Transformación reciente de ambientes intermareales bajo un escenario de ascenso del nivel marino: ejemplos del norte de España

The transformation of two intertidal environments from northern Spain during the last 150 years shows an evolution from a tidal flat into a salt marsh environment, wit han intermediate transitional stage. The environment of deposition was reconstructed based on benthic foraminifera and sand content. Sediments were put into a temporal framework using short-lived radioisotope activities and heavy metal concentrations. The observed natural evolution responds to the availability of abundant sediment and the current sea-level rise scenario, where intertidal environments are trying to adapt to increasing flooding periods by accreting sediment rapidlyLa transformación de dos ambientes intermareales en el norte de España durante los últimos 150 años muestra la evolución desde una llanura intermareal a una marisma, con una etapa de transición intermedia. El paleoambiente se reconstruyó mediante el contenido en foraminíferos bentónicos y en arena. Los sedimentos fueron datados utilizando radioisótopos de vida corta y concentraciones de metales pesados. La evolución natural observada responde a la disponibilidad de abundante sedimento y al escenario actual de ascenso en el nivel del mar, donde los ambientes intermareales están tratando de adaptarse a los crecientes períodos de inundación acrecionando sedimento rápidament

Antropozenoa: "Urre koloreko iltze"-aren bila

Antropozeno hitzak, gizakia, Holozeno Epokaren aurreko dinamika naturalak aldatzeko gai eta indar geologiko erabakigarri bihurtu den denbora tarte geologikoari egiten dio erreferentzia. 2009az geroztik, Antropozenoko lantaldea Antropozenoa ikuspegi geologikotik definitzen zentratu da, Estratigrafiari buruzko Nazioarteko Batzordeak ezarritako arauak jarraituz eta, hortaz, zer unitate kronoestratigrafikoa, beheko mugaren adina eta haren markatzaile estratigrafiko nagusiak adierazten dituzten proposamenak eginez. Erradionuklido artifizialek (137Cs, 241Am, 239Pu, 240Pu) potentzial handia eskaintzen dutela dirudi, ingurunean sinkronikoki agertzen direlako 1950 inguruko “Great Acceleration” prozesuaren ondorioz. Hala eta guztiz ere, oraindik azterketa sakonagoak behar dira denbora geologiko hau formalizatzeko behar diren irizpide estratigrafiko guztiak betetzen dituen GSSP egokia aurkitzeko. Lan honen helburua Antropozenoko lantaldearen jarduera, Antropozeno kontzeptua egituratzen duten eztabaida-elementu nagusiak eta orain arte lortutako ondorio nagusiak laburbiltzea da.; The term Anthropocene refers to the geological time interval in which humans have become a significant geological force capable of altering the previous relatively stable natural dynamics of the Holocene Epoch. Since 2009 the Anthropocene Working Group has been focused on defining the Anthropocene from a geological point of view, following the standards established by the International Commission on Stratigraphy and, thus, proposing what type of chronostratigraphic unit it represents, the age of the lower boundary and its main stratigraphic indicators. Artificial radionuclides (137Cs, 241Am, 239Pu, 240Pu) appear to offer great potential owing to their synchronous onset in the environment, coinciding approximately with the “Great Acceleration” of about 1950. However, more in-depth studies are still needed to find the appropriate GSSP that meets all the necessary stratigraphic criteria to formalize this geological time. This work is intended to summarize the activity of the Anthropocene Working Group, the main elements of discussion that vertebrate the Anthropocene concept and the main conclusions reached so far

Antropozenoa: Lurraren historiako pasarte berria?

Anthropocene is a geological informal term used to signal the time interval in which human activities have exherted a global impact on Earth dynamics. Its definiti on as a formal geochrono logical unit requires to determine the start date and to establish suitable strati graphic markers . ln this work, some sc ientific considerations which may help to define the Anthropocene are presented.; "Antropozenoa" esaten zaio informalki giza jarduerek Lurreko dinamikari eskala orokorrean eragin dioten denbora tarteari. Unitate geokronologiko formal modura onartua izateko, bere hasiera finkatzeaz gain markatza ile estratigrafiko egokiak ze haztu beharra dago. Lan honek Antropozenoa definitzeko lagungarri ak izan daitezkeen hainbat iritzi zientifiko biltzen ditu

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

ABSTRACT: 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.RESUMO: 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.info:eu-repo/semantics/publishedVersio

Coastal salt-marshes as geological archives of recent sea-level changes

In order to evaluate the accuracy and regional significance of salt-marsh reconstructions of former sea level based on foraminiferal transfer functions, we have calibrated the foraminiferal assemblages of a saltmarsh core from the Urdaibai estuary using the regional transfer function constructed previously for the southern Bay of Biscay. The foraminifera-based reconstructions were placed into a temporal framework using Pb-210, heavy metal concentrations, and Cs-137-derived sediment accumulation rates. The resulting relative sea-level curve has been compared with the nearest tide-gauge data (Santander) and with other geological records from regional salt-marshes. Relative sea-level trends from core sediments support in all cases the idea of accelerating sea levels over the last century when compared to previous centuries, providing a regional relative sea-level rise of 2.0 mm yr-1 for the 20th centur

Antropozenoa: Lurraren historiako pasarte berria?

