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The tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southern and northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world's largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time and out of necessity in order to address the most important outstanding scientific questions and to improve predictions of tropical Atlantic severe weather and global climate variability and change. The tropical Atlantic observing system is motivated by goals to understand and better predict phenomena such as tropical Atlantic interannual to decadal variability and climate change; multidecadal variability and its links to the meridional overturning circulation; air-sea fluxes of CO2 and their implications for the fate of anthropogenic CO2; the Amazon River plume and its interactions with biogeochemistry, vertical mixing, and hurricanes; the highly productive eastern boundary and equatorial upwelling systems; and oceanic oxygen minimum zones, their impacts on biogeochemical cycles and marine ecosystems, and their feedbacks to climate. Past success of the tropical Atlantic observing system is the result of an international commitment to sustained observations and scientific cooperation, a willingness to evolve with changing research and monitoring needs, and a desire to share data openly with the scientific community and operational centers. The observing system must continue to evolve in order to meet an expanding set of research priorities and operational challenges. This paper discusses the tropical Atlantic observing system, including emerging scientific questions that demand sustained ocean observations, the potential for further integration of the observing system, and the requirements for sustaining and enhancing the tropical Atlantic observing system.

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 with the neodymium isotopes, are powerful tools for understanding key oceanic, terrestrial, biological and even anthropogenic processes. Furthermore, their unique properties render them essential for various technological processes and products. Here, we delve into the characteristics of REE biogeochemistry and discuss normalization procedures and REE anomalies. We also examine the aqueous speciation of REEs, contributing to a better understanding of their behavior in aquatic settings, including the role of neodymium isotopes. We then focus on their environmental distribution, fractionation, and controlling processes in different environmental systems across the land‐ocean continuum. In addition, we analyze sinks, sources, and the mobility of REEs, providing insights into their behavior in these environments. We further investigate the sources of anthropogenic REEs and their bioavailability, bioaccumulation, and transfer along food webs. We also explore the potential effects of climate change on the cycling, mobility and bioavailability of REEs, underlining the importance of current research in this evolving field. In summary, we provide a comprehensive review of REE behavior in the environment, from their properties and roles to their distribution and anthropogenic impacts, offering valuable insights and pinpointing key knowledge gaps. Key Points: Rare earth elements (REE) are powerful tracers of both natural and anthropogenic processes within terrestrial and ocean environmentsREE are controlled by absorption, adsorption/desorption, co‐precipitation, remineralization, and particle dissolutionREE are technology‐critical metals with broad applications in the future low‐carbon global economy [ABSTRACT FROM AUTHOR]

The Sinos river receives the effluents released by one of the most important industrial centres in South Brazil. To evaluate the environmental impact of heavy metal contamination in the Sinos river is a difficult task, because the river basin is dominated by basaltic rocks that are naturally rich in metals. Therefore, a part of the metal concentrations in the river water originates from a natural source, i.e. rock weathering. The anthropogenic sources of heavy metals are also widespread along the river. The analysis of the heavy metal concentrations in the Sinos river water was not enough either to identify spatial gradients along the river, or to quantify the anthropogenic metal inputs partially responsible for these concentrations. To estimate the anthropogenic inputs, this study proposes an approach based on massbalance of heavy metal fluxes, including the estimate of the naturalcomponent using a natural tracer (Fe). The approach estimated the metal loads released by the anthropogenic activities into the river (Total approx. 28.0 ton yr-1: Cu 1.8 ton yr-1; Zn 8.3 ton yr-1; Cr 11.4 ton yr-1; Cd 1.5 ton yr-1; and, Pb 5.0 ton yr-1), and identified the critical river segment contaminated by heavy metals (87% of the total estimated anthropogenic inputs occur in the lower basin). These resultsagree with contamination source data reported by the governmental environment agency for effluent emitted into the Sinos river. [ABSTRACT FROM AUTHOR]

