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© 2015 Elsevier Ltd. The aim of the SEAS-ERA initiative (2010-2014), developed within the European Union Framework Programme (EU FPVII) (contract 249552), was to coordinate the structure of national and regional marine and maritime research programs to empower and strengthen marine research all across Europe. A major goal was the development and implementation of common research strategies and programs related to European seas basins. To achieve this goal, SEAS-ERA was applied at two different levels, regional and pan European, to identify common priorities and needs in five areas, namely strategic planning (marine research agendas), joint research activities (common programs and joint calls), marine research infrastructures and human capacity building to reduce imbalances among regions. SEAS-ERA was also strongly committed to enhancing public awareness of marine and maritime scientific and policy issues in Europe.

Oil spills relating to shipping incidents remain of substantial concern with respect to marine pollution. Whilst most frequently a reactive approach is adopted in post-incident monitoring (for the specific product involved), this paper reports important physical and compositional characteristics of commonly transported oils and oil products to afford pro-active assessments. These properties include specific gravity, viscosity, elemental composition and, of particular relevance, the relative class compositions between aliphatics, aromatics, resins and asphaltenes. The latter were determined experimentally using thin layer chromatography with flame ionization detection. Diagnostic ratios of specific compounds are reported, statistically analysed, and their significance in identification of different oil types and the weathering processes is discussed. The influence of the properties on fates under different environmental conditions (selected to represent contrasting European regional seas) are examined using the NOAA Automated Data Inquiry for Oil Spills (ADIOS2) model. Relative contributions of the different environmental conditions and properties to the fate of the oil at sea are discussed.

The Marine Strategy Framework Directive (MSFD) adopted in 2008 aims to protect the marine environment through the holistic Ecosystem Approach (EA). The MSFD requires Member States to develop and implement cost-effective measures to achieve and/or maintain “Good Environmental Status” (GEnS). To this end, interested parties require a large amount of data and this data should be appropriately managed. This is particularly true for EA applications, where data can come from diverse sources, in diverse formats, and from several disciplines. Preliminary steps for supporting reliable multi-disciplinary analysis include data collection, data management, and the implementation of an interoperable sharing system. In an effort to implement this type of multidisciplinary analysis, a working group from the KnowSeas project (www.knowseas.com) created a Spatial Data Infrastructure for the Mediterranean Sea, designed to define and analyze the GEnS concept across various geographical scales. This article describes the implementation of this SDI, demonstrating how an interoperable system can provide strong support in implementing the MSFD under the EA, and how marine spatial planning can assist policymakers in the decision making process.

Spills from wrecks are a potential major source of pollution in the deep ocean. However, not much is known about the fate of a spill at several kilometers depth, beyond the oceans continental shelves. Here, we report the phase distribution of hydrocarbons released from the wrecks of the Prestige tanker, several years after it sank in November 2002 to depths between 3500 and 3800 m. The released oil reached the surface waters above the wrecks without any signs of weathering and leaving an homogenous signature throughout the water column. At depths of several kilometers below the sea surface, the occurrence and spread of the deep sea oil spill could be evaluated better by quantifying and characterizing the dissolved hydrocarbon signature, rather than just the investigation of hydrocarbons in the suspended particulate matter.

Accidental marine pollution can have major ecological and economic consequences at national and trans-national levels, and there is a need to achieve a better integration of science into actual decision-making systems to support prevention measures, response systems and management activities.. Effective linking mechanisms between R&D and end-users/policy stakeholders are required to ensure the relevance of R&D, effective uptake of R&D outputs, and suitable policy development. Different issues and barriers to effectively link accidental marine pollution R&D effort to end-users concerns and needs and to develop a trans-national strategic approach are identified, analysed, and further developed into recommendations.

Descripció del recurs: el 16 de juny de 2010, Hoy en día existe una escasez de estudios sobre la distribución de los hidrocarburos en mar abierto, aunque el aumento de la explotación de yacimientos de petróleo y la intensificación del tráfico marítimo más allá de la plataforma continental haya aumentado. Asimismo, se han identificado nuevas fuentes de contaminación. En los últimos años se ha puesto en evidencia el alto número de barcos hundidos en los fondos marinos que podrían potencialmente generar futuros vertidos de petróleo. En esta tesis, se investiga el accidente del petrolero Prestige cerca de Galicia en el 2002 como caso de estudio de un vertido marino en profundidad en mar abierto, ya que aproximadamente unas 43.000 toneladas de fuel oil pesado que llevaba a bordo fueron vertidas una vez el barco de rompió en dos y se hundió. Además, la zona del hundimiento del Prestige es un área hidrodinámicamente compleja. La columna de agua esta formada por cinco masas de aguas principales, de diferente origen y con características físico-químicas diferentes, que pueden contribuir activamente extender el fuel liberado por el Prestige en las aguas cerca del Banco de Galicia. En este contexto, el principal objetivo de la presente tesis ha sido determinar la importancia de los pecios del Prestige como fuente de contaminación en las aguas cerca del Banco de Galicia varios años después del accidente e investigar el papel de las masas de agua en el transporte y distribución de los hidrocarburos en la zona del hundimiento. Estos objetivos se han alcanzado mediante la combinación de estudios de laboratorio y trabajo de campo. Por un lado, se realizaron diferentes experimentos bajo condiciones estables de temperatura y salinidad que dieron información sobre la disolución potencial del fuel del Prestige en agua marina. Además, dos campañas oceanográficas se llevaros a cabo en marzo y octubre del 2006 cerca de los pecios y las zonas adyacentes, con el objetivo de recoger agua marina. Se determinaron hidrocarburos en la mater, There is an apparent shortage of studies on the distribution and fate of oil hydrocarbons in open ocean waters. Nevertheless, given the increasing exploitation of oilfields in the high seas, and the intensification of maritime traffic, in the last decades, oil pollution of the marine environment beyond the continental platforms is increasing. In addition, new sources of pollution are being recognized. Thus, in recent years it has been noted that the high number of sunken vessels scattered in the oceans sea floor are potentially a present and future source of oil spills. In this thesis, the accident of the Prestige tanker in 2002 off the Galician coast is investigated as a case study of a deep sea spill in open ocean waters, since around 43,000 tonnes of heavy fuel oil were spilled after the vessel broke in two and sank. In addition, the area near the Galician Bank, where the Prestige wrecks are located, is hydrodynamically complex. The water column is comprised by five main water masses from different origins and physico-chemical properties, which may contribute to actively spread the oil released from the Prestige in different and distinct ways. In this context, the main aim of this study has been to determine the importance of the Prestige shipwrecks as a source of oil pollution in the waters near the Galician Bank several years after the accident took place and to investigate the role of the water masses in the sinking area in the transport and distribution of hydrocarbons. These objectives have been tackled by a combination of laboratory and field studies. First of all, several sets of experiments were carried out under controlled temperature and salinity conditions which provided information about the potential dissolution of the Prestige fuel oil in seawater. In addition, two oceanographic cruises were undertaken in March and October 2006, near the wrecks location and surrounding areas, to collect seawater samples. Hydrocarbons were determined in the suspended

