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.

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

There are large knowledge gaps concerning environmental levels and fate of many organic pollutants, particularly for chemicals of emerging concern in tropical regions of the Global South. In this study, we investigated the levels of chlorinated paraffins (CPs) and dechloranes in air and soil in rural, suburban, and urban regions in and around Dar es Salaam, Tanzania. Samples were also collected near the city's main municipal waste dumpsite and an electronic waste (e-waste) handling facility. In passive air samples, short chain CPs (SCCPs) dominated, with an average estimated concentration of 22 ng/m3, while medium chain CPs (MCCPs) had an average estimated concentration of 9 ng/m3. The average estimated air concentration of ∑dechloranes (Dechlorane Plus (DP) + Dechlorane 602 + Dechlorane 603) was three to four orders of magnitudes lower, 2 pg/m3. In soil samples, MCCPs dominated with an average concentration of 640 ng/g dw, followed by SCCPs with an average concentration of 330 ng/g dw, and ∑dechloranes with an average concentration of 0.9 ng/g dw. In both air and soil, DP was the dominating dechlorane compound. Urban pulses were observed for CPs and dechloranes in air and soil. CPs were in addition found in elevated levels at the municipal waste dumpsite and the e-waste handling facility, while DPs were found in elevated levels at the e-waste handling facility. This suggests that waste handling sites represent important emission sources for these pollutants. Investigations into seasonal trends and environmental fate of CPs and dechloranes showed that monsoonal rain patterns play a major role in governing air concentrations and mobility, particularly for the less volatile MCCPs and dechloranes. This study is the first to report levels of CPs in air from sub-Saharan Africa, and DP, Dechlorane 602, and Dechlorane 603 in soil from sub-Saharan Africa. | publishedVersion

There are large knowledge gaps concerning environmental levels and fate of many organic pollutants, particularly for chemicals of emerging concern in tropical regions of the Global South. In this study, we investigated the levels of chlorinated paraffins (CPs) and dechloranes in air and soil in rural, suburban, and urban regions in and around Dar es Salaam, Tanzania. Samples were also collected near the city's main municipal waste dumpsite and an electronic waste (e-waste) handling facility. In passive air samples, short chain CPs (SCCPs) dominated, with an average estimated concentration of 22 ng/m3, while medium chain CPs (MCCPs) had an average estimated concentration of 9 ng/m3. The average estimated air concentration of ∑dechloranes (Dechlorane Plus (DP) + Dechlorane 602 + Dechlorane 603) was three to four orders of magnitudes lower, 2 pg/m3. In soil samples, MCCPs dominated with an average concentration of 640 ng/g dw, followed by SCCPs with an average concentration of 330 ng/g dw, and ∑dechloranes with an average concentration of 0.9 ng/g dw. In both air and soil, DP was the dominating dechlorane compound. Urban pulses were observed for CPs and dechloranes in air and soil. CPs were in addition found in elevated levels at the municipal waste dumpsite and the e-waste handling facility, while DPs were found in elevated levels at the e-waste handling facility. This suggests that waste handling sites represent important emission sources for these pollutants. Investigations into seasonal trends and environmental fate of CPs and dechloranes showed that monsoonal rain patterns play a major role in governing air concentrations and mobility, particularly for the less volatile MCCPs and dechloranes. This study is the first to report levels of CPs in air from sub-Saharan Africa, and DP, Dechlorane 602, and Dechlorane 603 in soil from sub-Saharan Africa.

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts | An annual profile of the impacts of simulated oil spills on the Northeast Arctic cod and haddock fisheries | publishedVersion

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts.

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts.

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts. | An annual profile of the impacts of simulated oil spills on the Northeast Arctic cod and haddock fisherie | publishedVersion

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts. | publishedVersion

We simulate the combined natural and pollutant-induced survival of early life stages of NEA cod and haddock, and the impact on the adult populations in response to the time of a major oil spill in a single year. Our simulations reveal how dynamic ocean processes, controlling both oil transport and fate and the frequency of interactions of oil with drifting fish eggs and larvae, mediate the magnitude of population losses due to an oil spill. The largest impacts on fish early life stages occurred for spills initiated in Feb–Mar, concomitant with the initial rise in marine productivity and the earliest phase of the spawning season. The reproductive health of the adult fish populations was maintained in all scenarios. The study demonstrates the application of a simulation system that provides managers with information for the planning of development activities and for the protection of fisheries resources from potential impacts | publishedVersion

