugacity gradients and enhancing the diffusive air-water exchange fluxes. This is the first time that the influence of the biological pump on POP cycling is demonstrated for Oceanic waters. Finally, HCB was close to air-water equilibrium showing that neither the biological and degradative pumps are efficient sequestration processes for the highly persistent and mid-hydrophobic compounds. Overall, the results show clearly that biogeochemical processes occurring in the water column affect the atmospheric deposition and long range transport of POPs to remote regions.The magnitude of these processes may show a clear seasonality and are suitable to be perturbed under the current scenario of climate change.En la actualidad se usan en aplicaciones domésticas más de 200.000 compuestos orgánicos sintéticos. Muchos de estos compuestos químicos que se liberan al medio ambiente son nocivos para el medio ambiente y los humanos. Entre estos compuestos se encuentran los contaminantes orgánicos persistentes (COPs) que comprenden una serie de familias de compuestos que comparten una serie de características físico-químicas que les permiten estar distribuidos globalmente (semivolatilidad, elevada persistencia y capacidad de bioacumulacion por sus características hidrofóbicas). En la presente tesis doctoral se ha estudiado en profundidad el acoplamiento entre el transporte atmosférico y los ciclos biogeoquímicos Hexaclorociclohexanos (HCHs), Hexaclorobenceno (HCB) y Bifenilos Policlorados (PCBs) en los Océanos Polar Ártico y Polar Antártico. Durante esta tesis se han realizado tres campañas oceanográficas, una al Atlántico Norte y al Océano Polar Ártico (2007), y dos en el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica (2008 y 2009). Durante estas tres campañas oceanográficas se han tomado muestras de aire (gas y particulado), agua (disuelto y particulado) y biota (fitoplankton) de forma simultánea lo que permitió tener una amplio conocimiento de el ciclo de los COPs en zonas polares. En el caso de el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica se ha generado la mayor cantidad de datos en un mismo trabajo, incluso se han generado datos que hasta ahora no se habían publicado como las concentraciones de fitoplankton. La concentraciones medidas en el la atmósgera y aguas superficiales fueron bajas, siendo en algunos casos las concentraciones más bajas jamás encontradas en el océano polares, en el caso de el Océano Polar Antártico se ha encontrado una significativa tendencia histórica de concentraciones decrecientos lo cual es consistente con la reducción de emisiones de COPs en origen. El transporte atmosférico a larga distancia ha sido identificado como la vía de entrada principal de entrada de los COPs a sistemas polares. Sin embargo, se ha encontrado que hay fuentes secundarias provenientes de el suelo y la nieve con una clara influencia sobre las concentraciones atmosféricas en zonas de el continente Antártico y aguas costeras adyacentes en el caso de los HCHs. Los tiempos de residencia atmosférica calculados están en los mismos rangos con los modelos predictivos. Los tiempos de residencia atmosférica fieron más largos para los compuestos menos hidrofóbicos y más cortos para los más hidrófobicos lo cual es consistente con la bomba biológica. Una vez estos compuestos alcanzan las regions polares la principal ruta de entrada de estos compuestos al agua superficial es por deposición atmosférica, principalmente por intercambio difusivo entre la fase gas y la fase disuelta, se ha comprobado que la contribución de la deposición seca es significativamente menor. Los factores de bioconcentración revelaron que la concentración de COPs en el fitoplankton se correlacionaba con la hidrofobicidad química, pero se encontraron discrepancias con los modelos predictivos. Las bombas biológica y degradative han sido identificadas como los dos procesos principals que controlan el destino y ocurrencia de COPs en la columna de agua superficial e incluso son capaces de modular el transporte atmosférico de COPs a areas remotes. COPs como los HCHs son eficientemente degradados por las comunidades bacterianas de aguas superficiales disminuyendo su concentraciéon aumentando los flujos difusivos