[ESP] Hoy en día existe una escasez de estudios sobre la distribución de los hidrocarburos en mar abierto, aunque el aumento de la explotación de yacimientos de petróleo y la intensificación del tráfico marítimo más allá de la plataforma continental haya aumentado. Asimismo, se han identificado nuevas fuentes de contaminación. En los últimos años se ha puesto en evidencia el alto número de barcos hundidos en los fondos marinos que podrían potencialmente generar futuros vertidos de petróleo., En esta tesis, se investiga el accidente del petrolero Prestige cerca de Galicia en el 2002 como caso de estudio de un vertido marino en profundidad en mar abierto, ya que aproximadamente unas 43.000 toneladas de fuel oil pesado que llevaba a bordo fueron vertidas una vez el barco de rompió en dos y se hundió. Además, la zona del hundimiento del Prestige es un área hidrodinámicamente compleja. La columna de agua esta formada por cinco masas de aguas principales, de diferente origen y con características físico-químicas diferentes, que pueden contribuir activamente extender el fuel liberado por el Prestige en las aguas cerca del Banco de Galicia., En este contexto, el principal objetivo de la presente tesis ha sido determinar la importancia de los pecios del Prestige como fuente de contaminación en las aguas cerca del Banco de Galicia varios años después del accidente e investigar el papel de las masas de agua en el transporte y distribución de los hidrocarburos en la zona del hundimiento. Estos objetivos se han alcanzado mediante la combinación de estudios de laboratorio y trabajo de campo. Por un lado, se realizaron diferentes experimentos bajo condiciones estables de temperatura y salinidad que dieron información sobre la disolución potencial del fuel del Prestige en agua marina. Además, dos campañas oceanográficas se llevaros a cabo en marzo y octubre del 2006 cerca de los pecios y las zonas adyacentes, con el objetivo de recoger agua marina. Se determinaron hidrocarburos en la materia sólida en suspensión y la fase disuelta del agua en la columna de agua de las tres estaciones. Una se encontraba encima de los pecios del Prestige mientras que las otras dos se localizaron a 73 millas náuticas, una al norte y la otra al sur de este punto., En marzo del 2006, en la zona del hundimiento y en las otras dos estaciones, las concentraciones de hidrocarburos de origen petrogénico estaban dentro el rango los niveles descritos en la literatura para áreas similares, mientras que los niveles en octubre del mismo año era superiores. Las concentraciones de hidrocarburos poliaromáticos encontrados en la fase disuelta eran, tanto en marzo como en octubre, mucho mayores que los niveles de referencia establecidos para la zona. La huella química de los hidrocarburos en octubre del 2006 indicó que los pecios del Prestige habían estado liberando fuel oil durante varios años después del accidente. Sin embargo, a pesar de la amplia presencia de hidrocarburos provenientes del petróleo en la columna de agua de las tres estaciones, no se puede afirmar que el Prestige constituía la fuente más importante de contaminación en le área, ya que los hidrocarburos parecían provenir de múltiples orígenes. De hecho, varias masas de agua presentan contenidos distintivos de hidrocarburos en la fase disuelta y material particulado., El estudio realizado se puede entender como un ejemplo del potencial de un pecio hundido en el Noratlántico profundo como fuente de contaminación. Aunque cada pecio representa un caso único, el conocimiento obtenido sobre la distribución espacial y temporal de los hidrocarburos después del accidente del Prestige se puede utilizar en futuros vertidos., [ENG] There is an apparent shortage of studies on the distribution and fate of oil hydrocarbons in open ocean waters. Nevertheless, given the increasing exploitation of oilfields in the high seas, and the intensification of maritime traffic, in the last decades, oil pollution of the marine environment beyond the continental platforms is increasing. In addition, new sources of pollution are being recognized. Thus, in recent years it has been noted that the high number of sunken vessels scattered in the oceans sea floor are potentially a present and future source of oil spills., In this thesis, the accident of the Prestige tanker in 2002 off the Galician coast is investigated as a case study of a deep sea spill in open ocean waters, since around 43,000 tonnes of heavy fuel oil were spilled after the vessel broke in two and sank. In addition, the area near the Galician Bank, where the Prestige wrecks are located, is hydrodynamically complex. The water column is comprised by five main water masses from different origins and physico-chemical properties, which may contribute to actively spread the oil released from the Prestige in different and distinct ways., In this context, the main aim of this study has been to determine the importance of the Prestige shipwrecks as a source of oil pollution in the waters near the Galician Bank several years after the accident took place and to investigate the role of the water masses in the sinking area in the transport and distribution of hydrocarbons. These objectives have been tackled by a combination of laboratory and field studies. First of all, several sets of experiments were carried out under controlled temperature and salinity conditions which provided information about the potential dissolution of the Prestige fuel oil in seawater. In addition, two oceanographic cruises were undertaken in March and October 2006, near the wrecks location and surrounding areas, to collect seawater samples. Hydrocarbons were determined in the suspended particulate matter (SPM) and dissolved phase (DP) in the water column of three stations. One was located above the Prestige wrecks, and the other two 73 nautical miles north and south of the Prestige incident area., Hydrocarbons concentrations from petrogenic sources in the SPM above the wreck and surrounding areas in March 2006 were within the range of abundances previously reported for similar areas, but much higher in October 2006. The concentrations of polycyclic aromatic hydrocarbons found in the DP were, both in March and October 2006, well above any expected background levels. The chemical fingerprint of the hydrocarbons indicated that in October 2006 the oil at the Prestige station originated from the wrecks. This, together with the unusually high relative concentration of hydrocarbons in the DP at the Prestige station in March 2006, indicates that the Prestige wrecks had been releasing oil for several years after the accident. However, despite the widespread occurrence of oil hydrocarbons in the three stations and throughout their water columns, it could not be concluded that the Prestige was the main source of pollution in the area near the Galician bank, which most likely has multiple origins. In fact, different water masses contain distinct contents of hydrocarbons in the SPM and the DP, which in some instances may have remote sources., The study conducted can be viewed as an example of the potential of a sunken wreck in the deep North Atlantic as a source of pollution. Although each potentially polluting shipwreck represents a singular case, knowledge obtained about the temporal and spatial distribution of hydrocarbons after the accident of the Prestige could be applied to deal with other deep spills in the future.

