Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), Long COVID (LC19), post-traumatic stress disorder (PTSD), rheumatoid arthritis (RA), and multiple sclerosis (MS) are clinically distinct disorders that share substantial symptom overlap, including persistent fatigue, cognitive impairment, autonomic dysfunction, and immune dysregulation. Although these conditions differ in diagnosis and clinical presentation, their underlying biological mechanisms remain poorly understood and may involve convergent regulatory pathways. The EpiSwitch® 3D genomics platform and Orion knowledgebase were used to integrate chromosome conformation signatures with genome-wide association study (GWAS)-derived datasets across ME/CFS, LC19, PTSD, RA, and MS. Three-dimensional genomic anchors were mapped to coding genes and analysed using STRING protein–protein interaction networks and Cytoscape-based systems biology approaches. Disease-specific anchor datasets were generated and compared at both gene and network levels to identify shared biological processes and regulatory mechanisms. Analysis of the ME/CFS dataset identified 552 unique 3D genomic anchors mapped to 567 genes, with analogous disease-specific anchor sets generated for LC19, PTSD, RA, and MS. Direct overlap between disease-associated genes was limited; however, higher-order network analyses revealed substantial interconnectivity and convergence across conditions. Shared biological pathways included immune and cytokine signalling, interferon responses, mitochondrial function, metabolic regulation, and neuroendocrine processes. Highly connected hub genes included immune regulatory nodes such as LAG3 and components of the mTOR signalling pathway, implicating T-cell exhaustion, chronic immune activation, and immunometabolic dysregulation as common mechanisms underlying these disorders. These findings support a systems-level model in which clinically overlapping fatigue-associated syndromes arise from perturbations of interconnected regulatory networks rather than discrete disease-specific pathways. Despite limited genetic overlap, substantial convergence at the network level suggests shared biological architecture across ME/CFS, LC19, PTSD, RA, and MS. The identification of common regulatory pathways provides a mechanistic framework for the development of cross-disease diagnostic and therapeutic strategies. By capturing dynamic regulatory states, 3D genomic biomarkers offer significant potential for objective blood-based diagnostics, patient stratification, and the identification of shared therapeutic targets across complex chronic disorders. These findings support the application of precision medicine approaches and may accelerate the development of novel interventions for fatigue-associated multisystem diseases.

Perfluoroalkyl carboxylic acids (PFCAs) are persistent environmental contaminants found throughout different ecosystems, including the global oceans. Many of these compounds are bio-accumulative and toxic. Previous studies have shown that sea spray aerosol (SSA), formed by wave breaking and subsequent bubble bursting, is enriched in PFCAs and provides a means for their condensed-phase transport from the oceans to the atmosphere. This has been considered as a main pathway for PFCA distribution to even remote regions of the Arctic and Antarctic, impacting human and ecosystem health far away from sources. Here we present novel evidence that PFCAs transported into the atmosphere via SSA may subsequently partition to the gas phase. This previously unconsidered process may cause particle-only measurements and models to underestimate the total atmospheric PFCA burden associated with SSA emissions. Our field observations from the Eastern North Atlantic Ocean and laboratory studies using a high-resolution time-of-flight chemical ionisation mass spectrometer (HR-ToF-CIMS) reveal that the amount of gaseous PFCAs released from SSA may exceed particle-phase concentrations and depends primarily on the low pH of SSA particles, a result of the concentration of ocean water components in the particles upon formation and drying. To date, this mechanism has not been considered in estimates of oceanic PFCA emissions, indicating an underestimation of this source also for PFCA deposition. We encourage future studies to perform a systematic analysis of gas-phase PFCA emissions from SSA during different seasons and locations, both in field and controlled laboratory settings to constrain this newly identified source of gas-phase PFCAs.

Background/Objectives: Response to immune checkpoint inhibitors (ICIs) is associated with several biological pathways, including tumor immunogenicity and antitumor immunity. Identifying host factors involved in these pathways may guide personalized ICI treatment. Methods: We describe the application of chromatin conformation assays to blood from patients with advanced urothelial carcinoma from the phase 3 JAVELIN Bladder 100 trial (NCT02603432). This trial demonstrated a significant survival benefit with avelumab maintenance plus best supportive care (BSC) vs. BSC alone following non-progression with platinum-based chemotherapy as first-line therapy. Blood-based chromatin conformation markers (CCMs) were screened for associations with high/low immune effector gene expression in tumors and for interactions with outcomes and tumor mutation burden. Results: Candidate CCMs included genes involved in several immune response pathways, such as POU2F2, which encodes a transcription factor that regulates B-cell maturation. Conclusions: Our findings suggest that polygenic host factors may affect response to ICIs and support further investigation of chromatin conformation assays.

