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

Contribution of carbonate precipitation to the preservation of ripples in siliciclastic sediments colonized by microorganisms.

The present study traces a carbonate lamination in microbial mats in a siliciclastic coastal environment. The aim of this paper is to determine how physicochemical and biological processes influence the preservation of sedimentary structures such as ripple marks, covering it by carbonate precipitation. Such precipitation is a combination of the activity of microorganisms, and physicochemical factors. Biological factors, such as photosynthesis, composition and activity of the microbial community, and presence of exopolymeric substances (EPS), play a significant role in coastal environments, while high-energy hydrodynamic events supply seawater, providing calcium and carbonate ions, and trigger events like sediment transport, deposition, and erosion. The combination of these hydrodynamic events with the microbial activity creates physical sedimentary structures, such as ripple marks, which can be biostabilized. The study was conducted in Paso Seco (40°38’40´´S; 62°12´22´´W), a modern coastal flat within an elongated semi-closed basin colonized by microbial mats and categorized as a supratidal zone. Water samples were taken from different ponds within the flat with different degrees of evaporation, and in a tidal creek for hydrochemical analyses. Seawater level fluctuations were measured in the tidal flat over a 10-month period in 2018 using a HOBO water level logger. Ripple field formation over the tidal flat was documented after the occurrence of a strong storm and was monitored throughout three subsequent field trips, and sedimentary samples were taken in a field trip. Petrographic studies show a laterally continuous dense micritic calcite layer, 100–200 µm in thickness, covering the ripple structure, improving the preservation of these bedforms. The presence of microorganisms in the sedimentary environment enables the stabilization of ripple marks because their motility and abundant EPS secretion bind the sediment grains and generate an organic layer that protects them from erosion. On the other hand, the presence of microbial mats contributes to the early preservation of the ripples because they create the adequate conditions for carbonate precipitation. Our observations of modern sedimentary structures and the in situ study of their evolution and early lithification may provide an indicator of microbial colonization and stabilization of ripples in the paleoenvironmental reconstruction

What a mix! Volatile organic compounds and worker exposure in small business beauty salons in Tucson, Arizona

IntroductionSmall business beauty salons have volatile organic compounds (VOCs) in their workplace air. VOCs are present as ingredients in beauty or hair products. They may also form because of chemical reactions, where thermal-styling elements accelerate the volatilization of these compounds. Uncertainties remain about the relationship between air pollutant concentrations and the variety of beauty salon activities in a work shift. Investigating these associations can help determine high-risk services, associated products, and at-risk workers.MethodsIn this exploratory study, female community health workers recruited beauty salons from target zip codes in predominately Latino neighborhoods, including primarily Spanish-speaking small businesses. We collected salon chemical inventories, business characteristics, and participant activity logs to understand how chemicals and activities influence the total and specific VOC concentrations. We sampled personal total VOCs and specific VOCs from the same shop during the participant work shift. We also measured personal total VOCs for four work shifts per shop.ResultsA linear mixed effects model of log VOCs on the fixed effect of activity and the random effects of salon and shift within the salon showed that the variance between salons explains over half (55%) of the total variance and is 4.1 times bigger than for shifts within salons. Summa canisters detected 31 specific VOCs, and hazard scores ranged between 0 and 4.3. 2-Propanol (isopropyl alcohol) was the only VOC detected in all shifts of all salons.DiscussionIn this study, differences in VOC measurements were primarily between salons. These differences may result from differences in ventilation, services rendered, and product lines applied

Global wealth disparities drive adherence to COVID-safe pathways in head and neck cancer surgery

Peer reviewe

Modification of large microbial mat deformation structures before burial: A modern case study

The presence of microorganisms gives remarkable plasticity and flexibility to wet sediments. Under these circumstances, a coherent microbial mat is developed, which is loosely attached to the underlying sediment layer. These thick microbial mats are capable of being lifted from the underlying sediments in response to high-energy events, such as currents and waves forming several types of synsedimentary microbial mat deformation structures. This study analyses excellent examples of these structures developed in Paso Seco (Argentina), a modern coastal flat colonized by microbial mats frequently inundated during storms, and the modifications that affect them before burial. To achieve this, the hydrodynamic conditions in the coastal flat over time were interpreted from water level records obtained with HOBO loggers. Field photographs were obtained to document the microbial structures (such as flipped-overs, tear mats, roll-ups, mat chips, and folds) covering the area after a high-energy event and over the course of the following two years. Specifically, emphasise was put in roll-up structures because of their large size. Sediment samples were extracted to make thin sections for petrography analysis. Once the microbial structures are formed, they show gradual changes caused by the hydrodynamic conditions that control the sedimentary environment, and on several occasions, these changes are preserved in the sedimentary profile. Our observations and measurement of modern sedimentary structures and the in-situ documentation of their evolution may be helpful for the identification and interpretation of analogous sedimentary structures in the fossil record, which could have undergone similar modifications prior to their burial.Fil: Maisano, Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Geología; ArgentinaFil: Quijada, I. Emma. Universidad de Oviedo; EspañaFil: Raniolo, Luis Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Cuadrado, Diana Graciela. Universidad Nacional del Sur. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