de deposición entre la fase gas y la superficie disuelta en el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica. Por otro lado, la bomba biológica disminuye las concentraciones de el disuelto de los COPs más hidrofóbicos aumentando el gradiente de fugacidades y favoreciendo la deposición por intercambio difusivo aire-agua. La presente tesis es la primera que ha demostrado la influencia de la bomba biológica influye de forma significativa el ciclo de los COPs.El HCB se ha encontrado en equilibrio en ambas zonas de estudio y no se ha demostrado que hubiera influencia de la bomba biológica o de procesos degradativos en aguas superficiales. Como conclusion final se ha demostrado a través de los resultados que los procesos biogeoquímicos en la columna de agua afectan a la deposición atmosférica y el transporte a larga distancia de COPs a regiones remotas. La magnitud de estos procesos muestra una clara estacionalidad que puede ser perturbada en un actual escenario de cambio climático

Gaseous flux and distribution of polycyclic aromatic hydrocarbons across the air-water interface of southern Chesapeake Bay

Gaseous fluxes of polycyclic aromatic hydrocarbons (PAHs) across the air-water interface of Southern Chesapeake Bay were calculated for the period January 1994 through May 1995 using a modified two-film model. Additionally, the distributions of PAHs between the vapor and aerosol phase in the atmosphere, and between the freely dissolved and suspended particulate phase in the water column were investigated. Net instantaneous gaseous fluxes of PAHs were determined to vary in direction and magnitude both spatially and temporally across the air-water interface of Southern Chesapeake Bay at four sites ranging from remote to urban and highly industrialized. The magnitude of gas exchange fluxes was of the same order as wet and dry atmospheric depositional fluxes. Spatial variations in gaseous fluxes resulted from differences in the air-water concentration gradients between sites. Temporal variations in gas exchange fluxes resulted from seasonal changes in both water temperatures and vapor concentrations. Atmospheric PAH vapor concentrations increased exponentially with temperature at the non-rural sites suggesting volatilization from contaminated surfaces (soils, roads, vegetation) during warmer weather; whereas, PAH vapor concentrations at the rural site decreased with time. All sites experienced increased loadings of particulate-associated PAHs during winter. Mean total atmospheric PAH concentrations ranged from 7.87 ng/m&\sp3& at a rural (Haven Beach) site to 92.8 ng/m&\sp3& at an urban (Elizabeth River) site. Plots of the logarithm of the particle-vapor partitioning coefficient (C&\rm\sb{lcub}p{rcub}/TSP\sp\* C\sb{lcub}v{rcub})& versus inverse temperature indicate different particle characteristics or atmospheric partitioning processes at the urban and rural sites. Three methods (gas sparging, semipermeable membrane devices, filtration with sorption of the dissolved contaminant fraction to XAD-2 resin) for determining freely dissolved contaminant concentrations in estuarine waters were investigated. Mean total PAH concentrations in surface waters ranged from 24.2 ng/l at a mainstem bay site to 91.1 ng/l at the industrialized Elizabeth River site. Dissolved-particulate partitioning of PAHs approximated equilibrium theory at all sites and sampling periods. The results of this study support the hypothesis that gas exchange is a major transport process affecting concentrations and exposure levels of PAHs in the southern Chesapeake Bay Region

Soil – Atmosphere Interaction: Modeling the fate of semi-volatile organic compounds and chemical weathering of marine mudrocks