This study investigated the particle size distribution and atmospheric transport potential of perfluoroalkyl carboxylic acids (PFCAs) and certain perfluoroalkyl ether carboxylic acids (PFECAs) emitted from a mega fluoropolymer industrial park (FIP) in China. Ambient aerosols sampled in a residential area near the FIP were separated by a cascade impactor into five size fractions (<0.15 to 12.15 μm). Homologues of PFCAs (C5-C11) and five PFECAs were frequently detected in the samples (detection frequencies 40-100%), albeit not in all size fractions. Perfluorooctanoic acid (PFOA) exhibited the highest concentrations (6.5 to 2900 pg m-3). A noticeable mass mode in the >1 μm size range was observed for PFCAs and PFECAs in the samples that were directly influenced by wind from the direction of the FIP. Based on the PFOA concentrations in the aerosol samples, the emission rate of PFOA to air from the FIP was estimated to be 0.4-1.3 t year-1. Modeling results demonstrated that around 67% of the PFOA air emission was transported in the atmosphere above 1500 m in a 7 day continuous emission scenario, implying that the PFOA on <12.15 μm particles undergoes long-range atmospheric transport after being emitted from the FIP.

Multiple target and suspect per- and polyfluoroalkyl substances (PFAS), including the replacement fluorinated processing aid perfluoro(2-ethoxy-2-fluoroethoxy)-acetic acid ("EEA"), were measured in both air and surface water in the vicinity of a fluoropolymer production plant (FPP) in Thornton-Cleveleys (United Kingdom) during sampling campaigns in 2021 and 2023, respectively. Targeted and suspect screening methods were conducted using ultrahigh-performance liquid chromatography (UHPLC) coupled with Q-Exactive HF Orbitrap high-resolution mass spectrometry (HRMS). Summed PFAS levels in water nearby the plant ranged from 30 to 22,542 ng/L and were dominated by perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs), most notably perfluorooctanoic acid (PFOA; up to 20,624 ng/L), EEA (up to 1744 ng/L), H-PFOA (up to 1027 ng/L), and perfluorohexanoic acid (PFHxA; up to 650 ng/L). Additionally, various homologous series of PFAS suspects, such as hydrogen-substituted PFCAs (H-PFCAs), chlorine-substituted PFCAs (Cl-PFCAs), and monoether perfluoroether alkyl carboxylic acids (ME-PFECAs) were identified, some for the first time in Europe. In air, PFOA was detected in all but one sample collected 20 km from the plant at concentrations ranging from 0.51 to 2.50 pg/m3. The three air samples that showed detectable EEA concentrations also displayed evidence of long-chain targets and suspects and were associated with high wind speeds from a southwesterly direction. Overall, this study shows that this site continues to be a source of a complex mixture of legacy and scarcely monitored PFAS that occur in multiple environmental media. This highlights the importance of further research that assesses the toxicity of these substances and the resulting impacts on humans and wildlife.

Chemical ionization mass spectrometers are widely used for the detection of trace gases, particularly in the field of atmospheric science. Depending on the analytes of interest, chemical ionization instruments are operated under varying reactor conditions, which can make it difficult to compare instrument performance, even for the same reagent ion chemistry. This variability leads to inconsistent sensitivity distributions, particularly for weakly bound or labile analytes. As a result, determining sensitivity - instrument response per unit analyte concentration - is challenging, even when comparing the same compound detected with the same reagent ion across different studies. To address this issue, we employed multiple Vocus AIM reactors (Tofwerk AG) to systematically identify the critical parameters affecting sensitivity in flow tube chemical ionization mass spectrometers. Controlling these parameters for a given reactor geometry can significantly reduce sensitivity variations across instruments and operators. We demonstrate that sensitivity normalized to reagent ion concentration serves as a fundamental metric for interpreting results from different datasets operating under uniform chemical ionization conditions, such as those within regional networks or other monitoring applications. Calibrating the sensitivity of benzene cations to a group of hydrocarbons, and comparing it to the sensitivity of iodide anions to levoglucosan, a molecule known to react near the collision limit, reveals that it is possible to map kinetic constraints on sensitivity from one ion mode polarity to another, as long as the critical parameters are held constant. Additionally, we show that collision-limited sensitivity relative to the reagent ion is nearly constant across different ionization mechanisms for a given reactor geometry and set of conditions. This consistency enables the determination of the upper limit of sensitivity, even for reagent ions where the specific molecules reacting at the collision limit are unknown. As a result, the use of the voltage-scanning approach can be extended to a broader range of reagent ion chemistries. This study highlights how collision-limited sensitivity can enhance our understanding of the relationships between different instruments and simplify calibration requirements across various reagent ion chemistries.