The bacterial communities in two different shoreline matrices, rocks and sand, from the Costa da Morte, northwestern Spain, were investigated 12 months after being affected by the Prestige oil spill. Culture-based and culture-independent approaches were used to compare the bacterial diversity present in these environments with that at a nonoiled site. A long-term effect of fuel on the microbial communities in the oiled sand and rock was suggested by the higher proportion of alkane and polyaromatic hydrocarbon (PAH) degraders and the differences in denaturing gradient gel electrophoresis patterns compared with those of the reference site. Members of the classes Alphaproteobacteria and Actinobacteria were the prevailing groups of bacteria detected in both matrices, although the sand bacterial community exhibited higher species richness than the rock bacterial community did. Culture-dependent and -independent approaches suggested that the genus Rhodococcus could play a key role in the in situ degradation of the alkane fraction of the Prestige fuel together with other members of the suborder Corynebacterineae. Moreover, other members of this suborder, such as Mycobacterium spp., together with Sphingomonadaceae bacteria (mainly Lutibacterium anuloederans), were related as well to the degradation of the aromatic fraction of the Prestige fuel. The multiapproach methodology applied in the present study allowed us to assess the complexity of autochthonous microbial communities related to the degradation of heavy fuel from the Prestige and to isolate some of their components for a further physiological study. Since several Corynebacterineae members related to the degradation of alkanes and PAHs were frequently detected in this and other supralittoral environments affected by the Prestige oil spill along the northwestern Spanish coast, the addition of mycolic acids to bioremediation amendments is proposed to favor the presence of these degraders in long-term fuel pollution-aff

[CAT] Els contaminants orgànics persistents (COPs) són compostos tòxics, persistents, bioacumulables i capaços de ser transportats per l’atmosfera a tot el planeta, incloses aquelles zones remotes on mai s’han produït ni emprat. Aquesta tesi estudia la contaminació dels ecosistemes aquàtics mediterranis per una selecció de COPs: els bifenils policlorats (PCBs), el diclorodifeniltricloroetà (DDT) i els seus derivats (DDE i DDD), els hexaclorociclohexans (HCHs) i l’hexaclorobenzè (HCB)., Els resultats d’aquesta tesi s’han organitzat en tres capítols. En el primer d’ells s’estudia l’estat de la contaminació i la dinàmica dels COPs en el delta de l’Ebre. L’anàlisi de les mostres recollides (novembre de 2002 – octubre de 2003) mostrà com encara es produeixen aportacions no controlades de DDT al delta. Aquestes entrades poden ser la conseqüència de l’arrossegament de partícules enriquides mobilitzades des de diferents indrets de la conca i/o el resultat de les activitats agrícoles. La variabilitat estacional i geogràfica del lindà també indica l’existència d’aportacions recents. D’altra banda, les crescudes del riu provoquen un important augment de la descàrrega de COPs, bàsicament a la fase particulada, a causa de l’augment de l’escolament, la lixiviació, l’arrossegament de sòls i la remobilització dels sediments (ex. material dipositat als embassaments). Així, els períodes d’avinguda són claus en el còmput total de la descàrrega de COPs a la Mediterrània., En el segon dels capítols s’estudià el perfil vertical estratificat del riu a la seva desembocadura com un exemple dels estuaris de falca salina desenvolupats a la Mediterrània. La falca salina a l’Ebre provoca un canvi en la dinàmica vertical de diferents variables fisicoquímiques, de la matèria orgànica i dels COPs. La floculació induïda pel canvi salí vertical provoca un augment de la quantitat de partícules en suspensió a la falca salina i la barreja de partícules de diversos orígens (orgànic i mineral). Aquest material es barreja a la vegada amb el material marí i les partícules suspeses pateixen una disminució general de les concentracions de COPs. Tanmateix, la falca salina actua com una zona de retenció dels COPs ja que el seu moviment lent i la baixa renovació de l’aigua fan que els contaminants es mantinguin a l’estuari. D’altra banda, tot i que la interfície vertical entre l’aigua dolça – falca salina juga un paper molt important en la transformació i l’acumulació de la matèria orgànica, no s’han detectat màxims molts evidents de COPs en aquesta zona., Finalment, l’últim capítol presenta una visió més global i s’analitza l’abast i el risc ecològic de la utilització dels COPs a tota la conca mediterrània. Es realitzà una recopilació i valoració de la informació existent sobre COPs als sediments marins superficials com a indicadors i integradors del nivell de contaminació de la conca. Tot i les limitacions trobades en el recull d’informació (manca de dades per les costes est i sud de la conca, inexistència de procediments de mostreig i d’anàlisi normalitzats i manca de guies de qualitat ecotoxicològica) es van observar algunes tendències. Des del punt de vista geogràfic, s’ha demostrat com la contaminació per COPs als sediments mediterranis és un problema localment important en algunes zones urbanes/industrials, àrees de descàrrega de rius i zones semitancades (ports i llacs costaners). Malgrat això, les concentracions i el seu risc ecològic associat decreixen ràpidament en les zones de mar obert. Temporalment, tot i la gran variabilitat, s’observa una disminució general de les concentracions de COPs des dels anys setanta fins a l’actualitat., [ENG] Persistent Organic Pollutants (POPs) are compounds which have shown to be toxic, persistent, bioaccumulable and susceptible to atmospheric transport to remote areas where they have never been produced or used. This Thesis deals with the contamination of the Mediterranean Sea by a selection of POPs: hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDT) and its derivatives (DDE and DDD) and polychlorinated biphenyls (PCBs)., Results of this Thesis have been organized in three different chapters. The first chapter is focused on the contamination by POPs and their dynamics in the Ebro Delta. The analysis of collected samples (November 2002 – October 2003) have shown that even today, some DDT inputs are occurring in the Ebro Delta. These inputs can be related to the mobilization of enriched particles from several places in the basin and/or to agricultural activities. In the case of lindane, the seasonal and spatial variability also seems to indicate the existence of recent inputs of this pesticide in the area. On the other hand, the rises of the river flow leads to a significant increase in POP transport downstream, basically in the particulate phase, as a result of the increase in runoff, lixiviation, dragging of soils and the mobilization of sediments (ex. sediment stored in the dams). Flood episodes are thus contributing greatly to the total amounts of POPs annually discharged by the river into the Mediterranean., In the second chapter, the stratified vertical profile of the river in the mouth was studied as an example of the salt wedge estuaries developed in the Mediterranean. The salt wedge in the Ebro produces a great change in the vertical profiles of various physicochemical variables, as well as the concentrations of organic matter and POPs. Flocculation caused by the salinity gradient leads to an increase of suspended organic matter in the salt wedge and the mixing of particles from different sources (organic and mineral). In the salt wedge, this material is also mixed with marine suspended particulate matter and the concentrations of POPs in the suspended solids decrease. However, the salt wedge entraps a large amount of POPs due to the low renewal levels and lack of movement and, thus, keeps the pollutants in the estuary. Although the interface between fresh and salty waters has a crucial role in the transformation and accumulation of organic matter, the results do not show important maxima of POPs in this region., Finally, in the last chapter, from a more general standpoint, an assessment of POPs contamination and ecological risk in the Mediterranean was conducted, using the superficial sediments as indicators. In spite of all the limitations on gathering the existing information (lack of data in the eastern and southern Mediterranean, non-existence of standardised sampling and analytical procedures and ecotoxicological quality standards), some trends can be discerned. Geographically, it has been proved that POPs pollution in the Mediterranean sediments is a local problem and important in some urban and industrial locations, river discharge areas and semi-enclosed zones (harbours and coastal lagoons). In spite of this, the concentrations and their ecological risk are falling rapidly in open sea areas. Temporally, despite the great variability of data, a general decrease of POPs concentrations since the 1970s can be seen.

