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There is a current interest in the study of the geochemical behavior of the rare earth elements (REE) in aquatic systems since their identification as potential microcontaminants in natural waters. In this context, here we report the concentrations and patterns of dissolved REE (dREE) in the waters of the Gulf of Cádiz (GoC) and its major estuaries (Guadiana, Tinto-Odiel and Guadalquivir). Contamination in this area by metals has been extensively reported, linked to acid-mine inputs resulting from the mineralization of the Iberian Pyrite Belt, discharged mainly to the Tinto-Odiel river. However, the impact of these inputs on the concentrations and distribution of the dREE in the coastal waters of the GoC has not been addressed yet. Accordingly, elevated concentrations of dREE were obtained in the Tinto-Odiel estuary compared to the Guadiana and Guadalquivir, reflecting the impact of acid-mine drainage on this system. Only a significant fraction of anthropogenic gadolium (Gd) was observed in the Guadalquivir estuary, as a result of the input from major urban areas, where anthropogenic Gd fractions higher than 70% over the total dissolved pool were obtained for the freshwater end-member. Regarding the surface waters of the GoC, typical NE Atlantic distribution patterns of dREEs were obtained, but modified by two different end-members within this region. Accordingly, and despite the low water discharge of the Tinto-Odiel river, its elevated concentrations lead to an increase in the concentrations of dREEs in the nearshore waters of the GoC and producing a distinctive signature as observed for the MREE anomalies and HREE/LREE ratios. At the easternmost stations, close to the Strait of Gibraltar, these signals are also impacted by the inflow of Mediterranean waters and also by the discharge of the Guadalquivir river.

Cu is a vital micronutrient, but free Cu ions (Cu2+) in seawater, even at subnanomolar concentrations, can impede phytoplankton growth. Natural Cu complexation with organic ligands regulates Cu acquisition and, in most instances, reduces Cu2+ concentrations below toxic thresholds. Along the Antarctic coast, the sources and sinks of Cu and its associated ligands remain poorly defined. Despite the high productivity in the area, there are no studies on the role of trophic transfer in Cu cycling. This study explores penguin guano release of Cu and Cu ligands and its potential in neutralizing copper toxicity along the Antarctic coast. We collected guano in a Chinstrap penguin nesting location in the West coast of Deception Island and extracted its components into aqueous solution imitating natural processes. Copper concentration in guano was 0.4 mg (dry weight g)−1 constituting a potential toxic threat and showed biomagnification with respect to krill. Surface seawater samples collected from various locations varying in penguin activity, were analyzed to assess the potential influence of guano on the area. Visual examination and elevated levels of Al suggested that a substantial portion of guano was lithogenic. Consequently, only a modest 16 % of the total Cu present in guano could be extracted using mechanical methods. Notably, the concentrations of the extracted organic ligands were approximately 23 times higher than the concentrations of the extracted Cu. This significant presence of ligands effectively nullifies any potential toxicity that could have arisen from free Cu2+ ions. Guano ligands' conditional stability constants were lower than those in surface seawater suggesting phytoplankton exudation was the main ligand source in the area. Overall, guano acts as a key node for Cu cycling in coastal Antarctic waters but its deleterious potential is neutralized by ligands from krill digestion and the high background concentration of phytoplankton exudates.

Aquatic ecosystems are crucial in preserving biodiversity, regulating biogeochemical cycles, and sustaining human life; however, their resilience against climate change and anthropogenic stressors remains poorly understood. Recently, unmanned aerial vehicles (UAVs) have become a vital monitoring tool, bridging the gap between satellite imagery and ground-based observations in coastal and marine environments with high spatial resolution. The dynamic nature of water surfaces poses a challenge for photogrammetric techniques due to the absence of fixed reference points. Addressing these issues, this study introduces an innovative, efficient, and accurate workflow for georeferencing and mosaicking that overcomes previous limitations. Using open-source Python libraries, this workflow employs direct georeferencing to produce a georeferenced orthomosaic that integrates multiple UAV captures, and this has been tested in multiple locations worldwide with optical RGB, thermal, and multispectral imagery. The best case achieved a Root Mean Square Error of 4.52 m and a standard deviation of 2.51 m for georeferencing accuracy, thus preserving the UAV’s centimeter-scale spatial resolution. This open-source workflow represents a significant advancement in the monitoring of marine and coastal processes, resolving a major limitation facing UAV technology in the remote observation of local-scale phenomena over water surfaces.