Coastal ecosystems play a significant role in the cycling of greenhouse gases (GHGs), yet they remain understudied compared to open oceans and terrestrial systems. Here, we present measurements of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) concentrations from shallow coastal environments along the Swedish Baltic Sea coast and Auckland, New Zealand, highlighting the variability and drivers of GHG dynamics across diverse habitats.In the Baltic Sea, we conducted measurements in April and September 2024, utilizing cavity ring-down spectroscopy coupled with a water equilibration system. Our focus was on shallow coastal bays in the wider Stockholm archipelago, including eutrophic and habitat-altered bays. These environments exhibited exceptionally high CH₄ concentrations in the surface water reaching up to 580 nmol L-1, suggesting the potential for significant CH₄ emissions. Notably, CH₄ concentrations below 200 nmol L-1 showed a negative correlation with N₂O, while CH₄ levels above 200 nmol L-1 revealed a distinct shift to a positive correlation with N₂O. We hypothesize that this transition reflects a change in oxygen availability, where hypoxic conditions (0.2< O2 < 2 mL L-1) favor CH₄ production and reoxygenation of euxinic sediments contributes to an additional late-summer N₂O peak. Furthermore, GHG concentrations in the surface seawater were associated with environmental parameters such as water retention time, vegetation coverage, total organic carbon content, turbidity, chlorophyll-a concentration, pH, and total phosphorus levels.Expanding our investigation to coastal systems in the suburban regions of Auckland, New Zealand, in January 2025 we conducted a spatial survey across a range of coastal habitats, including tidal flats, mangroves and river estuaries. By linking the findings from the Baltic Sea with emerging insights from New Zealand’s coastal systems, we aim to better understand the influence of habitat type, redox conditions, and nutrient dynamics on GHG emissions in coastal zones globally.Our comparative study underscores the need for integrated approaches to better understand GHG emissions in coastal zones, which are often subject to compounded anthropogenic pressures, such as excessive nutrient inputs and habitat alteration. These findings contribute to the broader understanding of coastal zones as dynamic interfaces in the global carbon and nitrogen cycles and the development of evidence-based policies.

Sea spray aerosol (SSA) emission is a major source of atmospheric aerosols, influencing global climate and coastal air quality. Much of our knowledge about SSA derives from coastal observations near shorelines, but whether and when these observations accurately represent open oceans remain unclear. Here, we show that strong nearshore SSA production during high-wave periods greatly enhances downwind cloud condensation nuclei (CCN) and aerosol mass concentrations. Strong shoreline wave breaking is widespread globally, and swell waves, which are decoupled from local winds, play a dominant role in many coastal regions. Therefore, extrapolating results based on coastal measurements to open oceans may significantly overestimate SSA concentration and its contribution to CCN and, by extension, the impact of SSA on clouds and climate. Additionally, the strong enhancement of coastal aerosol population by shoreline wave breaking and its environmental impact on coastal communities cannot be captured by current regional models, which do not parameterize nearshore SSA generation using wave energy or completely neglect it.

Atmospheric aerosols contribute to the largest uncertainty in estimates of the Earth’s global energy balance. Their interactions with sunlight and their ability to affect cloud formation leads to both direct and indirect influence of radiative forcing. The substantial uncertainties associated with aerosol climate effects stem amongst others from the complexity of their sources, composition, and properties. Aerosols in coastal areas present a challenging mix of inorganic and organic particles from diverse sources, making measurements and characterization of their properties in these regions essential. This study presents measurements of the optical properties of ambient aerosols on Askö, Sweden, from October 2024 to January 2025. Askö, an island and nature reserve located approximately 80 km south of Stockholm, experiences low levels of local pollution, making it an ideal location for studying marine aerosols. Its location in the Trosa Archipelago, facing the Baltic Sea, also makes it well-suited for investigating the impact of long-range transport from Central and Eastern Europe.Instruments were placed in a container situated on top of a floating platform near the island. Scattering coefficients, measured with a nephelometer, and absorption coefficients, measured with an aethalometer, were used to calculate Scattering and Absorption Ångström Exponents. The Ångström matrix was used to characterize aerosol types found in the area at different times. The optical data set is further complemented by local meteorological data, particle size distributions, and back trajectory analysis. This combination of data will give valuable insights into aerosol sources at this remote location, the degree of aerosol ageing, and the identification of prevailing emissions sources such as local emissions versus long-range transport of air masses.

