Comparative investigations of microplastic (MP) occurrence in the global ocean are often hampered by the application of different methods. In this study, the same sampling and analytical approach was applied during five different cruises to investigate MP covering a route from the East-Siberian Sea in the Arctic, through the Atlantic, and into the Antarctic Peninsula. A total of 121 subsurface water samples were collected using underway pump-through system on two different vessels. This approach allowed subsurface MP (100 μm–5 mm) to be evaluated in five regions of the World Ocean (Antarctic, Central Atlantic, North Atlantic, Barents Sea and Siberian Arctic) and to assess regional differences in MP characteristics. The average abundance of MP for whole studied area was 0.7 ± 0.6 items/m3 (ranging from 0 to 2.6 items/m3), with an equal average abundance for both fragments and fibers (0.34 items/m3). Although no statistical difference was found for MP abundance between the studied regions. Differences were found between the size, morphology, polymer types and weight concentrations. The Central Atlantic and Barents Sea appeared to have more MP in terms of weight concentration (7–7.5 μg/m3) than the North Atlantic and Siberian Arctic (0.6 μg/m3). A comparison of MP characteristics between the two Hemispheres appears to indicate that MP in the Northern Hemisphere mostly originate from terrestrial input, while offshore industries play an important role as a source of MP in the Southern Hemisphere. The waters of the Northern Hemisphere were found to be more polluted by fibers than those of the Southern Hemisphere. The results presented here suggest that fibers can be transported by air and water over long distances from the source, while distribution of fragments is limited mainly to the water mass where the source is located. | publishedVersion

Comparative investigations of microplastic (MP) occurrence in the global ocean are often hampered by the application of different methods. In this study, the same sampling and analytical approach was applied during five different cruises to investigate MP covering a route from the East-Siberian Sea in the Arctic, through the Atlantic, and into the Antarctic Peninsula. A total of 121 subsurface water samples were collected using underway pump-through system on two different vessels. This approach allowed subsurface MP (100 μm–5 mm) to be evaluated in five regions of the World Ocean (Antarctic, Central Atlantic, North Atlantic, Barents Sea and Siberian Arctic) and to assess regional differences in MP characteristics. The average abundance of MP for whole studied area was 0.7 ± 0.6 items/m3 (ranging from 0 to 2.6 items/m3), with an equal average abundance for both fragments and fibers (0.34 items/m3). Although no statistical difference was found for MP abundance between the studied regions. Differences were found between the size, morphology, polymer types and weight concentrations. The Central Atlantic and Barents Sea appeared to have more MP in terms of weight concentration (7–7.5 μg/m3) than the North Atlantic and Siberian Arctic (0.6 μg/m3). A comparison of MP characteristics between the two Hemispheres appears to indicate that MP in the Northern Hemisphere mostly originate from terrestrial input, while offshore industries play an important role as a source of MP in the Southern Hemisphere. The waters of the Northern Hemisphere were found to be more polluted by fibers than those of the Southern Hemisphere. The results presented here suggest that fibers can be transported by air and water over long distances from the source, while distribution of fragments is limited mainly to the water mass where the source is located. | publishedVersion

Comparative investigations of microplastic (MP) occurrence in the global ocean are often hampered by the application of different methods. In this study, the same sampling and analytical approach was applied during five different cruises to investigate MP covering a route from the East-Siberian Sea in the Arctic, through the Atlantic, and into the Antarctic Peninsula. A total of 121 subsurface water samples were collected using underway pump-through system on two different vessels. This approach allowed subsurface MP (100 μm–5 mm) to be evaluated in five regions of the World Ocean (Antarctic, Central Atlantic, North Atlantic, Barents Sea and Siberian Arctic) and to assess regional differences in MP characteristics. The average abundance of MP for whole studied area was 0.7 ± 0.6 items/m³ (ranging from 0 to 2.6 items/m³), with an equal average abundance for both fragments and fibers (0.34 items/m³). Although no statistical difference was found for MP abundance between the studied regions. Differences were found between the size, morphology, polymer types and weight concentrations. The Central Atlantic and Barents Sea appeared to have more MP in terms of weight concentration (7–7.5 μg/m³) than the North Atlantic and Siberian Arctic (0.6 μg/m³). A comparison of MP characteristics between the two Hemispheres appears to indicate that MP in the Northern Hemisphere mostly originate from terrestrial input, while offshore industries play an important role as a source of MP in the Southern Hemisphere. The waters of the Northern Hemisphere were found to be more polluted by fibers than those of the Southern Hemisphere. The results presented here suggest that fibers can be transported by air and water over long distances from the source, while distribution of fragments is limited mainly to the water mass where the source is located.