In this dissertation, reactive transport modeling is applied to analyze coupled physical, biological, geochemical and hydrological processes at the soil-atmosphere interface. Focus is on mass transfer of compounds between different environmental compartments (e.g. groundwater, the unsaturated zone, soils, plants and the atmosphere). The influence of soil-atmosphere diffusive gas exchange and water infiltration is addressed with respect to environmental fate of semi-volatile organic compounds (SVOCs) as well as oxidation and carbon turnover during chemical weathering of pyrite- and kerogen-bearing mudrocks. Conceptual models considering soils, plants, and the atmospheric boundary layer were developed and solved numerically with a multicomponent reactive transport code (MIN3P). The models consider eddy diffusion and photochemical oxidation in the atmosphere, changes in the thickness of the atmospheric boundary layer, gas diffusion and heat transport in the soil, temperature dependence of sorption and partitioning in soils and plants as well as solute transport by seepage water. Besides these transport processes, biodegradation and geochemical changes in water and solids are considered. Model results on environmental fate of SVOCs show that on the long term (i.e. for centuries) soils are sinks for atmospheric pollutants because of strong sorption and thus limited bioavailability. Potential re-volatilization back into the atmosphere following declined anthropogenic emissions does not change this finding substantially. Modeling shows also that diurnal, temperature-driven volatilization of SVOCs from soils into the atmosphere cannot account for short-term concentration fluctuations often observed in the atmosphere. The latter can only be simulated if a rapidly-exchanging storage compartment is introduced into the model – a function that can be taken over e.g. by plants in conjuction with fast atmospheric mixing due to eddy diffusion. Numerical simulations of chemical weathering show that initially diffusion is the main physical control in the chemical weathering of pyrite- and kerogen-bearing mudrocks (e.g. Opalinus Clay of the Swabian Alb, Southwestern Germany). Pyrite and kerogen oxidation cause acidification of seepage water, which consequently leads to dissolution of carbonate minerals, i.e. calcite and siderite, and thus to an increase in porosity, release of CO2 into the atmosphere as well as elevated groundwater alkalinity. Seepage water chemistry highly depends on water infiltration rates (or fluid residence times). In case water infiltration rates are low, ions accumulate in the seepage water and finally gypsum precipitation starts. The latter has geotechnical consequences such as swelling of the ground, which is often observed for buildings founded in pyrite bearing mudrocks in Southern Germany. Overall this dissertation demonstrates the capability of reactive transport modeling to elucidate the controls on pollutant and gas exchange between different environmental compartments by considering various coupled physical, biological, geochemical and hydrological processes. This allows to investigate trends in long term soil and groundwater pollution as well as evolution of seepage water chemistry during chemical weathering of mudrocks including CO2 release into the atmosphere.In dieser Dissertation werden mit Hilfe eines numerischen Simulationsmodells für den reaktiven Transport von Wasserinhaltsstoffen physikalische, biologische, geochemische und hydrologische Prozesse im Übergangsbereich Boden - Atmosphäre untersucht. Der Fokus liegt dabei auf dem Stofftransfer und -austausch der Stoffe zwischen unterschiedlichen Umweltkompartimenten (z.B. Grundwasser/wassergesättigte Zone, vadose Zone, Boden, Pflanzen, Atmosphäre). Im Besonderen wird dabei auf den Einfluss des diffusiven Gasaustausches an der Grenzfläche Boden – Atmosphäre und der Infiltration von Niederschlagswasser in die Bodenzone auf das Verhalten und die Verteilung von sogenannten semi-volatilen organischen Verbindungen (SVOCs), sowie auf Oxidationsdynamik und Kohlenstoffumsatz während der Verwitterung von Pyrit- und Kerogen-haltigen Sedimentgesteinen, eingegangen. Dazu wurden konzeptionelle Modelle für die Verbindung bzw. Kopplung der Kompartimente Boden, Pflanze und atmosphärische Grenzschicht entwickelt und in Mehrkomponenten-Transportmodelle mit dem Modell-Code MIN3P umgesetzt. Die Modelle berücksichtigen Eddy-Diffusion und photochemische Oxidation in der Atmosphäre, Änderungen der Mächtigkeit der atmosphärische Grenzschicht, Gasdiffusion und Wärmeübertragung in Böden, Temperaturabhängigkeit von Stoffsorption und -verteilung in Böden und Pflanzen sowie den gelösten Stofftransport im Sickerwasser. Neben