Untreated sewage discharged increases the nutrient loads and changes ecosystem functions. It increases the values of the nitrogen isotopic signature (δ 15 N) of primary producers such as seagrasses. Itaparica Island (Bahia, Brazil) has undergone extensive urbanization over 50 years. Most of the island has no sewage treatment, and a bridge's construction could increase its population ten times. We evaluated the effects of sewage inputs on the δ 15 N of seagrass (Halodule wrightii) across Itaparica Island in 14 areas of the island with different degrees of urbanization. Average values of δ 15 N ranged from -3.95 ‰ (±1.04 SD) to 2.73 ‰ (±1.61). The highest human occupation site also has the highest mean value of δ 15 N, and seagrass shoot density. The significant correlation (p < 0.05) between δ 15 N values and shoot density may indicate a possible anthropogenic pressure impacting meadow abundance. Despite a positive correlation, increased anthropogenic nutrient supply can support algae growth and harm seagrass ecosystems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Matheus Fernandes Andrade reports equipment, drugs, or supplies and travel were provided by National Council for Scientific and Technological Development. Matheus Fernandes Andrade reports financial support was provided by Foundation for Research Support of Bahia State. Ana Cecilia Rizzatti de Albergaria Barbosa reports financial support was provided by National Council for Scientific and Technological Development. Vinicius Faria Patire reports financial support was provided by Coordination of Higher Education Personnel Improvement., (Copyright © 2023. Published by Elsevier Ltd.)

We sampled abiotic and food web components in an impacted estuarine system to assess the transfer and fate of rare earth elements (REE). REE (based on dry weight) were measured in sediments, suspended particulate matter (SPM), and organisms from different trophic levels. The highest ∑REE concentrations were measured in sediments (180 ± 4.24 mg kg -1 ) and SPM (163 ± 12.6 mg kg -1 ). Phytoplankton (45.7 ± 5.31 mg kg -1 ), periphyton (51.6 ± 1.81 mg kg -1 ), and zooplankton (68.5 ± 1.27 mg kg -1 ) are the major sources of exposure and transfer of REE to the food web. REE concentrations were several orders of magnitude lower in bivalves, crustaceans, and fish (6.01 ± 0.11, 1.22 ± 0.18, and 0.059 ± 0.003 mg kg -1 , respectively) than in plankton. The ∑REE declined as a function of the trophic position, as determined by functional feeding groups and δ 15 N, indicating that REE were subject to trophic dilution. Our study suggests that the consumption of seafood is unlikely to be an important source of REE for humans. However, given the numerous sources of dietary introduction of REE, they should be monitored for a possible harmful cumulative effect. This study provides new key information on REE's baseline concentrations and trophic transfers and patterns.

Shrimp farming is blooming worldwide, posing a severe threat to mangroves and its multiple goods and ecosystem services. Several studies reported the impacts of aquaculture on mangrove biotic communities, including microbiomes. However, little is known about how mangrove soil microbiomes would change in response to mangrove forest recolonization. Using genome-resolved metagenomics, we compared the soil microbiome of mangrove forests (both with and without the direct influence of shrimp farming effluents) with active shrimp farms and mangroves under a recolonization process. We found that the structure and composition of active shrimp farms microbial communities differ from the control mangrove forests, mangroves under the impact of the shrimp farming effluents, and mangroves under recolonization. Shrimp farming ponds microbiomes have lower microbial diversity and are dominated by halophilic microorganisms, presenting high abundance of multiple antibiotic resistance genes. On the other hand, control mangrove forests, impacted mangroves (exposed to the shrimp farming effluents), and recolonization ponds were more diverse, with a higher abundance of genes related to carbon mobilization. Our data also indicated that the microbiome is recovering in the mangrove recolonization ponds, performing vital metabolic functions and functionally resembling microbiomes found in those soils of neighboring control mangrove forests. Despite highlighting the damage caused by the habitat changes in mangrove soil microbiome community and functioning, our study sheds light on these systems incredible recovery capacity. Our study shows the importance of natural mangrove forest recovery, enhancing ecosystem services by the soil microbial communities even in a very early development stage of mangrove forest, thus encouraging mangrove conservation and restoration efforts worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

We determined the occurrence of pellets (2-5 mm) and their composition in terms of trace metals and rare earth elements (REE) on nine sandy beaches of the coast of Bahia, northeastern Brazil. We compared the occurrence of pellets between oceanic and sheltered beaches and the effect of fluvial contribution on the occurrence of these microplastics. The number of pellets found was surprisingly low (i.e., max 45 pellets per m 2 in an oceanic beach without fluvial river inputs). Thus, the studied beaches exhibited a very low pollution index. Concentrations of ∑REE in pellets varied between 0.36 and 1.74 mg kg -1 and were ~5-fold higher in white/transparent pellets than in brown pellets. The sum of trace metals (i.e., Fe, Cd, Cu, Ni, Pb, and Zn) was also highest in the white pellets (357 ± 12 mg kg -1 ). Plastic pellets are a potentially important vector of REE exposition to biota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