Surfactants, after use, enter the environment through diffuse and point sources such as irrigation with treated and non-treated waste water and urban and industrial wastewater discharges. For the group of non-ionic synthetic surfactant alcohol ethoxylates (AEOs), most of the available information is restricted to the levels and fate in aquatic systems, whereas current knowledge of their behavior in soils is very limited. Here we characterize the behavior of different homologs (C12-C18) and ethoxymers (E03, E06, and E08) of the AEOs through batch experiments and under unsaturated flow conditions during infiltration experiments. Experiments used two different agricultural soils from a region irrigated with reclaimed water (Guadalete River basin, SW Spain). In parallel, water flow and chemical transport were modelled using the HYDRUS-1D software package, calibrated using the infiltration experimental data. Estimates of water flow and reactive transport of all surfactants were in good agreement between infiltration experiments and simulations. The sorption process followed a Freundlich isotherm for most of the target compounds. A systematic comparison between sorption data obtained from batch and infiltration experiments revealed that the sorption coefficient (K-d) was generally lower in infiltration experiments, performed under environmental flow conditions, than in batch experiments in the absence of flow, whereas the exponent (beta) did not show significant differences. For the low clay and organic carbon content of the soils used, no clear dependence of K-d on them was observed. Our work thus highlights the need to use reactive transport parameterization inferred under realistic conditions to assess the risk associated with alcohol ethoxylates in subsurface environments. (C) 2020 The Authors. Published by Elsevier Ltd.

Surfactants, after use, enter the environment through diffuse and point sources such as irrigation with treated and non-treated waste water and urban and industrial wastewater discharges. For the group of non-ionic synthetic surfactant alcohol ethoxylates (AEOs), most of the available information is restricted to the levels and fate in aquatic systems, whereas current knowledge of their behavior in soils is very limited. Here we characterize the behavior of different homologs (C12–C18) and ethoxymers (EO3, EO6, and EO8) of the AEOs through batch experiments and under unsaturated flow conditions during infiltration experiments. Experiments used two different agricultural soils from a region irrigated with reclaimed water (Guadalete River basin, SW Spain). In parallel, water flow and chemical transport were modelled using the HYDRUS-1D software package, calibrated using the infiltration experimental data. Estimates of water flow and reactive transport of all surfactants were in good agreement between infiltration experiments and simulations. The sorption process followed a Freundlich isotherm for most of the target compounds. A systematic comparison between sorption data obtained from batch and infiltration experiments revealed that the sorption coefficient (Kd) was generally lower in infiltration experiments, performed under environmental flow conditions, than in batch experiments in the absence of flow, whereas the exponent (β) did not show significant differences. For the low clay and organic carbon content of the soils used, no clear dependence of Kd on them was observed. Our work thus highlights the need to use reactive transport parameterization inferred under realistic conditions to assess the risk associated with alcohol ethoxylates in subsurface environments.

peer reviewed | This preliminary study investigated the potential correlations between trace elements (mercury, zinc, cadmium, copper, selenium, lead, nickel, chromium, lithium and vanadium) concentrations, measured in red blood cells, and oxidative stress biomarkers (total thiols, total glutathione, total and selenium-dependent glutathione peroxidases, triglycerides, malondialdehyde) assessed in the respective serum, in males and females P. vitulina, sampled in the Wadden Sea in spring and autumn 2015. Only concentrations of total mercury and zinc showed significant differences by sex, and only lipid peroxidation was different by season. Moreover, significant positive and negative correlations were observed between biomarkers (triglycerides, thiols, malondialdehyde, glutathione) and trace element concentrations (copper, lead, mercury, nickel, zinc). These findings suggest that the studied biomarkers could be useful for the assessment of oxidative stress in harbour seals exposed to trace elements, but further research with larger sample sizes is needed to better understand their specific associations. | 14. Life below water

