An EU-funded initiative is underway to develop an integrated marine observation and monitoring strategy at a regional scale in Galicia, Spain, an area highly dependent on marine resources and known for its complex ecosystem within a dynamic upwelling system.To develop this strategy, over 200 marine researchers from diverse fields and from 14 research institutions across Galicia are collaborating through a participative approach involving the quintuple helix—government, academia, industry, civil society, and the natural environment— on four coastal and marine system key areas:i) advancing new observation technologies, tools, and platforms with a high degree of automation, enabling extensive and sustained collection of essential data for comprehensive ecosystem management. This effort particularly targets variables for which commercial technology is currently limited or unavailable;ii) creating an integrated marine big data platform that ensures high standards of data storage and standardization, adhering to FAIR principles and connecting with other ongoing international data platforms. A Marine Virtual Laboratory is also being developed within this platform to allow end-users to visualize and utilize the data effectively;iii) constructing a multi-scale, transdisciplinary marine simulator, a crucial tool for integrating data from multiple sources to generate insights and provide a structured framework to tackle environmental, social, and economic challenges. This simulator will aid in exploring and predicting the impacts of global change on the marine environment and will support knowledge-based decision-making processes for sustainable management of marine uses and resources; andiv) planning through a participatory approach the governance of marine monitoring in Galicia by fostering synergies among stakeholders, enhancing existing systems and services, increasing visibility, coordinating ongoing and future initiatives, implementing new monitoring strategies, developing services, refining data policies, and facilitating national and international collaborations in Galician observation efforts.The goal of this strategic plan is to lead to better-informed decision-making for the modernization and reinforcement of marine observation and monitoring as a foundation for a robust social, economic and environmental resilience, enabling sustainable use of Galicia’s marine environment ecosystems.

Green marine clays, known as glaucony and verdine facies, are unique iron-rich minerals typically found in shallow marine sedimentary environments covering large areas of continental shelves today. While on some occasions they have been used effectively as paleoenvironmental indicators associated with transgressive and highstand system tracts, their occurrence can vary in different sedimentary environments. This paper aims to provide a review of the nomenclature and mineralogical composition of these facies, their habits and morphologies, as well as the physico-chemical characteristics of their genesis. This includes water depth, temperature, and geochemical factors that influence the local environments and characteristics of their formation. The article also presents examples from the NW Galician Continental Shelf and discusses the variety of mechanisms behind their genesis and evolution, as well as the challenges surrounding their chronology. Comparisons are drawn with the old facies (ironstone), which can occur in a wider range of marine environments and are sometimes found alongside glaucony and verdine facies in ancient deposits. This highlights the importance of accurately reconstructing the environment of each deposit. The literature reveals many exceptions in relation to the zonal and bathymetric distribution, sedimentation rates, age, etc. of these facies, emphasizing the need for further investigation into their genesis in current and ancient environments. Such research would provide valuable insights for paleogeographic, paleoenvironmental, and stratigraphic interpretations.

In the latest years, the concentration levels of certain metals and metalloids in the sediments of the Galician Rías have shown an increasing trend (e.g., As, Zn, Cu, Pb, Hg). These areas are also characterized by their richness in nutrients and their great aquaculture or mariculture activity, with the presence of more than 3500 mussel rafts in the Rías Baixas. The inner areas of the Galician Rías are subjected to activities that resuspend the sediment such as high levels of maritime traffic and dredging or cleaning operations. It is likely that a transfer of these elements to the water column happens during the resuspension of sediments caused by natural events or anthropogenic activities. In this study, selected samples of surface sediments of the Ría de Pontevedra (NW Spain) were subjected to a procedure of aerobic oxidation to determine the concentration of some elements (Fe, Mn, Cu, Cr, Pb, Hg, and Zn) released from the sediment to the aqueous phase. The experiment was carried out within 5 days. Measurements of pH and total concentration were taken both in water and sediment samples. Furthermore, speciation of trace elements was carried out in the sediment samples. Trace element concentrations were lower in the sediments during aerobic oxidation, being released to the aqueous phase. From an environmental point of view, Cu was the only trace element released in quantities that may be toxic for the organisms in the area. This problem of sediment oxidation related to dredging activities or natural storm conditions should be considered in environmental impact studies and transferred to stakeholders.

