Miguel Caetano

• PhD in Marine Science
• Researcher at Portuguese Sea and Atmosphere Institute

In the last few years, the exploitation of deep-sea regions for minerals extraction raised international attention as an economically viable source for the mining industry. However, most of these minerals are found close to sensitive ecosystems that can be harmed by mining activities. Given the potential impact, there is a need for the establishmen...

To improve our understanding and guide future studies and applications, we review the biogeochemistry of the rare earth elements (REE). The REEs, which form a chemically uniform group due to their nearly identical physicochemical properties, include the lanthanide series elements plus scandium (Sc) and yttrium (Y). These elements, in conjunction wi...

The MONITOOL project (2017–2023) was carried out to describe the relationships between total dissolved and labile metal concentrations measured in spot water samples and in concurrently deployed Diffusive Gradients in Thin-films (DGTs) passive samplers, respectively. The ultimate aim was to adapt existing marine metal Environmental Quality Standard...

With the growing interest to exploit mineral resources in the deep-sea, there is the need to establish guidelines and frameworks to support hazard and risk assessment schemes. The present study used a subtidal species of filter-feeding bivalve, the clam Spisula solida, as a proxy to better understand the impacts of sediment plumes in marine organis...

The accumulation of microplastics (MP) by marine species of ecological and commercial interest represents a major concern, particularly for those present in human diet. This study analysed the accumulation of MP in three species of coastal pelagic fish with high commercial value, European sardine (Sardina pilchardus), European anchovy (Engraulis en...

Spatial patterns and temporal trends of the butyltin compounds tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) were investigated in a set of sediment samples collected along the SW Portuguese continental shelf. This region did not reach the Good Environmental Status (GES) in accordance with the Marine Strategy Framework Directive (MSFD)...

Mola mola is the largest teleost inhabiting our ocean and the presence of microplastics (MP) in this flagship species was, before this study, never described. Thus, this investigation focused on analysing MP ingestion in 53 ocean giant sunfish in the Northeast Atlantic Ocean. A total of 116 MP were found in 79% of the specimens, with a median of 1...

Platinum Group Elements (PGEs) are contaminants of emerging environmental concern considering their continuous increasing use and subsequent release in the environment. While recent field studies provided PGE levels in seawater, scarce knowledge still exists regarding PGE contamination in marine organisms, especially for rhodium (Rh). Water, macroa...

Integrative passive samplers, such as DGT (Diffusive Gradients in Thin-films), are identified in European Technical Guidance Documents as promising tools to improve the quality of the assessment, in the context of the WFD (EU Water Framework Directive). However, DGT results cannot yet be used directly in a regulatory framework to assess the chemica...

Industrial deep-sea mining will release plumes containing metals that may disperse over long distances; however, there is no general understanding of metal effects on marine ecosystems. Thus, we conducted a systematic review in search of models of metal effects on aquatic biota with the future perspective to support Environmental Risk Assessment (E...

Although most deep-sea areas are remote in comparison to coastal zones, a growing body of literature indicates that many sensitive ecosystems could be under increased stress from anthropogenic sources. Among the multiple potential stressors, microplastics (MPs), pharmaceuticals and personal care products (PPCPs/PCPs) and the imminent start of comme...

Our high-technology society is increasingly reliant on technology-critical elements (TCE), such as the Rare Earth Elements (REE). These elements are vital to "environmental-friendly" technologies, agriculture, and medical applications (e.g., MRI contrasts). With growing REE applications, emission to aquatic ecosystems rises through mining, ore proc...

Humans have exhaustively combusted fossil fuels, and released pollutants into the environment, at continuously faster rates resulting in global average temperature increase and seawater pH decrease. Climate change is forecasted to exacerbate the effects of pollutants such as the emergent rare earth elements. Therefore, the objective of this study w...

We report identification and mapping of areas in Europe’s seas and coastal areas impacted by contaminants, i.e., areas with concentrations above internationally agreed threshold values. The study is based on (1) a state-of-the-art data set anchored in national monitoring activities, (2) internationally agreed target values and (3) an updated versio...

Deep-sea mining activities are expected to impact deep-sea biota through the generation of sediment plumes that disperse across vast areas of the ocean. Benthic sessile suspension-feeding fauna, such as cold-water corals, may be particularly susceptible to increased suspended sediments. Here, we exposed the cold-water octocoral, Dentomuricea aff. m...