This preliminary study investigated the potential correlations between trace elements (mercury, zinc, cadmium, copper, selenium, lead, nickel, chromium, lithium and vanadium) concentrations, measured in red blood cells, and oxidative stress biomarkers (total thiols, total glutathione, total and selenium-dependent glutathione peroxidases, triglycerides, malondialdehyde) assessed in the respective serum, in males and females P. vitulina, sampled in the Wadden Sea in spring and autumn 2015.Only concentrations of total mercury and zinc showed significant differences by sex, and only lipid peroxidation was different by season. Moreover, significant positive and negative correlations were observed between biomarkers (triglycerides, thiols, malondialdehyde, glutathione) and trace element concentrations (copper, lead, mercury, nickel, zinc). These findings suggest that the studied biomarkers could be useful for the assessment of oxidative stress in harbour seals exposed to trace elements, but further research with larger sample sizes is needed to better understand their specific associations.

Simulations over eight years of continuous surface oil spills around Cuba are carried out to identify the most likely stranding (beaching) locations. The open source Lagrangian oil drift model OpenOil is applied with high resolution hydrodynamic forcing. The actual fraction of the released oil mass reaching different regions is calculated, revealing small differences between a light and a heavy crude oil type. Similar stranding rates for the two oil types are found. Another important conclusion is that, due to the high temporal variability in stranding rates, short term simulations of a few weeks are not suitable to assess environmental risk. The highest stranding rates are simulated in winter in Northern Cuba. It is also found that oil could reach Northern Cuba, Yucatan or Florida in about 3–5 days after a spill. | publishedVersion

Simulations over eight years of continuous surface oil spills around Cuba are carried out to identify the most likely stranding (beaching) locations. The open source Lagrangian oil drift model OpenOil is applied with high resolution hydrodynamic forcing. The actual fraction of the released oil mass reaching different regions is calculated, revealing small differences between a light and a heavy crude oil type. Similar stranding rates for the two oil types are found. Another important conclusion is that, due to the high temporal variability in stranding rates, short term simulations of a few weeks are not suitable to assess environmental risk. The highest stranding rates are simulated in winter in Northern Cuba. It is also found that oil could reach Northern Cuba, Yucatan or Florida in about 3–5 days after a spill.

Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC50) and effective (EC50) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC50 and EC50 concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC50 and EC50 values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04–0.2 km2), however deltamethrin impact zones covered much larger areas (mean area of 21.1–39.0 km2). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe. | publishedVersion

Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC₅₀) and effective (EC₅₀) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC₅₀ and EC₅₀ concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC₅₀ and EC₅₀ values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04–0.2 km²), however deltamethrin impact zones covered much larger areas (mean area of 21.1–39.0 km²). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe.

Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC50) and effective (EC50) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC50 and EC50 concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC50 and EC50 values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04–0.2 km2), however deltamethrin impact zones covered much larger areas (mean area of 21.1–39.0 km2). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe. | publishedVersion

An accurate representation of the particle organic matter (POM) footprint is necessary in order to effectively predict impacts upon benthic communities and the risk of excessive organic enrichment beneath aquaculture sea-cages. Consequently, bottom-related processes such as particle resuspension must be adequately parametrized and evaluated in the available numerical models. We implemented two approaches to model POM resuspension in a Lagrangian particle tracking model and compared their influence on footprint extension and gradients of depositional flux against a no-resuspension scenario. We performed simulations in both exposed and protected aquaculture locations, and at different stages of the Atlantic Salmon (Salmo salar) production cycle in Norway. Our results indicate that the use of sediment-dependent thresholds for resuspension has the potential to regulate the high levels of erosion produced when selecting a low critical value in constant-threshold approaches, particularly in dynamic environments with mixed sediment types. | publishedVersion

An accurate representation of the particle organic matter (POM) footprint is necessary in order to effectively predict impacts upon benthic communities and the risk of excessive organic enrichment beneath aquaculture sea-cages. Consequently, bottom-related processes such as particle resuspension must be adequately parametrized and evaluated in the available numerical models. We implemented two approaches to model POM resuspension in a Lagrangian particle tracking model and compared their influence on footprint extension and gradients of depositional flux against a no-resuspension scenario. We performed simulations in both exposed and protected aquaculture locations, and at different stages of the Atlantic Salmon (Salmo salar) production cycle in Norway. Our results indicate that the use of sediment-dependent thresholds for resuspension has the potential to regulate the high levels of erosion produced when selecting a low critical value in constant-threshold approaches, particularly in dynamic environments with mixed sediment types.