From carbonate-sulphate interbeds to carbonate breccias: The role of tectonic deformation and diagenetic processes (Cameros Basin, Lower Cretaceous, N Spain)

Carbonate breccias may be formed by a wide variety of processes, both syn- and postdepositional, which implies that interpreting the mechanism of formation requires a detailed study because different processes may produce similar features. This is the case of the Lower Cretaceous carbonate breccias of the Cameros Basin, which were previously interpreted as syn-depositional slump breccias and as post-depositional evaporite-solution collapse breccias. However, a detailed analysis suggests that these breccias were the result of a different process: tectonic flow of sulphate layers (now vanished) interbedded with carbonates. Similar tectonically-driven evaporite flow processes have been described in thrust faults, but the formation of carbonate breccias by tectonic sulphate flow may be overlooked if they are not related to thrusts, due to difficulties in their recognition. The analysis of the carbonate breccias of the Oncala Group provides useful criteria to recognize this type of brecciation. The studied carbonate breccias are interbedded with, and laterally associated to, alternating layers of carbonate mudstone and calcite and quartz pseudomorphs after gypsum. The carbonate breccias consist of angular carbonate mudstone fragments floating in a matrix made up of calcite and quartz crystals. The breccia fragments and the carbonate mudstone layers of the unbrecciated adjacent deposits show identical composition and features, and the matrix of the breccias has the same composition as the calcite and quartz pseudomorphs after gypsum of the unbrecciated adjacent layers, which suggests that the brecciated beds were originally composed of identical alternating carbonate mudstone and gypsum layers as the unbrecciated layers. The carbonate breccias are generally matrix-supported and their fragments are from very slightly displaced to chaotically arranged. The breccias are associated with deformation structures, and breccia fragments are commonly arranged describing frequently polyharmonic folds, whose axial planes strike between N114ºE and N168ºE. The deformation structures affecting the carbonate breccias are similarly oriented as the regional tectonic structures, which strike between N144ºE and N155ºE, suggesting that they are related with the alpine, contractional, tectonic deformation of this area of the Cameros Basin. All these features suggest that these carbonate breccias were formed by tectonic deformation of alternating layers of carbonate mudstone and calcium sulphate (anhydrite during burial), which have very different rheological behaviour. As a result, during tectonic deformation sulphate flowed and carbonate layers were broken and displaced, producing a breccia of carbonate fragments within a sulphate groundmass. Afterwards, the sulphate groundmass was replaced by quartz and pseudosparitic calcite, and the breccia acquired its final composition

Challenges to carbonate-evaporite peritidal facies models and cycles: Insights from Lower Cretaceous stromatolite-bearing deposits (Oncala Group, N Spain)

Peritidal carbonate-evaporite successions, since they are developed in the transition between continental and marine realms, provide essential keys for palaeobathymetric and palaeoclimatic interpretations. As a result, several facies models have been proposed to assist on the interpretation of ancient tidal flat deposits, and peritidal successions have been extensively used for cyclicity analyses. In this study, well-exposed, Lower Cretaceous peritidal deposits (Oncala Group, Cameros Basin, N Spain) are analysed and compared with the most commonly-used present-day analogues (from Shark Bay, the Arabian Gulf and the Bahamas) and with ancient peritidal successions, providing their palaeoenvironmental and palaeoclimatic interpretation, assessing the usefulness and limitations of the facies models, and evaluating the suitability of these deposits for analysis of decimetre to metre-scale cycles. The studied peritidal deposits consist of thinly-bedded to laminated dolostones, dolomitic stromatolites, stromatolite breccias, flat-pebble and edgewise breccias, and calcite and quartz pseudomorphs after anhydrite nodules. Abundant resemblances of the peritidal deposits of the Oncala Group with those of Shark Bay, including that they are largely composed of microbialites and intraclasts, makes the peritidal deposits of the Oncala Group one of the best fossil analogues of this present-day setting. However, the presence of anhydrite nodules indicates pervasive evaporite precipitation in the supratidal zone, which is a feature that does not occur in supratidal flats of Shark Bay, but is characteristic of arid sabkhas of the Arabian Gulf. Nevertheless, the fact that carbonate-evaporite tidal flats of the Oncala Group were laterally related with siliciclastic tidal flats with large freshwater input and broadly inhabited by dinosaurs, suggests that anhydrites precipitated under less arid climates than those of the Arabian Gulf nowadays, pointing to semiarid climatic conditions during deposition. Moreover, the fact that peritidal deposits with anhydrite nodules were exclusively formed in a low-subsidence area of the Cameros Basin suggests that the rate of accommodation space creation also played an important role in their development. Regarding the comparison with other fossil peritidal sediments, the studied deposits show more abundant similarities with Proterozoic and Cambrian successions, composed mainly of stromatolites, microbial laminites, and intraclasts, than with other Mesozoic peritidal deposits, in which bioclasts and burrowing are usually more abundant. This highlights the difficulties for assigning specific features to certain geological ages. Finally, peritidal facies of the Oncala Group may change laterally and vertically to any other facies, showing a patchy lateral distribution of facies and an unsystematic vertical stacking pattern. The sedimentary features of the stromatolite, breccia and thinly-bedded to laminated dolostone facies do not allow their assignment to a unique tidal zone. Moreover, sedimentary features indicative of subaerial exposure, such as anhydrite nodules formed in the capillary zone, occur within any of the carbonate facies and show limited lateral extent. This results in a succession that cannot be clearly subdivided into subsequent shallowing-upward cycles not even by using erosive surfaces or the anhydrite nodule layers as marker horizons of the upper part of the cycles, because their limited lateral extent prevents reliable correlations. Similar composite lateral and vertical facies relationships have been documented both in the present-day analogues and in ancient successions, which suggests that this kind of facies relationships may be common in peritidal successions and highlights the caution that must be taken when trying to perform cyclicity analysis on them

