Vertical transport and sinks of perfluoroalkyl substances in the global open ocean

Trend of PFAS concentrations and prediction of potential risks in Taihu Lake of China by AQUATOX

Per- and polyfluoroalkyl substances (PFAS) are recognized as emerging environmental pollutants due to their high persistence and toxicities to humans and animals. Understanding the temporal trend of PFAS in the environment is important for their pollution control and making appropriate policies. Many studies have reported the PFAS concentrations in Taihu Lake, the third largest lake in China, while their temporal trend during the years was seldom investigated. This study summarizes the PFAS concentrations in the water, sediment and organisms in Taihu Lake from 2009 to 2020 to depict their temporal trends. Meanwhile, the ecological model of AQUATOX was applied to evaluate and predict the potential risks of PFAS from 2012 to 2030. The results showed that the total PFAS concentrations varied but without distinct increase or decrease in both water and sediment during the years, while PFAS concentrations in organisms significantly decreased. The yearly mean concentrations of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in the water were 21.7-25.4 ng/L and 9.7-26.5 ng/L respectively, lower than the Standards for Drinking Water Quality of China and the suggested water quality criteria to protect the aquatic organisms. In sediment, PFOA and PFOS concentrations were 0.16-0.69 ng/g and 0.15-0.82 ng/g respectively, much lower than the recommended sediment quality guideline values. Based on the AQUATOX prediction, there will be no major threats caused by PFAS to the growth of biota in Taihu Lake in the near future, while the biomass of some species (e.g. carp) will be affected under the perturbation of PFAS. Both field investigation and AQUATOX simulation showed that PFOS concentrations in invertebrates and fish descend steadily, while no remarkable decrease in PFOA concentrations was expected. This study suggests a decreasing ecological risk of PFAS in Taihu Lake, while highlights the necessity of continuous monitoring of PFAS contamination.

Indirect Impact of Eutrophication on Occurrence, Air-Water Exchange, and Vertical Sinking Fluxes of Antibiotics in a Subtropical River

A significant challenge that warrants attention is the influence of eutrophication on the biogeochemical cycle of emerging contaminants (ECs) in aquatic environments. Antibiotics pollution in the eutrophic Pearl River in South China was examined to offer new insights into the effects of eutrophication on the occurrence, air-water exchange fluxes (Fair-water), and vertical sinking fluxes (Fsinking) of antibiotics. Antibiotics transferred to the atmosphere primarily through aerosolization controlled by phytoplankton biomass and significant spatiotemporal variations were observed in the Fair-water of individual antibiotics throughout all sites and seasons. The Fsinking of ∑AB14 (defined as a summary of 14 antibiotics) was 750.46 ± 283.19, 242.71 ± 122.87, and 346.74 ± 249.52 ng of m-2 d-1 in spring, summer, and winter seasons. Eutrophication indirectly led to an elevated pH, which reduced seasonal Fair-water of antibiotics, sediment aromaticity, and phytoplankton hydrophobicity, thereby decreasing antibiotic accumulation in sediments and phytoplankton. Negative correlations were further found between Fsinking and the water column daily loss of antibiotics with phytoplankton biomass. The novelty of this study is to provide new complementary knowledge for the regulation mechanisms of antibiotics by phytoplankton biological pump, offering novel perspectives and approaches to understanding the coupling between eutrophication and migration and fate of antibiotics in a subtropical eutrophic river.

Sediment-seawater partitioning, bioaccumulation, and biomagnification of perfluorobutane sulfonamide in marine environment

Environmental occurrence of perfluorobutane sulfonamide (PFBSA) has only been recently discovered. The current knowledge regarding the occurrence and environmental behaviors of PFBSA in the marine environment is still relatively limited. In this study, PFBSA and other 37 poly- and perfluoroalkyl substances were analyzed in seawater (n = 43), sediment (n = 43), and marine fish (n = 176) samples collected from East China Sea and Antarctic Ocean. PFBSA was detected in > 90% of seawater from East China Sea and Antarctic Ocean, with the concentrations of 1.0 - 19 ng/L and < LOD-228 pg/L, respectively. The field-based mean log-transformed sediment-seawater partitioning coefficients of PFBSA were 1.6 ± 0.19 L/kg dw and 1.1 ± 0.19 L/kg dw in East China Sea and Antarctic Ocean, respectively, which are lower than that of perfluorooctanoate and perfluorooctane sulfonate. This indicates its long-range transport potential in global oceans with ocean currents. The mean log-transformed bioaccumulation factor values of PFBSA determined in the multiple species of whole-body marine fishes from East China Sea and Antarctic Ocean were 2.3 L/kg ww and 2.4 L/kg ww, respectively, which are comparable to that of perfluoroheptanoate (2.3 L/kg ww) in marine fishes from East China Sea. We did not observe an obvious biomagnification or biodilution of PFBSA along the marine food chain in East China Sea or Antarctic Ocean. This study provides the first data on the environmental behaviors of PFBSA in the marine environment.

