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Microplastics (MPs) are ubiquitous pollutants in marine environments. Among the many detrimental consequences of microplastic pollution, its consumption by marine biota is of particular relevance for human health, due to exposure through the food web. Long-term time-series biotic samples are overlooked sources of information for microplastics research. These collections are extremely valuable for the detection and monitoring of changes in marine environments. However, there are very few long-term studies (>10 years) of the uptake of microplastics by biota. Here, we used Dove Time Series planktonic samples (from 1971 to 2020) to assess the presence and prevalence of microplastics in the English North Sea coast over time. Fish and brachyuran larvae were selected due to their commercial importance and consequent implications for human health. A custom enzymatic digestion method was used to extract microplastics for FTIR-ATR polymer identification. An increasing cumulative trend in MP ingestion was identified. Cellophane and polyethylene terephthalate were the polymer types found most frequently in both taxa. Although a total higher microplastics uptake was observed in fish, consumption was not significantly different between taxa over time. Equally, results were not clearly related to microplastics shape or polymer type. This work did not find significant long-term evidence on the increasing uptake of microplastic particles by zooplankton over time. However, the results of this report identified additives, plasticisers, and other more complex and hazardous compounds that should not be released to the environment (e.g., bis-(2-hydroxyethyl) dimerate, propylene glycol ricinoleate) inside marine biota. The study detailed herein provides a case study for the use of long-term time-series in providing accurate assessments of microplastic pollution in marine biota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Abstract The eutrophication status of the German Bight (North Sea) has been assessed the third time since 1998 according to the OSPAR-Comprehensive Procedure between 2006 and 2014. Since the 1980s nutrient discharges and atmospheric nitrogen deposition had declined significantly but chlorophyll a and nutrient concentrations remained above assessment levels inshore and in inner coastal waters, reflecting continuing eutrophication. Recently local river discharges stagnated or increased again and total nitrogen remained above a reduction target of 200 μM. Most nutrients and conversion products were imported by a coastal current, passing the German Bight. Organic matter was trapped in offshore bottom waters in the ancient Elbe valley, causing repeated annual oxygen minima (<6 mg/L) and a classification as Problem Area. Effects of national reduction measures are limited in the transit area German Bight because improvements in open coastal waters require international efforts, based on comprehensive analyses. Highlights • Eutrophication affects still European coastal ecosystems significantly. • German coastal waters are eutrophied, since 1980, by local and distant sources. • Open transit areas require international management and consistent assessment levels. [ABSTRACT FROM AUTHOR]

In coastal waters the identification of sources, trajectories and deposition sites of marine litter is often hampered by the complex oceanography of shallow shelf seas. We conducted a multi-annual survey on litter at the sea surface and on the seafloor in the south-eastern North Sea. Bottom trawling was identified as a major source of marine litter. Oceanographic modelling revealed that the distribution of floating litter in the North Sea is largely determined by the site of origin of floating objects whereas the trajectories are strongly influenced by wind drag. Methods adopted from species distribution modelling indicated that resuspension of benthic litter and near-bottom transport processes strongly influence the distribution of litter on the seafloor. Major sink regions for floating marine litter were identified at the west coast of Denmark and in the Skagerrak. Our results may support the development of strategies to reduce the pollution of the North Sea. [ABSTRACT FROM AUTHOR]

In the framework of the ICON project (Integrated Assessment of Contaminant Impacts on the North Sea), muscle tissue from a total of 135 common dab ( Limanda limanda ) (20–28 cm total length) was collected in seven offshore sampling areas in the North Sea, at Iceland and in the Baltic Sea during Aug/Sept and December 2008 for a chemical mercury speciation analysis by means of gas chromatography and detection by cold vapour atomic fluorescence spectroscopy (GC-CVAFS). There was a highly significant correlation between concentrations of methylmercury (MeHg + ) and inorganic mercury (Hg 2+ ) in individual fish, and the mean ratio of MeHg + compared to Σ Hg (MeHg + + Hg 2+ ) was 94.0%. The results revealed statistically significant differences in concentrations of MeHg + and Hg 2+ , respectively, between sampling areas. Mean concentrations in the German Bight (North Sea), in Icelandic waters and in Mecklenburg Bight (Baltic Sea) were low (MeHg + : 0.023–0.036; Hg 2+ : 0.001–0.002 mg/kg wet weight), while concentrations in dab from the Dogger Bank, Firth of Forth and the vicinity of the Ekofisk oil field (all North Sea) were significantly higher (MeHg + : 0.059–0.101; Hg 2+ : 0.003–0.004 mg/kg wet weight). Statistical correlation analysis on effects of host-specific factors revealed that neither length, weight, age, sex nor condition factor showed a significant relationship with Hg concentrations. However, Hg concentrations were significantly correlated with the Fish Disease Index (FDI), indicating a relationship between Hg concentrations and the health status of dab. Multiple linear regression analysis aiming to find factors affecting Hg concentrations revealed that only the sampling area had a highly significant main effect on Hg concentrations, and in some cases, additionally the condition factor contributed significantly to the final model. From the results, it cannot be excluded that elevated Hg concentration recorded in dab were linked to discharges from offshore oil and gas installations and that Hg affected the health status of dab. [ABSTRACT FROM AUTHOR]