Sediments sampled next to the Cíes Islands, a natural reserve of the National Park of Atlantic Islands in Ría de Vigo (Spain), 3 mo after the first tide of fuel from the ‘Prestige’ tanker arrived, were chemically and microbiologically characterized. The chemical analysis of the sediments, using oil fingerprinting techniques, showed the occurrence of fresh ‘Prestige’ fuel oil with a background of older hydrocarbon contamination. The cultured bacterial community of the contaminated sediments harbored a high population of total heterotrophs and alkane degraders and a small proportion of aromatic-degrading bacteria. Based on partial 16S ribosomal RNA gene sequence data, 37 different bacterial strains, isolated in diluted marine agar, were detected. Most of them were classified as members of the groups Gammaproteobacteria (59%) and Alphaproteobacteria (21%), although members of the Bacteroidetes (10%) and of Firmicutes (10%) were also found. Some of the different identified bacteria have previously been described as fuel oil–degrading species such as Alcanivorax, Shewanella, Vibrio, Pseudoalteromonas and Marinomonas. Seven independent isolates were able to grow with hexadecane. However, these 7 strains are grouped under the same phylotype, based on the 16S rRNA gene sequence, and were closely related to Alcanivorax borkumensis (Gammaproteobacteria). No aromatic-degrading activities were detected among the culturable bacteria. The presence of fresh fuel without a detected level of biodegradation suggests that Alcanivorax was an early colonizer after the ‘Prestige’ oil spill. To our knowledge, the isolation of Alcanivorax from environmental samples without the aid of an enrichment procedure has not been previously reported. Our results suggest the ability of Alcanivorax to compete and coexist with other heterotrophic marine bacteria in an oil polluted marine environment rich in the nutrients N and P.

A laboratory experiment was carried out to study immune function alteration of the mussel Mytilus galloprovincialis when exposed to the Prestige oil spilled in November 2002 on the northwestern Spanish coast. Mussels were maintained for 4 months in tanks with flowing seawater and with 1, 2, and 0 kg (controls) Prestige fuel oil. Polycyclic aromatic hydrocarbon concentrations, which were determined in gills and digestive glands, were higher in digestive glands. The methylphenantrene and dibenzothiophene profiles confirmed the real exposure of mussels to the fuel oil. Immune data analysis revealed that no differences between fuel-treated and control animals were found in the cellular immune parameters measured (hemocyte viability, phagocytic activity, nitric oxide production, and chemiluminescence emission). In addition, histologic observations did not reveal tissue lesions in any of the samples, probably because of the short time of fuel-oil exposure. In contrast, significant differences were found in serum protein concentration and lysozyme activity between the fuel-treated mussels and controls. However, these humoral immune parameters were dependant on numerous environmental and physiologic factors, so it was difficult to ascertain the real effect of the fuel oil on their variability. Because hemocytes are the primary line of defense of bivalve mollusks, the results obtained in the present study suggest that the mussel immune system was not significantly affected by exposure to the Prestige fuel oil

Polycyclic aromatic hydrocarbons (PAHs) were measured in the coastal sea surface microlayer (SML), the sub-surface waters (SSW) and the overlying atmosphere in order to investigate the influence of the SML on contaminant enrichment and air–sea exchange. Samples were collected at two contrasting locations of the NW Mediterranean, one urban influenced (off Barcelona, Spain) and another comparatively clean (off Banyuls-sur-Mer, France). Statistical data analysis confirmed the accumulation of PAHs in the SML with respect to the SSW (20.3 ± 9.1 vs. 13.1 ± 10.0 ng L 1 in the dissolved phase; 709 ± 207 vs. 158 ± 111 ng g 1 in the particulate phase). This accumulation was higher at the contaminated location (Barcelona station) compared with the more pristine one, with PAH enrichments 1.5 and 4.5 times higher for the dissolved and particulate phases, respectively, indicating that the enrichment of PAHs in the SML is dominated by particle transport processes.

A salt-wedge stratified microcosm, spiked with 31 target analytes, including PCBs, organochlorine and organophosphorous pesticides, triazines, organophosphate flame retardants and caffeine (an urban wastewater molecular marker), was setup. Compound behaviour was monitored during a four week period, by sampling at six different levels of the water column, in order to understand the transport and loss processes of the different classes of chemical substances. Compound transport from one water body to the other has been positively correlated with diffusion via their molar volume. Target analytes loss has been positively correlated with evaporation via their K(H) and with degradation via their half-lives. From these two processes, evaporation was found to be predominant using a multiparametric regression.

