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En los últimos años está cobrando gran relevancia la aplicación de metodologías de investigación basadas en la participación de la ciudadanía y de los grupos sociales, que devienen en una construcción colectiva de los conocimientos, problemas y soluciones. Estas, buscan dar formas innovadoras de conocer y abordar fenómenos complejos, englobándose bajo el paradigma de la interdisciplinariedad. A través de estos enfoques, no solo se abordan aspectos económicos o culturales, sino también naturales y ambientales, que tienen en el binomio sociedad-territorio su materialización. Desde el ámbito universitario, introducirse en estas técnicas de participación ciudadana requiere un abordaje que se construya tanto desde el plano teórico como desde el plano práctico, basado este segundo en un constante trabajo de campo. Un ejemplo de ello es la cartografía colaborativa, que se convierte en una herramienta de participación ciudadana sumamente útil en el proceso de investigación, pero también en su aplicación para la gestión urbano-territorial y ambiental. Asentadas las bases teóricas en el aula con los/las estudiantes, se llevará a cabo la aplicación de las mismas en un trabajo de campo directo con la sociedad que habita el espacio, en el que se aplicarán herramientas como los mapas colaborativos, no solo para aplicar estas metodologías de participación ciudadana, sino para asentar proyectos mucho más específicos que atiendan a las necesidades reales de estas poblaciones, creando así una metodología de docencia asentada en el binomio universidad-sociedad.

16 pages, 7 figures, supporting information https://doi.org/10.1002/lno.12286.-- Data availability statement: All relevant data are within the paper and its Supporting Information file, Dissolved organic carbon (DOC) plays an essential role in the global marine carbon cycle, with coastal vegetated communities as important DOC producers. However, the ultimate fate of this DOC remains still largely unknown due to the lack of knowledge about its chemical composition and lability. Furthermore, global change could alter both DOC fluxes and its bioavailability, affecting the carbon sequestration capacity of coastal vegetated communities. This study explores, in two contrasting seasons (winter and summer), the effects of an in situ simulated marine heatwave on carbon metabolism and DOC fluxes produced by seagrass (Cymodocea nodosa) and macroalgae (Caulerpa prolifera) communities. In addition, the fluorescent characteristics and biodegradability of the dissolved organic matter released directly by the communities under such conditions are evaluated. Under marine heatwave conditions, a significant increase in net community production (NCP) in C. nodosa and a shift to negative DOC fluxes in C. prolifera were observed. In control treatments, the seagrass-dominated community produced a substantial amount of labile (between 44% and 58%) and recalcitrant DOC (between 42% and 56%), while C. prolifera community produced mainly recalcitrant DOC (between 64% and 87%). Therefore, this research revealed that temperature is an important factor determining the NCP in benthic communities and the chemical structure and bioavailability of DOC produced by these communities, since both communities tended to produce more humic-like and less bioavailable DOC with increasing temperature, This study has been supported by the Spanish National Project PAVAROTTI (CTM2017-85365-R); by SER-CADY project (FEDER-UCA18-107451). This project was co-financed by the European Union under the 2014–2020 ERDF Operational Programme and by the Department of Economic Transformation, Industry, Knowledge, and Universities of the Regional Government of Andalusia; by the Spanish National Project RECOUNT (PID2020-120237RJ-I00). This project was financed by MCIN/AEI/10.13039/501100011033, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

9 pages, 5 figures, 1 table, supplementary materials https://doi.org/10.1016/j.watres.2023.120044.-- Data availability: Data will be made available on request, The purpose of this study was to investigate the occurrence of microplastics (MPs) in drinking water in Spain by comparing tap water from different locations using common sampling and identification procedures. We sampled tap water from 24 points in 8 different locations from continental Spain and the Canary Islands by means of 25 μm opening size steel filters coupled to household connections. All particles were measured and spectroscopically characterized including not only MPs but also particles consisting of natural materials with evidence of industrial processing, such as dyed natural fibres, referred insofar as artificial particles (APs). The average concentration of MPs was 12.5 ± 4.9 MPs/m3 and that of anthropogenic particles 32.2 ± 12.5 APs/m3. The main synthetic polymers detected were polyamide, polyester, and polypropylene, with lower counts of other polymers including the biopolymer poly(lactic acid). Particle size and mass distributions were parameterized by means of power law distributions, which allowed performing estimations of the concentration of smaller particles provided the same scaling parameter of the power law applies. The calculated total mass concentration of the identified MPs was 45.5 ng/L. The observed size distribution of MPs allowed an estimation for the concentration of nanoplastics (< 1 µm) well below the ng/L range; higher concentrations are not consistent with scale invariant fractal fragmentation. Our findings showed that MPs in the drinking water sampled in this work do not represent a significant way of exposure to MPs and would probably pose a negligible risk for human health, The authors acknowledge the financial support provided by Plastics Europe and that of the Spanish Government, Ministerio de Ciencia e Innovación, grants PID2020-113769RB-C21/C22., With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

6 pages, 4 figures, 2 tables.-- Data availability: The data are included in the manuscript, Ocean acidification and plastic pollution are considered as potential planetary boundary threats for which crossing certain thresholds could be very harmful for the world's societies and ecosystems well-being. Surface oceans have acidified around 0.1 units since the Industrial Revolution, and the amount of plastic reaching the ocean in 2018 was quantified to 13 million metric tonnes. Currently, both ocean threats are worsening with time. Plastic leaching is known to alter the biogeochemistry of the ocean through the release of dissolved organic matter. However, its impact in the inorganic chemistry of the seawater is less studied. Here we show, from laboratory experiments, that abiotic plastic degradation induces a decrease in seawater pH, particularly if the plastic is already aged, as that found in the ocean. The pH decrease is enhanced by solar radiation, and it is probably induced from a combination of the release of organic acids and the production of CO2. It is also related to the amount of leached dissolved organic carbon, with higher acidification as leaching increases. In coastal areas, where plastic debris accumulates in large quantities, plastic leaching could lead to a seawater pH decrease up to 0.5 units. This is comparable to the projected decrease induced in surface oceans by the end of the twenty-first century for the most pessimistic anthropogenic emissions scenarios, This work and C.R.-C.'s involvement were supported by a “Proyecto I+D+I Jóvenes Investigadores-2019” (PID2019-109889RJ-I00) funded by MCIN/AEI 10.13039/501100011033. This work acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) and the Thematic Network of Micro- and Nanoplastics in the Environment (RED2018-102345-T, EnviroPlaNet) funded by MCIN/AEI 10.13039/501100011033

This work aims at evaluating the fate of polystyrene (PS) microplastics along Fenton oxidation. Experiments were carried out under relatively severe operating conditions (80 ºC) given the high persistence of these solids to oxidation. Slight mass losses (up to 10%) were found after the Fenton treatment of microplastics in the micro range (100–250 m). Nevertheless, the particles clearly suffered important changes in their surface due to the introduction of oxygen groups, which made them more acidic and hydrophilic. These surface alterations completely changed the sorption properties of microplastics. For instance, their adsorption capacity for diclofenac was sharply decreased from 102 to 28 g g-1. Apart from surface modifications, microplastics clearly decreased their size after Fenton oxidation, which was more evident in the 50–100 m range. To further evaluate the oxidation yield of PS microplastics upon Fenton oxidation, particles in the sub-micro range (140 nm) were treated. Notably, up to 75% TOC mineralization was achieved, which proved that microplastics can be completely oxidized to CO2 upon Fenton oxidation. Finally, the biodegradability of the dissolved compounds leached from oxidized microplastics was evaluated. Remarkably, bacterial growth efficiency was higher in the solution coming from the oxidized PS microplastics than that of the fresh one.