There is a current interest in the study of the geochemical behavior of the rare earth elements (REE) in aquatic systems since their identification as potential microcontaminants in natural waters. In this context, here we report the concentrations and patterns of dissolved REE (dREE) in the waters of the Gulf of Cádiz (GoC) and its major estuaries (Guadiana, Tinto-Odiel and Guadalquivir). Contamination in this area by metals has been extensively reported, linked to acid-mine inputs resulting from the mineralization of the Iberian Pyrite Belt, discharged mainly to the Tinto-Odiel river. However, the impact of these inputs on the concentrations and distribution of the dREE in the coastal waters of the GoC has not been addressed yet. Accordingly, elevated concentrations of dREE were obtained in the Tinto-Odiel estuary compared to the Guadiana and Guadalquivir, reflecting the impact of acid-mine drainage on this system. Only a significant fraction of anthropogenic gadolium (Gd) was observed in the Guadalquivir estuary, as a result of the input from major urban areas, where anthropogenic Gd fractions higher than 70% over the total dissolved pool were obtained for the freshwater end-member. Regarding the surface waters of the GoC, typical NE Atlantic distribution patterns of dREEs were obtained, but modified by two different end-members within this region. Accordingly, and despite the low water discharge of the Tinto-Odiel river, its elevated concentrations lead to an increase in the concentrations of dREEs in the nearshore waters of the GoC and producing a distinctive signature as observed for the MREE anomalies and HREE/LREE ratios. At the easternmost stations, close to the Strait of Gibraltar, these signals are also impacted by the inflow of Mediterranean waters and also by the discharge of the Guadalquivir river

Remote-sensing ocean colour studies have already been used to determine coastal water quality, coastal biodiversity, and nutrient availability. In recent years, Unmanned Aerial Vehicles (UAVs) equipped with multispectral sensors, originally designed for agriculture applications, have also enabled water-quality studies of coastal waters. However, since the sea surface is constantly changing, commonly used photogrammetric methods fail when applied to UAV images captured over water areas. In this work, we evaluate the applicability of a five-band multispectral sensor mounted on a UAV to derive scientifically valuable water parameters such as chlorophyll-a (Chl-a) concentration and total suspended solids (TSS), including a new Python workflow for the manual generation of an orthomosaic in aquatic areas exclusively based on the sensor’s metadata. We show water-quality details in two different sites along the Maltese coastline on the centimetre-scale, improving the existing approximations that are available for the region through Sentinel-3 OLCI imagery at a much lower spatial resolution of 300 m. The Chl-a and TSS values derived for the studied regions were within the expected ranges and varied between 0 to 3 mg/m3 and 10 to 20 mg/m3, respectively. Spectral comparisons were also carried out along with some statistics calculations such as RMSE, MAE, or bias in order to validate the obtained results.

This study reports the only recent characterization of two contrasted wet deposition events collected during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean Sea) cruise in the open Mediterranean Sea (Med Sea) and their impact on trace metal (TM) marine stocks. Rain samples were analysed for Al, 12 TMs (Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrient (N, P, dissolved organic carbon) concentrations. The first rain sample collected in the Ionian Sea (Rain ION) was a typical regional background wet deposition event, whereas the second rain sample collected in the Algerian Basin (Rain FAST) was a Saharan dust wet deposition event. Even in the remote Med Sea, all background TM inputs presented an anthropogenic signature, except for Fe, Mn and Ti. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, due to the decrease in anthropogenic emissions during the preceding decades. The atmospheric TM inputs were mainly dissolved forms, even in dusty Rain FAST. The TM stocks in the mixed layer (ML, 0–20 m) at the FAST station before and after the event showed that the atmospheric inputs were a significant supply of particulate TMs and dissolved Fe and Co for surface seawater. Even if the wet deposition delivers TMs mainly in soluble form, the post-deposition aerosol dissolution could to be a key additional pathway in the supply of dissolved TMs. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as ML stocks for dissolved Fe, Co and Zn, highlighting the role of the atmosphere in their biogeochemical cycles in the stratified Med Sea. In case of intense dust-rich wet deposition events, the role of atmospheric inputs as an external source was extended to dissolved Co, Fe, Mn, Pb and Zn. Our results suggest that the wet deposition constitutes only