diesen Prozessen werden zudem der mikrobiologische Abbau der Stoffe und geochemische Änderungen in Wasser und Festphase betrachtet. Die Modellergebnisse zeigen, dass - langfristig betrachtet - Böden als Senken für SVOCs in der Atmosphäre fungieren. Die vergleichsweise starke Sorption und dementsprechend geringe Bioverfügbarkeit der SVOCs führt zu einer Anreichung im Oberboden. Eine denkbare Ausgasung der SVOCs in die Atmosphäre als Folge rückläufiger anthropogener Schadstoffemissionen ändert diesen Befund nur geringfügig. Die Simulationen zeigen auch, dass die in der Atmosphäre beobachteten kurzfristigen Konzentrationsschwankungen nicht durch die regelmäßige Ausgasung von SVOCs aus dem Boden aufgrund der täglichen Temperaturschwankungen erklärt werden können. In der Simulation ist dies nur dann möglich, wenn im Modell ein Speicherkompartiment eingeführt wird, welches einen schnellen Austausch ermöglicht - eine Funktion, die z.B. die Pflanzen in Verbindung mit einer schnellen Vermischung durch Eddy Diffusion übernehmen können. Numerische Simulationen zur chemischen Verwitterung von Pyrit- und Kerogen-haltigen Sedimentgesteinen (z.B. der Opalinuston der Schwäbischen Alb in Südwestdeutschland) belegen, dass die Diffusion der anfänglich kontrollierende physikalische Prozess ist. Pyrit- und Kerogen-Oxidation führen zu einer Versauerung des Sickerwassers, wodurch Karbonatmineralien (z.B. Kalzit und Siderit) gelöst werden und es schließlich zu einer Vergrößerung des Porenraums, einer Ausgasung von CO2 in die Atmosphäre sowie zu einer erhöhten Alkalinität des Grundwassers kommt. Der Chemismus des Grundwassers ist dabei abhängig von den relevanten Verweilzeiten, d.h. von der Höhe der Grundwasserneubildungsrate. Bei geringer Grundwasserneubildung kann es zur Akkumulation von Ionen im Sickerwasser und in der Folge zur Ausfällung von Gips kommen. Letzteres kann zu einer Volumenvergrößerung und schließlich zu Bodenhebungen führen, deren Folgen häufig an Gebäuden, die auf pyrithaltigem Sedimentgestein in Süddeutschland gebaut sind, zu beobachten sind. Insgesamt demonstriert diese Dissertation wie die reaktive Stofftransportmodellierung als Werkzeug genutzt werden kann, um die kontrollierenden Faktoren für den Austausch von Schadstoffen und Gasen zwischen verschiedenen Umweltkompartimenten zu ergründen, indem unterschiedliche physikalische, biologische, geochemische und hydrologische Prozesse gekoppelt betrachtet werden. Damit können langfristige Trends der Verunreinigung von Böden und Grundwasser untersucht und erklärt werden, ebenso wie die Entwicklung von Sickerwasserchemismus durch Gesteinsverwitterung und der ggf. resultierenden Freisetzung von CO2 in die Atmosphäre

Contaminant containment for sustainable remediation of persistent contaminants in soil and groundwater

Contaminant containment measures are often necessary to prevent or minimize offsite movement of contaminated materials for disposal or other purposes when they can be buried or left in place due to extensive subsurface contamination. These measures can include physical, chemical, and biological technologies such as impermeable and permeable barriers, stabilization and solidification, and phytostabilization. Contaminant containment is advantageous because it can stop contaminant plumes from migrating further and allow for pollutant reduction at sites where the source is inaccessible or cannot be removed. Moreover, unlike other options, contaminant containment measures do not require the excavation of contaminated substrates. However, contaminant containment measures require regular inspections to monitor for contaminant mobilization and migration. This review critically evaluates the sources of persistent contaminants, the different approaches to contaminant remediation, and the various physical-chemical-biological processes of contaminant containment. Additionally, the review provides case studies of contaminant containment operations under real or simulated field conditions. In summary, contaminant containment measures are essential for preventing further contamination and reducing risks to public health and the environment. While periodic monitoring is necessary, the benefits of contaminant containment make it a valuable remediation option when other methods are not feasible