El trabajo en los espacios mineros siempre ha estado caracterizado por su extrema dureza, sobre todo si las labores desarrolladas eran en el ámbito subterráneo. Sin embargo, esa dureza se acentuaba más cuando se trataba de los menores que con apenas 10 años, comenzaban a trabajar en la mina. Aunque el empleo de los niños y jóvenes era recurrente en la mayoría de las cuencas mineras españolas, variaba según el tipo de industria que allí se desarrollaba. El yacimiento de Las Minas (Hellín), explotaba uno de los minerales que mayores tasas de empleo de menores tenía: el azufre. Partiendo de esta premisa, el artículo presenta una caracterización del trabajo de los menores en Las Minas, basada en las Estadísticas Mineras de España y en el testimonio de uno de los antiguos mineros. Todo ello contextualizado con las normativas que se aplicaron y que no siempre tuvieron efectividad.

10 pages, 5 figures, 2 tables, supplementary data https://doi.org/10.1016/j.chemosphere.2022.136809.-- Data availability: Data will be made available on request, This work aims at evaluating the fate of microplastics (MPs) along Fenton oxidation. For such goal, realistic MPs (150–250 μm) of five representative polymer types (PET, PE, PVC, PP and EPS) were obtained from commercial plastic products by cryogenic milling. Experiments (7.5 h) were performed under relatively severe operating conditions: T = 80 °C; pH0 = 3; [H2O2]0 = 1000 mgL−1 (15 doses, 1 every 0.5 h); [Fe3+]0 = 10 mgL−1 (5 doses, 1 every 1.5 h). Slight MPs weight losses (∼10%) were achieved after Fenton oxidation regardless the MP nature. Nevertheless, oxidation yield clearly increased with decreasing the particle size given their higher exposed surface area (up to 20% weight loss with 20–50 μm EPS MPs). Clearly, MPs suffered important changes in their surface due to the introduction of oxygenated groups, which made them more acidic and hydrophilic. Furthermore, MPs progressively reduced their size. In fact, they can be completely oxidized to CO2, as demonstrated in the oxidation of PS nanoplastics (140 nm), where 70% mineralization was achieved. The nature of the plastic particles had a relevant impact on its overall oxidation, being more prone to be oxidized those polymers which contain aromatic rings in their structures (EPS and PET) compared to those formed by alkane chains (PE, PP and PVC). In the latter, the presence of substituents also reduced their oxidation potential. Remarkably, possible leachates released along reaction were more quickly oxidized than the MPs/NPs, so it can be assumed that these dissolved compounds would be completely removed once the solid particles are eliminated. Notably, the leachates obtained upon MPs oxidation were more biodegradable than the released from the fresh solids. All this knowledge is crucial for the understanding of MPs oxidation by the Fenton process and opens the door for the design and optimization of this technology either for water treatment or for analytical purposes (MPs isolation), This research has been supported by the Autonoma University of Madrid and Community of Madrid through the project SI1-PJI-2019-00006, and by the Spanish MINECO through the project PID2019-105079RB-I00. D. Ortiz thanks the Spanish MIU for the FPU predoctoral grant (FPU19/04816). M. Munoz and J. Nieto-Sandoval thank the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648) and the FPI predoctoral grant (BES-2017-081346), respectively. C. Romera-Castillo was supported by JIN-2019 project (PID2019-109889RJ-I00) from the Spanish Ministry of Science and Innovation and the Agencia Estatal de Investigación and acknowledges the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S)

Plastic litter dispersed in the different environmental compartments represents one of the most concerning problems associated with human activities. Specifically, plastic particles in the micro and nano size scale are ubiquitous and represent a threat to human health and the environment. In the last few decades, a huge amount of research has been devoted to evaluate several aspects of micro/nano-plastic contamination: origin and emissions, presence in different compartments, environmental fate, effects on human health and the environment, transfer in the food web and the role of associated chemicals and microorganisms. Nevertheless, despite the bulk of information produced, several knowledge gaps still exist. The objective of this paper is to highlight the most important of these knowledge gaps and to provide suggestions for the main research needs required to describe and understand the most controversial points to better orient the research efforts for the near future. Some of the major issues that need further efforts to improve our knowledge on the exposure, effects and risk of micro/nano-plastics are: harmonization of sampling procedures; development of more accurate, less expensive and less time-consuming analytical methods; assessment of degradation patterns and environmental fate of fragments; evaluating the capabilities for bioaccumulation and transfer to the food web; and evaluating the fate and the impact of chemicals and microorganisms associated with micro/nano-plastics. The major gaps in all sectors of our knowledge, from exposure to potentially harmful effects, refer to small size microplastics and, particularly, to the occurrence, fate and effects of nanoplastics.

56 pages, 4 figures, 3 tables, Plastic litter dispersed in the different environmental compartments represents one of the most concerning problems associated with human activities. Specifically, plastic particles in the micro and nano size scale are ubiquitous and represent a threat to human health and the environment. In the last few decades, a huge amount of research has been devoted to evaluate several aspects of micro/nano-plastic contamination: origin and emissions, presence in different compartments, environmental fate, effects on human health and the environment, transfer in the food web and the role of associated chemicals and microorganisms. Nevertheless, despite the bulk of information produced, several knowledge gaps still exist. The objective of this paper is to highlight the most important of these knowledge gaps and to provide suggestions for the main research needs required to describe and understand the most controversial points to better orient the research efforts for the near future. Some of the major issues that need further efforts to improve our knowledge on the exposure, effects and risk of micro/nano-plastics are: harmonization of sampling procedures; development of more accurate, less expensive and less time-consuming analytical methods; assessment of degradation patterns and environmental fate of fragments; evaluating the capabilities for bioaccumulation and transfer to the food web; and evaluating the fate and the impact of chemicals and microorganisms associated with micro/nano-plastics. The major gaps in all sectors of our knowledge, from exposure to potentially harmful effects, refer to small size microplastics and, particularly, to the occurrence, fate and effects of nanoplastics

12 pages, 6 figures, 5 tables, supplementary information https://doi.org/10.1038/s41598-021-82632-3.-- The datasets generated during the current study are available from the corresponding author on reasonable request, Seafloor structures related to the emission of different fluids, such as submarine mud volcanoes (MVs), have been recently reported to largely contribute with dissolved organic matter (DOM) into the oceans. Submarine MVs are common structures in the Gulf of Cádiz. However, little is known about the biogeochemical processes that occur in these peculiar environments, especially those involving DOM. Here, we report DOM characterization in the sediment pore water of three MVs of the Gulf of Cádiz. Estimated benthic fluxes of dissolved organic carbon (DOC) and chromophoric DOM (CDOM) were higher than in other marine sediments with an average of 0.11 ± 0.04 mmol m−2 d−1 for DOC and ranging between 0.11 and 2.86 m−1 L m−2 d−1, for CDOM. Protein-like components represented ~ 70% of the total fluorescent DOM (FDOM). We found that deep fluids migration from MVs (cold seeps) and anaerobic production via sulfate-reducing bacteria represent a source of DOC and FDOM to the overlying water column. Our results also indicate that fluorescent components can have many diverse sources not captured by common classifications. Overall, MVs act as a source of DOC, CDOM, and FDOM to the deep waters of the Gulf of Cádiz, providing energy to the microbial communities living there, This work was funded by the Spanish CICYT (Spanish Program for Science Technology) under the contract CTM2014-59244- C3-1-R and RTI2018-100865-B-C21. VA was financed by the National Research and Innovation Agency of Uruguay (ANII) with a Ph.D. fellowship (POS_EXT_2015_1_122780). CR-C was funded by a Postdoctoral Fellowship from the Spanish “Ministerio de Economía y Competitividad, Juan de la Cierva-Incorporación”.