The Arctic has been experiencing a rise in ambient temperature several times higher than the global average. This warming trend has led to a continuous decline in sea ice coverage and snowpack prevalence. Aerosol sources, such as those from the open ocean and tundra, have become more prevalent throughout the year. These sources emit primary biological aerosol particles (bioaerosols) some of which exhibit ice nucleating properties at high temperatures (>-15C). Ice nucleating particles (INPs) play a crucial role in cloud ice formation, affecting cloud physical and optical properties, as well as their lifetime. Consequently, this has a substantial impact on the Arctic climate. During the ARTofMELT2023 expedition (“Atmospheric Rivers and the Onset of Sea Ice Melt 2023”) conducted aboard the Swedish icebreaker Oden in the Atlantic sector of the Arctic Ocean, we assessed the relative importance of several natural bioaerosol sources, such as sea ice, snow melt (to simulate melt ponds) and bulk ocean water. This involved several sea spray simulation chamber and nebulizer experiments, referred to as “source experiments”. The aerosol particles generated in the 61 source experiments conducted were analyzed using single-particle ultraviolet fluorescence spectroscopy along with other complementary aerosol measurements. These included particle size, black carbon content, particle chemical composition, as well as the microbial community and INP concentration of emitted particles. Additionally, filter samples were obtained for transmission electron microscopy (TEM) analysis. Our findings indicate that sea ice and snow melt are more significant sources of bioaerosols compared to the bulk ocean water, including the sea surface microlayer, indicating the potential importance of melt ponds as a local Arctic bioaerosol source. Furthermore, we found significant differences in the chemical composition, black carbon content and size distribution of the various analyzed aerosol sources.

Primary biological aerosol particles (PBAPs) can influence the climate and affect human health. To investigate the aerosolization of PBAPs by sea spray aerosol (SSA), we conducted ship-based campaigns in the central Baltic Sea near & Ouml;stergarnsholm in May and August 2021. Using a plunging-jet sea spray simulation chamber filled with local seawater, we performed controlled chamber experiments to collect filters and measure aerosols. We determined the abundance of microbial cells in the chamber air and seawater using staining and fluorescence microscopy, normalizing these values to sodium concentrations to calculate enrichment factors. Our results showed that microbes were enriched in the aerosol by 13 to 488 times compared to the underlying seawater, with no significant enrichment observed in the sea surface microlayer. Microbial abundances obtained through microscopy were compared with estimates of fluorescent PBAPs (fPBAPs) using a single-particle fluorescence spectrometer. We estimated microbial emission fluxes using two independent approaches: (1) applying the enrichment factors derived from this study with mass flux estimates from previous SSA parameterizations and (2) using a scaling approach from a companion study. Both methods produced microbial emission flux estimates that were in good agreement and of the same order of magnitude as previous studies, while fPBAP emission flux estimates were significantly lower. Furthermore, 16S rRNA sequencing identified the diversity of bacteria enriched in the nascent SSA compared to the underlying seawater.

Perfluoroalkyl acids (PFAAs) are highly persistent anthropogenic pollutants that have been detected in the global oceans. Our previous laboratory studies demonstrated that PFAAs in seawater are remobilized to the air in sea spray aerosols (SSAs). Here, we conducted field experiments along a north-south transect of the Atlantic Ocean to study the enrichment of PFAAs in SSA. We show that in some cases PFAAs were enriched >100,000 times in the SSA relative to seawater concentrations. On the basis of the results of the field experiments, we estimate that the secondary emission of certain PFAAs from the global oceans via SSA emission is comparable to or greater than estimates for the other known global sources of PFAAs to the atmosphere from manufacturing emissions and precursor degradation.