This report summarizes current threats to the Tagus estuary and adjacent ecosystems, presented in Lisbon in June 2021, and prioritizes actions to maintain or improve ecosystem services for a densely populated area close to the deep ocean.

Potassium hydroxide (KOH) digestion protocols are currently applied to separate microplastics from biological samples, allowing efficient digestion with minor degradation of polymers in a time- and cost-effective way. For biota samples with high-fat content, KOH reacts with triglycerides generating an overlying soap layer, making difficult the dige...

The Minamata Convention recognized mercury (Hg) as a chemical of global concern. Research in the Tagus Estuary started in the late 70’s; however, knowledge on Hg contamination in this system has greatly improved in the last decade. Results showed two highly contaminated zones, whereas, in areas far from the sources, Hg and monomethylmercury (MMHg)...

[Please note that the article can be freely downloaded from https://authors.elsevier.com/c/1fW0wB8ccuoOJ before September 20, 2022 ] In order to move forward in the acceptance of a novel contaminant monitoring technique (Diffusive Gradients in Thin-films: DGT) for assessment of marine water bodies, sensu the WFD, an Inter-Laboratories Comparison (I...

In the last decades, there has been an exponential increase in rare earth elements demand associated with the development of new technologies and their wide use in various applications. Studies report an anthropogenic enrichment of gadolinium (Gd) in rivers and estuaries around the world due to the use of Gd-based contrast agents in complementary m...

Please note that the article and supplementary material can be freely downloaded from : https://doi.org/10.1016/j.marpolbul.2022.113715 This study investigates the relationships among Ni, Cd and Pb's different chemical forms determined by different methodologies in coastal and transitional waters across a broad geographical scale. Concentrations w...

The authors wish to make the following corrections to this paper [...]

Studies dealing with Rare Earth Elements (REE) ecotoxicological behavior are scattered and with potential conflicting results. Climate change impacts on aquatic biota and is known to modify contaminants toxicokinetic. Nevertheless, the current knowledge on the potential interactions between climate change and REE is virtually non-existent. Therefor...

Lanthanum (La) is one of the most abundant emergent rare earth elements. Its release into the environment is enhanced by its use in various industrial applications. In the aquatic environment, emerging contaminants are one of the stressors with the ability to compromise the fitness of its inhabitants. Warming and acidification can also affect their...

Anthropogenic increased atmospheric CO2 concentrations will lead to a drop of 0.4 units of seawater pH and ocean warming up to 4.8°C by 2100. Contaminant's toxicity is known to increase under a climate change scenario. Rare earth elements (REE) are emerging contaminants, that until now have no regulation regarding maximum concentration and discharg...

Increased Rare earth elements (REE) usage culminates in discharges into the environment. Mussels have been chosen as models in biomonitoring, hence, REE concentrations in Mytilus galloprovincialis from six locations on the Portuguese coast were accessed to determine natural concentrations and possible linkage to local ecosystem characteristics and...

Among the environmental emerging concern rare earth elements, lanthanum (La) is one of the most common and reactive. Lanthanum is widely used in numerous modern technologies and applications, and its intense usage results in increasing discharges into the environment, with potentially deleterious consequences to earthlings. Therefore, we exposed th...

Wild fish (Cyprinus carpio, Mugil cephalus, Platichthys flesus) from an estuary of the NE Atlantic coast were investigated for plastic contamination (N = 128). From the 1289 particles recovered from fish samples, 883 were plastics. Among these, 84% were fibres and 97% were microplastics. Thirty-six polymers were identified. The number of microplast...

Deep-sea sediments (DSS) are one of the largest biotopes on Earth and host a surprisingly diverse microbial community. The harsh conditions of this cold environment lower the rate of natural attenuation, allowing the petroleum pollutants to persist for a long time in deep marine sediments raising problematic environmental concerns. The present work...

Just nearby the largest submarine canyon in Europe – off the western coast of Portugal – is located the Nazaré artificial reef (NAR) deployed in 2010 and the first of its kind in this coast. NAR aimed to improve social and economic resilience of the local communities, mainly by creating a safer and closer area for fishing and to enhance commerciall...

This protocol was developed based on the knowledge acquired in the framework of the Interreg MONITOOL project (EAPA_565/2016) where extensive sampling campaigns were performed in transitional and coastal waters covering eight European countries. It provides detailed procedures and guidelines for the sampling of these waterbodies by concurrent colle...