The distribution of mass, water-soluble inorganic salts and mineral elements of size-segregated aerosols (PM 1 , PM 2.5-1 and PM 10-2.5 ), precursor gaseous pollutants, black carbon, and nanoparticles (10–300 nm size range) at the Southern Bight of the North Sea has been studied. The concentrations of air pollutants peaked over shipping lanes, open-water anchorage areas and frequently navigated waters, due to the presence of mobile emission sources. A considerable decrease in air pollutant levels was seen when diverting from these marine areas towards remote or coastal banks. These findings showed the rapid dispersion of pollutants in the marine air. The nano-aerosol count, originating from ocean-going ships, peaked at lower average aerodynamic diameters (e.g., ≈28 nm) than those, observed from low-displacement vessels (45–50 nm, e.g., for fishing boats). The average diameter of nano-PM depended also on weather conditions, e.g., it was higher (≈50 nm) in air of higher humidity. [ABSTRACT FROM AUTHOR]

The importance of the North Sea is emphasised by the recent Flouse of Lords report on maritime cooperation there. This prompts a consideration of the international legal principles underpinning such cooperation, as well as a description of the means by which the North Sea States have given practical effect to this cooperation, particularly in relation to living resources and the marine environment. [ABSTRACT FROM AUTHOR]

Seasonal mean oxygen depletion in offshore and coastal North Sea bottom waters was shown to range between 0.9 and 1.8 mg/L, corresponding to 95–83% saturation, between July and October over a 30-year assessment period (1980–2010). The magnitude of oxygen depletion was controlled by thermal stratification, modulated by water depth and nitrogen availability. Analyses were based on about 19,000 combined data sets. Eutrophication problem areas were identified mainly in coastal waters by oxygen minima, the lower 10th percentile of oxygen concentrations, and deviations of oxygen depletion from correlated stratification values. Connections between oxygen consumption and nitrogen sources and conversion, including denitrification, were indicated by correlations. Mean oxygen consumption reflected a minimum seasonal turnover of 3.1 g N/m 2 in the south-eastern North Sea, including denitrification of 1 g N/m 2 . Oxygen depletion was underestimated in shallow coastal waters due to repeated erosion of stratification as indicated by local high variability. [ABSTRACT FROM AUTHOR]

In this paper, we use concentrations of persistent organic pollutants (POPs) and of chlorophyll a to infer POP-induced effects on marine primary production in the Kattegat and the North Sea between the 1990s and the 2000s. To do so, we modelled phytoplankton dynamics using four classical drivers (light and nutrient availability, temperature and zooplankton grazing) and tested whether extending this model with a POP-induced phytoplankton growth limitation term improved model fit to observed chlorophyll a concentrations. Including monitored concentrations of PCBs and pesticides did not lead to a better model fit, suggesting that POP-induced growth limitation of marine phytoplankton in the North Sea and the Kattegat is small compared to the limitations caused by the classical drivers. In an attempt to more fully represent the multitude of POPs in the marine environment, the monitored concentrations were multiplied with a factor 10 and 100. Under these two configurations, region-specific contributions of POPs in the phytoplankton growth limitation were found. The inferred contribution of POPs to phytoplankton growth limitation was ca. 1% in Belgian marine waters, but in the Kattegat POPs explained ca. 10% of the phytoplankton growth limitation. These results suggest that there are regional differences in the contribution of POPs to the phytoplankton growth limitation. [ABSTRACT FROM AUTHOR]

