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Although microbial degradation is a key sink of polycyclic aromatic hydrocarbons (PAH) in surface seawaters, there is a dearth of field-based evidences of regional divergences in biodegradation and the effects of PAHs on site-specific microbial communities. We compared the magnitude of PAH degradation and its impacts in short-term incubations of coastal Mediterranean and the Maritime Antarctica microbiomes with environmentally relevant concentrations of PAHs. Mediterranean bacteria readily degraded the less hydrophobic PAHs, with rates averaging 4.72 ± 0.5 ng L h-1. Metatranscriptomic responses showed significant enrichments of genes associated to horizontal gene transfer, stress response, and PAH degradation, mainly harbored by Alphaproteobacteria. Community composition changed and increased relative abundances of Bacteroidota and Flavobacteriales. In Antarctic waters, there was no degradation of PAH, and minimal metatranscriptome responses were observed. These results provide evidence for factors such as geographic region, community composition, and pre-exposure history to predict PAH biodegradation in seawater.

Background and chronic pollution by organic pollutants (OPs) is a widespread threat in the oceans with still uncharacterized effects on marine ecosystems and the modulation of major biogeochemical cycles. The ecological impact and toxicity of this anthropogenic dissolved organic carbon (ADOC) is not related to the presence of a single compound but to the co-occurrence of a myriad of synthetic chemicals with largely unknown effects on heterotrophic microbial communities. We have analyzed the metabolic capacity of metagenome-assembled genomes (MAGs) of natural oceanic communities from the north Pacific (Costa Rica dome) and Atlantic oceans challenged with environmentally relevant levels of ADOC. In the Atlantic, ADOC-exposed MAGs responded transcriptionally more strongly compared to controls than in the Pacific, possibly mirroring the higher relevance of ADOC compounds as carbon source in oligotrophic environments. The largest proportions of transcripts originated from MAGs belonging in the families Rhodobacteraceae and Flavobacteriaceae, known to play a role on consumption of several OPs. In the Atlantic, archaeal Poseidoniales showed the highest transcription levels after 2 h of ADOC exposure, although no increase of relative abundances in the DNA pool was recorded after 24 h, whereas Methylophaga showed the opposite pattern. Both taxa are suggested to be actively involved in the consumption of biogenic alkanes produced by cyanobacteria. We observed similar gene expression profiles of alkane degradation and methylotrophy signature genes. These findings, plus the chemical degradation of alkanes measured in the experiments, provides experimental evidence of the consumption of anthropogenic hydrocarbons and synthetic chemicals at the low concentrations found in the ocean, and modulation of microbiomes by ADOC.

The sources, biogeochemical controls and sinks of perfluoroalkyl substances, such as perfluoroalkyl acids (PFAAs), in polar coastal regions are largely unknown. These were evaluated by measuring a large multi-compartment dataset of PFAAs concentrations at coastal Livingston and Deception Islands (maritime Antarctica) during three austral summers. PFAAs were abundant in atmospheric-derived samples (aerosols, rain, snow), consistent with the importance of atmospheric deposition as an input of PFAAs to Antarctica. Such PFAAs deposition was unequivocally demonstrated by the occurrence of PFAAs in small Antarctic lakes. Several lines of evidence supported the relevant amplification of PFAAs concentrations in surface waters driven by snow scavenging of sea-spray aerosol-bound PFAAs followed by snow-melting. For example, vertical profiles showed higher PFAAs concentrations at lower-salinity surface seawaters, and PFAAs concentrations in snow were significantly higher than in seawater. The higher levels of PFAAs at Deception Island than at Livingston Island are consistent with the semi-enclosed nature of the bay. Concentrations of PFOS decreased from 2014 to 2018, consistent with observations in other oceans. The sink of PFAAs due to the biological pump, transfer to the food web, and losses due to sea-spray aerosols alone are unlikely to have driven the decrease in PFOS concentrations. An exploratory assessment of the potential sinks of PFAAs suggests that microbial degradation of perfluoroalkyl sulfonates should be a research priority for the evaluation of PFAAs persistence in the coming decade.