15 pages, 5 figures, 3 tables, supplementary material https://doi.org/10.3389/fmars.2020.00126, The Gulf of Cádiz (GoC) connects the Mediterranean Sea with the Atlantic Ocean through the Strait of Gibraltar. Particular hydrographic processes take place in the GoC, such as riverine discharges and surface circulation marked by wind-induced seasonal upwelling. Although physical processes have been widely studied, little is known about the biogeochemical processes that occur in the basin, especially those involving organic matter. Therefore, vertical and seasonal dynamics of dissolved organic carbon (DOC) and optical properties of dissolved organic matter (DOM, absorbance and fluorescence) were measured in 766 samples collected between 5 and 800 m depth during four oceanographic cruises to obtain quantitative and qualitative information about DOM in the GoC. We performed parallel factor analysis (PARAFAC) to identify the main fluorophores present in the GoC, and an optimum multiparameter water mass analysis to differentiate the effect of water mass mixing from the biogeochemical processes in deep waters. PARAFAC analysis validated six fluorescent components; three humic-like, two protein-like, and a possible mixture of polycyclic aromatic hydrocarbon-like with protein-like material. DOC average concentration was 77.0 ± 12.7 μM, with higher values in surface and coastal waters during summer, mainly related to primary production. Linear relationships between DOC and apparent oxygen utilization indicate differences in oxygen consumption within the deep waters, which could be related to upwelling zones. Seasonal and spatial differences were also observed in the distribution of fluorescent DOM. Protein-like components were the most abundant fraction, with an average contribution of 64.75% ± 7.85%, being higher in summer and surface waters, associated with an increase in biological activity. Our results indicate that water mass mixing is the main driver of the major humic-like components, while biogeochemical processes at a local scale explain DOC and protein-like components distribution. Our findings suggest that modeling DOM dynamics in the GoC is complicated due to its complex hydrography and the presence of multiple sources and sinks of DOM, This work was funded by the Spanish CICYT (Spanish Program for Science Technology) under the contract CTM2014-59244-C3-1-R and RTI2018-100865-B-C21. VA was financed by the Uruguayan Agency for Research and Innovation (ANII) with a Ph.D. fellowship (POS_EXT_2015_1_122780). CR-C was funded by a Juan de la Cierva-Incorporación Postdoctoral Fellowship from the Spanish “Ministerio de Economía y Competitividad”, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

14 pages, 9 figures, 4 tables, Estuarine systems receive large amounts of organic matter that enhance the production of greenhouse gases (GHGs), such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Despite considerable research on GHGs and dissolved organic matter (DOM) distribution in estuaries, little is known about the linkage between these gases and DOM composition. Here we evaluated the relationship between three GHGs (CO2, CH4, and N2O) and DOM composition, determined through optical properties, in Guadalete estuary (Bay of Cadiz, Spain). The partial pressure of CO2, and CH4 and N2O concentrations ranged between 332.8 and 6807.1 μatm, 19.9–6440.1 nM, and 6.8–283.9 nM, respectively. Thus, the Guadalete estuary was a source of CO2, CH4 and N2O to the atmosphere. We validated three PARAFAC components related to humic-like fluorescence from terrestrial, microbial and effluent sources, and one with protein-like material. Humic-like components accounted for 86% ± 6% of the total FDOM pool, indicating a predominantly allochthonous DOM origin. The three GHGs were significantly linked to DOC concentration and DOM composition, exhibiting different patterns in these linkages. Terrestrial and microbial humic-like substances with increasing aromaticity might enhance pCO2 in Guadalete estuary. Dissolved CH4 concentrations showed the strongest relationship with DOM composition, indicating that humic and protein-like material are linked with their distribution. In contrast, dissolved N2O was only related with the protein-like fraction and with humic-like material derived from anthropogenic activities (sewage and agriculture). Our results further indicate that a possible coupling between benthic fluxes of GHGs and DOM might be occurring in this shallow estuary. We conclude that it is important to account for DOM composition when studying GHGs distribution in estuarine systems to understand their roles and potential responses associated with climate change, Valentina Amaral was financed by the National Research and Innovation Agency of Uruguay (ANII) with a Ph.D. fellowship (POS_EXT_2015_1_122780). Cristina Romera-Castillo was funded by the Spanish Ministry of Science and Innovation through a JIN Project with reference PID2019-109889RJ-I00. This study was financed by the Spanish CICYT (Spanish Program for Science and Technology) under contract RTI2018-100865-B-C21, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

12 pages, 5 figures, 2 tables, Most dissolved organic carbon (DOC) sequestered in the deep ocean has residence times of decades to thousands of years, with clear implications for climate regulation, though some net removal is typically observed with increasing water mass age. Here, a high‐quality‐high‐resolution data set has allowed us to identify net additions of recalcitrant DOC in specific water masses of the deep South Atlantic. Overall, the South Atlantic is a net source of recalcitrant DOC, adding 0.027 ± 0.019 Pg C/year, while the North Atlantic is a net sink that removes 0.298 ± 0.141 Pg C/year. We find that the balance of addition/removal of recalcitrant DOC depends not only on the origin but also on the temperature, age, and depth of the water masses that circulate and mix in the Atlantic Ocean. Future changes in the water mass composition and circulation patterns due to climate change would eventually affect that balance, altering the carbon cycle, C. R.‐C. was supported by a Juan de la Cierva‐ Incorporación Postdoctoral Fellowship (IJCI‐2015‐23357) from the Spanish “Ministerio de Economía y Competitividad” and XAA‐S by the Spanish MINECO Grant CTM2015‐ 69392‐C3‐2‐R. Data collection on U.S. CLIVAR sections and involvement by C. R.‐C. and D. A. H. were supported by U.S. NSF OCE1436748

Fluorescent dissolved organic matter (FDOM) in open surface waters ( 70%) than for the amino acid-like components ( 200 m), the relationships of C1 and C2 with AOU indicate a higher C1/AOU and C2/AOU ratios of the humic-like substances in the dark ocean than in the surface ocean where a net effect of photobleaching is also detected. C3 (tryptophan-like) and C4 (tyrosine-like) variability was mostly dictated by salinity (S), by means of positive non-linear relationships, suggesting a primary physical control of their distributions at the global surface ocean scale that could be related to the changing evaporation-precipitation regime. Remarkably, bacterial biomass (BB) only contributed to explain a minor part of the variability of C1 and C4.