In the North Sea, the amount of litter present in the marine environment represents a severe environmental problem. In order to assess the magnitude of the problem and measure changes in abundance, the results of two beach litter monitoring programmes were compared and analysed for long-term trends applying multivariate techniques. Total beach litter pollution was persistently high. Spatial differences in litter abundance made it difficult to identify long-term trends: Partly more than 8000 litter items year −1 were recorded on a 100 m long survey site on the island of Scharhörn, while the survey site on the beach on the island of Amrum revealed abundances lower by two orders of magnitude. Beach litter was dominated by plastic with mean proportions of 52%–91% of total beach litter. Non-parametric time series analyses detected many significant trends, which, however, did not show any systematic spatial patterns. Cluster analyses partly led to groupings of beaches according to their expositions to sources of litter, wind and currents. Surveys in short intervals of one to two weeks were found to give higher annual sums of beach litter than the quarterly surveys of the OSPAR method. Surveys at regular intervals of four weeks to five months would make monitoring results more reliable. [ABSTRACT FROM AUTHOR]

Continuous operational monitoring by means of remote sensing contributes significantly towards less occurrence of oil spills over European waters however, operational activities show regular occurrence of accidental and deliberate oil spills over the North Sea, particularly from offshore platform installations. Since the areas covered by oil spills are usually large and scattered over the North Sea, satellite remote sensing particularly Synthetic Aperture Radar (SAR) represents an effective tool for operational oil spill detection. This paper describes the development of a semi-automated approach for oil spill detection, optimized for near real time offshore platform sourced pollution monitoring context. Eight feature parameters are extracted from each segmented dark spot. The classification algorithm is based on artificial neural network. An initial evaluation of this methodology has been carried out on 156 TerraSAR-X images. Wind and current history information also have been analyzed for particular cases in order to evaluate their influences on spill trajectory. [ABSTRACT FROM AUTHOR]

Abstract: In European marine waters, existing monitoring programs of beach litter need to be improved concerning litter items used as indicators of pollution levels, efficiency, and effectiveness. In order to ease and focus future monitoring of beach litter on few important litter items, feed-forward neural networks consisting of three layers were developed to relate single litter items to general categories of marine litter. The neural networks developed were applied to seven beaches in the southern North Sea and modeled time series of five general categories of marine litter, such as litter from fishing, shipping, and tourism. Results of regression analyses show that general categories were predicted significantly moderately to well. Measured and modeled data were in the same order of magnitude, and minima and maxima overlapped well. Neural networks were found to be eligible tools to deliver reliable predictions of marine litter with low computational effort and little input of information. [Copyright &y& Elsevier]

Abstract: Over the years many policy measures have been taken to prevent illegal oil discharges from ships, like the MARPOL 73/78 Convention (1983) and the Bonn Agreement (1969/1983). However, the number of discharges remained high, leading to chronic oiling of seabirds and sensitive coastlines, therefore further measures were taken. The aim of this study is to quantify the effectiveness of two key legislative regulations: the IMO-designation of the North Sea as MARPOL Special Area which took effect in 1999, and the adoption of the EU Directive on Port Reception Facilities in 2000. Under study is the heavily navigated Belgian Surveillance Area, monitored since 1991, characterised by shallow waters with ecologically important sandbanks. The aerial surveillance data from 1991 to 2010 show a stepwise decrease in ship-source oil pollution. Three time periods can be distinguished with two turning points coinciding with the actual implementation of these key legislative measures, confirming their effectiveness. [Copyright &y& Elsevier]

Abstract: Polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP) that are present in routine discharges of produced water (PW) from the offshore industry continue to cause concern. The suitability of biological methods and chemical based passive samplers to determine exposure to these compounds was tested by deploying them around an oil installation and at reference locations in the North Sea. PAH and AP were analysed either as parent compounds in passive samplers and mussel tissue or as metabolites in fish bile. Generally the pattern of exposure relative to proximity to the discharge was represented by mussels, SPMDs and fish for PAH. Fish and SPMDs showed good correlation for PAH accumulations, whereas some differences were apparent between mussels and SPMDs. POCIS was the only technique tested that could accurately measure the most abundant AP in PW. The advantages of biologically independent measures of exposure for inclusion in discharge monitoring studies are outlined. [Copyright &y& Elsevier]