The volcanic eruption that occurred in La Palma Island (Canary Islands, Spain) in 2021 resulted in molten lava flowing into the ocean and forming a delta in the coastline, besides the emission of large amounts of ashes being deposited in a vast area around the Canary Islands. In order to assess the effects of the eruption on seawater, two oceanographic cruises were carried out, one at the beginning of the eruption and a second one a month later. We used an oceanographic CTD rosette sampler for collecting seawater in different areas of La Palma coastline together with Unmanned Aerial Vehicles (UAVs) equipped with a sampling device to collect surface samples near the delta newly formed on the coastal fringe. We sequenced the 16S rRNA gene in order to assess the response of bacterioplankton to such natural disturbance. The results show that the abundance of Thiomicrospirales, Gammaproteobacteria capable of oxidizing poly-metal sulfides, increased significantly in UAV samples collected near the lava delta. Moreover, in stations where the largest physical-chemical anomalies were recorded with the CTD, sequence data showed drastic changes in the prokaryotic community structure; cyanobacterial abundance decreased while the ammonia-oxidizing archeon Nitrosopelagicus and the bacterial SAR324 clade, with potential sulfur-based chemolithoautotrophic lifestyle, dominated the communities. The combined used of shipboard operations and UAVs provided a unique opportunity to study the prokaryotic response to a massive lava input, an event that is rarely observed and sampled in real time.

Iron plays a crucial role in the high-nutrient, low-chlorophyll Southern Ocean regions, promoting phytoplankton growth and enhancing atmospheric carbon sequestration. In this area, iron-rich Antarctic krill (Euphausia superba) and baleen whale species, which are among their main predators, play a large role in the recycling of iron. However, penguins have received limited attention despite their representing the largest seabird biomass in the southern polar region. Here, we use breeding site guano volumes estimated from drone images, deep learning-powered penguin census, and guano chemical composition to assess the iron export to the Antarctic waters from one of the most abundant penguin species, the Chinstrap penguin (Pygoscelis antarcticus). Our results show that these seabirds are a relevant contributor to the iron remobilization pool in the Southern Ocean. With an average guano concentration of 3 mg iron g-1, we estimate that the Chinstrap penguin population is recycling 521 tonnes iron yr-1, representing the current iron contribution half of the amount these penguins were able to recycle four decades ago, as they have declined by more than 50% since then.

This study was conducted to address the changes in the surface distribution of trace metals (cobalt, copper, iron, cadmium, nickel, zinc, lead and molybdenum) as they are advected from the Gulf of Cadiz to the Alboran Sea, through the Strait of Gibraltar (south Iberian Peninsula), regions of great ecosystemic importance. Trace metals concentrations were measured in samples collected during two oceanographic cruises, together with the main factors affecting their spatial distribution and temporal variability (i.e., wind and surface currents). Several rivers, the main source of trace metals in this region, flow into the Gulf of Cadiz which is connected with the Alboran Sea through the Strait of Gibraltar by the general circulation pattern. The surface circulation pattern leads to an offshore-eastward gradient that is highly influenced by wind variability. An increase in vertical turbulence induced by the winds or the tidal cycle causes the dilution of trace metals' concentration by mixing rich-metal superficial waters with poor-metal subsurface waters. Additionally, along the eastward displacement of surface waters, several water retention zones have been described (Trafalgar, Camarinal, the Coastal Cyclonic Gyre) that imply an increase in trace metals concentration close to the coast. In addition, our results suggest that the coastal edges of the Strait of Gibraltar also act as a source of certain metals to the Alboran Sea, probably due to the industries in the proximity areas.