15 pages, 8 figures, 4 tables, supplementary data https://doi.org/10.1016/j.marchem.2020.103857, The Gulf of Cádiz, located in the Southern Iberian Atlantic Basin, connects the North Atlantic Ocean and the Mediterranean Sea and receives freshwater input from three main estuaries: Guadalquivir, Guadiana, and Tinto-Odiel. These estuaries differ in their hydrology, basin characteristic, and land use. One of them, Tinto-Odiel, is one of the most polluted estuaries in the world. However, little is known about the export of DOM from these estuaries to the Gulf of Cádiz. In this work, the estuaries were sampled during the dry season. Dissolved organic matter (DOM) was chemically characterized along a longitudinal gradient to better understand the reactivity and fate of carbon exported to the Gulf of Cádiz. We also performed a tidal study at the mouth of each estuary to understand how the tide affects the composition of DOM and its export to the coastal zone. Fluorescent DOM (FDOM) modeling employing multivariate parallel factor analysis and pyrolysis-gas chromatography-mass spectroscopy analysis (Py-GC–MS) were used to characterize DOM. DOM from Guadalquivir and Guadiana estuaries presented a predominant allochthonous origin with humic-like compounds making up to ~80% of the total fluorescent DOM. These estuaries receive lateral inputs from surrounding watersheds and agricultural practices. Instead, in Tinto-Odiel estuary, DOM was predominantly autochthonous with a higher content of protein-like material associated with the prevalence of the marine influence over the low water discharges and anthropogenic pollution from industrial activities. Tidal cycles affected the distribution of DOM and its quality with higher humic-like material during low tide and protein-like substances predominating during high tide. During the dry season, the three estuaries represented a source of DOM to the Gulf of Cádiz. Guadalquivir was the main contributor with 1.25 Kg C s and 0.22 × 10 m s, for DOC and CDOM, respectively. Around 70% of the FDOM exported from the three estuaries was of humic nature. The results obtained in this work highlight the importance of local conditions, such as the basin characteristic and estuarine biogeochemical reactivity in the composition of the DOM exported to the coastal ocean. Moreover, Py-GC–MS analysis was a useful technique, complementary to fluorescence spectroscopy, which improves DOM characterization in estuarine systems, Valentina Amaral was financed by the National Research and Innovation Agency of Uruguay (ANII) with a Ph.D. fellowship (POS_EXT_2015_1_122780). Cristina Romera-Castillo was funded by a Juan de la Cierva-Incorporación Postdoctoral Fellowship from the Spanish “Ministerio de Economía y Competitividad”. [...] This study was financed by the Spanish CICYT (Spanish Program for Science and Technology) under contracts CTM2014-59244-C3-1-R and RTI2018-100865-B-C21

9 pages, 5 figures, 1 table, supplementary data https://doi.org/10.1016/j.watres.2020.115678, Although there are numerous studies concerning the occurrence of microplastics (MP) in the environment and its impact on the ecosystem, dissolved organic matter (DOM) leached from MP (MP-DOM) has received little attention, and its characteristics have been rarely examined. It is presumed that the DOM leaching from plastics could be accelerated when plastics lost their protective additives during their transport and weathering processes in aquatic systems. In this study, two additive-free MPs (or micro-sized plastic polymers) were leached in artificial freshwater under UV irradiation and dark conditions. The leached DOM was characterized by typical analyses for naturally occurring DOM (N-DOM) such as dissolved organic carbon (DOC), size exclusion chromatography (SEC), and Fourier-transform infrared spectroscopy (FTIR). The potential to generate trihalomethanes (THMs), a well-known environmental impact of N-DOM, was also explored for the DOM with plastic origins for the first time. The leaching results demonstrated that UV irradiation promoted the leaching of DOM from the plastic polymers with an amount corresponding to ∼3% of the total mass of the polymers. The leached amounts were much greater than those previously reported using commercial plastics which presumably contained protective additives. The SEC results revealed that, different from typical aquatic N-DOM, MP-DOM is mostly composed of low molecular weight fractions, This work was supported by grants from the National Research Foundation of Korea funded by the Korean government (2020R1A2C2007248, 2020R1A4A2002823, and NRF-2017-Fostering Core Leaders of the Future Basic Science Program/Global Ph.D. Fellowship Program). C.R.-C. thanks ComFuturo Program from Fundación General CSIC, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Tras el desarrollo de la industria minera del azufre en la pedanía de Las Minas de Hellín (Albacete), sobre todo durante los siglos XVIII-XIX, este espacio rural ha quedado en la actualidad totalmente abandonado fruto de la quiebra de su explotación. A pesar de su devastador cierre en 1960, el poblado minero, aunque muy deteriorado, se conserva en nuestros días encerrando vestigios de un pasado que logró posicionar a esta zona minera como la primera a nivel nacional. Todas esas huellas de la actividad extractiva han ido modelando diferentes escenarios que se han convertido (sobre todo para las comunidades locales), en auténticos referentes simbólicos y culturales, que ahora tienen la oportunidad de enmarcarse en una nueva etapa de transición dadas las oportunidades que le ofrece su patrimonio minero-industrial, a través de labores de reconversión y restauración, que constituyen una de las principales líneas estratégicas en el desarrollo local. Following the development of the mining industry of the sulphur in the hamlet of Las Minas de Hellín (Albacete), especially during the 18th - 19th, this rural area has currently been totally abandoned fruit of the bankruptcy of their exploitation. Despite its devastating closure in 1960, the town mining, although very deteriorated, is preserved in our days enclosing relics of a past that managed to position this mining area as the first national. All these traces of the extractive activity have been modeling different scenarios that have become (especially for local communities) in authentic concerning symbolic and cultural, that now have the opportunity of framing in a new stage of transition given the opportunities offered by its mining heritage, through work of conversion and restoration, which constitute one of the main strategic lines in local development.

XIX Seminario Ibérico de Química Marina (SIQUIMAR), VI Simposio Internacional de Ciencias del Mar - VI International Symposium of Marine Sciences (ISMS 2018), 20- 22 June 2018, Vigo.-- 1 page, More than 5.25 trillion of plastic pieces have been estimated to be floating at the sea surface (Eriksen et al., 2014). Plastic marine debris on beaches and floating in seawater is exposed to solar UV radiation undergoing weathering degradation (Andrady, 2011). It can develop surface cracks and fragment into progressively smaller particles reaching microscopic sizes (< 5 mm, microplastics). Detrimental effects of plastics on marine organisms at different trophic levels have been widely reported, making plastic pollution a global environmental concern. However, the impacts of plastic debris on the lowest trophic levels, such as the microbial food web, remain enigmatic. Plastic is known to leach organic compounds to the aquatic media (Suhrhoff et al., 2016). The smaller the piece, the higher its surface to volume ratio and its potential for leaching. However, the contribution of plastic leaching to the dissolved organic carbon (DOC) pool in the ocean and its impact on the lowest trophic levels, such as the microbial food web, is still unknown. In this work we present experimental evidence that plastics release dissolved organic carbon (DOC) into the ambient seawater stimulating the activity of heterotrophic microbes. About 60% of the DOC leached from plastics is available to microbial utilization in less than 5 days. It is predicted that plastic waste entering the ocean will increase by 10-fold over the next decade (Jambeck et al., 2015), resulting in an increase in plastic-derived DOC that could have unaccounted consequences for the activity of marine microbes and for the ecosystem, This research was supported by the Austrian Science Fund (FWF) projects Z194-B17 and P28781-B21. X.A.A.-S was funded by the project MODMED (CSIC–PIE, 201730E020) project

Free radicals are produced in aquatic environments through photochemical reactions. They can affect the concentration and composition of organic matter and have negative effects on aquatic organisms. Free radical scavengers (antioxidants) can remove these highly reactive species from the media. Some dissolved organic matter (DOM) constituents are widely known to present antioxidant properties (e.g. phenols and hydroquinones). However, little is known about the free radical scavenger capacity of DOM. Here we applied two simple, analytical assays (ABST and DPPH) to assess the antioxidant capacity of aquatic DOM, after their validation against a more complex electrochemical technique. These assays were applied to DOM from various environmental settings, including freshwater marshes, fringe mangrove estuaries and a coastal bay in Everglades National Park, Florida. All the samples presented different degrees of antioxidant activity depending on their origin and thus DOM quality. Samples associated with mangrove areas presented the highest antioxidant activity, possibly due to the presence of tannins, which are known to be powerful antioxidants. The free radical scavenging capacity or antioxidant properties of DOM may have important implications in aquatic photochemistry as well as in microbial processes.