The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km(2). Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a "garbage patch', where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and poly-styrene fragments of small size ranges (2.5-10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km². Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a ‘garbage patch’, where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and polystyrene fragments of small size ranges (2.5–10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

Knowledge of the ecology and at-sea distribution of migratory species like seabirds has substantially increased over the last two decades. Furthermore, an increasing number of studies have recently focused on chemical contamination of birds over their annual cycle. However, the understanding of the combined effects of spatial movements and contamination on seabirds’ life-history traits is still scarce. During winter, seabirds can use very different areas, at the large-scale. Such overwintering strategies and distribution may expose individuals to contrasting environmental stressors, including pollutants. Here, we studied the winter distribution and contamination with mercury (Hg), and their combined effects on reproduction, in a great skua (Stercorarius skua) population breeding in Bjørnøya, Svalbard. We confirmed that individuals of this specific population overwinter in three different areas of the North Atlantic, namely Africa, Europe and northwest Atlantic. The highest Hg concentrations in feathers were measured in great skuas wintering off Europe (Linear Mixed Models - mean value ± SD = 10.47 ± 3.59 μg g 1 dw), followed by skuas wintering in northwest Atlantic (8.42 ± 3.70) and off Africa (5.52 ± 1.83). Additionally, we found that female winter distribution and accumulated Hg affected the volume of their eggs (Linear Mixed Models), but not the number of laid and hatched eggs (Kruskal-Wallis tests). This study provides new insights on the contamination risks that seabirds might face according to their overwinter distribution and the possible associated carry-over effects. Mercury Reproduction Spatial ecotoxicology Biologging Carry-over effects | acceptedVersion

Knowledge of the ecology and at-sea distribution of migratory species like seabirds has substantially increased over the last two decades. Furthermore, an increasing number of studies have recently focused on chemical contamination of birds over their annual cycle. However, the understanding of the combined effects of spatial movements and contamination on seabirds’ life-history traits is still scarce. During winter, seabirds can use very different areas, at the large-scale. Such overwintering strategies and distribution may expose individuals to contrasting environmental stressors, including pollutants. Here, we studied the winter distribution and contamination with mercury (Hg), and their combined effects on reproduction, in a great skua (Stercorarius skua) population breeding in Bjørnøya, Svalbard. We confirmed that individuals of this specific population overwinter in three different areas of the North Atlantic, namely Africa, Europe and northwest Atlantic. The highest Hg concentrations in feathers were measured in great skuas wintering off Europe (Linear Mixed Models - mean value ± SD = 10.47 ± 3.59 μg g ⁻¹ dw), followed by skuas wintering in northwest Atlantic (8.42 ± 3.70) and off Africa (5.52 ± 1.83). Additionally, we found that female winter distribution and accumulated Hg affected the volume of their eggs (Linear Mixed Models), but not the number of laid and hatched eggs (Kruskal-Wallis tests). This study provides new insights on the contamination risks that seabirds might face according to their overwinter distribution and the possible associated carry-over effects.

Numerical models point to the south-east Bay of Biscay as a convergence area for floating particles, including plastics. The few existing studies on plastic abundance in the area mainly focus on open waters and yet information on the coastal area is limited. To fill this gap, neustonic samples were taken along the coastal waters of the south-east Bay of Biscay (2017-2020) to define the spatial distribution of plastic abundances and composition. Results show an average plastic abundance of 739,395 +/- 2,625,271 items/km(2) (998 +/- 4338 g/km(2)). French waters were more affected, with five times higher plastic abundances than Spanish coasts. Microplastics represented 93 % of the total abundance of plastic items (28 % in weight), mesoplastics 7 % (26 %) and macroplastics 1 % (46 %). This study demonstrates that this area is a hotspot for plastic with levels in coastal waters similar to those in the Mediterranean Sea or other litter aggregation areas.

Numerical models point to the south-east Bay of Biscay as a convergence area for floating particles, including plastics. The few existing studies on plastic abundance in the area mainly focus on open waters and yet information on the coastal area is limited. To fill this gap, neustonic samples were taken along the coastal waters of the south-east Bay of Biscay (2017–2020) to define the spatial distribution of plastic abundances and composition. Results show an average plastic abundance of 739,395 ± 2,625,271 items/km² (998 ± 4338 g/km²). French waters were more affected, with five times higher plastic abundances than Spanish coasts. Microplastics represented 93 % of the total abundance of plastic items (28 % in weight), mesoplastics 7 % (26 %) and macroplastics 1 % (46 %). This study demonstrates that this area is a hotspot for plastic with levels in coastal waters similar to those in the Mediterranean Sea or other litter aggregation areas.