The temporal trend of polycyclic aromatic hydrocarbons (PAHs) in coastal waters with highly dynamic sources and sinks is largely unknown, especially for polar regions. Here, we show the concurrent measurements of 73 individual PAHs and environmental data, including the composition of the bacterial community, during three austral summers at coastal Livingston (2015 and 2018) and Deception (2017) islands (Antarctica). The Livingston 2015 campaign was characterized by a larger snow melting input of PAHs and nutrients. The assessment of PAH diagnostic ratios, such as parent to alkyl-PAHs or LMW to HMW PAHs, showed that there was a larger biodegradation during the Livingston 2015 campaign than in the Deception 2017 and Livingston 2018 campaigns. The biogeochemical cycling, including microbial degradation, was thus yearly dependent on snow-derived inputs of matter, including PAHs, consistent with the microbial community significantly different between the different campaigns. The bivariate correlations between bacterial taxa and PAH concentrations showed that a decrease in PAH concentrations was concurrent with the higher abundance of some bacterial taxa, specifically the order Pseudomonadales in the class Gammaproteobacteria, known facultative hydrocarbonoclastic bacteria previously reported in degradation studies of oil spills. The work shows the potential for elucidation of biogeochemical processes by intensive field-derived time series, even in the harsh and highly variable Antarctic environment.

The occurrence, long-range atmospheric transport and deposition of micro and nano plastics (MNPLs) remains un-quantified for the oceanic atmosphereopen ocean. Here we show the characterisation of MNPLs and the aerosol composition (PM10) in a north-south Atlantic transect from Vigo (Spain) to Punta Arenas (Chile). The analytical procedure to assess the composition of MNPLs consisted of a double suspect screening approach of the polymers and additives, the two constituents of plastics. Polymers were analysed by size exclusion chromatography coupled with high-resolution mass spectrometry using an atmospheric pressure photoionization source operated in positive and negative conditions (HPLC(SEC)-APPI(+/-)-HRMS). Plastic additives were screened with high-performance liquid chromatography coupled to high-resolution mass spectrometry using an electrospray ionisation source (HPLC-ESI(+/-)-HRMS). The most common polymers were polyethylene (PE), polypropylene (PP), polyisoprene (PI), and polystyrene (PS), with the highest polymer concentration being 51.7 ng·m-3 of PI. The air mass back trajectories showed the variable influence of oceanic and terrestrial air masses. These differences were reflected in the aerosol composition with different contributions of Saharan dust, sea spray aerosol, organic/elemental carbon, and MNPLs. Results showed that samples largely influenced by sea-spray and air masses originating from coastal South America and the north Atlantic subtropical gyre were more contaminated by MNPLs. Moreover, this information was complemented by the characterisation of the largest particles using scanning electron microscopy (SEM) and µ-Fourier Transform Infrared Spectroscopy (µ-FTIR). This work provides the first field evidence of the long-range transport of MNPLs in most of the Atlantic Ocean, as the result of dynamic coupling between the lower atmosphere and the surface ocean. Sea-spray formation arises as a key driver for the aerosolisation of MNPLs, and atmosphe

Small phytoplankton is a fundamental part of the Antarctic marine ecosystem, in particular for its role in carbon fixation and the trophic web. Despite its importance in the carbon cycle, there is a lack of high-resolution datasets of its temporal and spatial abundance, size and phenotypic diversity. Here we present high-frequency flow-cytometry data of total small phytoplankton collected from surface waters during the ANTOM2 cruise, which sailed through the Bransfield Strait and Bellingshausen Sea during austral summer 2021-2022. The cruise consisted on a north-south transect along the Antarctic peninsula coast and a second south-north transect along the edge of the continental shelf. Seawater was taken by a faucet linked to a continuum seawater pump (5 m depth) with an automatic sampler connected to a flow-cytometer that sampled every 15 minutes during two weeks yielding a total of 1250 samples. Total phytoplankton abundance ranged between 102 and 104 cells·ml-1; with higher values along the coast. The optical properties of each single cell (light scatter and pigment fluorescence), which are considered phenotypic attributes, were used to estimate phenotypic diversity using computational cytometry bioinformatic tools. Phenotypic alpha diversity varied throughout the entire cruise and peaked at port Foster (Deception Island), the site with the lowest abundances of small phytoplankton. Similarity among stations (beta-diversity) was well explained by salinity. As far as we know, this is the first study using this spatial and temporal resolution in the maritime Antarctica

