Recent anthropogenic transformation of the Pasaia bay (Guipuzcoa, N. Spain): multiproxy analysis of its sedimentary record

El registro sedimentario reciente en la bahía de Pasaia ha sido estudiado mediante 3 sondeos submareales. Los testigos muestran un sedimento de grano fino, unos valores muy elevados de contaminantes metálicos y una presencia muy escasa de microfauna, sugiriendo malas condiciones ambientales que han sido persistentes durante al menos las últimas 6 décadas. Estas circunstancias son decisivas para desarrollar una adecuada gestión de este medio estuarino.The recent sedimentary record of the Pasaia bay has been analysed using 3 subtidal cores. These contain fine-grained sediments, very high metallic pollutants and very scarce microfauna. They are indicative of negative environmental conditions that have been persistent in this area at least during the last 6 decades. These characteristics are decisive in order to perform an adequate management of this estuarine setting.Trabajo financiado por los proyectos Antropicosta (CGL2013-41083-P), Harea-Grupo de Investigación en Geología Litoral (GV, IT976-16) y Unidad de Formación e Investigación en Cuaternario (UPV/EHU,UFI11/09)

Sedimentation rate and contamination levels profile of potentially toxic elements in the Limoncocha lagoon RAMSAR wetland in the Ecuadorian Amazon

The aim of this study is to analyze the recent sedimentation rate in the center of the Limoncocha lagoon, a Ramsar site in the Ecuadorian Amazon, using the 210Pb dating method and identifying the potentially toxic elements along a 50 cm sediment core. A strategy based on the application of three single and four integrated indices is used to evaluate trace element contamination with depth. Single indices show mainly As and Mo, and Cu, Ba, Cd, Ni, and Pb to a lesser extent, as responsible elements of a minor enrichment between −10 and −40 cm. The multielement slight pollution shows a mixture of potential contamination sources, probably due to agricultural, oil activities, and urban wastewater discharges. However, integrated indices applied, classify the complete core as without potential risk. The 210Pbexcess profile shows three differentiated sections. A surface section where new materials with lower concentrations have been found, probably due to the underground currents that connect the lagoon and the nearby Napo River; a central section where CF-CS model and mass accumulation rate calculations provide a sediment accumulation rate of 0.56 ± 0.03 cm y−1; finally, a deeper section with a constant 210Pbexces profile, showing sediment reworking probably due to local flooding’s

Estudio del impacto humano en una Reserva Natural: las Marismas de Santoña (Cantabria, España)

ABSTRACT: The Santoña Marshes Nature Reserve is one of the most important ecosystems of the Spanish Cantabrian coast due to its ecological value as a wintering area for migratory birds. Since an increase in population and substantial changes in the use of land have been observed in this area during the last century, the aim of this work was to attempt to see if anthropogenic activities are recorded in the accumulating sediments. Two sediment cores (50 cm length) were collected for isotopic dating (210Pb and 137Cs) and geochemical study (heavy metals). The data indicate an increasing trend in sedimentation rates during the last century, probably related to the progressive loss of the estuarine domains and the changes in their original hydrodynamic conditions due to infilling and the construction of dykes. However, no significant anthropogenic inputs of heavy metals have been detected in recent times.RESUMEN: La Reserva Natural de las Marismas de Santoña, situada en la costa cantábrica, posee un gran valor ecológico como lugar de invernada de aves migratorias. Dado el importante aumento de la presencia humana en la zona durante el último siglo, este trabajo tiene como objetivo estudiar si estas actividades antrópicas han dejado su huella en los sedimentos acumulados. Para ello se ha abordado la datación isotópica (137Cs y 210Pb) y el estudio geoquímico (metales pesados) de dos sondeos de 50 cm de longitud. Los resultados obtenidos señalan la existencia de un importante incremento en las tasas de sedimentación durante el ultimo siglo, posiblemente relacionado con la pérdida progresiva de la superficie y de las dinámicas estuarinas como consecuencia de los rellenos y de la construcción de diques. Sin embargo, no se han detectado niveles significativos de contaminación en metales pesados en los sedimentos más recientes

Environmental evolution of the Deba estuary (Basque Coast Geopark) during the Holocene and Anthropocene