A screening ecological risk assessment (ERA) was conducted for the first time in the Mediterranean basin in order to assess the toxicity posed to the benthic community by PCBs, DDTs and HCB in marine sediments. The characterization of the exposure was conducted by means of an extensive literature survey, generating a database with more than 2000 samples. The effects were assessed by the adoption of guidelines previously developed in the literature, because ecotoxicological information about persistent organic pollutants (POPs) in the Mediterranean sediments was lacking. Existing sediment quality guidelines (SQGs) for the target pollutants were compiled and consensus values were calculated for three different categories of toxicity, namely threshold effect concentration (TEC), probable effect concentration (PEC) and extreme effect concentration (EEC). The combination of exposure and effects characterization enabled the identification of some areas of concern in the vicinity of industrial and urban locations and in the mouths of the main Mediterranean rivers. Beyond the Mediterranean continental shelf, the level of toxicity for the benthic community was generally low. The evaluation of the toxicity induced by the mixture of the target pollutants spotted the importance of DDT contamination in the Mediterranean sediments, despite the fact that main inputs to the sea have been significantly reduced during the last decades.

The adsorption of dissolved organic contaminants on glass fibre filters throughout water dissolved/particulate phase decoupling studies was examined. A total of 49 different compounds were considered at low concentration levels (ng L−1), including PAHs, PCBs, organochlorine and organophosphorus pesticides, triazines, thiocarbamates, pyrethroids, phosphate esters and caffeine. Their adsorption on the filters was positively correlated with their logKow and solubilities, indicating that filter adsorption increased with hydrophobicity. The influence of water properties (i.e. salinity and dissolved organic carbon (DOC) content) was also studied by means of a star experimental design (n = 11). Salinity was the main factor in increasing the adsorption, due to the salting out effect. The influence of DOC suggested that part of the contaminant losses during water filtration may have been caused by the retention on the organic matter adsorbed on the filter surface. Nevertheless, a decrease in filter retention was observed for water with the highest DOC contents, which was probably due to an enhancement of the contaminant solubility in these conditions. Although several factors may control the adsorption process in naturally occurring waters, the extent of the retention of dissolved target analytes on the glass fibre filters should not be underestimated in the analysis of hydrophobic contaminants in marine and estuarine waters at very low concentrations (ppt level).

A compilation of information about levels of selected persistent organic pollutants, namely polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroetane and its degradation products (DDTs) and hexachlorobenzene (HCB), in Mediterranean sediments, including data published from 1971 to 2005, has been conducted in order to assess their main drivers and pressures in the environment. The application of mapping tools GIS) and statistical instruments enabled the assessment of geographical and temporal trends. Chemical contamination mainly originates from land-based sources, and decreases significantly when moving off-shore. Contamination hot spots are generally located along the Northern coastline. The data for open sea sediments enabled the establishment of background levels of contamination for the region. A decreasing temporal trend in concentrations was found, more evident in the case of DDTs probably due to a more efficient regulation of this chemical. Finally, some gaps in reliable data were also identified which were related to the lack of information in the southern and eastern parts of the Mediterranean as well as the variety of analytical methodologies used., Key information for policy decision makers is provided on the levels of certain POPs in Mediterranean sediments.

[EN] The activity of the antioxidant defences catalase (CAT, EC 1.11.1.6), glutathione peroxidase (t-GPX, EC 1.11.1.9), glutathione reductase (GR, EC 1.6.4.2), phase II glutathione S-transferase (GST, EC 2.5.1.18) along with the NADPH-dependent cytochrome c (CYP) reductase (EC 1.6.2.4), NADH-dependent cytochrome c reductase (EC 1.6.2.2), and NADH-dependent ferricyanide (b5) reductase (EC 1.18.1.1) was determined in the digestive gland of mussels Mytilus galloprovincialis fed with Tetraselmis sp. pre-exposed to the water accommodated fraction of the Prestige oil. Mussel gills were also used for measuring acetylcholinesterase activity (AChE, EC 3.1.1.7) and lipid peroxidation (LP) as an indication of neurotoxicity and oxidative stress damage respectively. Bioaccumulation of the selected polycyclic aromatic hydrocarbons (2 to 6 rings PAHs) in mussels after 2, 4, 7 and 10 days of exposure did not show any significant trend; the 2-3 ring PAHs were best represented (51%). A significant (p<0.05) bioaccumulation in exposed mussels was only observed for some alkylated 2-3 ring PAHs. Biochemical antioxidant responses (CAT, t-GPX and GR) significantly increased over time, regardless of exposure, whereas NADH-dependent reductases and LP were affected, regardless of the length of exposure. However, due to the low solubility of the Prestige crude, the PAH levels reached in exposed mussels were not sufficient to cause a clearly associated biochemical response., [ES] La actividad enzimática de las defensas antioxidantes: catalasa (CAT, EC 1.11.1.6), glutatión peroxidasa (t-GPX, EC 1.11.1.9), glutatión reductasa (GR, EC 1.6.4.2), el enzima de fase II glutatión S-transferasa (GST, EC 2.5.1.18) y la actividad citocromo c reductasa NADPH-dependiente (CYP) (EC 1.6.2.4), NADH-dependiente (EC 1.6.2.2) y la ferricianida reductasa NADH-dependiente (b5) (EC 1.18.1.1) se determinaron en la glándula digestiva de mejillón Mytilus galloprovincialis alimentado con algas (Tetraselmis sp.) pre-expuestas a la fracción acomodada del agua de crudo del Prestige. En branquias de mejillón se midió la actividad acetilcolinesterasa (AChE, EC 3.1.1.7) como indicador de neurotoxicidad y la peroxidacion lipídica (LP) como indicador de daño por estrés oxidativo. La bioacumulación en mejillones de determinados hidrocarburos aromáticos policíclicos (PAHs de 2 a 6 anillos) después de 2, 4, 7 y 10 días de exposición, no mostró ninguna tendencia significativa, siendo los PAHs de 2-3 anillos los mejor representados (51%). En los mejillones expuestos sólo se observó una bioacumulación significativa (p<0.05) en PAHs alquilados de 2-3 anillos. Las respuestas antioxidantes (CAT, t-GPX y GR) incrementaron de manera significativa con el tiempo, independientemente de la exposición, mientras que las reductasas NADH-dependientes y la LP se vieron afectadas por la exposición pero no por el tiempo de exposición. Sin embargo, debido a la baja solubilidad del crudo del Prestige, los niveles de PAHs alcanzados en los mejillones expuestos, no fueron lo suficientemente altos como para originar una respuesta bioquímica asociada clara.