San Simon Bay is located in the inner part of a Galician ria. Three rivers enter the bay from the north, forming shallow estuaries. Tidal range is mesotidal (2 to 4 m with an average of 2.2 m). High productivity ecosystems develop due to upwelling processes, which are common in all the Galician rias. The aim of this paper is the study of fluvial and tidal interactions giving rise to distinctive facies architecture in the context of the Holocene transgression. Vertical facies distributions and architecture show alternating units of well-defined estuarine channel-fill and tidal flat deposits. Two millennial-scale, fining-upward sequences show an initial incision evolving into channel fill and tidal flat deposits. An age model has been developed based on AMS C-14 and Pb-210 and Cs-137 dating to put them in the context of the established climatic and sea-level changes. Older dated deposits give an age of 5.9 ky cal BP close to the last Holocene eustatic maximum. Millennial-scale sedimentation rates are about 1.0-1.6 mm y(-1), whereas the last few decades show values 5 to 6 times higher. Differences in sedimentation rates are attributed to increasing human influence over recent decades. Incision stages at the base of the sequences (5.1 to 4.8 cal. ka BP and 2.3 to 2.0 cal. ka BP) followed by aggradation are interpreted in terms of high frequency climatic oscillations and related changes in sediment supply and river activity (incision taking place with a decrease in sediment supply). Meter-scale sequences are developed in channel-fill units, indicating superimposed minor, centennial-scale, climatic instabilities giving way to changes in channel activity.

We analyze potential Late Holocene metal contamination along a sediment core collected in the distal zone of Ria de Vigo (North Spain). Statistical treatment of the dataset based on a multiproxy approach enabled us to identify and disentangle factors influencing the depositional processes and the preservation of the records of this activity in the area over the last ≈3000 years bp. Some layers of the analyzed core have significant enrichment in Cu and a moderate enrichment in Ag, Mo, As, Sb, S, Zn, Ni, Sn, Cd, Cr, Co, Pb, and Li. The enrichment of these elements in some layers of this core may be related to mining activities that have taken place since classical times in the region. Successive phases of pollution were identified along the core KSGX24 related to the Late Bronze Age (≈3000–2450 years bp), Iron Age (≈2450–1850 years bp), Roman times (≈1850–1550 years bp), Middle Ages (≈1250–500 years bp), and industrial and modern (≈250–0 years bp) anthropic activities. The protection of the Cies Islands, the erosive and transport capacity of the rivers in the region, oscillations of the oceanographic and climatic regime, atmospheric contamination, and diagenetic sedimentary processes might have contributed to the accumulation and preservation of this record in the distal region of the Ria de Vigo. The studied core shows that the industrial and preindustrial anthropic impacts caused an environmental liability and contributed to the presence of moderate to heavy pollution of various metals in surface and subsurface sediment layers in the distal sector of the Ria de Vigo, which could be a hazard to biota.