RESUMEN: Se han estudiado las asociaciones de foraminíferos de dos sondeos largos y uno corto en el estuario del Deba con el fin de realizar la interpretación ambiental de su registro sedimentario. Adicionalmente, se han llevado a cabo análisis geoquímicos en el sondeo corto, y análisis microfaunísticos y geoquímicos en ocho muestras superficiales tomadas a lo largo del estuario. Los resultados han permitido la reconstrucción de sus ambientes sedimentarios durante el Holoceno y el Antropoceno. El registro holoceno está principalmente controlado por el ascenso relativo del nivel marino, mientras que las muestras superficiales y el sondeo corto muestran la influencia antropogénica en los sedimentos más recientes.ABSTRACT: Benthic foraminiferal assemblages of two long boreholes and one short core drilled in the Deba estuary were studied for environmental interpretation of its sedimentary record. Additional geochemical analyses in the short core, together with the microfaunal and geochemical analysis of eight surface samples along the estuary were also performed. The results allow for the reconstruction of the Deba estuary environment during the Holocene and Anthropocene. The Holocene record is mainly controlled by the relative sea-level rise, whereas the surface samples and the short core exhibit human influence in the most recent sediments.Trabajo financiado por los proyectos Antropicosta (CGL2013-41083-P), Harea-Grupo de Investigación en Geología Litoral (IT976-16) y Estuarios del Geoparque de la Costa Vasca (US13/02). Francisco Fatela (Universidade de Lisboa) y un/a revisor/a anónimo/a mejoraron la versión original de este trabajo con sus indicaciones. Contribución nº 49 de la Unidad de Investigación Geo-Q Zentroa (Laboratorio Joaquín Gómez de Llarena). N. El Bani Altuna ha estado financiada por la beca no. 223259 para Centros de Excelencia del Consejo de Investigación Noruego

Recent sediments dating using short-lived radionuclides

Se presentan las características principales del método de datación de sedimentos recientes mediante el radioisótopo natural ²¹⁰Pb y su validación utilizando radionucleidos artificiales tales como ¹³⁷Cs y ²³⁹,²⁴⁰Pu. Se hace una revisión de los principios generales de esta metodología, se aportan recomendaciones prácticas para la recogida de testigos sedimentarios en el campo y su posterior procesamiento en el laboratorio, se describen diferentes técnicas analíticas utilizadas en la determinación de sus concentraciones y se explican brevemente varios modelos para la interpretación de los perfiles obtenidos. Por último, se incluyen ejemplos prácticos de su aplicación en secuencias sedimentarias procedentes de distintos ambientes marinos (estuario, bahía y plataforma continental) en el norte de la Península Ibérica.The main characteristics of the dating method of recent sediments using the natural radioisotope ²¹⁰Pb and its validation with artificial radionuclides such as ¹³⁷Cs and ²³⁹,²⁴⁰Pu are presented. A review of the general principles of this methodology is made, practical recommendations for the collection of sedimentary cores in the field and their subsequent processing in the laboratory are provided, several analytical techniques used to measure their concentrations are described and several models for the interpretation of the profiles are briefly explained. Finally, practical examples of its application in sedimentary sequences from different marine environments (estuary, bay and continental shelf) in the northern Iberian Peninsula are also included.Agradecimientos: Este artículo se ha inspirado en el manual de referencia publicado por Sanchez-Cabeza, J.A., Díaz-Asencio, M., Ruiz-Fernández, A.C., eds. (2012). Radiocronología de sedimentos costeros utilizando 210Pb: Modelos, Validación y Aplicaciones. Organismo Internacional de Energía Atómica, Viena, 105 pp., donde se profundizan diferentes aspectos tratados aquí. Trabajo financiado por los proyectos RTI2018-095678-B-C21, MCIU/AEI/FEDER, UE (MINECO) e IT976-16 (EJ/GV). Dos revisoras/es anónimas/os mejoraron el manuscrito original con sus comentarios y sugerencias. Contribución nº 56 de la Unidad de Investigación Geo-Q Zentroa (Laboratorio Joaquín Gómez de Llarena)