The Gulf of Mexico (GoM) is one of the most dynamic marginal seas in the world owing to the intrusion of the Loop Current and the shedding of anticyclonic eddies (LCE) that travel westward across the Gulf. However, the impacts of these mesoscale dynamics on the supply and removal of bioessential trace metals in surface waters remain unclear. We study the impact of mesoscale eddies on the distribution of dissolved nickel (Ni), a biologically active element scarcely studied in the region. The vertical distribution of Ni was determined in the deep-water region of the GoM during summer of 2017, when two anticyclonic LCE (Quantum and Poseidon) were present. Nutrient-like profiles of Ni in the GoM resemble those from the Atlantic Ocean, but they showed high spatial variability within the first 1000 m, which was associated with the impact of mesoscale eddies. Similarly to subtropical gyres, macronutrients were almost depleted in surface waters, while Ni never fell below 1.51 nmol kg-1, suggesting low Ni lability or alternatively, slow biological uptake compared to that of macronutrients. In particular, lowest levels of Ni and macronutrients (PO4 and NO3) were recorded in surface waters of the anticyclonic eddies and the Loop Current area. Anticyclonic LCEs deepened these Ni-poor waters pushing the Ni-rich core of Tropical Atlantic Central Water up to 600 m, whereas its shallowest position (up to 200 m) was recorded under cyclonic conditions in Campeche Bay. This eddy-induced vertical displacement of water masses also affected the integrated Ni and macronutrient concentrations in the upper 350 m but without modifying their stoichiometries. We suggest that a significant decrease in surface inventories of Ni and macronutrient in areas impacted by LCEs is a consequence of the trapping of the water within eddies, the biological uptake of Ni and macronutrients combined with their limited replenishment from below, which likely affects autotrophic groups. In conclusion, the mesosc

Surgical face masks are more present than ever as personal protective equipment due to the COVID-19 pandemic. In this work, we show that the contents of regular surgical masks: i) polypropylene microfibres and ii) some added metals such as: Al, Fe, Cu, Mn, Zn and Ba, may be toxic to some marine life. This work has got two objectives: i) to study the release rate of the products from face masks in marine water and ii) to assess the toxicity in Phaeodactylum tricornutum of these by-products. To achieve these two objectives, we performed release kinetic experiments by adding masks in different stages of fragmentation to marine water (i.e. whole face masks and fragments of them 1.52 ± 0.86 mm). Released microfibres were found after one month in shaking marine water; 0.33 ± 0.24 and 21.13 ± 13.19 fibres·mL−1 were collected from the whole and fragmented face masks, respectively. Significant amounts of dissolved metals such as Mn, Zn and Ni, as well as functional groups only in the water containing the face mask fragments were detected. Water from both treatments was employed to study its toxicity on the marine diatom. Only the water from the face mask fragments showed a significant, dose-dependent, decrease in cell density in P. tricornutum; 53.09 % lower than in the controls. Although the water from the face mask fragments showed greater effects on the microalgae population than the water from the whole face mask, the latter treatment did show significant changes in the photosynthetic apparatus and intrinsic properties of the cells. These results indicate that during fragmentation and degradation face masks a significant chemical print can be observed in the marine environment., Marta Sendra wishes to acknowledge her contract Juan de la Cierva Incorporación (IJC2020-043162-I) funded by MCIN/AEI/10.13039/ 501100011033 and European Union NextGenerationEU/PRTR. Dr. Araceli Rodríguez-Romero is supported by the Spanish grant Juan de la Cierva Incorporación referenced as IJC2018–037545-I.

This textbook offers a comprehensive and authoritative introduction to the latest analytical methods, tools and techniques used in the marine environment, bringing together the two fields of chemical oceanography and analytical chemistry. Divided into 11 chapters, the book starts with an overview of the main parameters of the marine carbon system, and it covers different sampling strategies used by the marine scientific community, and the different chemical analyses to measure trace metals, radionuclides and organic matter in the marine environment. Particular attention is given to the identification and quantification of marine persistent organic pollutants, emerging organic contaminants and microplastics. Readers will also find accessible explanations and real life examples of the application of remote sensing and in-situ sensing technologies to monitor the marine environment. The textbook finishes with a chapter on data treatment that outlines the relevant statistical approaches, uncertainty estimation and quality assurance of marine chemical measurements. This textbook provides both students and professionals alike with a transdisciplinary and comprehensive foundation for the chemical analysis of our oceans and seas.