The omnipresence of chromophoric dissolved organic matter (CDOM) in the open ocean enables its use as a tracer for biochemical processes throughout the global overturning circulation. We made an inventory of CDOM optical properties, ideal water age (τ), and apparent oxygen utilization (AOU) along the Atlantic, Indian, and Pacific Ocean waters sampled during the Malaspina 2010 expedition. A water mass analysis was applied to obtain intrinsic, hereinafter archetypal, values of τ, AOU, oxygen utilization rate (OUR), and CDOM absorption coefficients, spectral slopes and quantum yield for each one of the 22 water types intercepted during this circumnavigation. Archetypal values of AOU and OUR have been used to trace the differential influence of water mass aging and aging rates, respectively, on CDOM variables. Whereas the absorption coefficient at 325 nm (a325) and the fluorescence quantum yield at 340 nm (Φ340) increased, the spectral slope over the wavelength range 275–295 nm (S275–295) and the ratio of spectral slopes over the ranges 275–295 nm and 350–400 nm (SR) decreased significantly with water mass aging (AOU). Combination of the slope of the linear regression between archetypal AOU and a325 with the estimated global OUR allowed us to obtain a CDOM turnover time of 634 ± 120 years, which exceeds the flushing time of the dark ocean (>200 m) by 46%. This positive relationship supports the assumption of in situ production and accumulation of CDOM as a by-product of microbial metabolism as water masses turn older. Furthermore, our data evidence that global-scale CDOM quantity (a325) is more dependent on aging (AOU), whereas CDOM quality (S275–295, SR, Φ340) is more dependent on aging rate (OUR).

Natural dissolved organic matter (DOM) is the major absorber of sunlight in most natural waters and a critical component of carbon cycling in aquatic systems. The combined effect of light absorbance properties and related photo-production of reactive species are essential in determining the reactivity of DOM. Optical properties and in particular excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis (EEM-PARAFAC) have been used increasingly to track sources and fate of DOM. Here we describe studies conducted in water from two estuarine systems in the Florida Everglades, with a salinity gradient of 2 to 37 and dissolved organic carbon concentrations from 19.3 to 5.74 mg C L(-1), aimed at assessing how the quantity and quality of DOM is coupled to the formation rates and steady-state concentrations of reactive species including singlet oxygen, hydroxyl radical, and the triplet excited state of DOM. These species were related to optical properties and PARAFAC components of the DOM. The formation rate and steady-state concentration of the carbonate radical was calculated in all samples. The data suggests that formation rates, particularly for singlet oxygen and hydroxyl radicals, are strongly coupled to the abundance of terrestrial humic-like substances. A decrease in singlet oxygen, hydroxyl radical, and carbonate radical formation rates and steady-state concentration along the estuarine salinity gradient was observed as the relative concentration of terrestrial humic-like DOM decreased due to mixing with microbial humic-like and protein-like DOM components, while the formation rate of triplet excited-state DOM did not change. Fluorescent DOM was also found to be more tightly coupled to reactive species generation than chromophoric DOM.

13 pages, 4 figures, 4 tables, Despite representing only a small fraction of the ocean's dissolved organic matter pool, dissolved free amino acids (DFAA) have high turnover rates and are major nitrogen and carbon sources for bacterioplankton. Both phytoplankton and bacterioplankton assimilate and release DFAA, but their consumption and production are difficult to quantify in nature due to their short residence times (min) as dissolved monomers. We segregated DFAA production by phytoplankton and bacterial consumption by measuring individual DFAA concentrations in four axenic phytoplankton cultures during the exponential growth phase, and also after 4 d incubations in the presence of a natural bacterioplankton community. The amounts and composition of the DFAA pool varied widely among phytoplankton species. The proportion of dissolved organic carbon attributed to DFAA varied among cultures. The picoeukaryotic prasinophyte, Micromonas pusilla, released higher amounts of DFAA than the other species tested (diatoms and dinoflagellate), especially alanine, which has been reported as the dominant individual DFAA in some oligotrophic environments. Community structure of heterotrophic prokaryotes responded to differences in the quality of organic matter released among microalgal species, with Roseobacter-related bacteria responding strongly to exudate composition. Our results demonstrate the specificity of DFAA extracellular release among several algal species and their preferential uptake by members of bacterial communities, This work was supported by projects STORM (CTM2009-09352/MAR) and ICARO (PIE 200830I120) and DOREMI (CTM2012-34294) funded by Spanish Ministerio de Economia y Competitividad. H.S. benefited from fellowships from the Spanish ‘Ministerio de Educación y Ciencia’ (JCI-2008-2727) and Brazilian ‘Ciências sem Fronteiras’ Program from CAPES (BJT 013/2012); C.R.-C. was funded by a I3P-CSIC predoctoral fellowship within the project MODIVUS, CTM2005-04795/MAR; J.P. was funded by the Crafoord Foundation and the Swedish governmental strong research program Ecochange; G.T.T. was partially supported by a sabbatical fellowship from the Spanish ‘Ministerio de Educación y Ciencia’

Galí, Martí ... et al.-- 10 pages, Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY) for DMS photolysis varied according to the quantity and quality of its photosensitizers, chiefly chromophoric dissolved organic matter (CDOM) and nitrate. AQY compiled from the literature and unpublished studies ranged across 3 orders of magnitude at the 330 nm reference wavelength. The smallest AQY(330) were observed in coastal waters receiving major riverine inputs of terrestrial CDOM (0.06–0.5 m3 (mol quanta)−1). In open-ocean waters, AQY(330) generally ranged between 1 and 10 m3 (mol quanta)−1. The largest AQY(330), up to 34 m3 (mol quanta)−1), were seen in the Southern Ocean potentially associated with upwelling. Despite the large AQY variability, daily photolysis rate constants at the sea surface spanned a smaller range (0.04–3.7 d–1), mainly because of the inverse relationship between CDOM absorption and AQY. Comparison of AQY(330) with CDOM spectral signatures suggests there is an interplay between CDOM origin (terrestrial versus marine) and photobleaching that controls variations in AQYs, with a secondary role for nitrate. Our results can be used for regional or large-scale assessment of DMS photolysis rates in future studies

The inventories of carbon residing in organic matter dissolved in the ocean [dissolved organic carbon (DOC)] and in the atmosphere as CO2 are of the same order of magnitude, such that small changes in the DOC pool could have important consequences in atmospheric carbon and thus climate. DOC in the global ocean is largely formed in the sunlit euphotic zone, but identifying predictable controls on that production is an important yet unrealized goal. Here, we use a testable and causative correlation between the net production of DOC and the consumption of new nutrients in the euphotic zone of the Atlantic Ocean. We demonstrate that new nutrients introduced to the euphotic zone by upwelling in divergence zones and by winter convective overturn of the water column, and the primary production associated with those nutrients, are the ultimate driver of DOC distributions across the Atlantic basins. As new nutrient input will change with a changing climate, the role of DOC in the ocean's biological pump should likewise be impacted.

Corrigendum: Turnover time of fluorescent dissolved organic matter in the dark global ocean

Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (200 m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, which persist significantly longer than the ~350 years that the dark global ocean takes to renew. In parallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is also detected. We propose the use of DOM fluorescence to study the cycling of resistant DOM that is preserved at centennial timescales and could represent a mechanism of carbon sequestration (humic-like fraction) and the decaying DOM injected into the dark global ocean, where it decreases at centennial timescales (tyrosine-like fraction).