Climate change brings about significant changes in the physical environment in the Arctic. Increasing temperatures, sea ice retreat, slumping permafrost, changing sea ice regimes, glacial loss and changes in precipitation patterns can all affect how contaminants distribute within the Arctic environment and subsequently impact the Arctic ecosystems. In this review, we summarized observed evidence of the influence of climate change on contaminant circulation and transport among various Arctic environment media, including air, ice, snow, permafrost, fresh water and the marine environment. We have also drawn on parallel examples observed in Antarctica and the Tibetan Plateau, to broaden the discussion on how climate change may influence contaminant fate in similar cold-climate ecosystems. Significant knowledge gaps on indirect effects of climate change on contaminants in the Arctic environment, including those of extreme weather events, increase in forests fires, and enhanced human activities leading to new local contaminant emissions, have been identified. Enhanced mobilization of contaminants to marine and freshwater ecosystems has been observed as a result of climate change, but better linkages need to be made between these observed effects with subsequent exposure and accumulation of contaminants in biota. Emerging issues include those of Arctic contamination by microplastics and higher molecular weight halogenated natural products (hHNPs) and the implications of such contamination in a changing Arctic environment is explored.

Increasing amounts of organic synthetic chemicals are currently emitted to the environment by human activities. The more recalcitrant fraction of this pollutant mixture reaches marine ecosystems mainly through rivers, continental run-off, and diffuse atmospheric inputs. Once in seawater, it represents the anthropogenic fraction of the dissolved organic carbon (ADOC) pool. However, the total amount of ADOC is unknown, while its effects to ecosystems and detailed composition is largely unknown. Over the past decades, the scientific research effort has focused on the effects of organic pollutants (OPs) in marine biota, especially in oil spills events or under toxicological testing in laboratories, neglecting the importance of the chronic pollution perturbation of the biosphere composition caused by diffusive inputs of large number of pollutants at low concentrations. Our aim was to combine functional genomic tools with quantitative biogeochemical approaches under manipulated conditions to determine the bidirectional interaction between marine microbial community structure and function and the ADOC present in coastal seawater. Additionally, it was also intended to perform similar experiments in areas with diverse environmental conditions to elucidate the role of the trophic conditions and levels of pollutants in the response. In order to fulfil the proposed objectives, several OP amendment experiments were performed with different OP additions and contrasted seawater from the North-Western Mediterranean, the Arctic and the Antarctic. On the one hand, the effect caused by 4 families of pollutants individually (alkanes, polycyclic aromatic hydrocarbons, organophosphate esters and perfluoroalkyl substances (PFAS)) was tested in 5 marine bacterial communities of the NW Mediterranean, and the specific effect of perfluorooctanesulfonate (PFOS) and perfluorooctanoate acids (corresponding to the family of PFAS) in communities from Deception Island (Antarctica). On the other han

The sampling cruise ANTOM-2 is the second of the two campaigns of the ANTOM project, which aims to understand the long-range transport and biogeochemistry of organic pollutants at global scale and how these reach the Antarctic Ocean, as well the pollutant interactions with marine microbiomes. During the campaign, samples of air, seawater, microbiomes, zooplankton and plastics are taken. In addition, a number of experiments are performed with the objective to assess the microbial degradation of pollutants, and the effects of organic pollutants and anthropogenic organic matter on marine microbiomes