Assessing potential human health and ecological implications of PFAS from leave-in dental products

Contaminated water and food are the main sources of documented per- and polyfluoroalkyl substances (PFAS) exposure in humans. However, other sources may contribute to the overall PFAS intake. While several studies documented the presence of PFAS in consumer products, PFAS evaluation in dental products has been limited to floss and tape to date. This study estimated PFAS exposures from a convenience sample of leave-in dental products (night guards and whitening trays), which remain in contact with the mouth for longer durations than previously evaluated dental products. This analysis evaluated whether consumer usage of these dental products meaningfully contributes to oral exposure of PFAS. Leaching of PFAS upon disposal of products was also considered. Out of 24 PFAS measured, perfluorobutanoic acid (PFBA; 3.24-4.17 ng/product or 0.67-0.83 ng/g) and perfluorooctanesulfonic acid (PFOS; 7.25-16.45 ng/product or 1.2-2.3 ng/g) were detected in night guards, and no PFAS were detected in whitening trays. Non-targeted analysis showed additional possible PFAS, which could not be characterized. The findings showed that PFOS and/or PFBA present in night guards were unlikely to pose a health concern. From an ecological perspective, the dental products examined were shown to constitute a negligible contribution to environmental PFAS. In conclusion, the examined dental products do not represent a significant source of exposure to PFAS for humans or the environment. The study demonstrates how risk assessment can be integrated by the industry into product stewardship programs to evaluate the potential health and environmental impacts of chemicals in consumer products.

Per- and polyfluoroalkyl substances (PFAS) in little penguins and associations with urbanisation and health parameters

Per- and Polyfluoroalkyl substances (PFAS) are increasingly detected in wildlife and present concerning and unknown health risks. While there is a growing body of literature describing PFAS in seabird species, knowledge from temperate Southern Hemisphere regions is lacking. Little penguins (Eudyptula minor) can nest and forage within heavily urbanised coastal environments and hence may be at risk of exposure to pollutants. We analysed scat contaminated nesting soils (n = 50) from 17 colonies in lutruwita/Tasmania for 16 PFAS, plasma samples (n = 45) from nine colonies, and three eggs for 49 PFAS. We detected 14 PFAS across the sample types, with perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) most commonly detected. Mean concentration of PFOS in plasma was 2.56 ± 4.3 ng/mL ( Collapse

Key Words

• Ecotoxicology
• Genotoxicity
• Human impacts
• Seabird sentinels
• Wildlife health

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MESH Headings

• Male
• Female
• Animals
• Spheniscidae
• Urbanization
• Alkanesulfonic Acids/analysis
• Environmental Pollutants/analysis
• Fluorocarbons/analysis
• Soil
• Sulfonic Acids

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Affiliation(s)

Melanie R Wells Department of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart 7001, Tasmania, Australia; Institute for Marine and Antarctic Studies, Battery Point 7004, Tasmania, Australia.
Timothy L Coggan Environment Protection Authority Victoria, 200 Victoria Street, Carlton 3053, Victoria, Australia; ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Gavin Stevenson Australian Ultra-Trace Laboratory, National Measurement Institute, North Ryde 2113, New South Wales, Australia
Navneet Singh ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Matthew Askeland ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Mary-Anne Lea Institute for Marine and Antarctic Studies, Battery Point 7004, Tasmania, Australia; Centre for Marine Socioecology, University of Tasmania, Hobart 7001, Tasmania, Australia
Annie Philips Wildlife Veterinary Consultant, Hobart 7000, Tasmania, Australia
Scott Carver Department of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart 7001, Tasmania, Australia; Odum School of Ecology, University of Georgia, GA, USA 30602; Center for the Ecology of Infectious Diseases, University of Georgia, GA, USA 30602

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Inputs, amplification and sinks of perfluoroalkyl substances at coastal Antarctica

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.