Holocene vs Anthropocene sedimentary records in a human-altered estuary: The Pasaia case (northern Spain)

This work deals with the microfaunal (benthic foraminifera) and geochemical (trace metals, 14C, 210Pb, 137Cs, and 239/240Pu) study of two boreholes (1200 and 1400 cm length) and three subtidal sediment cores (38?58 cm length) collected in the Pasaia estuary (northern Spain). Foraminiferal assemblages in the Holocene deposits depend on the paleogeographic setting, while different species appear in the Anthropocene sediments as a consequence of the physical transformation of the estuary into an estuarine port. Regarding the geochemical composition, the impact of ancient mining activities (probably of Roman age) can be recognized in the form of peaked values of Pb and Zn. However, older sediments exhibit relatively low contents of trace metals which are conditioned by hydrodynamic patterns and lithogenic inputs. In the Anthropocene record, the influence of these factors is displaced by the decisive role of human activities, as evidenced by the enhanced concentrations of trace metals and the occurrence of artificial radioisotopes and glass microspheres. Additionally, this work provides information about trace metal contamination that may be of interest to corresponding authorities in order to set priorities of action and to take specific measures to prevent further degradation.This research was funded by Spanish MINECO (CGL2009-08840, CGL2013-41083-P and RTI2018-095678-B-C21, MCIU/AEI/FEDER, UE), EJ/GV (IT365-10, IT767-13 and IT976-16) and UPV/EHU (UFI11/09) projects. The P9 borehole was kindly provided by Juan Pamo (TerraNova s.l.). Borehole and core samples were prepared initially by Iván A. Pérez Herrera and Ainhoa Maguregui respectively, and Aintzane Goffard analysed a few samples of core PAS2. Marina Sáez-Muñoz and Josefina Ortiz (Universitat Politècnica de València) carried out the 239+240Pu determinations. Cores were X-radiographed at the Basurto Hospital, Bilbao (Radiodiagnostic Service) thanks to Dr. Txomin Grande, Eva M. Gallo, Esther Luz and Arkaitz Arteaga. Two anonymous reviewers improved the original manuscript with their comments and constructive suggestions. It is contribution 54 of the Geo-Q Zentroa Research Unit (Joaquín Gómez de Llarena Laboratory)

Recent coastal anthropogenic impact recorded in the Basque mud patch (southern Bay of Biscay shelf)

The historical anthropogenic impact on sediments from the Basque Mud Patch (southern Bay of Biscay) is explored using a multidisciplinary approach including the analysis of natural (210Pb) and artificial (137Cs, 239/240Pu) radiotracers, major elements (Al, Mn), metals (Zn, Pb, Cu, Cr), Pb isotopic ratios, and foraminiferal and pollen contents. The study of three short cores (19?46 cm), despite being hindered by the effects of biomixing, allow the calculation of a sedimentation rate of 1 ± 0.1 mm yr?1. Distribution with depth of Al-normalised concentrations of metals reflects an increasing trend since 1880 CE, related to the industrialization of the Basque coastal area. According to the Sediment Quality Guidelines applied, contents of Zn and Pb appear as a potential cause of concern, given that they exceed the values from which adverse biological effects can be occasionally expected. However, foraminiferal assemblages do not show recognizable changes along the cores following increasing trace metal concentrations. Finally, pollen results reveal an increasing trend of coniferous taxa and a parallel reduction of authochthonous Deciduous Quercus, probably as a consequence of reforestation works. Data obtained confirm that effects of coastal anthropogenic activities extend to the adjacent shelf, where muddy deposits are likely to act as a trap for contaminants.All samples were kindly provided by Dr Ana Pascual (UPV/EHU).Aintzane Goffard (UPV/EHU) prepared samples and produced for-aminiferal results from core KI-06. This research was funded by SpanishMINECO (CGL2013-41083-P and RTI2018-095678-B-C21, MCIU/AEI/FEDER, UE), UPV/EHU (UFI11/09) and EJ/GV (IT976-16) projects.Aitor Fernández Martín-Consuegra was supported by a predoctoralgrant from the Basque Government (PRE_2017_1_0173). The authorsthank technical and human support provided by SGIker ( UPV/EHU/ERDT, EU). Two anonymous reviewers improved the original manu-script with their comments and constructive suggestions. This is con-tribution 53 of the Geo-Q Zentroa Research Unit (Joaquín Gómez deLlarena Laboratory)