Deep-sea sediments record palaeoenvironmental and oceanographic changes over time through variations in their magnetochemical and sedimentological properties. This study presents the Late Quaternary sedimentary reconstruction of three sediment cores extracted from a source-to-sink sedimentary system located in a high marginal platform of the north-west Iberian Margin. The aim of this reconstruction is to explore the palaeoclimatic, palaeoproductivity and diagenetic changes over the last 172 cal ka bp attending to geochemical, magnetic and sedimentological variations. The record is comprised of four sedimentary units consisting of pelagic, hemipelagic and detrital facies, the latter associated with ice-rafted debris events at Heinrich Stadials. These findings allowed the reconstruction of the lithostratigraphy attending to climatic changes, covering the last eleven Heinrich Stadials. These units and facies successions are controlled by the superposition of the Milankovitch and Dansgaard-Oeschger cycles. Low sedimentation rates have been reported, especially during cold periods. Palaeoproductivity was assessed using total organic carbon and calcium carbonate content, together with biogenic barium (Ba-bio) and organic phosphorus (P-org), both calculated via total digestion analysis using standard calculations. Mass accumulation rates for total organic carbon, Ba-bio and P-org were calculated. Furthermore, a sequential extraction was performed to explore the different phases of the barium within sediments: biogenic barite (Ba-bar), barium associated with iron and manganese oxides (Ba-ox) and Ba associated with aluminosilicates (Ba-det). Results display a limitation in the use of the biogenic barium and phosphorus and mass accumulation rates, suggesting detrital Ba (Ba-detr) contribution during Heinrich Stadials, which could mask the calculations. In contrast, only calcium carbonate fluctuates attending to glacial/interglacial cycles. Regarding some diagenetic proxies (i.e. Mn, Mn/Fe and Mn/Ti), they reveal oxidation fronts of different generations, suggesting that the early diagenesis has not reached steady-state, because the redoxcline fluctuates. This fact suggests an erosional activity that causes the continuous oxygenation of the sediment and non-steady-state conditions.

The purpose of this study was to investigate the microplastic (MP) pollution in sediments, surface waters, and four fish species in the northern coast of the Persian Gulf. Sampling was conducted in seven important regions during December 2019. The abundance of MPs was respectively 190 ± 35.5 items/kg dry weight for sediments, 9.28 ± 2.1 items/km2 for surface waters, and 0.33 ± 0.05 items/individual for fish. There was no correlation between MP abundance in surface water, sediment, and fish samples. Except for Cynoglossus arel, abundance of isolated MPs did not show significant relationships with body weight, body length, and gastrointestinal tract weight (P > 0.05). MPs were ranged from 0.3 to 5 mm in size and were prevailed by fiber in shape; black, red, and blue in color; and polypropylene and polyethylene in polymer. This study may help in increasing our knowledge regarding MP pollution in marine water systems and biota.

Studies of the most surficial sedimentary record from passive continental margins provide crucial knowledge about sedimentary dynamics and its changes through recent geological times. These studies allow understanding in detail the influence of both tectonic activity and long-term bottom-current circulation over the Late Quaternary sedimentary dynamics. Using a large dataset of multibeam bathymetry, chirp and multi-channel seismic (MCS) records, ROV seabed direct observations and a magneto-chemical facies characterisation, we provide a well-dated record of the tectono-sedimentary processes on an isolated high marginal platform over the Late Quaternary. Our results display several structural and geomorphological features and tectonic pulses that indicate intense faulting, folding, and deformation of the most recent sedimentary cover. Furthermore, we document four main sedimentary systems acting at the study area and controlled by different water masses (MOW, LSW and NADW): the (hemi)pelagic, bottom current-controlled (hemi)pelagic, contourite and downslope sedimentary systems; as well as a new typology of contourite associated to giant depressions, named as pockmarks-related drift. The record also shows erosive features and extremely low sedimentation rates for the last 172 cal ka BP. Results suggest that the topographic configuration of the high marginal platform and reorganizations of the water masses associated to climate changes causes a constriction of the water masses that induce an enhancement of the bottom-current activity, favouring erosion, winnowing and redistribution of sediments. Therefore, this study provides new insight into the tectonic control and bottom current activity effect over the Late Quaternary sedimentary cover from an isolated and elevate offshore morphostructural province, located at the Galician Continental Margin.