This good practice guide is focused on the DGT devices, which are the most widely used passive sampler for metals, covering the following aspects: ■ Principle ■ Handling passive sampling devices for metals ■ Estimation of appropriate field deployment time ■ A Good Practice Guide for the Use of DGTs ■ Passive sampling device preparation and assembly...

This document provides guidance on best practice for the use of Diffusive Gradient in Thin films (DGT) passive samplers devices in sampling of transitional and coastal waters for water quality monitoring. The methodology to be addressed in this guide was developed by the consortium of the European Union's Interreg MONITOOL Project in order to ensur...

The available data on trace elements (TE) of deep-sea organisms is scarce and nonexistent for rare earth elements (REE). Hence, this study characterizes REE and TE in five porifera genera (Jaspis, Geodia, Hamacantha, Leiodermatium, Poliopogon) collected in deep-sea areas (between 481 and 2656 m) of the North Atlantic. Aluminium was the most common...

The current study evaluates the effect of seawater physico-chemical characteristics on the relationship between the concentration of metals measured by Diffusive Gradients in Thin films (DGT) passive samplers (i.e., DGT-labile concentration) and the concentrations measured in discrete water samples. Accordingly, Inductively Coupled Plasma Mass Spec...

Rhodium and platinum are among the less studied elements in estuarine waters and the understanding of their speciation analysis and environmental fate remains limited. In this study, we address the occurrence and discrimination of soluble/insoluble Rh and Pt species in aquatic systems, as well as their potential transport. Particulate and dissolved...

Sediments colonised by three halophyte species, Spartina maritima (Curtis) Fernald, Halimione portulacoides (L.) Aellen and Sarcocornia fruticosa (L.) Scott) and bulk sediment from a SW European salt marsh (Tagus estuary, Portugal) were subjected to sequential extractions and analysed to assess the rare earth elements (REE) geochemical fractionatio...

Temporal variations of rare earth elements (REE) and their fractionation patterns, major elements, Pb and Hg were determined in two multicores collected at 445 and 2100 meters water depth (mwd) in the Cascais submarine canyon (CSC). The PAAS-normalized REE patterns suggest mixing of Tagus estuarine and marine sediments, marked by MREE (Nd - Dy seri...

The deep-sea is the biggest ecosystem in the world and despite the extreme conditions that characterize it, is highly biodiverse and complex. Deep-sea mining has been foreseen as a potential and concerning new stressor, and among the deep-sea mining associated stressors, sediment plumes, likely to be released into the water column as a side effect...

Halimione portulacoides plants were exposed to dissolved cerium (Ce) in a hydroponic medium for five days. Ce accumulation in plants followed the metal’s increase in the medium although with a very low translocation factor (TF < 0.01) between roots and shoots. Ce median concentrations in roots were 586, 988 and 1103 μg/g (dry wt.), while in shoots...

It has been emphasized that seafood consumers may have a higher risk of mercury (Hg) exposure. Nevertheless, the co-occurrence of selenium (Se) in organisms may affect the toxicity and bioavailability of Hg. In this work, we aim to demonstrate the possible role of Se as a potential protective element against Hg in muscle and liver tissues of three...

The correct Table 2 is presented in this paper.

Cumulative and continuing human emissions of greenhouse gases to the atmosphere are causing ocean warming. Rising temperature is a major threat to aquatic organisms and may affect physiological responses, such as acid-base balance, often compromising species fitness and survival. It is also expected that warming may influence the availability and t...

This work addresses the study of a sediment core retrieved in the estuary of the Grande-de-Xubia River (Ria of Ferrol), which is among the first industrialized areas in the Iberian Peninsula and has links to the shipbuilding industry since 1750. The chemical analysis of trace elements (i.e. As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, V, and Zn) was coupled...

Yttrium and lanthanides (REE) contents were quantified in Rosário's salt marsh (SW Europe) sediments and in the halophyte plant Halimione portulacoides, to evaluate the plant's ability to accumulate these elements as well as the translocation into their aerial organs, and increase the knowledge on the relations between these metals and the salt mar...

Road dust is a major reservoir of anthropogenic Pt and Rh. However, information about how these elements are released to the aquatic systems under environmentally relevant conditions is scarce. In this work, an innovative combination of analytical strategies is used to provide insight into the speciation analysis of those elements. A composite samp...

Myctophids are key members of mesopelagic communities with a world biomass estimated at 600 million tons. They play a central role in oceanic food webs and are known to perform diel vertical migrations, crossing the thermocline and reaching the oxygen minimum zone, however, very scarce information exists on trace element content in these organisms....