Plankton samples (20-350 microm and >350 microm) collected at three transects along the Galician coast (NW Spain) were analysed for individual aliphatic and aromatic hydrocarbons by GC-MS. Sample collection was performed in April-July 2003, after the Prestige oil spill (November 2002), to determine whether the hydrocarbons released into the water column as a consequence of the spill were accumulated by the planktonic communities during the subsequent spring and early summer blooms. Surface sediments were also collected to assess the presence of the spilled oil, removed from the water column by downward particle transport. Plankton concentrations of PAHs (Sigma14 parent components) were in the range of 25-898 ng g(-1)dw, the highest values being close to coastal urban areas. However, the individual distributions were highly dominated by alkyl naphthalenes and phenanthrenes, paralleling those in the water dissolved fraction. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes, and methyl phenanthrenes and dibenzothiophenes) showed the occurrence of background petrogenic pollution but not related with the Prestige oil, with the possible exception of the station off Costa da Morte in May 2003, heavily oiled after the accident. The dominant northerly wind conditions during the spring and early summer 2003, which prevented the arrival of fresh oil spilled from the wreck, together with the heavy nature of the fuel oil, which was barely dispersed in seawater, and the large variability of planktonic cycles, could be the factors hiding the acute accumulation of the spilled hydrocarbons. Then, with the above exception, the concentrations of PAHs found in the collected samples, mostly deriving from chronic pollution, can be considered as the reference values for the region.

On November 13th, 2002, the tanker Prestige, operated by a Greek shipping company under a Bahamas flag, and carrying 77,000 tonnes of heavy fuel-oil, suffered a severe structural failure of the starboard cargo tanks 30 miles off the Finisterre coast (Galicia, NW Spain) and started to leak oil. On November 14th, considering the risk of serious pollution of Costa da Morte and Rias Baixas, one of the first mussel producer regions worldwide, the authorities decided to tow away the ship, travelling first north-eastward until November 15th and south-westward until November 19th, when the tanker broke in two, 130 miles from the Galicia south-coast, after the spill of about 20,000 tonnes of fuel (Fig. 1 and Fig. 2). The two parts of the wreck sank on the southwestern part of the Galicia Seamount, in the Galicia continental margin (NW Atlantic Spanish margin); the stern at 3565 m water depth (42°10.6 N, 012°03.0 W), and the bow at 3830 m water depth (42°10.8 N, 012°03.6 W). The 58,000 tonnes of fuel oil remaining in the tanker continued to ooze from several cracks in the bow, giving rise to an additional spill of about 40,000 tonnes until the recovery operations of the fuel in the wreck started in summer 2003, which required, by the way, an outstanding technological effort.

Over 30 sea surface microlayer (SML) samples from two contrasting sites in the North Western Mediterranean – Barcelona (Spain) and Banyuls-sur-Mer (France) – were collected using three different sampling devices, namely, glass plate, metal screen (MS) and a surface slick sampler (SS), and compared with the corresponding underlying water (16 samples). The distributions of 41 polychlorinated biphenyl congeners (PCBs) were determined in the different phases: particulate (1.17–10.8 ∑PCB ng L−1), truly dissolved (0.080–16.7 ∑PCB ng L−1) and colloidal matter (1.17–43.0 ∑PCB ng L−1), being the last two estimated from the analysis of the apparently dissolved phase. Concentrations of PCBs in the SML were higher than those in the underlying water (ULW), giving rise to enrichment factors (EF=[C]SML/[C]ULW) up to first-order of magnitude. The ANOVA statistical approach was used to assess differences of bulk data (e.g. dissolved organic carbon, DOC; particulate organic carbon, POC; suspended particulate matter, SPM) among sampling devices, whilst p-tailed t paired tests were used in order to compare the enrichments obtained for each sampling date. In this respect, no significantly different enrichment factors were found among sampling devices (p<0.05), although the surface SS showed lower enrichments, probably due to the dilution of the SML with the ULW during sampling. The MS seemed to be the most suitable device for the determination of PCBs in the SML in terms of sampling efficiency under a variety of meteorological conditions.

Postlarval recruits of mussels Mytilus galloprovincialis were sampled in February 2003 at 7 localities along the Galicia coast (NW Spain) exhibiting different levels of impact from the ‘Prestige’ oil spill. These localities are important grounds for seed collection used in raft culture. The concentrations of polycyclic aromatic hydrocarbons (PAHs) as well as different biochemical and ecophysiological variables were determined in mussel tissues, as indicators of the toxic impact of the spilled oil. The following parameters were measured: size frequency distributions and size–weight relationships, survival in air, biochemical composition (proteins, carbohydrates, glycogen and lipids), lipid classes (phospholipids, sterol esters and waxes, triacylglycerols, free fatty acids and sterols), and fatty acid composition. The study determined sub-lethal effects in wild mussel seed populations sampled 3 mo after the oil spill. These effects are shown in the form of survival indices and alterations of lipid metabolism, especially in trygliceride and sterol fractions, as well as in saturated/monounsaturated fatty acid ratios. Monitoring these effects in wild mussel recruits is important for analysing growth, production and biochemical reserve cycle throughout the raft cultivation period and evaluating the capacity of the individuals to repair alterations detected in the juvenile stage.

The sea surface microlayer (SML) may play an important role on the transport and fate of persistent organic pollutants in the marine environment. In order to evaluate the appropriateness of a number of sampling devices for the analysis of 14 parent polycyclic aromatic hydrocarbons (3–5 aromatic rings), marine SML waters were sampled using a glass plate, a rotating drum/roller, a metal screen and a surface slick sampler. The underlying waters were also sampled for the determination of the corresponding enrichment factors (EF=[C]microlayer/[C]underlying water). The EFs were phase dependent, ranging from 1 to 3 for the dissolved phase and between 4 and 7 for the particulate phase. In order to better assess the performance of the different sampling methods, in terms of phase partitioning, the truly dissolved and colloidal phases were also estimated. Generally, no significant differences were found for the enrichment factors provided by the different methods, due to the observed large variability in concentrations that can be attributed to small-scale coastal processes. However, the metal screen is recommended as the most efficient sampling method for the study of PAHs taking into account the amount of water collected versus time.