An Assessment of Polychlorinated Biphenyl Contamination in Fish from the Inland and Great Lakes of Michigan

Fish within the Great Lakes region of North America are an invaluable resource with economic and cultural significance. While these fish are vital, they contain chemical pollutants that are hazardous to human health. One such man-made group of chemicals, polychlorinated biphenyl compounds (PCBs), continue to be a problem long after the ban on production (1979). The objective of this research thesis was to assess PCB contamination in fish within the Great Lakes Region. This objective was completed by determining the sources of PCB contamination, defining the ecosystem characteristics that significantly affect fish contamination, predicting when it will be safe to consume a desired amount of fish, identifying which water bodies have higher contamination, and determining if PCBs have significantly declined since the early 1990s. The assessment of inland lake contamination revealed that lakes impacted by point sources of PCBs can de differentiated from lakes whose only source of PCBs is atmospheric. Principal Component Analysis of PCB concentrations in common fish species revealed that lakes impacted by local, point sources of PCBs had congener distributions in fish dominated by heavier congeners. Similar results were obtained for sites in the Great Lakes; PCBs in Lake Superior fish were found to be derived primarily from atmospheric deposition while the lower lakes had significant contributions from local sources. It was discovered that deeper inland lakes had higher levels of fish contamination based on multiple linear regression analysis where mean depth was the best predictor of total PCB concentration in fish (r2=0.73). The importance of developed watersheds to Great Lakes fish contamination was revealed using the same form of analysis. Lakes with lower primary production tended to have higher PCB contamination. The use of a lake model to predict dissolved PCB concentrations from atmospheric concentrations and the EPA’s Bioaccumulation and Aquatic System Simulator (BASS) to model food web dynamics predicted that if atmospheric concentrations continue to decline at the same rate, fish in Michigan’s inland lakes will be safe to consume at a rate of 2 meals per day in roughly 20 years. For most sites in the Great Lakes, there has been a significant decline in PCB contamination since the early 1990s. However, the Great Lakes have a higher level of PCB contamination compared to inland Michigan Lakes. This thesis research provides the public and scientific community an explanation of the trends in PCB contamination in the Great Lakes Region. Safer fish consumption habits according to PCB contamination are now possible without prohibiting the use of this resource. Modeling tools revealed what can be improved upon to adequately predict chemical accumulation in an aquatic ecosystem. The research provides a better and more comprehensive method to assess chemical contamination in fish so that the safety of humans and the environment can be secured for the future

Climate change impact on the photodegradation of polycyclic aromatic hydrocarbons in soils

Les avaluacions del Panell Intergovernamental del Canvi Climàtic han evidenciat que l’augment d’emissions amb efecte hivernacle ha causat que el clima canviï més ràpidament. Encara que s’espera un impacte a escala global, les regions més septentrionals del planeta, juntament amb la zona mediterrània, són àrees especialment vulnerables. L’increment de la temperatura i la radiació UV-B alterarà el comportament de nombrosos contaminants, com per exemple els hidrocarburs aromàtics policíclics (HAPs). Per tant, aquests contaminants són potencialment vulnerables al canvi climàtic. L’objectiu d’aquesta tesi doctoral és l’avaluació de l’impacte de la temperatura i la intensitat de la llum en el comportament dels HAPs en sòls mediterranis. S’analitzaren a nivell de laboratori les variacions en les concentracions dels 16 HAPs de la US EPA en sòls, juntament amb l’impacte ecotoxicològic i la identificació de subproductes de la fotodegradació. Es van comparar les condicions