Horizontal and Vertical Distribution of Perfluoroalkyl Acids (PFAAs) in the Water Column of the Atlantic Ocean

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.

Global ocean contamination of per- and polyfluoroalkyl substances: A review of seabird exposure

Per- and polyfluoroalkyl substances (PFAS) have been extensively produced and used as surfactants and repellents for decades. To date, the global contamination pattern of PFAS in marine biota has seldomly been reviewed. Seabirds are ideal biomonitoring tools to study environmental contaminants and their effects. Here, we compiled and synthesized reported PFAS concentrations in various seabird species to reflect spatiotemporal patterns and exposure risks of major PFAS on a global ocean scale. Perfluorooctane sulfonic acid (PFOS) was the most studied PFAS in seabirds, which showed the highest level in eggs of common guillemots (U. aalge) from the Baltic Sea, followed by great cormorants (P. carbo) from the North Sea and double-crested cormorants (P.auritus) from the San Francisco Bay, whereas the lowest were those reported for Antarctic seabirds. The temporal pattern showed an overall higher level of PFOS in the late 1990s and early 2000s, consistent with the phase-out of perfluorooctane sulfonyl fluoride-based products. Maximum liver PFOS concentrations in several species such as cormorants and fulmars from Europe and North America exceeded the estimated toxicity reference values. Systematic evaluations using representative species and long time-series are necessary to understand contamination patterns in seabirds in South America, Africa, and Asia where information is lacking. In addition, limited research has been conducted on the identification and toxic effects of novel substitutes such as fluorotelomers and ether PFAS (F-53B, Gen-X etc.) in seabirds. Further research, including multi-omics analysis, is needed to comprehensively characterize the exposure and toxicological profiles of PFAS in seabirds and other wildlife.

The role of PFAS in unsettling ocean carbon sequestration

Poly- and perfluoroalkyl substances (PFAS) and global climate change have attracted worldwide attention. PFAS have been found all across the planet, from the polar regions to the global ocean. Global oceans have emerged as a substantial sink for the carbon in the environment due to their remarkable capacity to absorb atmospheric carbon. Oceans absorb around 24% of the world's CO₂ emissions. Thus, the ocean plays a prominent role in the earth's carbon cycle. However, the widespread application of PFAS in a wide range of products and the inefficient management of PFAS-containing wastes made them ubiquitous pollutants, which are increasingly getting as a pollutant of emerging concern. Marine PFAS pollutants can produce harmful effects on gas exchange and the ocean's carbon cycle. Thus, it leads to an increase in greenhouse gas emissions, which eventually adversely affects global warming and climate change. Consequently, threats of marine PFAS to oceans carbon sequestration are discussed in this paper. Marine PFAS pollutants adversely affect the following sectors: (1) The growth and photosynthesis of phytoplankton, (2) development and reproduction of zooplankton by causing toxicity in zooplankton, (3) marine biological pomp, and (4) carbon stock of oceans. In this way, marine PFAS can pose a threat to ocean carbon sequestration. It is expected that this study can develop knowledge about the potential impact of PFAS on ocean carbon sequestration. However, the need for further research to investigate the hidden dimensions of this issue, including the potential scope and scale of this impact, should not be overlooked.

Research progress of the POP fugacity model: a bibliometrics-based analysis

With the emergence of environmental issues regarding persistent organic pollutants (POPs), fugacity models have been widely used in the concentration prediction and exposure assessment of POPs. Based on 778 relevant research articles published between 1979 and 2020 in the Web of Science Core Collection (WOSCC), the current research progress of the fugacity model on predicting the fate and transportation of POPs in the environment was analyzed by CiteSpace software. The results showed that the research subject has low interdisciplinarity, mainly involving environmental science and environmental engineering. The USA was the most paper-published country, followed by Canada and China. The publications of the Chinese Academy of Sciences, Lancaster University, and Environment Canada were leading. Collaboration between institutions was inactive and low intensity. Keyword co-occurrence analysis showed that polychlorinated biphenyls, organochlorine pesticides, and polycyclic aromatic hydrocarbons were the most concerning compounds, while air, water, soil, and sediment were the most concerning environmental media. Through co-citation cluster analysis, in addition to the in-depth exploration of traditional POPs, research on emerging POPs such as cyclic volatile methyl siloxane and dechlorane plus were new research frontiers. The distribution and transfer of POPs in the soil-air environment have attracted the most attention, and the regional grid model based on fugacity has been gradually improved and developed. The co-citation high-burst detection showed that the research hotspots gradually shifted from pollutant persistence and long-range transport potential to pollutant distribution rules among the different environmental media and the long-distance transmission simulation.