Penguin colonies significantly influence the distribution and diversity of vegetation communities in Maritime Antarctica, as they serve as vital sources of nutrients for both terrestrial and aquatic ecosystems. Remote sensing techniques are becoming increasingly common for monitoring these vast Antarctic areas, especially with Unmanned Aerial Vehicles (UAVs) imagery, which provides the highest spatial resolutions to date. In fact, the use of hyperspectral (HS) sensors is crucial for accurately identifying and distinguishing between the main ground characteristics and vegetation communities in an Antarctic penguin colony, making this study one of the first UAV-based HS approaches to our knowledge. Consequently, this study provides a spectral library covering the entire spectral range from 400 to 2500 nm for the five main vegetation communities found at Hannah Point penguin colony (Livingston Island, Antarctica). Through this library, two valuable wavelength regions have been identified for distinguishing these communities based on pigments composition, specifically in the green (495–570 nm) and near-infrared (800–900 nm) ranges, that served as a reference for validating the results using 35 ground reference spectrometry data collected in 1667 wavelength bands within the 320–876 nm range. In addition, the supervised classification approach known as the “Spectral Angle Mapper” has been employed to monitor the coverage of each vegetation community based on the information provided by the aforementioned spectral library. The observed ecological gradient, which reveals an increase in vegetation complexity away from the high-nutrient content guano areas, highlights the influence of guano on the distribution of the main vegetation patterns across the entire penguin colony. The results of this study could serve as a reference point for more sophisticated research involving the use of UAV-based HS or MS sensors in Antarctica, offering unique opportunities to detect small vari

This campaign report collects the orthomosaics generated with the images obtained from Unmanned Aerial Vehicles (UAV) during the XXXIV Spanish Antarctic Campaign in Deception Island (South Shetlands Islands, Antarctica) as part of the PiMetAn polar project (Ref RTI2018-098048-B-100). PiMetAn Project (http://pimetan.csic.es/) aims to evaluate the role of penguins in the biogeochemical cycles of trace elements in Antarctica and their effects on the Antarctic ecosystem. To achieve this, the Project includes, among many other activities, the use of different sensors boarded on UAVs to characterize and monitoring the regions of study. Thus, a total 42 UAV flights were carried out in different areas of Deception Island: Antarctic Spanish Base (BAE) Gabriel de Castilla, Vapour Col penguin colony, Baily Head penguin colony, Fumarole Bay, Murature’s region, Crater and Irizar lakes. The equipment used to collect the images were: these flights consists of the following UAVs and sensors: (1) Hexacopter (Condor, Dronetools ©) with three-bladed propellers with DJI6010 brushless type electric motor (130 kv) The drone could be equipped with the Micasense RedEdge-MX dual 10-band multispectral sensor, the FLIR Vue Pro R thermal camera, the Zenmuse Z30 video camera and the Alpha Sony 6000 RGB camera; (2) Quadcopter (Mavic 2 Pro, DJI ©) with integrated RGB sensor (Hasselblad Camera); and (3) Quadcopter (Phantom 4 Multispectral:P4M, DJI ©) with an integrated 5-band multispectral camera. After images were collected, orthomosaics was generated using the Pix4D Mapper software (Pix4D SA, Lausanne Switzerland).