Planktivorous pelagic fish are susceptible to accumulating microplastics (MP), which have the same size range as their prey and accumulate in their feeding and spawning grounds. We analyzed stomach contents of pelagic fish (European sardine, horse mackerel, anchovy, chub mackerel, Atlantic mackerel, and bogue) from Atlanto‐Iberian waters to investi...

Microplastics (MP) pollution has received increased attention over the last few years. However, while the number of studies documentating the ingestion of microplastics by fish has increased, fewer studies have addressed the toxicological effects derived from the ingestion of these small items in wild conditions. Here, MP contamination and effect b...

The spatial distribution of Pt and Rh was assessed in Tagus estuary and their sources discussed. Both elements were analysed in superficial sediment samples (n = 72) by adsorptive cathodic stripping voltammetry. Concentrations varied within the following ranges: 0.18–5.1 ng Pt g⁻¹ and 0.02–1.5 ng Rh g⁻¹. Four distinct areas were established: “refer...

A multimetric approach was used to detect structural, compositional, and functional shifts in the underlying macrobenthic communities of an offshore mussel (Mytilus galloprovincialis) farm in a Portuguese Aquaculture Production Area. Sampling stations distributed inside and outside this area were used to evaluate sediment descriptors and macrobenth...

Los elementos químicos de las tierras raras (REE) se suelen utilizar como trazadores de sedimentos en sistemas costeros. El curso del río Louro está parcialmente situado dentro de la cuenca de drenaje del monte Galiñeiro, que es rico en minerales con REE. Se plantea la hipótesis de que los REE pueden estar presentes en el sedimento del río Louro y...

The rare earth elements (REE) increased use has resulted in a large widespread in the aquatic environment. In estuaries, where salt marshes act as a natural sink of different contaminants from industrial and urban wastes (Brito et al., 2018b) the REE use may be fingerprinted. Halophyte plants, such as Halimione portulacoides, known to sequester som...

Purpose Rare earth elements have been used as sediment tracers in river, estuarine and coastal environments but rarely applied as fluvial tributary tracers. Lanthanides (Ln) and yttrium (Y) were quantified in fluvial sediments of the Minho River lower course (NW Iberian Peninsula), where the catchment contains heterogeneous lithologies, to define t...

Microplastic pollution is presently considered a high concern topic by scientists, policy makers, governmental bodies, non-governmental organizations and the general public. Microplastics are highly widespread in all environmental compartments (e.g. air, water, sediments and biota) and increasing empirical evidence points towards potential negative...

The deep-sea is the biggest ecosystem in the world and is characterized by extreme conditions such as high pressure, low temperatures and absence or limited light. Despite the scarce studies due to inaccessibility, these ecosystems are considered highly biodiverse. The deep-sea is subjected to anthropogenic stressors with deep-sea mining being a li...

Deep-sea mining has gained international interest to provide materials for the worldwide industry. European oceans and, particularly, the Portuguese Exclusive Economic Zone present a recognized number of areas with polymetallic sulphides rich in metals used in high technology developments. A large part of these resources are in the vicinity of sens...

The yttrium and rare earth elements (YREE) increased use has resulted in a large widespread in the aquatic environment, and particularly, in estuaries, where salt marshes act as natural deposits of different contaminants from industrial and urban wastes (Brito et al., 2018). Halophyte plants, such as Sarcocornia fruticosa and Spartina maritima, kno...

The Mira River-estuary system located in southwestern of Portugal features an urbanized and agricultural catchment with no industrial influences. The river basin crosses the Iberian Pyrite Belt, a massive sulphide deposits, and is one of the few Portuguese rivers that flows in the Southeast-Northwest direction. The objective of this study was to ev...

The presence of platinum-group elements (PGE) in the environment has been attributed to anthropogenic emissions over the past decades, mainly deriving from automotive catalytic converters (ACC). However, other sources may contribute significantly to the increase of PGE in aquatic systems, such as industrial activities, medicinal uses and jewellery....

Platinum-group elements (PGE), in which (Pt) and rhodium (Rh) are included, are widely used in a variety of technology-based industries. Thus, PGE are emergent contaminants in the environment, potentially bioavailable and posing hazardous impacts. Despite being well characterised in urban environments, Pt and Rh remain poorly understood in aquatic...

The growing economic interest in the exploitation of mineral resources on deep-ocean beds, including those in the vicinity of sensitive-rich habitats such as hydrothermal vents, raise a mounting concern about the damage that such actions might originate to these poorly-know ecosystems, which represent millions of years of evolution and adaptations...