Primary biological aerosol particles (PBAPs) can significantly influence the Earth's climate as ice-nucleating particles. To enhance our comprehension of PBAP aerosolization, particularly bacteria, through sea spray aerosol, we conducted mesocosm experiments in the Azores archipelago using a sea spray simulation chamber. Using fluorescence microscopy, 16S rRNA sequencing for microbial community analysis, and data from an online bioaerosol spectrometer, we quantified and characterized biological particles present in the seawater and aerosol. Microbial enrichment factors, normalized to sodium concentration, ranged from 9 to 158, and a comparison of the airborne cell estimates with bioaerosol spectrometer data revealed notable differences between the measurement approaches. Additionally, 16S rRNA sequencing unveiled selective aerosolization of specific taxa, resulting in a less diverse aerosol community compared to seawater. Selective growth in the seawater led to a reduction in alpha diversity and closer clustering of the community composition with nascent sea spray aerosol samples throughout each mesocosm experiment.

Aerosols and clouds are key components of the marine atmosphere, impacting the Earth’s radiative budget with a net cooling effect over the industrial era that counterbalances greenhouse gas warming, yet with an uncertain amplitude. Here we report recent advances in our understanding of how open ocean aerosol sources are modulated by ocean biogeochemistry and how they, in turn, shape cloud coverage and properties. We organize these findings in successive steps from ocean biogeochemical processes to particle formation by nucleation and sea spray emissions, further particle growth by condensation of gases, the potential to act as cloud condensation nuclei or ice nucleating particles, and finally, their effects on cloud formation, optical properties, and life cycle. We discuss how these processes may be impacted in a warming climate and the potential for ocean biogeochemistry—climate feedbacks through aerosols and clouds.

Ship-based measurements of sea spray aerosol (SSA) gradient fluxes in the size range of 0.5-47 mu m in diameter were conducted between 2009-2017 in both the Baltic Sea and the North Atlantic Ocean. Measured total SSA fluxes varied between 8.9 x 103 +/- 6.8 x 105 m-2 s-1 for the Baltic Sea and 1.0 x 104 +/- 105 m-2 s-1 for the Atlantic Ocean. The analysis uncovered a significant decrease (by a factor of 2.2 in the wind speed range of 10.5-14.5 m s-1) in SSA fluxes, with chlorophyll a (chl a) concentration higher than 3.5 mg m-3 in the Baltic Sea area. We found statistically significant correlations for both regions of interest between SSA fluxes and various environmental factors, including wind speed, wind acceleration, wave age, significant wave height, and wave Reynolds number. Our findings indicate that higher chl a concentrations are associated with reduced SSA fluxes at higher wind speeds in the Baltic Sea, while the influence of wave age showed higher aerosol emissions in the Baltic Sea for younger waves compared to the Atlantic Ocean. These insights underscore the complex interplay between biological activity and physical dynamics in regulating SSA emissions. Additionally, in both measurement regions, we observed weak correlations between SSA fluxes and air and water temperature and between SSA fluxes and atmospheric stability. Comparing the Baltic Sea and the North Atlantic, we noted distinct emission behaviors, with higher emissions in the Baltic Sea at low wave age values compared to the Atlantic Ocean. This study represents the first comparative analysis of SSA flux measurements using the same methodology in these contrasting marine environments.

The process by which perfluoroalkyl acids (PFAAs) become enriched on sea spray aerosol (SSA) is complex and likely influenced by several factors. In this study, we utilized a plunging water jet in a controlled laboratory setup to generate SSA. We investigated the enrichment process of PFAAs on nascent SSA by systematically varying three key parameters: 1) total organic carbon (TOC), 2) water jet flow rate, and 3) inorganic ion composition. The results showed a significant enhancement in enrichment when organic matter was introduced into artificial seawater. However, this enhancement did not exhibit a consistent trend when increasing the TOC from 1 to 2 mg L-1. The enrichment was increased at higher water jet flow rates (3.2 L min(-1)) compared to lower flow rates (1.6 and 2.4 L min(-1)), and the effect was particularly pronounced for submicrometer SSA particles. There was minimal difference in the enrichment of PFAAs when SSA was generated using sodium chloride solution instead of artificial seawater at the same salinity. Overall, these findings shed light on the complex process of PFAA enrichment on SSA and improved our understanding of the uncertainties associated with varying dissolved organic matter, water jet flow rate, and inorganic ion composition.