Anthropocene is a geological informal term used to signal the time interval in which human activities have exherted a global impact on Earth dynamics. Its definiti on as a formal geochrono logical unit requires to determine the start date and to establish suitable strati graphic markers . ln this work, some sc ientific considerations which may help to define the Anthropocene are presented.; "Antropozenoa" esaten zaio informalki giza jarduerek Lurreko dinamikari eskala orokorrean eragin dioten denbora tarteari. Unitate geokronologiko formal modura onartua izateko, bere hasiera finkatzeaz gain markatza ile estratigrafiko egokiak ze haztu beharra dago. Lan honek Antropozenoa definitzeko lagungarri ak izan daitezkeen hainbat iritzi zientifiko biltzen ditu

Holocene sea-level database from the Atlantic coast of Europe

International audienceWe have developed a Holocene relative sea-level (RSL) database for the Atlantic coast of Europe (ACE). We estimated rates of RSL change from the ACE database using a spatiotemporal empirical hierarchical model. The database contains 214 index points, which precisely locate the RSL position in space and time, and 126 limiting dates, which can constrain RSL to above or below a certain elevation. The temporal distribution extends to ∼9 ka BP, with only 20% index points older than 7 ka BP. The spatial distribution spans 1700 km from French Flanders (France) to Algarve (Portugal), but more than 50% of the index points are from the French coast. We subdivided the database into 13 regions based on distance from the British-Irish and Fennoscandian Ice Sheets. The ACE database shows RSL was below present during the Holocene. Rates of RSL change were highest during the early Holocene and have decreased over time, due, primarily, to the diminishing rate of glacial isostatic adjustment and reduction of meltwater input. For example, in the Coast of Vendée (France), where there are 32 index points, RSL was-14.0 ± 0.8 m at 9 ka BP and rose to-1.1 ± 0.4 at 4 ka BP. The rate of RSL rise decreases from 1.7 ± 0.4 mm/yr between 8 ka BP and 4 ka BP to 0.5 ± 0.4 mm/yr, after 4 ka BP. Comparison of the data to output from a glacial isostatic adjustment model indicates that deglaciation of the British-Irish and Fennoscandian Ice Sheets dominate the large-scale variability captured by the ACE database. The maximum rate of late Holocene RSL rise occurred in West Brittany (Northwest France) with rates of 0.9 ± 0.4 mm/yr. The rate of rise decreased from the Northwest to Southeast ACE coastline, which reflects the increasing distance from the former ice sheets, and reflects a decreasing influence of the collapsing peripheral forebulge

Holocene environmental evolution and relative sea-level change in the Oka estuary (Urdaibai Biosphere Reserve, northern Spain)

The Holocene environmental evolution in coastal areas, including deltas and estuaries, is vital to understanding coastal dynamics and how they may change in the future. Here, we studied the Holocene environmental evolution of the Oka estuary (Urdaibai Biosphere Reserve, northern Spain) from sedimentary cores that were 11–49 m long. We applied a multi-proxy approach of benthic foraminifera and grain size, and a temporal framework of radiocarbon dates to reconstruct paleoenvironments. The benthic foraminifera assemblages varied from near-marine (allochthonous and autochthonous hyaline species such as Lobatula lobatula, Rosalina irregularis, Ammonia tepida and Haynesina germanica) to brackish intertidal (autochthonous hyaline species such as A. tepida and H. germanica) to salt-marsh (autochthonous agglutinated species Trochammina inflata and Entzia macrescens) environments. Grain size analysis supported the foraminiferal assemblages and the sedimentary sequences were sand-dominated in near-marine intertidal environments and mud-dominated in the brackish intertidal and salt-marsh environments. The chronology was constrained by thirty four radiocarbon dates from plant macrofossils, marine shells and wood fragments. Our paleoenvironmental reconstructions were used to produce an updated local Holocene relative sea-level (RSL) record based on new data, revised reconstructions, and age recalibration of previous research. Marine limiting dates showed that RSL changed from above −20.4 ± 0.2 m at ∼9100 cal. yrs. BP to above −4.2 ± 0.2 m at ∼6700 cal. yrs. BP. In the late Holocene, sea-level index points (SLIPs) reconstructed the RSL position from −2.7 ± 1.2 m at ∼4900 cal. yrs. BP to −1.4 ± 1.2 m at ∼1500 cal. yrs. BP. Estimates of rates of RSL change from the Errors-in-Variables Integrated Gaussian Process (EIV-IGP) model show RSL gradually rose at 0.3 ± 2.1 mm yr−1 in the late Holocene. There was a progressive shallowing of the estuary as rates of RSL rise reduced during the Holocene. Between ∼9000 and 7000-6000 cal. yrs. BP pre-Holocene fluvial gravels (Lowstand Systems Tract) were replaced by both sandy marine and brackish intertidal sediments (Transgressive Systems Tract). After ∼7000-6000 cal. yrs. BP salt-marsh sediments deposited (Highstand Systems Tract). The sequence was overlain by anthropogenic deposits derived from agricultural, dredging and dumping activities since the 18th century (Anthropogenic Systems Tract). The Holocene environmental evolution and relative sea-level change of Oka is broadly consistent with previous studies in northern Spain, although it places the onset of the Highstand Systems Tract ∼2000 years earlier.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThis research was funded through the years by the projects UNESCO04/05, UNESCO06/08, Harea-Coastal Geology Group (Basque Government, IT332-07, IT365-10, IT767-13, IT976-16 and IT1616-22), TANYA (MICINN, CGL2009-08840), K-Egokitzen II (Basque Govern- ment, Climate Change: Impact and Adaptation, Etortek 2010), Antro- picosta (MINECO, CGL2013-41083-P), Antropicosta-2 (RTI2018- 095678-B-C21, MCIN/AEI/10.13039/501100011033 and ERDF A way of making Europe and European Union) and UFI11/09 (UPV/EHU). BPH and TL are supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE-T2EP50120-0007, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centers of Excellence initiative