Surficial sediments on the seafloor from passive continental margins can provide insight into recent Late Quaternary sedimentary dynamics acting over offshore sedimentary systems. This work focuses on the study of some particular ferruginous tubular structures resembling bioforms (FTB) located in the distal Galician Continental Margin (NW Iberian Margin) at water depths between ~ 1550 and ~ 2200 m. The characterisation of these structures made it possible to study in depth their formation environment and subsequent sedimentary evolution during the Late Pleistocene and Holocene. The FTB consist of goethite with a framboidal texture. They were interpreted as formed by an initial pyrite precipitation in reducing microenvironments conditioned by the activity of sediment-dwelling organisms during the early diagenesis. This is followed by the oxidation of pyrite by a combination of hydrothermal fluids and erosional processes, which triggers the formation of the framboidal oxyhydroxides. The data allowed obtaining a comprehensive understanding of the environmental context and the significance of these ferruginous tubules, as there are no previous studies in the scientific literature that describe these structures in a source-to-sink sedimentary system.

Textural, geochemical and geochronological analyses on two gravity and two box cores recovered from the outer and inner sectors of the Ria de Muros allowed reconstructing and timing the anthropogenic imprint on the sedimentary record from this ria. The chronological framework for the last 8 kyr was built based on Pb-210 dating (Constant Rate of Supply model) and C-14 dating. Recent sedimentation rates were an order of magnitude higher than those of the oldest analyzed sediments, and the periods of upwelling enhancement were constrained. Assessing the human influence on sediment metal contents required the establishment of local background levels. Since the 16th century the enrichment factors of copper, zinc and lead increased (up to 2.7, 1.5 and 2.1, respectively, at or close to present), and a remarkable increase in the fine-grained particles' content happened in the outer ria sector, due to deforestation. The anthropogenic signature identified in the sedimentary record is assigned to fishing, harbor activities, mining, salting, and, or canning activities, depending on the considered period, which caused a local demographic increase since the 16th century in the region. Such population growth caused a rise in the marine signature of the organic matter, which likely results from enhanced primary production due to eutrophication caused by increased soil erosion and human and livestock waste inputs. Furthermore, the metal enrichment trend during the 20th century, which was more significant in the inner than in the outer ria sector, follows the different demographic evolution of the villages (related to urban and industrial development). The present study highlights the need for conjunction of varying dating techniques when reconstructing the anthropization trends in coastal environments.

Ferruginous tubular structures concretions are widely distributed over the seafloor surrounding the Gran Burato depression in the Transitional Zone (TZ) province of the Galician Continental Margin (NW Iberian Margin). These bioforms-like structures are created by iron oxides precipitations into the tube-dwelling macrozoobenthos as a result of Fe2+ upward diffusion and O2 ventilation and diffusion acting in the water-sediment interphase in a non-steady state early diagenesis. X-ray diffraction analyses display that goethite is the main mineralogical component of these bioforms-like structures. Furthermore, non-steady state diagenesis has been identified by several oxidations fronts recognised in three piston cores, reflecting that the redoxcline has not achieved the deeper equilibrium in the study area. Afterwards, these ferruginous tubes were eroded, remobilised and redistributed over the seabed by bottom currents. Ocean-floor observations show erosion and sea-bottom current structures as ripples, grooves, erratic blocks, accumulations of pteropods and carbonate crusts associated with hardgrounds. Sedimentation rates calculated in a piston core display very low values for the last 30 cal ka BP (mean of 1.57 cm ky−1) with a marked hiatus between 17.80 to 10.45 cal ka BP, meanwhile abraded surfaces have been identified by high-resolution seismic data confirming erosional processes in this area of the TZ province. We conclude that the ferruginous bioforms accumulation over the deep-ocean floor is indicative of a present-day vigorous seafloor current acting and eroding the sediments of the TZ province. This bottom current is a direct consequence of the general seafloor elevation of the TZ province that causes constriction of the water masses (MOW and LSW) that induces a general intensification of the bottom currents and greater erosional capacity. This erosional process causes the continuous oxygenation of the upper sediments, and it prevents to reach the steady-state diagenesis, playing this fact an essential role in the ferruginous formations and accumulations in the study area.