Abstract: A 3D coupled biogeochemical–hydrodynamic model (MIRO-CO2&CO) is implemented in the English Channel (ECH) and the Southern Bight of the North Sea (SBNS) to estimate the present-day spatio-temporal distribution of air–sea CO2 fluxes, surface water partial pressure of CO2 (pCO2) and other components of the carbonate system (pH, saturation state of calcite (Ω ca) and of aragonite (Ω ar)), and the main drivers of their variability. Over the 1994–2004 period, air–sea CO2 fluxes show significant inter-annual variability, with oscillations between net annual CO2 sinks and sources. The inter-annual variability of air–sea CO2 fluxes simulated in the SBNS is controlled primarily by river loads and changes of biological activities (net autotrophy in spring and early summer, and net heterotrophy in winter and autumn), while in areas less influenced by river inputs such as the ECH, the inter-annual variations of air–sea CO2 fluxes are mainly due to changes in sea surface temperature and in near-surface wind strength and direction. In the ECH, the decrease of pH, of Ω ca and of Ω ar follows the one expected from the increase of atmospheric CO2 (ocean acidification), but the decrease of these quantities in the SBNS during the considered time period is faster than the one expected from ocean acidification alone. This seems to be related to a general pattern of decreasing nutrient river loads and net ecosystem production (NEP) in the SBNS. Annually, the combined effect of carbon and nutrient loads leads to an increase of the sink of CO2 in the ECH and the SBNS, but the impact of the river loads varies spatially and is stronger in river plumes and nearshore waters than in offshore waters. The impact of organic and inorganic carbon (C) inputs is mainly confined to the coast and generates a source of CO2 to the atmosphere and low pH, of Ω ca and of Ω ar values in estuarine plumes, while the impact of nutrient loads, highest than the effect of C inputs in coastal nearshore waters, also propagates offshore and, by stimulating primary production, drives a sink of atmospheric CO2 and higher values of pH, of Ω ca and of Ω ar. [Copyright &y& Elsevier]

Abstract: Regime shifts in the marine environment have recently received much attention. To date, however, few large-scale meta-analyses have been carried out due to insufficient data coverage and integration between sustained observational datasets because of diverse methodologies used in data collection, recording and archival. Here we review the available data on regime shifts globally, followed by a review of current and planned policies with relevance to regime shifts. We then focus on the North and Baltic Seas, providing examples of existing efforts for data integration in the MarBEF Network of Excellence. Existing gaps in data coverage are identified, and the added value from meta-analyses of multiple datasets demonstrated using examples from the MarBEF integrated data project LargeNet. We discuss whether these efforts are addressing current policy needs and close with recommendations for future integrated data networks to increase our ability to understand, identify and predict recent and future regime shifts. [ABSTRACT FROM AUTHOR]

Abstract: Strandings of oiled seabirds are used to signal the problem of chronic oil pollution. Species-specific oil rates reflect the risk for marine birds to become oiled at sea. High oil rates were characteristic for seabirds common in areas with frequent oil spills; low oil rates for birds wintering away from the busiest shipping lanes. Declining trends in oil-rates were found, reflecting a reduction in the amount of oil intentionally discharged over the past 50years. Spatial patterns in the risk to become oiled could be identified, when the winter distribution patterns of the affected birds were incorporated in the analysis. Declines in oil rates were most pronounced in coastal birds. These trends were consistent with tendencies to police nearshore waters more effectively than offshore waters. While levels of chronic oil pollution are much reduced, future emphasis should be to reduce chronic oiling more effectively in offshore waters. [ABSTRACT FROM AUTHOR]

Spatial and temporal distribution of the flame retardant hexabromocyclododecane (HBCD) in the North Sea was examined for the period from 1995 to 2005 using a pollutant transport model FANTOM. Model calculations allow conclusions on relevant sinks and fluxes in and out of the North Sea and on the time needed to establish a steady state. Calculations were performed for two additional scenarios with different rates of primary degradation ranging from fast degrading to absolute persistency. Concentrations calculated in the scenarios with degradation are in line with the monitoring data available for HBCD. Concentrations calculated in the "persistent" scenario disagree with measured data. According to our model calculations, steady state is established within months for the water and the top layer sediment with no evidence for a temporal trend, except for the "persistent" scenario, in which concentrations increase continuously in the southeastern part of the North Sea, where hydrographic and circulation characteristics produce areas of converging currents. Our model study enables a better understanding of the fate of HBCD in the North Sea, its potential for transport and overall elimination. We discuss these findings in the light of different concerns for PBT substances. [ABSTRACT FROM AUTHOR]