The concentrations of PCBs, DDTs, HCHs, HCB and OCS were determined in sediments and associated biota, both invertebrates (Physella acuta, Hirudo medicinalis, chironomid larvae, Hydrous pistaceus, Helochares lividus) and vertebrates (Rana perezi), in a temporary aquatic system, a rice field in the Ebro Delta (NE Spain). The qualitative and quantitative distribution of organochlorine compounds in sediments and aquatic biota has been explained by two mechanisms: equilibrium partitioning and/or biomagnification through the trophic web. Nevertheless, bioaccumulation processes are by far more complex, since several biotic and abiotic factors contribute to the observed pollutant loads in the organisms. In this respect, the biological characteristics of the organisms considered (e.g. species, age, lipid contents, feeding habits, etc.), as well as ecological factors (e.g. the habitat of the species and vertical distribution), have been shown to account for the organochlorine levels observed.

Muscle concentrations of organochlorinated compounds as well as biliary levels of polycyclic aromatic hydrocarbon (PAH) metabolites were determined in red mullet Mullus barbatus as a sentinel species for assessing the pollution along the western Mediterranean coast. A battery of biochemical markers‹biotransformation and antioxidant enzymes‹were also measured in liver subcellular fractions to assess exposure to pollutants. Among them, 7-ethoxyresorufin O-deethylase (EROD) activity, as well as 7-penthoxyresorufin O-deethylase (PROD) activity and cytochrome P450 1A (CYP1A) content evidenced strong differences among sampling sites, and a good correlation with the amount of PCBs bioaccumulated by fish. No clear pollution-related response was observed for cytosolic glutathione S-transferase, whereas uridine-diphosphate UDP-glucuronyltransferase (UDPGT) was elevated in fish from polluted sites. Antioxidant enzymes‹superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX)‹were used to assess oxidative stress. Among them, catalase activity was well related to PCB body burden.

An analytical approach is described for bioaccumulation and ecotoxicology assessment studies of organophosphorous pesticides (OPs), organochlorine compounds (OCls) and polycyclic aromatic hydrocarbons (PAHs) in bivalves cultured in the Ebro Delta. Species exhibiting a wide range of lipid contents, namely Mytilus galloprovincialis, Ostrea edulis, Crassostrea gigas and Ruditapes decussata were selected. Analyses of OPs were performed by gas chromatography (GC) with nitrogen-phosphorus detection (NPD), OCls were determined by GC with electron capture detection (ECD) and total PAHs using a flow injection system (FIS) with fluorescence detection. Residue analyses indicated differences among species, that were reduced when concentrations were normalized to lipid content. A seasonal fluctuation of pollutants was also observed that was related to the biological cycle of the organisms and to the management of the waters in the rice crop fields of the delta. Toxicity thresholds for bivalves were not reached; nevertheless, more sensitive species such as crustaceans could be potentially affected. Toxicological implications to humans might be of concern during field treatments with pesticides. Copyright (C) 2000 Elsevier Science Ltd.

Xenobiotic metabolising enzymes, namely the cytochrome P450 monooxygenase system and glutathione S-transferase, as well as antioxidant enzymes were determined in the liver of 3 deepsea fish species (Lepidion lepidion, Bathypterois mediterraneus and Coryphaenoides guentheri). These organisms were collected from 3 stations along the NW Mediterranean, at depths ranging from 1500 to 1800 m. The enzymatic activities detected in deep-sea fish indicated the ability of these organisms to cope with pollutants and oxidative stress. Differences among the studied species may be related to habitat and diet, viz. the highest monooxygenase and antioxidant enzyme activities were observed in L. lepidion, a typical middle slope species, whereas the lowest activities were recorded for B. mediterraneus, an organism adapted to live at greater depths. Tissue concentration of persistent organochlorinated compounds, like polychlorinated biphenyls, DDTs and hexachlorobenzene, were in the lower range of those reported for coastal fish, and significant differences among sampling stations were not observed. Overall, the obtained results contribute to the knowledge of the NW Mediterranean deepsea basin and reflect the chronic contamination of the area in terms of organochlorinated compounds, rather than the influence of coastal discharges

Wild mussels were collected from two stations with different pollution loads. Soft tissues were analyzed for their aromatic hydrocarbon and polychlorinated biphenyl content. Mixed function oxidase (MFO) system components and antioxidant defenses (catalase, superoxide dismutase and glutathione peroxidase) were determined in digestive gland microsomal and cytosolic fractions, respectively, and the magnitude of biochemical responses related with pollutant tissue levels. Results showed that significant differences existed in hydrocarbon content between mussels from the two stations, while a smaller difference in the biological response was detected

Seasonal variations in the mixed-function oxygenase (MFO) system components (cytochrome P450, “418” peak, and NADPH-cytochrome c[P450] reductase) and antioxidant enzymes (catalase, superoxide dismutase [SOD], glutathione peroxidase [GPX], and DT-diaphorase) of the mussel Mytilus galloprovincialis have been evaluated. Its relation with contaminant body burden (PAHs, PCBs, DDTs, and lindane) as well as environmental parameters (water temperature, salinity, oxygen concentrations, and suspended matter) was determined. As a general trend, low MFO and antioxidant enzyme activities were detected in February-March, a peak in late April, and a gradual decrease with a minimum in June. This pattern was similar to tissue concentrations of PAHs, PCBs, DDTs, and lindane normalized to lipid weight. Cytochrome P450 content, however, exhibited a steady decrease from February to June. The observed seasonal variations are presumably related to the metabolic status of the animal, itself dependent on such factors as gonadal ripening, food availability, and the hydrological cycle, which regulates productivity in the area

Dimethyl sulfide (DMS), dissolved dimethylsulfoniopropionate (DMSPd) and dimethylsulf-oxide (DMSO) were measured in Mediterranean seawater. In the open surface waters of late spring to early summer, DMSO (18 nM) was the main methylated sulfur compound and dominated over DMS (1.7 nM) by 1 order of magnitude. Conversely, DMSPd occurred at lower concentrations (0.55 nM) than DMS. The higher abundance of DMS over DMSPd, the poor correlation between surface DMS and chlorophyll a, and microscopic examination of the algal populations suggest that DMS essentially originated from decomposition of the DMSPd generated in a late decay phase of the spring phytoplankton development. On the other hand, the vertical profile of the dissolved dimethyl sulfur species and the depth distribution of both biological DMS production and consumption rates point to the concurrence of the biogenic cycles of DMS and carbon. Thus, highest DMS production occurs near the subsurface chlorophyll maximum in coincidence with the water column layers of highest microbial heterotrophic activity. Finally, the high DMSO concentrations suggest that this species may act as a major nonvolatile dimethyl sulfur pool in these waters