Next generation per- and poly-fluoroalkyl substances: Status and trends, aquatic toxicity, and risk assessment

Widespread application of poly- and per-fluoroalkyl substances (PFAS) has resulted in some substances being ubiquitous in environmental matrices. That and their resistance to degradation have allowed them to accumulate in wildlife and humans with potential for toxic effects. While specific substances of concern have been phased-out or banned, other PFAS that are emerging as alternative substances are still produced and are being released into the environment. This review focuses on describing three emerging, replacement PFAS: perfluoroethylcyclohexane sulphonate (PFECHS), 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFAES), and hexafluoropropylene oxide dimer acid (HFPO-DA). By summarizing their physicochemical properties, environmental fate and transport, and toxic potencies in comparison to other PFAS compounds, this review offers insight into the viabilities of these chemicals as replacement substances. Using the chemical scoring and ranking assessment model, the relative hazards, uncertainties, and data gaps for each chemical were quantified and related to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) based on their chemical and uncertainty scores. The substances were ranked PFOS > 6:2 Cl-PFAES > PFOA > HFPO-DA > PFECHS according to their potential toxicity and PFECHS > HFPO-DA > 6:2 Cl-PFAES > PFOS > PFOA according to their need for future research. Since future uses of PFAS remain uncertain in the face of governmental regulations and production bans, replacement PFAS will continue to emerge on the world market and in the environment, raising concerns about their general lack of information on mechanisms and toxic potencies.

Per- and polyfluoroalkyl substances in the environment

Over the past several years, the term PFAS (per- and polyfluoroalkyl substances) has grown to be emblematic of environmental contamination, garnering public, scientific, and regulatory concern. PFAS are synthesized by two processes, direct fluorination (e.g., electrochemical fluorination) and oligomerization (e.g., fluorotelomerization). More than a megatonne of PFAS is produced yearly, and thousands of PFAS wind up in end-use products. Atmospheric and aqueous fugitive releases during manufacturing, use, and disposal have resulted in the global distribution of these compounds. Volatile PFAS facilitate long-range transport, commonly followed by complex transformation schemes to recalcitrant terminal PFAS, which do not degrade under environmental conditions and thus migrate through the environment and accumulate in biota through multiple pathways. Efforts to remediate PFAS-contaminated matrices still are in their infancy, with much current research targeting drinking water.

Contaminants of Emerging Concern in the Lower Volta River, Ghana, West Africa: The Agriculture, Aquaculture, and Urban Development Nexus

Contaminants of emerging concern (CECs) are ubiquitous in aquatic environments across all continents and are relatively well known in the developed world. However, few studies have investigated their presence and biological effects in low- and middle-income countries. We provide a survey of CEC presence in the Volta River, Ghana, and examine the microbial consequences of anthropogenic activities along this economically and ecologically important African river. Water and sediment samples were taken by boat or from shore at 14 sites spanning 118 km of river course from the Volta estuary to the Akosombo dam. Sample extracts were prepared for targeted analysis of antimicrobial CECs, N,N-diethyl-meta-toluamide, and per- and polyfluoroalkyl substances (PFAS; water only). Concurrent samples were extracted to characterize the microbial community and antibiotic-resistant genes (ARGs). Antibiotics and PFAS (PFAS, 2-20 ng/L) were found in all water samples; however, their concentrations were usually in the low nanograms per liter range and lower than reported for other African, European, and North American studies. N,N-Diethyl-meta-toluamide was present in all samples. The number of different genes detected (between one and 10) and total ARG concentrations varied in both water (9.1 × 10^-6 to 8.2 × 10^-3 ) and sediment (2.2 × 10^-4 to 5.3 × 10^-2 ), with increases in gene variety at sites linked to urban development, sand mining, agriculture, and shellfish processing. Total ARG concentration spikes in sediment samples were associated with agriculture. No correlations between water quality parameters, CEC presence, and/or ARGs were noted. The presence of CECs in the lower Volta River highlights their global reach. The overall low concentrations of CECs detected is encouraging and, coupled with mitigation measures, can stymie future CEC pollution in the Volta River. Environ Toxicol Chem 2022;41:369-381. © 2021 SETAC.