Marine anthropogenic litter has long been recognised as an emerging pollutant of global concern. Its ubiquitous distribution and its direct and indirect impacts on aquatic ecosystems, marine fauna and local economies have been recently highlighted by several studies and international organisations around the world. Although comprised of different m...

The increased use of platinum group elements (PGEs) in a variety of human activities has led to a concern over their environmental impact and biological accumulation. To reduce the emission of contaminant gases from motor vehicles, the automobile industry coupled with oil producers invested in the development of a system to diminish this global pol...

Deep-sea mining is emerging as an attractive potential solution to provide non-living resources for the worldwide industry. This interest is evidenced by the growing number of deep-sea exploration applications submitted to the International Seabed Authority (ISA). The analysis of the potential deep-sea exploitation activities impacts in European oc...

Scarce research about small European rivers from non-human impacted areas to determine their natural background state has been undertaken. During the annual hydrological cycle of 2008–9 the patterns of particulate supply (SPM, POC, PON, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, V, Zn) from the rivers Sor, Mera Landro, Lourido and Landoi to the Northern Galic...

Six campaigns were performed in North Channel (CNOR), Barcas Channel (BC) and lower zones (EZ) of Tagus estuary to better understand methylmercury (MMHg) and mercury (Hg) transport and fate. Highest concentrations of particulate and dissolved MMHg were observed in CNOR in bottom waters and in the warmest months. The MMHg distribution coefficients b...

The distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg-1 and 18 to 210mg·kg-1, respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg an...

The Anthropocene has been proposed as a new geo-stratigraphic epoch where humans have become a global factor affecting the ecosystems. Estuarine sediments constitute a biogeochemical reservoir where trace elements (TEs) from natural sources mix with a fraction generated by human activities. This study assessed the natural lithogenic imprint of TEs...

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The use of platinum-group elements (PGE) has wide applications being transversal to technology from the automobile industry to medicine. The demand of these elements has increased over the past years leading to their increase in the different environmental matrixes. This work presents the first data on the pathways and spatial distribution of Pt an...

Mercury (Hg) dynamics was evaluated in contaminated sediments and overlying waters from Tagus estuary, in two sites with different Hg anthropogenic sources: Cala Norte (CNOR) and Barreiro (BRR). Environmental factors affecting methylmercury (MMHg) production and Hg and MMHg fluxes across sediment/water interface were reported. [THg] and [MMHg] in s...

Awarded Best Poster Presentation of the Symposium on Chemical, Biological and Environmental Engineering

The determination of Platinum-group elements (PGE) in relevant environmental matrices is a challenging task. Sensitive and accurate analytical procedures for simultaneous determination of Pt and Rh are still needed. In this study, we report for the first time on the use of second derivative signal transformation to the ultra-trace simultaneous dete...

Nazaré is a picturesque fishing town highly sought by tourists during summer. One of its natural attractions is the submarine canyon. Despite its attractiveness to extreme surfers and tourists, this canyon presents a paradox for fishermen: on the one hand, the adjacent deep allows a greater volume of water, thus generating more fruitful catches at...

Recent coastal planning measures in south-east Portugal (Algarve), where offshore aquaculture developments were set up in fishing areas aiming to maximize expected utility of seafood production activities, raised some discontentment. Public policies created to safeguard offshore aquaculture (OSA) producers and limit small-scale fishing (SSF) activi...

Trace element contributions from small rivers to estuaries is an issue barely addressed in the literature. In this work, freshwater flowing into the Ria of Cedeira (NW Iberian Peninsula) was studied during a hydrological year through the input from three rivers, one considered uncontaminated (the Das-Mestas River), a second affected by urban treate...

Stable Pb isotopic ratios and concentrations of Al, Cu and Pb were measured in a 5 m long sediment core (VC2B) retrieved at 96 m water depth in the southwestern Iberian Atlantic shelf. Five phases during the last 9.5 kyrs were identified, two of them (Roman Period and modern mining) marked by a decrease of ²⁰⁶Pb/²⁰⁷Pb ratios reflecting additional i...

Octopus vulgaris is a sedentary organism that inhabits coastal waters being exposed to anthropogenic compounds. Lead concentration in coastal environments reflects many processes and activities namely weathering, industrial and domestic discharges, and atmospheric deposition. Since lead isotopic composition is little affected by kinetic processes o...