Abstract: In many coastal regions, oil spills can be considered as one of the most important and certainly the most noticeable forms of marine pollution. Efficient contingency management responding to oil spills on waters, which aims at minimizing pollution effects on coastal resources, turns out to be critically important. Such a decision making highly depends on the importance attributed to different coastal economic and ecological resources. Economic uses can, in principal, be addressed by standard measures such as value added. However, there is a missing of market in the real world for natural goods. Coastal resources such as waters and beach cannot be directly measured in money terms, which increases the risk of being neglected in a decision making process. This paper evaluates these natural goods of coastal environment in a hypothetical market by employing stated choice experiments. Oil spill management practice in German North Sea is used as an example. Results from a pilot survey show that during a combat process, beach and eider ducks are of key concerns for households. An environmental friendly combat option has to be a minor cost for households. Moreover, households with less children, higher monthly income and a membership of environmental organization are more likely to state that they are willing to pay for combat option to prevent coastal resources from an oil pollution. Despite that choice experiments require knowledge of designing questionnaire and statistical skills to deal with discrete choices and conducting a survey is time consumed, the results have important implications for oil spill contingency management. Overall, such a stated preference method can offer useful information for decision makers to consider coastal resources into a decision making process and can further contribute to finding a cost-effective oil preventive measure, also has a wide application potential in the field of Integrated Coastal Zone Management (ICZM). [Copyright &y& Elsevier]

Abstract: A biotest system for environmentally realistic exposure of fish to produced water (PW) was developed and tested. Authentic PW was collected at an oil production platform in the North Sea and preserved by freezing in multiple aliquots a 25L. After transport to the test laboratory onshore, daily PW aliquots were thawed, homogenised and administered to the test fish, Atlantic cod (Gadus morhua), in two diluted exposure concentrations, 0.1% and 0.5%, during a 15 d period, using a continuous flow-through exposure setup. Positive control groups were exposed to two crude oil treatments for comparison. Chemical analyses showed that alkylphenol (AP) and PAH concentrations in PW exposure waters were very low. Observations of significantly increased AP and PAH metabolite levels in PW exposed fish demonstrated the suitability of the biotest system for its use in biological exposure/effect studies of PW, and it also demonstrated the sensitivity of bile metabolites as PW exposure markers in fish. The relevance of the biotest system for PW effect studies and for validating modelled environmental risk estimates of PW dischargers from offshore oil production is discussed. [Copyright &y& Elsevier]

Several marine holoplanktonic organisms show a high degree of geographically structured diversity for which it often remains unclear to what extent this differentiation is due to the presence of cryptic taxa. For the genetically distinct diatom Pseudo-nitzschia pungens var. pungens, we used six microsatellite markers to investigate the spatial and temporal genetic composition in the heterogeneous Southern Bight of the North Sea. Although our sampling area (ca. 100 km) comprised water bodies with different environmental conditions (marine, estuary, saline lake) and different degrees of connectivity (from complete isolation to supposedly free exchange between environments), no evidence of genetic differentiation was found. Expanding our sampling area (ca. 650 km), suggested a homogenous population structure over even larger areas in the North Sea. Our results suggest that the population structure of this diatom is mainly shaped by strong homogenizing effects of gene flow preventing genetic drift, even in water bodies with limited connectivity. [ABSTRACT FROM AUTHOR]

Abstract: Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) were found to differ in the ability to metabolize polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Biomagnification factors (BMFs), calculated between both predators and their prey (sole –Solea solea and whiting –Merlangius merlangus), had a large range of variation (between 0.5 and 91 for PCBs and between 0.6 and 53 for PBDEs). For the higher chlorinated PCBs and the highest brominated PBDEs, the BMF values in adult males were significantly higher than in the juvenile individuals of both species. BMF values of hexa- to octa-PCBs were the highest, suggesting reduced ability to degrade these congeners. Harbour porpoises had higher BMFs for lower chlorinated PCBs and for all PBDEs compared to harbour seals. Other factors, which may influence biomagnification, such as the octanol–water partition coefficients and the trophic level position measured through stable isotope (δ 15N) analysis, were found to be of lesser importance to predict biomagnification in the studied food chain. [Copyright &y& Elsevier]