Perfluoroalkyl Substances in the Western Tropical Atlantic Ocean

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 (∑₈PFAS) 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.

Organic pollutants in deep sea: Occurrence, fate, and ecological implications

The deep sea - an oceanic layer below 200 m depths - has important global biogeochemical and nutrient cycling functions. It also receives organic pollutants from anthropogenic sources, which threatens the ecological function of the deep sea. In this Review, critically examined data on the distribution of organic pollutants in the deep sea to outline the role of biogeochemical and geophysical factors on the global distribution and regional chemodynamics of organic pollutants in the deep sea. We found that the contribution of deep water formation to the influx of perfluorinated compounds reached a maximum, following peak emission, faster in young deep waters (< 10 years) compared to older deep waters (> 100 years). For example, perfluorinated compounds had low concentrations (< 10 pg L^-1) and vertical variations in the South Pacific Ocean where the ocean currents are old (< 1000 years). Steep geomorphologies of submarine canyons, ridges, and valleys facilitated the transport of sediments and associated organic pollutants by oceanic currents from the continental shelf to remote deep seas. In addition, we found that, even though an estimated 1.2-4.2 million metric tons of plastic debris enter the ocean through riverine discharge annually, the role of microplastics as vectors of organic pollutants (e.g., plastic monomers, additives, and attached organic pollutants) in the deep sea is often overlooked. Finally, we recommend assessing the biological effects of organic pollutants in deep sea biota, large-scale monitoring of organic pollutants, reconstructing historical emissions using sediment cores, and assessing the impact of deep-sea mining on the ecosystem.

Spatial and Temporal Trends of Perfluoroalkyl Substances in Global Ocean and Coastal Waters

Per- and polyfluoroalkyl substances (PFAS) have been widely detected in global surface waters since the early 2000s. Here, we have compiled and analyzed the published data for perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) in surface waters of coastal seas, the Great Lakes, and open oceans to examine temporal and geospatial trends. Mass discharges from major rivers were also estimated. A large number of measurements of individual PFAS have been made in these surface waters (29 500 values), with seven C4-C10 PFSAs and nine C4-C12 PFCAs accounting for 83% of all data. However, most results (85% for PFSAs; 80% for PFCAs) were for the coastal seas of Western Europe, China, Korea, and Japan, while results were limited for coastal North America and lacking for South America and Africa. Highest median concentrations of PFCAs and PFSAs were reported in the Bohai and Yellow Seas region of China as well as in the North and Baltic seas in Europe. Significant declines in median PFSAs and C7-C12 PFCAs were also observed for the period 2012-2018 in these same regions, and for 2004-2017 in the Great Lakes. Mass discharge estimates indicated continued substantial riverine emissions of long chain (C7-C12) PFCAs in the period 2015-2019 for the coastal seas of China and reductions in emissions for Western European rivers compared to earlier time periods.

Enhanced Sinks of Polycyclic Aromatic Hydrocarbons Due to Kuroshio Intrusion: Implications on Biogeochemical Processes in the Ocean-Dominated Marginal Seas

The biogeochemical processes of polycyclic aromatic hydrocarbons (PAHs) in the South China Sea (SCS) are influenced by the exchanges of water masses, energies, and materials between this marginal sea and the Pacific Ocean. To investigate the impact of oceanic water intrusion on semivolatile compounds, we collected seawater samples in the Western Pacific, northern, and central SCS in 2017 and analyzed for dissolved PAHs. PAH concentrations in the water columns of the Pacific Ocean and SCS were 1.7-11 and 1.1-7.3 ng L^-1, respectively, showing spatial distinctions in terms of the composition and source characteristics. A common depletion for three-ring PAHs was found in the northern SCS by comparing the modeling results of conservative mixing by Kuroshio intrusion. Kuroshio water increased the levels of temperature, dissolved oxygen, and nutrients when intruding into the northern SCS and was likely to enhance the bioavailability of PAHs and stimulate their biodegradation process. In the water column, the most effective layer under the Kuroshio intrusion impact is different for three- and four-ring PAHs, where the three-ring PAHs' depletion was most significant at the surface; however, for four-ring PAHs, that was at the deep chlorophyll maximum layer. This study highlighted the effect of ocean currents on PAHs for their water-column processes both from physical and biogeochemical perspectives.