Microbes are a fundamental part of the Antarctic marine ecosystem, and their study is essential for understanding the functioning of carbon, nutrient and pollutant biogeochemical cycles. However, there is a dearth of high-resolution data sets of their temporal and spatial abundance, size, distribution and phenotypic diversity. Here we present flow-cytometry data on total bacteria and small phytoplankton collected from surface waters during the ANTOM2 cruise, which sailed through the Bransfield Strait and Bellingshausen Sea during austral summer 2022. The cruise consisted in a north-south transect along the Antarctic peninsula coast and a second south-north transect along the edge of the continental shelf. Sea-water was taken by a faucet linked to a continuum pump (5 m depth) with an automatic sampler connected to a flowcytometer that was sampling every 15 minutes during two weeks yielding a total of 2500 sampling points. Quality assurance and control of the data set was performed by contrasting approaches, including the comparison of microbial data with boat movement along its axis (pitch and roll) as well weather conditions, indicating these did not affect the measurements. Total small phytoplankton abundance ranged between 102 and 104 cells·ml-1; with higher values along the coast. Total bacteria abundance ranged between 105 and 106 cells·ml- 1; abundance values tended to increase in the Bellingshausen Sea at latitudes between 68° and 71° S. In the Bransfield Strait, there was a maximum in bacterial abundance at Deception Island, probably due to several factors including stable human and animal presence, volcano emissions, and the limited water exchange with the open ocean. For each data point, we collected the mean of the forward light scatter emission which are surrogates of the relative size of the cells. Larger sized cells were observed in Marguerite Bay and at the edge of the shelf after crossing 65° South. Finally, the optical properties of each single cell

Semivolatile organic pollutants have potential for long range atmospheric transport and can thus reach pristine remote lakes by atmospheric deposition. Polycyclic aromatic hydrocarbons (PAHs) are among the most abundant and toxic semivolatile pollutants affecting lakes, however, the main factors controlling their fate are still poorly known. Here we show two contrasting lines of evidence for the importance of microbial degradation on the environmental fate of PAHs in a high altitude deep lake. The first evidence is given by an assessment of the metagenomes from surface and deep waters from Lake Redon (Pyrenees Mountains), which shows the occurrence of the initial ring hydroxylating dioxygenases as well as other PAH degrading genes from the complete metabolic route of PAH degradation. The second line of evidence is by the application of an environmental fate model for PAHs to Lake Redon under two contrasting scenarios considering the inclusion or not of degradation. When degradation is included in the model, PAH concentrations in the sediment are predicted within a factor of two of those measured in Lake Redon. Finally, the extent of the degradation sink is quantified and compared to other cycling PAH fluxes in the lake.

Increasing resolution has always been a goal for environmental chemistry and toxicology in their quest to expand knowledge on the transport, biogeochemistry, and sinks of natural- and anthropogenic chemicals in the environment, as well as their functions and effects in ecosystem and human health. Linking biology and chemistry is at the core of environmental sciences, (1) and it is now possible to study comprehensive cell signatures by means of single-cell approaches. The trend toward the analysis of increasingly smaller samples, eventually reaching nanosamples and even single-cell approaches, (1−5) has resulted in massive data sets. The measures at cellular level, at higher temporal and spatial scale resolution, require significant methodological development, but allows for new questions with eventual knowledge breakthroughs.

As much as 400 Tg of carbon from airborne semivolatile aromatic hydrocarbons is deposited to the oceans every year, the largest identified source of anthropogenic organic carbon to the ocean. Microbial degradation is a key sink of these pollutants in surface waters, but has received little attention in polar environments. We have challenged Antarctic microbial communities from the sea-surface microlayer (SML) and the subsurface layer (SSL) with polycyclic aromatic hydrocarbons (PAHs) at environmentally relevant concentrations. PAH degradation rates and the microbial responses at both taxonomical and functional levels were assessed. Evidence for faster removal rates was observed in the SML, with rates 2.6-fold higher than in the SSL. In the SML, the highest removal rates were observed for the more hydrophobic and particle-bound PAHs. After 24 h of PAHs exposure, particle-associated bacteria in the SML showed the highest number of significant changes in their composition. These included significant enrichments of several hydrocarbonoclastic bacteria, especially the fast-growing genera Pseudoalteromonas, which increased their relative abundances by eightfold. Simultaneous metatranscriptomic analysis showed that the free-living fraction of SML was the most active fraction, especially for members of the order Alteromonadales, which includes Pseudoalteromonas. Their key role in PAHs biodegradation in polar environments should be elucidated in further studies. This study highlights the relevant role of bacterial populations inhabiting the sea-surface microlayer, especially the particle-associated habitat, as relevant bioreactors for the removal of aromatic hydrocarbons in the oceans.