Abstract: Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) are two representative top predator species of the North Sea ecosystem. The median values of sum of 21 polychlorinated biphenyl (PCB) congeners and sum of 10 polybrominated diphenyl ether (PBDE) congeners were 23.1μg/g lipid weight (lw) and 0.33μg/g lw in blubber of harbour seals (n =28) and 12.4μg/g lw and 0.76μg/g lw in blubber of harbour porpoises (n =35), respectively. For both species, the highest PCB concentrations were observed in adult males indicating bioaccumulation. On the contrary, the highest PBDE concentrations were measured in juveniles, likely due to better-developed metabolic capacities with age in adults. A higher contribution of lower chlorinated and non-persistent congeners, such as CB 52, CB 95, CB 101, and CB 149, together with higher contributions of other PBDE congeners than BDE 47, indicated that harbour porpoises are unable to metabolize these compounds. Harbour seals showed a higher ability to metabolize PCBs and PBDEs. [Copyright &y& Elsevier]

Abstract: The potential of triclosan (TCS) acting as an endocrine disruptor has led to growing concern about the presence of TCS in the environment. In this study, seawater samples were collected from the German Bight during sampling campaigns conducted with the German research ships Gauss and Ludwig Prandtl. TCS was determined both in the dissolved phase and in the suspended particulate matters with concentrations ranging 0.8–6870pgL−1 and <1–95pgL−1, respectively. High concentrations of TCS were present in the estuaries of the Elbe and the Weser, indicating significant input of TCS by the river discharge. The correlation coefficient (R 2) between the dissolved concentration and salinity was 0.79 for the data obtained from the Gauss cruise, showing an obvious declining trend from the coast to the open sea. [Copyright &y& Elsevier]

Heat shock proteins 70 (hsp70) are known to be induced by a great variety of chemical stressors. The effects of different environmental contaminants, which were identified in sediments of the North Sea and the Baltic Sea as main contaminants or as contaminants of special toxicological interest, on the extent of expression of hsp70 in a permanent cell line Epithelioma papulosum cyprini (EPC) were investigated. Concentrations of the single contaminants leading to elevated hsp70 levels were compared to the respective concentrations of these contaminants encountered in the sediment extracts thus allowing an assessment of their contribution to the toxicity of these sediments. Analysis of hsp70 was performed using western blotting techniques with subsequent comparative quantification by densitometry. Eleven of thirteen contaminants have shown a dose-dependent increase in hsp70 levels. An expression of hsp70 was observed in most cases between 0. 1 and 10μg/mL test solution. Some of the investigated stressors led to extremely high hsp70 contents even at low concentrations. However, in most cases contaminant concentrations in sediments were too low to cause an effect. For this reason, effects of the tested sediments are attributed to other contaminants or rather to mixtures of stressors. [Copyright &y& Elsevier]

Previous studies have described high levels of polychlorobiphenyls (PCB), polybrominated diphenylether (PBDE), toxaphene, p,p′-dichlorodiphenyltrichloroethane (DDT), and p,p′-dichlorodiphenyldichloroethylene (DDE) in the blubber of the harbour porpoise from the North Sea raising the question of a potential endocrine disruption in this species. In the present study, the thyroids of 57 harbour porpoises from the German and Danish (North and Baltic Seas), Norwegian, and Icelandic coasts have been collected for histological and immunohistological investigations. The number of follicles and the relative distribution of follicles, connective, and solid tissues (%) were quantified in the thyroid of each individual. Then, the potential relationship between the thyroid morphometry data and previously described organic compounds (namely, PCB, PBDE, toxaphene, DDT, and DDE) was investigated using factor analysis and multiple regressions. Thyroid morphology differed strongly between sampling sites. Porpoises from the German (North and Baltic Seas) and Norwegian coasts displayed a high percentage of connective tissues between 30 and 38% revealing severe interfollicular fibrosis and a high number of large follicles (diameter >200 μm). A correlation-based principal component analysis (PCA) revealed two principal components explaining 85.9% of the total variance. The variables PCB, PBDE, DDT, and DDE compounds loaded highest on PC1 whereas toxaphene compound loaded most on PC2. Our results pointed out a relationship between PC1 (PCBs, PBDE, DDE, and DDT compounds) and interfollicular fibrosis in the harbour porpoise thyroids. Such an association is not alone sufficient for a cause–effect relationship but supports the hypothesis of a contaminant-induced thyroid fibrosis in harbour porpoises raising the question of the long-term viability in highly polluted areas. [ABSTRACT FROM AUTHOR]