16 pages, 4 figures, 3 tables, The Mediterranean coast receives large inputs of dust with a potential fertilization effect. We evaluated the effect of a wet dust deposition event on microbial abundance and activity, community structure and metabolic balance. Dust collected during a dust storm event was added to a series of microcosms. We added a realistic concentration (0.05 g L–1) based on the phosphorus concentration contained in the dust and, in addition, we included a P amended tank to distinguish the effect of dust from that of the phosphorus in the dust. We also included a higher dust concentration tank (0.5 g L–1). Dust increased the initial water–phosphorus concentration by 0.3 µM and the dissolved organic carbon (DOC) concentration by 14 µM, and increased bacterial abundance (1.8-fold) and bacterial production (5-fold). At the end of the experiment, primary production and community respiration were stimulated by dust and by P, but the net result of the addition of low amounts of dust was an initial switch towards heterotrophy, whereas the net result of the high-dust (DH) additions and the P addition was a shift towards autotrophy. Bacterial community structure changed little between P and low dust, but these were very different from the control and the DH communities, This work was supported by Spanish projects MODIVUS (CTM2005-04795/MAR), VARITEC (CTM2004-0442-C02) and STORM (CTM2009-09352/MAR), and is a contribution to the European Network of Excellence EUROCEANS and MARBEF

Catalá, Teresa S. ... et. al.-- 8 pages, 4 figures, 1 table, supplementary information http://www.nature.com/ncomms/2015/150129/ncomms6986/full/ncomms6986.html#/supplementary-information, Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (>200 m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, which persist significantly longer than the ∼350 years that the dark global ocean takes to renew. In parallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is also detected. We propose the use of DOM fluorescence to study the cycling of resistant DOM that is preserved at centennial timescales and could represent a mechanism of carbon sequestration (humic-like fraction) and the decaying DOM injected into the dark global ocean, where it decreases at centennial timescales (tyrosine-like fraction). © 2015 Macmillan Publishers Limited. All rights reserved, This study was financed by the Malaspina 2010 circumnavigation expedition (grant number CSD2008–00077). C.R.-C. acknowledges funding through a Beatriu de Pinos postdoctoral fellowship from the Generalitat de Catalunya. M.N.-C. was funded by the CSIC Program ‘Junta para la Ampliación de Estudios’ cofinanced by the ESF

Tumor necrosis factor (TNF)-alpha converting enzyme (TACE, also called ADAM17) is a key sheddase that releases TNF-alpha from its inactive cell-bound precursor. TACE protein expression levels in peripheral blood mononuclear cells were measured by Western blot analysis in 20 healthy controls and 80 multiple sclerosis (MS) patients before and after treatment with IFNbeta [20 patients with primary progressive (PP) MS, 20 patients with secondary progressive (SP) MS, and 40 patients with relapsing- remitting (RR) MS (20 patients during clinical remission and 20 patients in relapse)]. TNF-alpha serum levels were also measured by enzyme-linked immunoassay in the MS patients and healthy controls. TACE protein expression levels were lower in healthy controls and PPMS patients compared with SPMS patients and RRMS patient during clinical remission. No differences in TACE protein levels were observed between RRMS patients in relapse and during remission. TACE protein levels were increased in PPMS patients treated with IFNbeta. Serum TNF-alpha levels were higher in RRMS patients in relapse compared with RRMS patients during remission, and positive and negative correlations were found between TACE protein expression and serum TNF-alpha levels in RRMS patients during relapse and during remission respectively. These findings point to different regulatory mechanisms of the TACE-TNF-alpha pathway in the clinical MS subtypes and expand the role of TACE in MS pathogenesis.

A short ischemic event (ischemic preconditioning) can result in subsequent resistance to severe ischemic injury (ischemic tolerance). Glutamate is released after ischemia and produces cell death. It has been described that after ischemic preconditioning, the release of glutamate is reduced. We have shown that an in vitro model of ischemic preconditioning produces upregulation of glutamate transporters which mediates brain tolerance. We have now decided to investigate whether ischemic preconditioning-induced glutamate transporter upregulation takes also place in vivo, its cellular localization and the mechanisms by which this upregulation is controlled. A period of 10 min of temporary middle cerebral artery occlusion was used as a model of ischemic preconditioning in rat. EAAT1, EAAT2 and EAAT3 glutamate transporters were found in brain from control animals. Ischemic preconditioning produced an up-regulation of EAAT2 and EAAT3 but not of EAAT1 expression. Ischemic preconditioning-induced increase in EAAT3 expression was reduced by the TNF-alpha converting enzyme inhibitor BB1101. Intracerebral administration of either anti-TNF-alpha antibody or of a TNFR1 antisense oligodeoxynucleotide also inhibited ischemic preconditioning-induced EAAT3 up-regulation. Immunohistochemical studies suggest that, whereas the expression of EAAT3 is located in both neuronal cytoplasm and plasma membrane, ischemic preconditioning-induced up-regulation of EAAT3 is mainly localized at the plasma membrane level. In summary, these results demonstrate that in vivo ischemic preconditioning increases the expression of EAAT2 and EAAT3 glutamate transporters the upregulation of the latter being at least partly mediated by TNF-alpha converting enzyme/TNF-alpha/TNFR1 pathway.

12 páginas, 9 figuras, 2 tablas, The distributions of humic-like fluorescent dissolved organic matter (at excitation/emission wavelengths of 340 nm/440 nm, F(340/440)) and apparent oxygen utilization (AOU) are determined from water samples taken at 27 stations along 7.5°N, in the equatorial Atlantic Ocean. The relationship between F(340/440) and AOU is evaluated. The influence of water mass mixing is removed through multiple regressions of both F(340/440) and AOU with salinity and temperature for the ocean interior. A general and significant relationship between the residuals of F(340/440) and AOU is found for the entire water column deeper than 200 m (R2=0.79, n=360, p-value, Funding comes from the Spanish government through the MOC2 (CTM2008-06438-CO2), TIC-MOC (CTM2011-28867), and DOREMI (CTM2012-34294) projects of the R+D Spanish research program, and from the ECLIPSE project financed by Total Foundation. P. De La Fuente would like to thank the Agència de Gestió d׳Ajuts Universitaris i de Recerca de la Generalitat de Catalunya (AGAUR) for their financial support through a FI-AGAUR fellowship. A. Canepa was funded by CONICYT (PFCHA/Doctorado al Extranjero 4a Convocatoria, 72120016). C. Romera-Castillo was funded by a Beatriu de Pinós post-doctoral fellowship from the AGAUR of the Generalitat de Catalunya