Changes in recent benthic foraminiferal assemblages of the Nalón estuary (Asturias)

Se ha analizado el registro sedimentario reciente del estuario del Nalón a partir de dos sondeos intermareales que han sido datados mediante 210Pb y 137Cs. Los resultados muestran por primera vez sus asociaciones características de foraminíferos bentónicos, constituidas por un total de 46 especies, así como los importantes cambios experimentados por estas asociaciones, en consonancia con las variaciones en el magnetismo ambiental, como consecuencia, posiblemente, de las actividades mineras desde 1850 CE que sugieren unas condiciones ambientales deterioradas. Estas malas condiciones persistieron durante décadas, incluso más allá del cese de la minería de mercurio y carbón, hasta el siglo XXI cuando se ha comenzado a observar una leve recuperación ambiental.The recent sedimentary record of the Nalón estuary was analysed using two intertidal cores and dated by 210Pb and 137Cs. The results show for the first time its characteristic benthic foraminiferal assemblages constituted by a total of 46 species, as well as the important changes experienced by these assemblages, in agreement with the environmental magnetism variations, probably due to mining activities since 1850 CE that suggest degraded environmental conditions. These characteristics persisted for decades, even beyond the closure of the coal and mercury mining activities, until the 21st century, when a slight environmental regeneration process has been observed

Transformação ambiental de um estuário industrializado no século XIX: o registo sedimentar de Avilés (Asturias, N Espanha)

The Avilés estuary is one of the most important industrial ports in northern Spain, whose natural characteristics have been largely altered since the 1830s. Here, the environmental transformation of this estuary during the 19th century is explored using a multi-proxy approach including benthic foraminiferal content, sedimentology (grain-size), trace metals and short-lived radionuclides (210Pb and 137Cs) analysed from a 50-cm-long sediment core and a surface sample collected from the middle part of the estuary in the Pedro Menéndez Channel. The obtained results provide evidence that indicate an evolution from a naturally-driven environment with high a marine influence towards a more restricted setting under brackish conditions. The observed environmental change is interpreted as being mostly derived from physical modifications linked to the marsh reclamation and channelling starting in 1833 and intensified since 1860. This study provides a preindustrial environmental reference framework for future studies in coastal areas of the NW Atlantic Iberian margin.O estuário de Avilés é um dos portos industriais mais importantes do norte de Espanha, cujas características naturais foram bastante alteradas desde 1830. A transformação ambiental deste estuário durante o século XIX é estudada usando uma abordagem multi-proxy incluindo foraminíferos bentónicos, sedimentologia (dimensão do grão), metais traço e radionuclídeos de vida curta (210Pb e 137Cs) analisados a partir de sedimento de um testemunho de sondagem com 50 cm de comprimento e uma amostra recolhida à superfície na parte média do estuário do Canal de Pedro Menéndez. Os resultados obtidos fornecem evidências que indicam evolução de um ambiente com elevada influência marinha para um ambiente mais restrito em condições salobras. A alteração ambiental observada é interpretada como resultado de modificações físicas ligadas à recuperação e canalização de pântanos a partir de 1833, e intensificada desde 1860. Este estudo fornece um exemplo de referência ambiental pré-industrial para estudos futuros em áreas costeiras da margem NW Ibérica do Atlântico.Acknowledgements: This research was funded by the projects “ANTROPICOSTA-2: Anthropocene sedimentary record of the coastal and marine areas of Northern Atlantic Iberia” (RTI2018-095678-B-C21 (MCIU/AEI/FEDER, UE)) and Harea-Geología Litoral (IT976-16). Jon Gardoki was supported by a predoctoral grant from the Basque Government (PRE_2020_1_0035). Lígia Castro (Universidade Nova de Lisboa) and one anonymous reviewer improved the original manuscript with their comments and suggestions. It is contribution 55 of the Geo-Q Zentroa Research Unit (Joaquín Gómez de Llarena Laboratory)