An accurate representation of the particle organic matter (POM) footprint is necessary in order to effectively predict impacts upon benthic communities and the risk of excessive organic enrichment beneath aquaculture sea-cages. Consequently, bottom-related processes such as particle resuspension must be adequately parametrized and evaluated in the available numerical models. We implemented two approaches to model POM resuspension in a Lagrangian particle tracking model and compared their influence on footprint extension and gradients of depositional flux against a no-resuspension scenario. We performed simulations in both exposed and protected aquaculture locations, and at different stages of the Atlantic Salmon (Salmo salar) production cycle in Norway. Our results indicate that the use of sediment-dependent thresholds for resuspension has the potential to regulate the high levels of erosion produced when selecting a low critical value in constant-threshold approaches, particularly in dynamic environments with mixed sediment types. | publishedVersion

Chlordecone, applied on soils until 1993 to control banana weevil, has polluted water resources in the French West Indies for more than 40 years. At the watershed scale, chlordecone applications were not homogenous, generating a spatial heterogeneity of the pollution. The roles of climate, hydrology, soil, agronomy, and geology on watershed functioning generate a temporal heterogeneity of the pollution. This study questions the interactions between practices and the environment that induce such variability. We analyzed hydrological and water pollution datasets from a 2-year monitoring program on the Galion watershed in Martinique (French West Indies). We conjointly analyzed (i) weekly chlordecone (CLD) concentration monitored on 3 river sampling sites, (ii) aquifer piezometric dynamics and pollutions, and (iii) agricultural practices on polluted soils. Our results showed that chlordecone pollution in surface waters are characterized by annual trends and infra-annual variations. Aquifers showed CLD concentration 10 times higher than surface water, with CLD concentration peaks during recharge events. We showed strong interactions between rainfall events and practices on CLD pollution requiring a systemic management approach, in particular during post-cyclonic periods. Small sub-watershed with high CLD pollution appeared to be a substantial contributor to CLD mass transfers to the marine environment via rivers and should therefore receive priority management. We suggest increasing stable organic matter return to soil as well as external input of organic matter to reduce CLD transfers to water. We identified hydrological conditions—notably drying periods—and tillage as the most influential factors on CLD leaching. In particular, tillage acts on 3 processes that increases CLD leaching: organic matter degradation, modification of water paths in soil, and allophane clay degradation.

Chlordecone, applied on soils until 1993 to control banana weevil, has polluted water resources in the French West Indies for more than 40 years. At the watershed scale, chlordecone applications were not homogenous, generating a spatial heterogeneity of the pollution. The roles of climate, hydrology, soil, agronomy, and geology on watershed functioning generate a temporal heterogeneity of the pollution. This study questions the interactions between practices and the environment that induce such variability. We analyzed hydrological and water pollution datasets from a 2-year monitoring program on the Galion watershed in Martinique (French West Indies). We conjointly analyzed (i) weekly chlordecone (CLD) concentration monitored on 3 river sampling sites, (ii) aquifer piezometric dynamics and pollutions, and (iii) agricultural practices on polluted soils. Our results showed that chlordecone pollution in surface waters are characterized by annual trends and infra-annual variations. Aquifers showed CLD concentration 10 times higher than surface water, with CLD concentration peaks during recharge events. We showed strong interactions between rainfall events and practices on CLD pollution requiring a systemic management approach, in particular during post-cyclonic periods. Small sub-watershed with high CLD pollution appeared to be a substantial contributor to CLD mass transfers to the marine environment via rivers and should therefore receive priority management. We suggest increasing stable organic matter return to soil as well as external input of organic matter to reduce CLD transfers to water. We identified hydrological conditions—notably drying periods—and tillage as the most influential factors on CLD leaching. In particular, tillage acts on 3 processes that increases CLD leaching: organic matter degradation, modification of water paths in soil, and allophane clay degradation.