To compare in situ and laboratory estimates of sea spray aerosol (SSA) production fluxes, we conducted two research campaigns in the vicinity of an eddy covariance (EC) flux tower on the island of Östergarnsholm in the Baltic Sea during May and August 2021. To accomplish this, we performed EC flux measurements for particles with diameters between 0.25 and 2.5 µm simultaneously with laboratory measurements using a plunging jet sea spray simulation chamber containing local seawater sampled close to the footprint of the flux tower. We observed a log-linear relationship between wind speed and EC-derived SSA emission fluxes, a power-law relationship between significant wave height and EC-derived SSA emission fluxes, and a linear relationship between wave Reynolds number and EC-derived SSA emission fluxes, all of which are consistent with earlier studies. Although we observed a weak negative relationship between particle production in the sea spray simulation chamber and seawater chlorophyll-α concentration and a weak positive relationship with the concentration of fluorescent dissolved organic matter in seawater, we did not observe any significant impact of dissolved oxygen on particle production in the chamber. To obtain an estimate of the size-resolved emission spectrum for particles with dry diameters between 0.015 and 10 µm, we combined the estimates of SSA particle production fluxes obtained using the EC measurements and the chamber measurements in three different ways: (1) using the traditional continuous whitecap method, (2) using air entrainment measurements, and (3) simply scaling the chamber data to the EC fluxes. In doing so, we observed that the magnitude of the EC-derived emission fluxes compared relatively well to the magnitude of the fluxes obtained using the chamber air entrainment method as well as the previous flux measurements of Nilsson et al. (2021) and the parameterizations of Mårtensson et al. (2003) and Salter et al. (2015). As a result of these measurements, we have derived a wind-speed-dependent and wave-state-dependent SSA parameterization for particles with dry diameters between 0.015 and 10 µm for low-salinity waters such as the Baltic Sea, thus providing a more accurate estimation of SSA production fluxes.

Veterinary oncology has a critical need for an accurate, specific, and sensitive non-invasive (blood) biomarker assay to assess multiple canine oncological indications early to better inform therapeutic interventions. Extended from clinical applications in human oncology, here we report on a novel 3D genomics approach to identify systemic blood biomarkers for canine diffuse large B-cell lymphoma (DLBCL), T-zone lymphoma (TZL), hemangiosarcoma (HSA), histiocytic sarcoma, osteosarcoma, and canine malignant melanoma, in a single assay format that encompasses multiple classes and phenotypes of cancer. In the validation of the independent test cohort the 3D whole-genome profiling in peripheral blood demonstrated high sensitivity and specificity for lymphomas and sarcomas as a class, with accuracy >80%; and high sensitivity and specificity for individual indications, with accuracy >89%. This study demonstrates a 3D genomic approach can be used to develop a non-invasive, blood-based test for multiple choice diagnosis of canine oncological indications. The modular EpiSwitch® Specific Canine Blood (EpiSwitch SCB) test promises to help veterinary specialists to diagnose the disease, make more informed treatment decisions, better utilize alternative effective treatments, minimize or avoid unnecessarily toxicity, and efficiently manage costs and resources.### Competing Interest StatementEH, MS, RP, AD, TN, DV, KS, MI, CW, AH, ST, AG, JG, TG and AA are full-time employees at Oxford BioDynamics plc. AA is a company director. The remaining authors have no conflict of interest.

Perfluoroalkyl acids (PFAAs) are widely distributed in the oceans which are their largest global reservoir, but knowledge is limited about their vertical distribution and fate. This study measured the concentrations of PFAAs (perfluoroalkyl carboxylic acids (PFCAs) with 6 to 11 carbons and perfluoroalkanesulfonic acids (PFSAs) with 6 and 8 carbons) in the surface and deep ocean. Seawater depth profiles from the surface to a 5000 m depth at 28 sampling stations were collected in the Atlantic Ocean from ∼50° N to ∼50° S. The results demonstrated PFAA input from the Mediterranean Sea and the English Channel. Elevated PFAA concentrations were observed at the eastern edge of the Northern Atlantic Subtropical Gyre, suggesting that persistent contaminants may accumulate in ocean gyres. The median ΣPFAA surface concentration in the Northern Hemisphere (n = 17) was 105 pg L-1, while for the Southern Hemisphere (n = 11) it was 28 pg L-1. Generally, PFAA concentrations decreased with increasing distance to the coast and increasing depth. The C6-C9 PFCAs and C6 and C8 PFSAs dominated in surface waters, while longer-chain PFAAs (C10-C11 PFCAs) peaked at intermediate depths (500-1500 m). This profile may be explained by stronger sedimentation of longer-chain PFAAs, as they sorb more strongly to particulate organic matter.