Semivolatile organic pollutants have potential for long range atmospheric transport and can thus reach pristine remote lakes by atmospheric deposition. Polycyclic aromatic hydrocarbons (PAHs) are among the most abundant and toxic semivolatile pollutants affecting lakes, however, the main factors controlling their fate are still poorly known. Here we show two contrasting lines of evidence for the importance of microbial degradation on the environmental fate of PAHs in a high altitude deep lake. The first evidence is given by an assessment of the metagenomes from surface and deep waters from Lake Redon (Pyrenees Mountains), which shows the occurrence of the initial ring hydroxylating dioxygenases as well as other PAH degrading genes from the complete metabolic route of PAH degradation. The second line of evidence is by the application of an environmental fate model for PAHs to Lake Redon under two contrasting scenarios considering the inclusion or not of degradation. When degradation is included in the model, PAH concentrations in the sediment are predicted within a factor of two of those measured in Lake Redon. Finally, the extent of the degradation sink is quantified and compared to other cycling PAH fluxes in the lake.

[ES] Investigadores del IDAEA, ICM, IQOG y la Universidade de Vigo tomarán muestras de agua y aire del océano Austral para analizar la contaminación antropogénica, [CAT] Investigadors de l’Institut de Diagnosi Ambiental i Estudis de l’Aigua (IDAEA-CSIC), l’Institut de Ciències del Mar (ICM-CSIC), l’Institut de Química Orgánica General (IQOG-CSIC) i la Universitat de Vigo comencen l’expedició ANTOM-II a l’oceà Austral per analitzar l’impacte dels contaminants emergents i compostos orgànics semi volàtils d’origen humà, [GA] As e os investigadores da UVigo, IDEAE-CSIC, ICM-CSIC e IQOG-CSIC partían nas últimas horas do porto arxentino de Ushuaia, a bordo do buque de investigación oceanográfica Hespérides, desde onde tomarán, no océano Austral, mostras de auga e aire para analizar a contaminación antropoxénica

The large-scale use of organophosphate esters (OPEs) as flame retardants and plasticizers has led to their prevalence in the environment, with still unknown broader impacts. This Review describes the transport and occurrence of OPEs in marine systems and summarizes emerging evidence of their biogeochemical and ecosystem impacts. Long-range environmental transport via the atmosphere and ocean currents distributes OPEs from industrialized regions to the open ocean. OPEs are most prevalent in coastal regions, but notable concentrations are also found in the Arctic and regions far from shore. Air–water interactions are important for the transport of OPEs to remote oceans and polar regions. Processes such as degradation and sinking of particle-bound compounds modulate the properties and fate of OPEs in the water column, where they are potentially a non-accounted source of anthropogenic organic phosphorus for microbial communities. Some OPEs have toxic effects in marine species and are found in measurable quantities in fish and other aquatic organisms. However, there is conflicting evidence on the potential for bioaccumulation and biomagnification of OPEs. Future work must constrain the large-scale impact of OPEs on marine biota and biogeochemistry to support more effective regulation and mitigation.

Climate change brings about significant changes in the physical environment in the Arctic. Increasing temperatures, sea ice retreat, slumping permafrost, changing sea ice regimes, glacial loss and changes in precipitation patterns can all affect how contaminants distribute within the Arctic environment and subsequently impact the Arctic ecosystems. In this review, we summarized observed evidence of the influence of climate change on contaminant circulation and transport among various Arctic environment media, including air, ice, snow, permafrost, fresh water and the marine environment. We have also drawn on parallel examples observed in Antarctica and the Tibetan Plateau, to broaden the discussion on how climate change may influence contaminant fate in similar cold-climate ecosystems. Significant knowledge gaps on indirect effects of climate change on contaminants in the Arctic environment, including those of extreme weather events, increase in forests fires, and enhanced human activities leading to new local contaminant emissions, have been identified. Enhanced mobilization of contaminants to marine and freshwater ecosystems has been observed as a result of climate change, but better linkages need to be made between these observed effects with subsequent exposure and accumulation of contaminants in biota. Emerging issues include those of Arctic contamination by microplastics and higher molecular weight halogenated natural products (hHNPs) and the implications of such contamination in a changing Arctic environment is explored.