The validity and usefulness of multivariate statistical tools for the facies characterization in deep-marine environments have been applied on the geochemical, sedimentological and magnetic data from a piston core extracted from the Transitional Zone in the Galician Continental Margin. The combination of geochemical profiles of Fe, Mn, Ti, Ba and Ca and magnetic susceptibility (MS) obtained using the ItraxTM Core Scanner at the University of Vigo, together with the grain-size, grey level and R (red) G (green) B (blue) colour analyses have allowed characterizing and classifying the sediments of the core PC13-3 using SPSS package v. 23. Cluster Analysis (CA) displays, in the first level of the hierarchy, two major groups that correspond with clay-silt and sand facies. In a second level, it is possible to observe six subfacies that match de visu preliminary classification and allowed us to complete and improve the characterization and the facies limits in the whole core. Discriminant Analysis (DA) confirmed the validity of the cluster analyses and enhanced the results of the classification. The Principal Component Analysis (PCA) shows four principal components: coarse lithogenic fraction (PC1), fine lithogenic fraction (PC2), high density fraction (PC3) and biogenic fraction (PC4). These results are in concordance with the Pearson correlation coefficient and the SEM observations. In general terms, the results confirm the utility of the multivariate statistical methods applied on high resolution geochemical and magnetic data acquired with ItraxTM corer scanner, as a quick and complementary tool in sedimentary facies analysis and description in deep marine environments.

This work combines planktonic foraminiferal assemblages, stable isotope, transfer function estimated sea surface paleotemperatures (SST) and export productivity (Pexp) with sedimentological records from the PC7 core to document paleoclimatic and paleoceanographic changes on a distal region of the NW Iberian Margin since the last glaciation (<approximate to 68 ka). Neodymium and strontium isotope data are also used to identify the provenance of ice rafted debris (IRD) during Heinrich event 5 (H5). Our results are compared and combined with previously published records and evidence that melt water and icebergs from the Canada, Greenland, Iceland and Europe ice sheets arrived to the NW Iberian Margin causing a significant decrease of SST during the last six Heinrich Stadials (HS) and some Dansgaard-Oeschger (D-O) stadial events. epsilon Nd and Sr-87/Sr-86 indicate that the studied locality mostly received sediments from European Ice Sheets (EIS) during H5. During the HS and D-O stadial events, SSTs were in general higher than in other cores collected in inner areas of the NW Iberian Margin. The presence and intensification of Portugal Current probably induced heat transfer to this distal region of the Iberian Margin. Our results also suggest the occurrence of high variability in the intensity and wind patterns during the last glaciation. In some periods, the intensity of northerly winds could have been very strong and contributed to a significant stimulation of ocean productivity in this distal area through the intensification of upwelling. In general, oceanic productivity decreased during the HS and D-O as the presence of cold and less saline water prevented nutrient rich waters from deep levels reaching the surface. The high productivity events were bracketed by periods characterized by the highest influence of the Azores Current eastern branch during which northerly winds and the oceanic productivity should have been weakened.

Based on multiple proxies, such as major and trace elements, mineralogy, Corg/Ntotal ratio and δ13C, we assessed the natural and anthropogenic depositional record in a tropical estuary (Caravelas, Brazil). The Caravelas estuary was once a pristine area of highly important ecological role, due to its mangroves and proximity to the largest reef system in the South Atlantic (Abrolhos Archipelago). However, during the past decades, the estuary has been subjected to both natural and anthropogenic impacts, such as a natural opening of an inlet and changes in land use. This study is based on three dated cores, taken from the inlet to the main channel. A shift in the organic and inorganic proxies, in the early 1960s, shows the impact of this natural opening on the hydrodynamics and sediment distribution. Furthermore, there is a clear spatial pattern in the contribution of the main sources to the organic matter content in the cores: the core collected further away from the inlet shows a strong C3 plant contribution while the ones recovered closer show a higher marine influence. Only a slight increase in enrichment factors of the selected trace metals has been observed and they have been attributed to land use changes rather than direct inputs from industrial and urban sources. Such information is vital for the effective management of coastal systems, mainly when considering natural and ongoing anthropogenic changes in its forcing conditions that are exacerbated by climate change.