The role of seagrass meadows in the cycling and accumulation of rare earth elements and yttrium (REEY) is unknown. Here, we measured the concentration of REEY in the different compartments of Halodule wrightii (shoots, rhizomes, and roots) and soils in seagrass meadows near sandy beaches, mangroves, and coral reefs in the Todos os Santos Bay, Brazil. We provide data on the accumulation dynamics of REEY in seagrass compartments and demonstrate that plant compartments and soil properties determine accumulation patterns. The ∑REEY in soils were ~1.7-fold higher near coral reefs (93.0 ± 5.61 mg kg -1 ) than near mangrove sites (53.9 ± 31.5 mg kg -1 ) and were slightly higher than in sandy beaches (81.7 ± 49.1 mg kg -1 ). The ∑REEY in seagrasses varied between 35.4 ± 28.1 mg kg -1 near coral reefs to 59.2 ± 21.3 mg kg -1 near sandy beaches, respectively. The ∑REE bioaccumulation factor (BAF) was highest in seagrass roots near sandy beaches (BAF = 0.67 ± 0.48). All values of ∑REE translocation are <1, indicating inefficient translocation of REE from roots to rhizome to shoot. PAAS normalized REE was enriched in light REE (LREE) over heavy REE (HREE). The REEY accumulation in Halodule wrightii revealed a low potential of the seagrass to act as a sink for these elements. However, their bioavailability and potential uptake may change with soil properties. Our results serve as a basis for a better understanding of REE biogeochemical cycling and its fate in the marine environment. REE have experienced increased use as they are central to new technologies revealing an urgent need for further investigations of potential impacts on coastal ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The present study evaluated the occurrence of 24 Polycyclic Aromatic Hydrocarbons (PAHs) in sediments and shellfish (Anomalocardia flexuosa, Crassostrea rhizophorae, and Mytella guyanensis) of Todos os Santos bay (BTS, Brazil). Total PAHs levels ranged from 89 to 921 ng g -1 dry weight (d.w.) in sediments, and from 66 to 505 ng g -1 d.w. in shellfish, signalizing that BTS was moderately contaminated by PAHs, mostly from pyrogenic activities. The bioaccumulation factor (BAF) of total PAHs ranged from 0.20 to 2.9 and did not show a clear trend among the studied species. BAFs of high molecular weight compounds were higher for A. flexuosa (specie found buried in fine sediment), while those of low molecular weight compounds were higher for C. rhizophorae (specie found in the roots of mangrove trees). High concentrations of PAHs, especially benzo[a]pyrene and dibenzo[a,h]anthracene, suggest that contamination compromises shellfish quality and raise concern about seafood consumption safety., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Considering the large occurrence of anthropogenic Gd concentrations in natural waters, its continuous usage increase in technology developments and products and the lack of data on potential Gd human exposure due to ingestion of contaminated waters, it is urgently needed to understand how gadolinium contrast agents (Gd-CAs) reacts in the human digestive system. Here, we aimed to identify through in vitro bioaccessibility tests whether Gd-CAs can be potentially assimilated by humans after oral uptake and if there is a significant difference between contrast agents. We also roughly estimated the potential bioaccessibility of anthropogenic Gd for tap waters worldwide. Gd-CAs are highly bioaccessible (77 to 112%). The macrocyclic complexes pose the highest potential risk, because there are more stable than linear complexes in the gastrointestinal tract and, as such, tend to remain in solution and thus might bring Gd at the intestinal barrier making it potentially bioavailable. The estimated range of potential intake of Gd varied from 13 to 4839 μg in a lifespan of 70 years. The high bioaccessibility of anthropogenic Gd in tap waters calls for appropriate actions to develop better practices to treat wastewater contaminated by Gd-CAs in order to safeguard population and ecosystem health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Mangrove soils with high organic carbon (C org ) content are likely to contain C org that is vulnerable to remineralization during land use changes. Mangrove conversion to different land uses might deplete soil C org stocks causing variable carbon dioxide emissions, but the extent of these emissions and the fraction of soil C org (i.e., labile or stable/recalcitrant) that is mostly lost is poorly understood. Here, we study mangrove soil C org degradability and its susceptibility to mineralization after mangrove disturbance. We measured changes in soil properties, organic matter (OM) stability and C org pools and sources across a mangrove disturbance gradient (i.e., pristine forests, degraded mangroves receiving domestic sewage and shrimp farm effluents, and shrimp ponds). Results showed that the conversion of mangroves to shrimp ponds caused the most severe changes in soil properties, OM and C org characteristics. Shrimp pond soils contained the lowest OM-C org pools, consisted mostly of stable OM (i.e., recalcitrant and refractory; 36.0 ± 5.7% of the total OM) and enriched δ 13 C org (-22.6 ± 2.7‰). Conversely, control mangrove soils had the largest OM-C org pools consisting of a large unstable OM fraction (i.e., labile; 46.4 ± 4.2%) and lighter δ 13 C org (-26.8 ± 0.4‰) being characteristic of C org from a mangrove origin. Conversion of mangroves to shrimp ponds and its degradation by shrimp farm and domestic sewage effluents caused a loss of 97%, 61%, and 35% of soil C org stocks in the upper meter, representing potential emissions of ~1200, 800, and 400 Mg CO 2 ha -1 , respectively. These losses were explained by enhanced OM mineralization of unstable fractions driven by the loss of the physico-chemical protection provided by fine-grained soils and vegetation cover. The differences in C org stability among sites can be used to predict potential carbon dioxide produced during mineralization, hence aid at prioritizing areas for conservation, restoration or management., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The dispersion of perfluoroalkyl substances (PFAS) in surface and deep-water profiles (down to 5845 m deep) was evaluated through the Western Tropical Atlantic Ocean (TAO) between 15°N and 23°S. The sum concentrations for eight quantifiable PFAS (∑ 8 PFAS) in surface waters ranged from 11 to 69 pg/L, which is lower than previously reported in the same area as well as in higher latitudes. Perfluoroalkyl carboxylic acids (PFCAs) were the predominant PFASs present in the Western TAO. The 16 surface samples showed variable PFAS distributions, with the predominance of perfluorooctanoic acid (PFOA) along the transect (67%; 11 ± 8 pg/L) and detection of perfluoroalkyl sulfonic acids (PFSAs) only in the Southern TAO. Perfluoroheptanoic acid (PFHpA) was often detected in the vertical profiles. PFAS distribution patterns (i.e., profiles and concentrations) varied with depth throughout the TAO latitudinal sectors (North, Equator, South Atlantic, and in the Brazilian coastal zone). Vertical profiles in coastal samples displayed decreasing PFAS concentrations with increasing depth, whereas offshore samples displayed higher PFAS detection frequencies in the intermediate water masses. Together with the surface currents and coastal upwelling, the origin of the water masses was an important factor in explaining PFAS concentrations and profiles in the TAO.