Tras el desarrollo de la industria minera del alcrebite en la pedanía de Las Minas de Hellín sobre todo en los siglos XVIII-XIX, este espacio rural ha quedado en la actualidad totalmente abandonado fruto de la quiebra de su explotación. A pesar de su devastador cierre el poblado minero, aunque muy deteriorado, se conserva en nuestros días encerrando vestigios de un pasado que logró posicionar a esta zona minera como la primera a nivel nacional. Ha sido la propia configuración de este espacio situado entre los ríos Mundo y Segura la que lo ha dotado como uno de los emplazamientos más singulares a la par que desconocido, generando una gran carencia de información acerca del mismo que sin duda está quedando compensada mediante los grandes pleitos sociales que hoy ocupan un importante apartado en su historia. After the development of the mining industry in Hellin´s Mines especially in the centuries XVIII-XIX, this rural space has stayed at present totally left fruit of the bankruptcy of its exploitation. In spite of its devastating closing the mining settlement, thought very damaged, it remains nowadays enclosing vestiges of a past that managed to position to this mining zone as first national. It has been the own configuration of this space placed between the rivers Mundo and Segura the one that has endowed as one of the most singular emplacements at par that not known, generating a great lack of information brings over of the same one that undoubtedly is remaining compensated by means of the big social lawsuits that today occupy an important paragraph. Depois de desenvolver a indústria de mineração alcrebite na aldeia de Las Minas de Hellín especialmente no século XVIII, a área rural foi agora totalmente abandonada resultado da falência de sua exploração. Apesar de sua devastadora perto da cidade mineira, embora muito deteriorado, abrangendo hoje conserva vestígios de um passado que foi capaz de posicionar esta área de mineração como a primeira em todo o país. Foi a configuração do espaço entre Mundo e rios Segura que lhe forneceu um dos locais mais originais, ao mesmo tempo desconhecido, gerando uma grande falta de informação sobre o assunto, que é, certamente, ser compensado pela grandes processos sociais ocupam agora uma parte importante de sua história.

Granulite terranes from Central Spain are Hercynian anatectic areas of mid-crustal levels (P-T conditions: 750–800° C and 4–6 kb). The granulite xenolith suite of the same sector comes from the lower crust as deduced from their P-T estimates (850–950° C and 8–11 kb). Chemical differences between granulites from terranes and those from xenoliths are less marked in Central Spain than in other places as this xenolith suite lack mafic lithologies. Granulitic xenoliths show U and Rb depletion, and occasionally a subtle enrichment in Ba, Fe, Mg, Ti, (V) and HREE. Contents in Zr, Th, Y, and REE in both granulite types might be explained as a consequence of the minor role of accessory phases in controlling the geochemistry of the residual rocks in the lower crust. Migmatitic leucosomes and other felsic anatectic melts show the same trend of Rb and K enrichment and Fe, Mg, Ti, Cr, Ni, V and Th, Y, Zr, Nb, REE impoverishment (compared to protoliths) than granitic plutons. Although plutonic granites show higher Ca (Na), Fe and Mg contents a genetic link with anatectic melts is suggested. Isotopic differences (Sr, O) between granitic plutons and anatectic melts might be a reflection of their derivation from a different crustal level in an isotopically stratified crust.

Surface freshwater samples from Everglades National Park, Florida, were used to investigate the size distributions of natural dissolved organic matter (DOM) and associated fluorescence characteristics along the molecular weight continuum. Samples were fractionated using size exclusion chromatography (SEC) and characterized by spectroscopic means, in particular Excitation-Emission Matrix fluorescence modeled with parallel factor analysis (EEM-PARAFAC). Most of the eight components obtained from PARAFAC modeling were broadly distributed across the DOM molecular weight range, and the optical properties of the eight size fractions for all samples studied were quite consistent among each other. Humic-like components presented a similar distribution in all the samples, with enrichment in the middle molecular weight range. Some variability in the relative distribution of the different humic-like components was observed among the different size fractions and among samples. The protein like fluorescence, although also generally present in all fractions, was more variable but generally enriched in the highest and lowest molecular weight fractions. These observations are in agreement with the hypothesis of a supramolecular structure for DOM, and suggest that DOM fluorescence characteristics may be controlled by molecular assemblies with similar optical properties, distributed along the molecular weight continuum. This study highlights the importance of studying the molecular structure of DOM on a molecular size distribution perspective, which may have important implications in understanding the environmental dynamics such materials.

16 pages, 9 figures, 3 tables, We investigated the short-term effects of variable solar irradiance and spectrum on the gross biological production of dimethylsulfide (DMS), a trace gas with potential climatic effects, in eight experiments performed at different times of the year in a northwest Mediterranean coastal site. Experimentally determined net community DMS production, DMS photolysis, and dark microbial DMS consumption rates were used to calculate gross community DMS production by budgeting. In addition, the composition of the bacterioplankton and phytoplankton communities in the initial samples, and the photoinhibition of bulk bacterial heterotrophic activity and phytoplankton photosynthetic efficiency were monitored. Our results show that: (1) gross DMS production is irradiance dependent, with a maximum short-term stimulation factor of 2- to 6-fold compared to dark incubations; (2) its spectral shape is variable but generally similar to that of phytoplankton photoinhibition or photodamage, with more effective stimulation at shorter ultraviolet wavelengths; and (3) stronger stimulation occurs when samples are overexposed with respect to their prior exposure. Remarkably, the photoresponse of gross DMS production was in most cases strong enough to (at least) compensate the photochemical DMS loss at the water subsurface. Such response would prevent DMS depletion in stratified and highly irradiated waters. Since the initial microbial communities were representative of meso- to oligotrophic conditions, our observations should apply to a wide variety of oceanic regimes, M.G. acknowledges the receipt of a Junta de Ampliación de Estudios (JAE) scholarship from the Consejo Superior de Investigaciones Científicas (CSIC). This work was supported by the (former) Spanish Ministry of Science and Innovation through the projects ‘‘Organic matter sources, microbial diversity, and coastal marine pelagic ecosystem functioning (respiration and carbon use)’’ (MODIVUS) (Ciencias y Tecnologías Marinas-CTM2005-04795/MAR) and ‘‘Surface mixing modulation of the exposure to solar radiation’’ (SUMMER) (CTM2008-03309/MAR). This is a contribution of the Research Group on Marine Biogeochemistry and Global Change and the Research Group on Aquatic Microbial Food Webs, supported by the Generalitat de Catalunya

8 páginas, 4 figuras, 1 tabla, A harmonic analysis of three years of data collected with fortnight to monthly frequency in the oligotrophic Bay of Blanes (NW Mediterranean) revealed that the water column mixing-stratification cycle dictated the seasonal build-up of the bulk and different coloured fractions of dissolved organic matter (DOM). Dissolved organic carbon (DOC) accumulated at late summer, reaching the annual maximum by early September, half a month later than water temperature. The seasonal cycle of the protein-like fluorescence (F(280/350)) was in phase with DOC, suggesting that reduced heterotrophic activity, due to severe P limitation, is likely the reason behind the late summer accumulation of these materials. The absorption due to conjugated carbon double bonds of DOM (aCDOM(254)) reached the annual maximum by early August, concomitant to the seasonal maximum of microbial activity, suggesting that biological production prevailed over photo-degradation of these compounds. On the contrary, the fluorescence of humic-like substances absorbing in the UV-A region (F(340/440)) presented the annual maximum in early February, coinciding with the seasonal maximum of autotrophic biomass, and the minimum in early August, because of the prevalence of photo-degradation over microbial production. The optical properties of DOM allowed distinguishing between three DOC pools of contrasting origin, photo- and bio-reactivity, in the oligotrophic NW Mediterranean Sea., This study was funded by an I3P-predoctoral fellowship to C.R.-C. from the Consejo Superior de Investigaciones Científicas (CSIC) within the projects: MODIVUS (CTM2005-04795/MAR), SUMMER (CTM2008-03309/MAR) and STORM (CTM2009-09352).