This risk assessment on dichloromethane was carried out specifically for the marine environment, following methodology given in the EU risk assessment Regulation (1488/94) and Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of `predicted environmental concentrations' (PEC) to `predicted no-effect concentrations' (PNEC) for the marine aquatic environment. In total, 23 studies for fish, 17 studies for invertebrates and 6 studies for algae were evaluated. Both acute and chronic toxicity studies were taken into account and appropriate assessment factors used to define a PNEC value of 830 μg/l. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1983–1995) support a typical PEC for dichloromethane lower than 0.2 μg/l and a worst case PEC of 13.6 μg/l. Dichloromethane is not a `toxic, persistent and liable to bioaccumulate' substance sensu the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). The calculated PEC/PNEC ratios give margins of 60 to 4000 between the PNEC and PEC, dilution within the sea would further increase these margins. It can be concluded that the present use of dichloromethane does not present a risk to the marine aquatic environment. [ABSTRACT FROM AUTHOR]

This risk assessment on 1,1,1-trichloroethane was carried out specifically for the marine environment, accordingly to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1996). 1,1,1-trichloroethane is being phased out of most uses because of its ozone depletion potential (ODP) under the Montreal Protocol. Production for emissive uses has already been phased out end 1995 in Europe and 1996 in the United States, Japan and other industrial countries. The risk assessment study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programmes in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the Predicted Environmental Concentration (PEC) and the Predicted No-Effect Concentration (PNEC) for the marine aquatic environment. In total 14 studies for fish, 7 studies for invertebrates and 9 studies for algae have been evaluated. Both acute and chronic studies have been taken into account and the appropriate assessment factors have been used to calculate a PNEC value of 21 μg/l based on long term exposure. The PEC was derived from monitoring data. The PEC was set at 0.206 μg/l (worst case) and 0.024 μg/l (typical case) for coastal waters and estuaries and 0.6 μg/l (worst case) and <0.1 μg/l (typical case) for river waters. The calculated PEC/PNEC ratios, which do not take into account any dilution factor within the sea, correspond to a safety margin of 35 to 1000 between the aquatic effect and the exposure concentration. 1,1,1-trichloroethane is not a `toxic, persistent and liable to bioaccumulate' substance according to the criteria as mentioned by the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). It can be concluded that the present use of 1,1,1-trichloroethane does not present a risk to the marine aquatic environment. [ABSTRACT FROM AUTHOR]

This risk assessment on carbon tetrachloride was carried out specifically for the marine environment, according to the methodology laid down in the European Union (EU) risk assessment Regulation (1488/94) and the Technical Guidance Documents for New and Existing Substances (TGD, 1996). The Montreal Protocol on ozone depleting substances scheduled a phase-out of carbon tetrachloride except for some essential and feedstock uses. This study consisted of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the Predicted Exposure Concentration (PEC) and the Predicted No-Effect Concentration (PNEC) for the marine aquatic environment. In total 15 studies for fish, 7 studies for invertebrates and 5 for algae have been evaluated. The appropriate assessment factor has been used to calculate a PNEC of 7 μg/l based on long-term exposure for three trophic levels. For coastal waters and estuaries a typical and worst case PEC of 0.003 and 0.31 μg/l are derived. For river waters a typical and worst case PEC of 0.02 and 0.12 μg/l are derived, respectively. These ratios, which do not take into account any dilution within the sea, correspond to safety margins from 25 to 2500 between the aquatic effect and the exposure concentration. Carbon tetrachloride does not meet the criteria of `toxic, persistent and liable to bioaccumulate' substances as mentioned by the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). It can be concluded that the present use of carbon tetrachloride does not present a risk to the marine aquatic environment. [ABSTRACT FROM AUTHOR]

The exploration and production of North Sea oil and gas reserves has resulted in the accumulation of large quantities of drill cuttings on the seabed surrounding drill sites. This complex mixture of man-made and natural substances contains higher concentrations of certain metals (Ba, Cr, Cu, Ni, Pb, and Zn) and hydrocarbons than are observed in background sediments. With decommissioning of older platforms underway, an evaluation of the environmental interactions and chemical fate of the drill cuttings accumulations is required.This review concentrates on contaminants within drill cutting accumulations in the Northern and Central North Sea (56 °N–62 °N). Present literature reviewed reveals that hydrocarbons within the cuttings piles remain relatively unchanged with time. A considerable proportion of the associated contaminants are likely to remain within the cuttings pile unless they are disturbed which will then increase exchanges of porewater and solids back to the seabed surface resulting in pathways of exposure for organisms. [Copyright &y& Elsevier]