This paper describes a novel method based on an ultrasound-assisted extraction microscale device (UAE-MSD) for the rapid and simultaneous determination of polycyclic aromatic hydrocarbons (PAH) and polycyclic aromatic sulfur heterocycles (PASH) in marine sediments. Solvent extraction conditions were optimized by applying a simplex-centroid mixture design. Optimum conditions were used to validate and determine the concentrations of 17 PAH and 7 PASH. The best conditions were obtained by extracting sediments with 500 µL of DCM:MeOH (65:35, v:v) over 23 min of sonication. Analytes were determined by gas chromatography/mass spectrometry in selective ion monitoring (GC-MS/SIM). Matrix effects were evaluated, and matrix-matched calibration was used for quantitation. Analytical method validation was carried out using the certified reference material NIST SRM 1941b, as well as sediment spiked with PASH at three concentration levels. Recoveries ranged between 70.0 ± 3.5% and 119 ± 9.1% for PAH and 80.6 ± 10.4% and 120 ± 10% for PASH. Linearity (R 2 ) was ≥0.99 for all compounds. Method detection limits ranged from 8.8 to 30.2 ng g -1 , while limits of quantification ranged from 29.4 to 1011 ng g -1 . UAE-MSD was applied to marine sediments exposed to different anthropogenic impacts collected in Todos os Santos Bay, Brazil. PAH concentrations ranged from -1 , while PASH levels were -1 . Dibenzothiophene was the compound presented in the highest concentration in all samples, with values up to 249 ng g -1 . The results indicated contributions of pyrogenic sources from all compounds. The developed method can potentially be applied to extract trace levels of compounds in different solid matrices to minimize extraction time and solvent consumption., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)