15 pages, 6 figures, 4 tables, Bacterial community activity and structure are thought to be directly or indirectly related to phytoplankton development and, in particular, to the phytoplankton species dominating specific algal blooms. To test this hypothesis, we performed a mesocosm experiment designed to generate blooms of different types of phytoplankton through the additions of silicate, urea and phosphorus to oligotrophic water from the Blanes Bay Microbial Observatory (NW Mediterranean). Over 10 d of incubation bacterial activity, bacterial abundance, nutrient composition and free-living bacterial community structure were monitored, as well as phytoplankton composition and the fluorescence characteristics of dissolved organic matter (DOM). While we found clear effects of the different nutrient additions on chlorophyll levels, bacterial production and the type of dominant DOM, bacterial abundance followed a similar pattern across different nutrient treatments, which deviated from that observed in the control. While phytoplankton composition in the treatment with added silicate evolved differently with respect to the other treatments, free-living bacterial community structure (as determined with DGGE) did not show conspicuous differences between treatments. Our results reveal that the changes in bacterial community composition were mostly due to the variation in grazing pressure with time, with a small contribution from changes in bottom-up nutrient supply mediated by the shifts in phytoplankton composition, This work was supported by the NoE Marine Genomics Europe and MARBEF, and by the Spanish projects MODIVUS (CTM2005-04795/MAR) and STORM (CTM2009-09352/MAR). We thank V. Balagué, I. Forn and everyone participating in the Blanes Bay sampling program, particularly M. Sala, F. Not, E. Vázquez-Domínguez, E.L. Sà and C. Rodríguez for various help. The students of the ‘Marine Genomics Europe Summer Course on Plankton Bloom Dynamics’ also provided feedback, and we particularly thank F. Gómez for a first appraisal of phytoplankton diversity

An understanding of the distribution of colored dissolved organic matter (CDOM) in the oceans and its role in the global carbon cycle requires a better knowledge of the colored materials produced and consumed by marine phytoplankton and bacteria. In this work, we examined the net uptake and release of CDOM by a natural bacterial community growing on DOM derived from four phytoplankton species cultured under axenic conditions. Fluorescent humic-like substances exuded by phytoplankton (excitation/emission [Ex/Em] wavelength, 310 nm/392 nm; Coble's peak M) were utilized by bacteria in different proportions depending on the phytoplankton species of origin. Furthermore, bacteria produced humic-like substances that fluoresce at an Ex/Em wavelength of 340 nm/440 nm (Coble's peak C). Differences were also observed in the Ex/Em wavelengths of the protein-like materials (Coble's peak T) produced by phytoplankton and bacteria. The induced fluorescent emission of CDOM produced by prokaryotes was an order of magnitude higher than that of CDOM produced by eukaryotes. We have also examined the final compositions of the bacterial communities growing on the exudates, which differed markedly depending on the phytoplankton species of origin. Alteromonas and Roseobacter were dominant during all the incubations on Chaetoceros sp. and Prorocentrum minimum exudates, respectively. Alteromonas was the dominant group growing on Skeletonema costatum exudates during the exponential growth phase, but it was replaced by Roseobacter afterwards. On Micromonas pusilla exudates, Roseobacter was replaced by Bacteroidetes after the exponential growth phase. Our work shows that fluorescence excitation-emission matrices of CDOM can be a helpful tool for the identification of microbial sources of DOM in the marine environment, but further studies are necessary to explore the association of particular bacterial groups with specific fluorophores, This work was supported by project SUMMER, grant number CTM2008–03309/MAR, C.R.-C. was funded by a I3P-CSIC predoctoral fellowship within the project MODIVUS, CTM2005-04795/MAR and H.S. benefited from fellowships from the Spanish ‘Ministerio de Educación y Ciencia’ (SB2006-0060 and JCI-2008-2727) and Portuguese ‘Fundação para a Ciência e a Tecnologia’ (FRH/BPD/34041/2006).

Original research paper, The optical properties of coloured dissolved organic matter (CDOM) – absorption coefficient, induced fluorescence, and fluorescence quantum yield – were determined in the coastal eutrophic system of the Ría de Vigo (NW Spain) under two contrasting situations: a downwelling event in September 2006 and an upwelling event in June 2007. Significantly different optical properties were recorded in the shelf surface (higher absorption coefficient and lower quantum yield) and bottom (lower absorption coefficient and higher quantum yield) waters that entered the embayment during downwelling and upwelling conditions, respectively. Continental waters presented distinctly high CDOM levels. The spatial and temporal variability of the induced fluorescence to absorption coefficient ratio during the mixing of shelf and continental waters was used to quantify the relative importance of photochemical and microbial processes under these contrasting hydrographic conditions. Photochemical processes were dominant during the downwelling episode: 86% of the variability of CDOM can be explained by photochemical degradation. On the contrary, microbial processes prevailed during the upwelling event: 77% of the total variability of CDOM was explained by microbial respiration., The Xunta de Galicia, grant number PGIDIT-05MA40201PR; the project SUMMER, grant number CTM2008-03309/MAR; a I3P-CSIC predoctoral fellowship and a Marie Curie I.O.F., 2,751

9 pages, 3 figures, 3 tables, Incubation experiments with axenic cultures of four common phytoplankton species of the genera Chaetoceros, Skeletonema, Prorocentrum, and Micromonas were performed to test for the production of fluorescent dissolved organic matter (FDOM) by marine phytoplankton. Our results prove that the four species exuded both fluorescent protein-like and marine humic–like materials in variable amounts, with more production by the diatoms Chaetoceros sp. and Skeletonema costatum and less by Prorocentrum minimum. Whereas the exudation of protein-like substances by healthy phytoplankton cells has been recognized, the in situ production of marine humic-like substances is still a matter of debate. Using axenic cultures, we demonstrate unequivocally that phytoplankton can directly contribute to the autochthonous production of colored humic-like substances in the ocean. Extrapolation of these findings to the field indicates that about 20% of the marine humic–like substances produced in the highly productive coastal upwelling system of the Rıa de Vigo could originate from growing phytoplankton. Therefore, the exudation of FDOM by marine phytoplankton should be considered in future studies of the dynamics of colored DOM in marine systems, This study was funded by an I3P-predoctoral fellowship to C.R.-C. from the Consejo Superior de Investigaciones Cientıficas (CSIC) within the project "Organic matter sources, microbial diversity, and coastal marine pelagic ecosystem functioning (respiration and carbon use)" (MODIVUS, CTM2005-04795/MAR). H.S. benefitted from fellowships from the Spanish Ministerio de Educación y Ciencia (SB2006-0060 and JCI-2008-2727) and the Portuguese Fundaçao para a Ciência e a Tecnologıa (FRH/BPD/34041/2006)

U–Pb SHRIMP ages obtained in zircons from the Sotosalbos and Toledo anatectic complexes in Central Spain give new constraints to the evolution of the inner part of the Hercynian Iberian belt. Pre- Hercynian ages in zircons from the Sotosalbos complex (~464 Ma) are well preserved and reveal that an age diversity of the Lower Paleozoic magmatism in the area exists, as previous data on westernmost orthogneisses yield significant older ages. Zircon ages in the pelite-derived granites from the Toledo complex also show an important Neoproterozoic age component which points to a metasedimentary protolith deposited maximally 560 Ma ago. Younger zircon populations in both complexes at ~330 Ma in the Sotosalbos region and ~317 Ma in the Toledo complex indicate an important diachronism between the anatectic processes in both areas but also that these processes are mainly unrelated to the generation of the later Hercynian granite batholith of Central Spain, which could be of deeper crustal derivation. In addition, as migmatization occurred late in the metamorphic cycle, after peak conditions were attained, the age of anatexis is younger than the age of the main Hercynian metamorphic event, which still is not well constrained.