A comparative study on the presence of the Mixed-Function Oxygenase (MFO) system components (cytochrome P450, cytochrome b5 and NADPH-cytochrome c (P450) reductase) and antioxidant enzymes (catalase, superoxide dismutase (SOD), glutathione peroxidase (GPX) and DT-diaphorase) has been carried out in four bivalve species: mussel, Mytilus galloprovincialis; oyster, Ostrea edulis; western oyster, Crassostrea gigas; and clam, Tapes semidecussata. The tissular concentrations of certain organic pollutants (e.g. PAHs, PCBs, DDTs, hexachlorobenzene and lindane) have been determined and the qualitative and quantitative differences in their bioconcentration patterns assessed. In general, cytochrome P450 content, NADPH-cytochrome c (P450) reductase and microsomal NAD(P)H-dependent DT-diaphorase activities correlated well with tissular PAHs concentrations, whereas a certain correlation between glutathione peroxidase (GPX) activity and organochlorinated compounds accumulation was also detected

The distributions of organochlorinated pesticides (DDTs, hexachlorobenzene -HCB- and lindane) and polychlorinated biphenyls (PCBs) have been determined in mussels from two bays of the Ebro Delta (Western Mediterranean) during the period 1980-1992. The data obtained enabled us to assess the fate and trends of these compounds in the area. A general decline in concentrations was observed for all organochlorinated pesticides during the studied period, reflecting a positive response to the existing regulations. However, the decline of PCBs was less evident, although a relative decrease of the low chlorinated congeners with time, possibly indicating a lack of recent inputs, was observed

An analytical procedure is described for a comprehensive determination of the composition of hydrocarbons in the atmosphere, based on: (a) aerosol filtration and subsequent adsorption of the vapor phase onto active charcoal and polyurethane foam; (b) GPC and HPLC fractionation of the extracts, and (c) analysis of the fractions by GC-MS under EI and NICI modes. Special emphasis is placed on n-alkanes, PAHs and their oxygenated derivatives. The characterization of samples collected in a coastal urban area (Barcelona city), and far away over the Western Mediterranean, at sea level and at 1100 m of altitude, revealed significant changes in the aerosol composition, mainly attributed to initial vapor-particle partitioning processes, influenced by ambient temperature variations, and to others taking place during long-range atmospheric transport, related with the different compound photoreactivities and with an unexplained source-decoupling phenomenon. © 1991 Springer-Verlag

Data on hydrocarbons, PCBs and total DDT in muscle, liver and gonads of Mullas barbatus. Trachurus trachurus, Merluccius merluccius, Engraulis enchrasicholus and Micromesistius poutassou collected along the Catalan Coast (NW Mediterrenean) are reported for the first time. The species and the collection sites-off Barcelona to the north (Palamôs) and to the south (Ehro Delta)-were selected for the assessment of the effects of coastal pollutant sources on commercially valuable organisms. Mullus barbatus reflects the influence of local sources, and is therefore a useful bioindicator for organic pollutants. Despite some scattering of the results, concentrations are in general of the same order of magnitude for juvenile and adult specimens, although the pollutants considered exhibit different biological fates. Hydrocarbons are accumulated primarily in liver, whereas organochlorinated compounds are accumulated in gonads. Liver and muscle contents could reflect acute and chronic pollutants inputs respectively. The accumulation in muscle is more important for aromatic and chlorinated hydrocarbons than for the saturated ones, which are probably metabolized in the liver. © 1987

A suite of samples from the lacustrine facies of the Cerdanya Basin (Miocene) containing early diagenetic phosphatized sediments in several horizons has been examined for phosphate mineralogy and organic content. The phosphates consisted of anapaite and farifeldite occurring as veins, spaherulite beds and septarian-like nodules. The hydrocarbon and fatty acid distributions of the samples studied show that terrestrial inputs were generally predominant throughout the sedimentary record. Furthermore, the good correlation of higher molecular weight n-alkanes and n-alkanoic acids with total organic carbon (TOC) suggests that the productivity of the lake was determined to a large extent by the amounts of detrital organic matter entering into the system. Thus, the phosphate accumulations studied here are different from those of marine origin usually described in the literature. However, several common characteristics are found when comparing these terrestrial phosphate deposits with those of marine origin, namely an intermediate TOC content (0.5-1.3%) and important microbial inputs, suggesting that phosphatogenesis occurred at rather mild oxidizing/reducing conditions and was mediated by intense microbial degradation. Furthermore, the results presented here extend previous observations from marine phosphate basin studies in the sense that phosphate generation seems to be a phenomenon much more dependent on the environmental conditions of deposition and early diagenetic processes rather than on a specific type of sediment or organic matter source. © 1989.

We report here an assessment of sources and inputs of organic and inorganic pollutants to the Doñana National Park (SW Spain), one of the finest wetlands in Europe. In the absence of local pollution sources, the occurrence and distribution of heavy metals (Zn, Cu, Pb), organochlorine compounds (DDT and PCBs) and hydrocarbons (both natural and anthropogenic) in different biotic and abiotic compartments of the park are explained in terms of transport processes related to geographical, hydrological and biological factors. In this respect, it has been recognised that drainage waters from the northern opencast-worked polymetallic sulphide deposits constitute a chronic input of heavy metals into the park. Waste waters from olive-oil manufacturing mills in the area may also contribute to the mobilisation of metals towards the park. However, the resulting relative distributions of Zn, Cu and Pb within the park differ from those of mine effluents, indicating a differential transport of these metals through the water systems. Zinc seems to be the best indicator of input from the mining area. Petroleum hydrocarbons enter the park from the SE via the main rivers and tidal sea movements, whereas PAHs, PCBs and DDTs are uniformly distributed at very low levels in surface sediments, indicating a contribution by aeolian transport. Evidence of inefficient recycling of organic matter in the shallow ponds is obtained by the identification of well preserved natural products from local plants and chemical markers of denitrifying bacteria (cyanobacterial markers).