The redox speciation of iron was determined during the iron fertilization LOHAFEX and for the first time, the chemiluminescence assay of filtered and unfiltered samples was systematically compared. We hypothesize that higher chemiluminescence in unfiltered samples was caused by Fe(II) adsorbed onto biological particles. Dissolved and particulate Fe(II) increased in the mixed layer steadily 6-fold during the first two weeks and decreased back to initial levels by the end of LOHAFEX. Both Fe(II) forms did not show diel cycles downplaying the role of photoreduction. The chemiluminescence of unfiltered samples across the patch boundaries showed strong gradients, correlated significantly to biomass and the photosynthetic efficiency and were higher at night, indicative of a biological control. At 150 m deep, a secondary maximum of dissolved Fe(II) was associated with maxima of nitrite and ammonium despite high oxygen concentrations. We hypothesize that during LOHAFEX, iron redox speciation was mostly regulated by trophic interactions.

his study reports the only recent characterisation of two contrasted wet deposition events collected during the PEACETIME cruise in the Mediterranean open seawater, and their impact on trace metals (TMS) marine stocks. Rain samples were analysed for Al, 12 trace metals (TMs hereafter, including Co, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V and Zn) and nutrients (N, P, DOC) concentrations. The first rain sample collected in the Ionian Sea (rain ION) was a wet typical regional background deposition event whereas the second rain collected in the Algerian Basin (rain FAST) was a Saharan dust wet deposition. The concentrations of TMs in the two rain samples were significantly lower compared to concentrations in rains collected at coastal sites reported in the literature, suggesting either less anthropogenic influence in the remote Mediterranean environment, or decreased emissions during the last decades in the Mediterranean Sea. The TMs inventories in the surface microlayer and mixed layer (0–20 m) at ION and FAST stations before and after the events, compared to atmospheric fluxes, showed that the atmospheric inputs were a significant source of particulate TMs for both layers. At the scale of the western and central Mediterranean, the atmospheric inputs were of the same order of magnitude as marine stocks within the ML for dissolved Fe, Co and Zn, underlining the role of the atmosphere in their biogeochemical cycle in the stratified Mediterranean Sea. In case of intense wet dust deposition event, the contribution of atmospheric inputs could be critical for dissolved stocks of the majority of TMs.

This study was conducted to address the changes in the surface distribution of trace metals (cobalt, copper, iron, cadmium, nickel, zinc, lead and molybdenum) as they are advected from the Gulf of Cadiz to the Alboran Sea, through the Strait of Gibraltar (south Iberian Peninsula), regions of great ecosystemic importance. Trace metals concentrations were measured in samples collected during two oceanographic cruises, together with the main factors affecting their spatial distribution and temporal variability (i.e., wind and surface currents). Several rivers, the main source of trace metals in this region, flow into the Gulf of Cadiz which is connected with the Alboran Sea through the Strait of Gibraltar by the general circulation pattern. The surface circulation pattern leads to an offshore-eastward gradient that is highly influenced by wind variability. An increase in vertical turbulence induced by the winds or the tidal cycle causes the dilution of trace metals' concentration by mixing rich-metal superficial waters with poor-metal subsurface waters. Additionally, along the eastward displacement of surface waters, several water retention zones have been described (Trafalgar, Camarinal, the Coastal Cyclonic Gyre) that imply an increase in trace metals concentration close to the coast. In addition, our results suggest that the coastal edges of the Strait of Gibraltar also act as a source of certain metals to the Alboran Sea, probably due to the industries in the proximity areas., Firstly, we would like to thank the two anonymous reviewers for their thoughtful comments and efforts towards improving our manuscript. The authors gratefully acknowledge the crew and technical staff of the R.V. Sarmiento de Gamboa and R.V. Ángeles Alvariño for their help during the cruises, and scientific teams of MEGAN and MEGOCA projects. Authors also gratefully acknowledge the Spanish Puertos del Estado for the freely available datasets: High-Frequency Radar daily observations and SAMPA numerical simulations that were collected from their Institution's website (http://opendap.puertos.es/), and Copernicus Marine Service for the Chlorophyll-a satellite imagery used in this work (OCEANCOLOUR_ATL_CHL_L4_NRT_OBSERVATIONS_009_037). This work has been supported by the Spanish National Research Plan through the projects: CTM2013-49048 (MEGAN), CTM2014-59244-C3-3-R (MEGOCA), and STOCA (Instituto Español de Oceanografía). M. Andrea Orihuela-García is supported by a grant from the FPI fellowship program. Marina Bolado-Penagos and Iria Sala were supported by a grant from the FPI fellowship program, in Spain., Peer Reviewed, Postprint (published version)