Formation and preservation of vertebrate tracks in semi‐liquid sediments: Insights from tidal flats and laboratory experiments

International audienceABSTRACT Despite the valuable palaeoecological and palaeoenvironmental information provided by vertebrate tracks, those made in semi‐liquid sediments have been largely overlooked because they are assumed to be preserved as a mass of disrupted sediment and to have a low preservation potential. Nevertheless, understanding their mechanisms of formation, infilling and preservation is crucial since they could be more abundant in the fossil record than expected or be misinterpreted as other soft‐sediment deformation structures. To solve these aspects, this study analyses consecutive cross‐sections performed along a human track made by a shod foot in semi‐liquid sediments in the upper intertidal flats of the Bay of Mont‐Saint‐Michel (north‐west France) and monitored until its complete burial. These were compared with cross‐sections of tracks made in a flume tank. Cross‐sections reveal that the sediment structures associated with these tracks reflect the mechanism of their formation and infilling, and even the footstep dynamics. These structures comprise: (i) marginal rims that developed at both sides of tracks during foot penetration; (ii) upward deformation structures produced during foot withdrawal; (iii) a syn‐track infilling , which almost entirely fills the tracks during the withdrawal, formed by sediment collapsed from the track walls or by liquefied sediment; (iv) a post‐track infilling that fills the tracks completely during their subsequent flooding. This work demonstrates that these tracks have a high preservation potential in tidal settings, especially if they are made after the peak of a spring tide period, and undergo desiccation and consolidation during neap tides, which prevents their erosion and favours their burial by sediment. The identification of the above‐mentioned structures in fossil counterparts provides useful palaeoenvironmental information, because they allow discriminating these tracks from those made in sediments with less water content and from other soft‐sediment deformation structures (i.e. convolute bedding and balls‐and pillows) with which they share strong resemblances

Revisiting the age and palaeoenvironments of the Upper Jurassic–Lower Cretaceous? dinosaur-bearing sedimentary record of eastern Spain: implications for Iberian palaeogeography

An integrated stratigraphic, palaeontological, palaeoenvironmental and palaeogeographical study of the traditionally considered Upper Jurassic–Lower Cretaceous dinosaur-bearing sedimentary record (DSR) of eastern Spain is accomplished for the first time. Several areas where dinosaur fossils are abundant (western Maestrazgo and South-Iberian basins) have been studied in detail. In all the areas, the DSR comprises a carbonate-dominated lower part (CLP), and an essentially siliciclastic upper part (SUP). Deposition occurred in a shallow-very shallow marine carbonate platform, laterally connected towards the N and W to coastal and alluvial environments. The overall upwards evolution is regressive with a transgresive episode at the uppermost part. The DSR includes deposits previously assigned, depending on the studied area, from the Kimmeridgian to the Barremian (locally even to the Aptian–Albian). However, ages obtained in this work from larger benthic foraminifera (LBF), demonstrate a Kimmeridgian–Tithonian age (locally Kimmeridgian-Early Berriasian?) for the DSR. These findings have important implications regarding the age of dinosaur fossils of these deposits, traditionally assigned to the Jurassic-Cretaceous transition, or even to the Early Cretaceous, erroneously, and have necessitated a deep litho- and chronostratigraphic revision of the units previously established in the studied areas: new data indicate that the DSR is correlatable with deposits of the Villar del Arzobispo Fm and that the usage of the Aldea de Cortés and El Collado Fms, traditionally assigned to the Early Cretaceous, should be avoided. New data also reveal that the DSR should be correlated with other Kimmeridgian–Tithonian dinosaur-bearing deposits of Iberia, such as those of the Cameros Basin, Asturias and Portugal, and have encouraged a revision of the Iberian palaeogeography at that time. In fact, ages obtained from LBF agree with data provided by the systematics of dinosaurs, since dinosaur faunas of eastern Spain are similar to those of the other Late Jurassic Iberian areas, especially to those of the Lusitanian Basin