Enrichment of perfluoroalkyl substances in the sea-surface microlayer and sea-spray aerosols in the Southern Ocean

Sea-spray (or sea-salt) aerosol (SSA) formation and their subsequent atmospheric transport and deposition have been suggested to play a prominent role in the occurrence of ionizable perfluoroalkyl substances (PFAS) in the maritime Antarctica and other remote regions. However, field studies on SSA's role as vector of transport of PFAS are lacking. Following a multiphase approach, seawater (SW), the sea-surface microlayer (SML) and SSA were sampled simultaneously at South Bay (Livingston Island, Antarctica). Average PFAS concentrations were 313 pg L^-1, 447 pg L^-1, and 0.67 pg m^-3 in SW, the SML and SSA, respectively. The enrichment factors of PFAS in the SML and SSA ranged between 1.2 and 5, and between 522 and 4690, respectively. This amplification of concentrations in the SML is consistent with the surfactant properties of PFAS, while the large enrichment of PFAS in atmospheric SSA may be facilitated by the large surface area of SSA and the sorption of PFAS to aerosol organic matter. This is the first field work assessing the simultaneous occurrence of PFAS in SW, the SML and SSA. The large measured amplification of concentrations in marine aerosols supports the role of SSA as a relevant vector for long-range atmospheric transport of PFAS.

Occurrence of legacy and emerging organic contaminants in snow at Dome C in the Antarctic

Concentrations of 9 organophosphate esters (OPEs), 16 perfluoroalkylated substances (PFASs) and 17 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface snow samples collected at Dome C on the Antarctic Plateau in summer 2016. Tris(1-chloro-2-propyl) phosphate (TCPP), tris-(2-chloroethyl) phosphate (TCEP) and tri-n-butylphosphate (TnBP) were the dominant compounds of OPEs, with mean concentrations of 8157 ± 4860, 1128 ± 928 and 1232 ± 1147 pg/L. Perfluorooctanoic acid (PFOA, mean: 358 ± 71 pg/L) was the dominant compound of PFASs, and following by perfluoro-n-hexanoic acid (PFHxA, mean: 222 ± 97 pg/L), perfluoro-n-heptanoic acid (PFHpA, 183 ± 60 pg/L) and perfluoro-n-pentanoic acid (PFPeA, 175 ± 105 pg/L). 2-(Heptafluoropropoxy)propanoic acid (HFPO-DA, mean: 9.2 ± 2.6 pg/L) was determined in the Antarctic for the first time. Significantly positive correlations were observed between HFPO-DA and the short-chain PFASs, implying they have similar emission sources and long-range transport potential. High levels of 2-methylnaphthalene and 1-methylnaphthalene, as well as the ratios of PAH congeners indicated PAHs were attributable mostly to combustion origin. Occurrence and profiles of the indicators of OPEs, PFASs and PAHs, as well as air mass back-trajectory analysis provided direct evidences of human activities on Concordia station and posed obvious impacts on local environments in the Antarctic. Nevertheless, the exchange processes among different environmental matrices may drive the long-range transport and redistribution of the legacy and emerging Organic contaminants from coast to inland in the Antarctic.

Fate of environmental pollutants: A review

A review of the literature published in 2019 on topics associated with the fate of environmental pollutants is presented. Environmental pollutants covered include pharmaceuticals, antibiotic-resistant bacteria and genes, pesticides and veterinary medicines, personal care products and emerging pollutants, PFAS, microplastics, nanomaterials, heavy metals and radionuclides, nutrients, pathogens and indicator organisms, and oil and hydrocarbons. For each pollutant, the occurrence in the environment and/or their fate in engineered as well as natural systems in matrices including water, soil, wastewater, stormwater, runoff, and/or manure is presented based on the published literature. The review includes current developments in understanding pollutants in natural and engineered systems, and relevant physico-chemical processes, as well as biological processes.