climàtiques actuals i les de l’escenari de canvi climàtic extrem RCP8.5 segons previsions de l’IPCC per la regió mediterrània. Els resultats van demostrar que la dinàmica dels HAPs és regulada per les propietats fisicoquímiques de cada HAP, la temperatura, la intensitat de la llum i la textura del sòl. Aquest experiment també es va dur a terme sota l’efecte de la radiació solar, fet que va afavorir la fotodegradació dels HAPs en comparació amb l’experiment previ a nivell de laboratori. L’augment de la temperatura i la intensitat de la llum també va provocar que es formessin més subproductes de la fotodegradació, com oxi- i nitro- HAPs. Aquests derivats són més tòxics que els propis HAPs, de manera que l’impacte del canvi climàtic podria ser dramàtic pels ecosistemes i la salut humana.Las evaluaciones del Panel Intergubernamental del Cambio Climático han evidenciado que el aumento de emisiones con efecto invernadero ha provocado que el clima cambie más rápidamente. Aunque se espera un impacto a escala global, las regiones más septentrionales del planeta, juntamente con la zona Mediterránea, son áreas especialmente vulnerables. El incremento de la temperatura y la radiación UV-B alterará el comportamiento de numerosos contaminantes, como por ejemplo los hidrocarburos aromáticos policíclicos (HAPs). Por lo tanto, estos contaminantes son potencialmente vulnerables al cambio climático. El objetivo de esta tesis doctoral era llevar a cabo la evaluación del impacto de la temperatura y la intensidad de la luz en el comportamiento de los HAPs en suelos Mediterráneos. Se analizaron a nivel de laboratorio las variaciones en las concentraciones de los 16 HAPs de la US EPA en suelos, juntamente con el impacto ecotoxicológico y la identificación de subproductos de la fotodegradación. Se compararon las condiciones climáticas actuales y las del escenario de cambio climático extremo RCP8.5 según proyecciones del IPCC para la región Mediterránea. Los resultados demostraron que la dinámica de los HAPs está regulada por las propiedades físicoquimicas de cada HAP, la temperatura, la intensidad de la luz y la textura del suelo. Este experimento también se llevó a cabo bajo el efecto de la radiación solar, hecho que favoreció la fotodegradación de los HAPs en comparación con el experimento previo a escala de laboratorio. El aumento de la temperatura y la intensidad de la luz también causaron la formación de más subproductos de la fotodegradación, como oxi- y nitro- HAPs. Estos derivados son más tóxicos que los propios HAPs, de forma que el impacto del cambio climático podría ser dramático para los ecosistemas y la salud humana.The Intergovernmental Panel on Climate Change (IPCC) assessments have evidenced that the Earth’s climate is changing faster, because of an increasing emission of greenhouse gases. Although a global impact is expected, high latitude and Mediterranean regions are especially vulnerable areas. The increase of temperature and UV-B radiation will alter the fate and behavior of a wide range of pollutants, such as polycyclic aromatic hydrocarbons (PAHs). Therefore, these pollutants are potentially vulnerable to the climate change. This PhD thesis was aimed at evaluating the impact of temperature and light intensity on the fate of PAHs in Mediterranean soils. Concentration changes of the 16 US EPA priority PAHs in soils, its ecotoxicological impact, and the identification of photodegradation by-products, were experimentally conducted at lab scale by comparing current environmental conditions and the IPCC RCP8.5 climate change scenario, for the Mediterranean region. Physicochemical properties of each individual PAH, temperature, light intensity and soil texture were identified as key factors regulating the PAH dynamics. The experiment was also conducted under solar radiation, which significantly enhanced the PAH photodegradation in comparison to values at lab scale. An increase of PAH photodegradation by-products, such as oxy- and nitro-PAHs, was also detected in soils subject to high temperature and light intensity. Because these new substances might be more toxic than parental compounds, the impact of climate change may be dramatic for the ecosystems and the human health