The biomagnification of per- and polyfluoroalkyl substances (PFASs) was investigated in a tropical mangrove food web from an estuary in Bahia, Brazil. Samples of 44 organisms (21 taxa), along with biofilm, leaves, sediment and suspended particulate matter were analyzed. Sum (∑) PFAS concentrations in biota samples were dominated by perfluorooctane sulfonate (PFOS, 93% detection frequency in tissues; 0.05 to 1.97 ng g -1 ww whole-body (wb)), followed by perfluorotridecanoate (PFTrDA, 57%; 0.01 to 0.28 ng g -1 ww wb). PFOS precursors such as perfluorooctane sulfonamide (FOSA, 54%; 0.01 to 0.32 ng g -1 ww wb) and N-ethyl perfluorooctane sulfonamide (EtFOSA; 30%; 0.01 to 0.21 ng g -1 ww wb) were also detected. PFAS accumulation profiles revealed different routes of exposure among bivalve, crustacean and fish groups. Statistics for left-censored data were used in order to minimize bias on trophic magnification factors (TMFs) calculations. TMFs >1 were observed for PFOS (linear + branched isomers), EtFOSA (linear + branched isomers), and perfluorononanoate (PFNA), and in all cases, dissimilar accumulation patterns were observed among different trophic positions. The apparent biodilution of some long-chain PFCAs through the food chain (TMF < 1) may be due to exposure from multiple PFAS sources. This is the first study investigating bioaccumulation of PFASs in a tropical food web and provides new insight on the behavior of this ubiquitous class of contaminants., Competing Interests: Declaration of competing interest There are no conflicts of interest to declare., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Many hypotheses have been raised about the controls of the distribution and fractionation of the rare earth elements (REE) in coastal ecosystems. Here, REE were measured in estuarine sediments and in six mangrove soil profiles along the estuarine salinity gradient of the Jaguaripe estuary, northeastern Brazil. The aim of this study was to evaluate the fractionation, distribution, remobilization, and possible sources of these elements. The ΣREE and Y in oxic estuarine sediments ranged from 202 to 220 mg kg -1 and from 12 to 15 mg kg -1 , respectively. The normalized abundances to the Post Archean Australian Shale (PAAS) showed that light REE (LREE; La, Ce, Pr, and Nd) were consistently enriched over heavy REE (HREE; Er, Tm, Yb, and Lu). Among the REE, only LREE showed significant correlation with Al (r = 0.85) and Fe (r = 0.96) indicating that Al and Fe oxy-hydroxides are the main host phases of the LREE in estuarine sediments. The average ΣREE for mangrove soils throughout the salinity gradient ranged from 161 ± 18 mg kg -1 (lower estuary) to 183 ± 16 mg kg -1 (upper estuary). Al-normalized Mn and Fe concentrations showed small peaks down-core, indicating diagenetic remobilization. Vertical REE profiles have shown that post-deposition processes might contribute to the patterns in the abundances of the ΣREE and their fractionation at the surface and subsurface mangrove soils. Below the top 15 cm, diagenetic alteration after burial is not leading to substantial variation in the LREE/HREE profiles. The coincidence of peaks in individual REE/Al down core along with Fe and Mn peaks reflects the participation of the REE in early diagenesis. The REE abundances observed here corroborate to the characterization of the Jaguaripe estuary as a pristine system and can be used as a background for the region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

We present an assessment on the sediment flux caused by the tailing dam failure at Mariana, Minas Gerais Estate, Brazil. Field data of water level, water flow, and suspended sediment concentrations (SSCs) were obtained during the period from 21 November to 5 December 2015, when the muddy waters reached the coast. A rating curve of the coastal tidal signal was built, allowing a robust estimate of the flow at the mouth of the Doce River. Together with SSC data, early sediment delivered to the coastal sea was of 15 × 104 t, what may account for only 0.5% of the total material remobilized at the accident site. This accounted for >25 000 t of Fe and between 1 and 4 t of other trace metals, such as Co, Ni, and Zn. Integr Environ Assess Manag 2020;16:661-668. © 2020 SETAC., (© 2020 SETAC.)

The aim of the present study was to evaluate the presence of polycyclic aromatic hydrocarbons (PAHs) in oysters (Crassostrea rhizophorae) collected from Todos os Santos Bay (Bahia, Brazil). The total PAH concentration was highest in Madre de Deus (36.3 to 37.8 ng g -1 in dry weight, dw), which is located near a petrochemical complex, oil refinery, and commercial port. In the Paraguaçu river estuary, PAH concentrations varied between 23.2 and 25.7 ng g -1 dw. The lowest concentrations (1.55 ng g -1 dw) were found in the Jaguaribe river estuary, which can be considered a relatively preserved area. The main source of PAHs in the study areas was observed to be pyrogenic. Values of benzo[a]pyrene toxic equivalent ranged from 0.28 to 4.20. The concentrations of PAHs in oysters from the Paraguaçu river estuary and in Madre de Deus indicate the possible lifetime risk of developing cancer in humans who feed on it., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)