An analytical method is presented, which allows the simultaneous extraction of neutral and acidic compounds from 20-L seawater samples at ambient pH (∼8.3). It is based on a solid-phase extraction by means of a polystyrene–divinylbenzene sorbent and gas chromatographic-mass spectrometric detection, and provides detection limits in the lower pg/L range. The method was applied to the screening of samples from different North Sea areas for clofibric acid, diclofenac, ibuprofen, ketoprofen, propyphenazone, caffeine and N,N-diethyl-3-toluamide (DEET). Whereas clofibric acid, caffeine and DEET showed to be present throughout the North Sea in concentrations of up to 1.3, 16 and 1.1 ng/L, respectively, propyphenazone could only be detected after further clean-up. Diclofenac and ibuprofen were found in the estuary of the river Elbe (6.2 and 0.6 ng/L, respectively) but in none of the marine samples. Ketoprofen was below the detection limit in all samples. [Copyright &y& Elsevier]

The fate of linear alkylbenzenesulponates (LAS) in estuaries and coastal areas of the North Sea has been characterized with simple environmental models. The predicted concentration range in the estuaries around the North Sea (0.9-9 µg LAS l[sup -1]) was validated by monitoring data (19 µg LAS l[sup -1]). In offshore sites of the North Sea, it is estimated — and experimentally verified for a few sites — that the LAS concentration is below analytical detection limit (i.e., 0.5 µg LAS l[sup -1]). The effects of LAS on marine organisms have been reviewed. For short-term acute tests, there was no significant difference (p = 0.83) between the mean LC[sub 50] values of freshwater and marine organisms (mainly pelagic species tested, 4.1 and 4.3 mg LAS l[sup -1], respectively). For longer-term chronic tests, it appeared that the sensitivity (mean no-observed effect concentration (NOEC) value) of marine and freshwater organisms (0.3 and 2.3 mg LAS l[sup -1], respectively) was significantly different (p[sub t-test] = 0.007). The predicted no-effect-concentrations (PNEC) were 360 and 31 µg LAS l[sup -1], for freshwater and marine pelagic communities, respectively. Given that the maximum expected estuarine and marine concentrations are 3 to > 30 times lower than the PNEC, the risk of LAS to pelagic organisms in these environments is judged to be low. [ABSTRACT FROM AUTHOR]

The seasonal phytoplankton biomass distribution pattern in stratified temperate marine waters is traditionally depicted as consisting of spring and autumn blooms. The energy source supporting pelagic summer production is believed to be the spring bloom. However, the spring bloom disappears relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is often comprised of intact phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering, Limnol. Oceanogr., 12, 196–206, 1967)] occurring in these blooms may be greater than that occurring in the spring bloom in the same regions. Thus, such blooms may explain apparent discrepancies in production yields between different temperate marine systems. [ABSTRACT FROM PUBLISHER]

Presents observations of the surface effects of bottom-generated turbulence in a tidally influenced and will mixed region of the North sea, as derived from acoustic and visual images. How turbulence in shelf sea affects the spread of pollution; Finding that at any one time, 20-30% of the water surface is affected by boils, which are circular regions of local upwelling, of diameter 0.9 plus or minus 0.2 times the water depth; How the boils enhances the fluxes of gases between atmosphere and ocean.

Discusses the contribution of regional river treaties to the protection of the North Sea, as discussed at the "Toxics Reductions Programmes in the North and Baltic Sea: A Comparative Perspective on Two Regional Marine Environment Protection Regimes in Northern Europe" colloquium at the Vrije Universiteit Brussel in February 1997. Response of North Sea Ministers to this issue; River conventions within the North Sea catchment; Operations of the Rhine Commission, particularly their dealings with the practical implementation of river treaties; Future contribution by river treaties to North Sea protection.

The article reviews available information on time trends in metal concentration in biota from monitoring studies in the North Sea. Data collected in Danish marine waters are presented as examples of changes in metal concentrations since 1975. Causes of trends and problems associated with the use of measurements in biota when assessing time trends in metals are discussed. Although emissions of many metals have apparently been reduced during the last 15 years due to different regulations, it has only been possible to detect any significant changes in the environment in very few of the more contaminated coastal areas. It is argued that this might well be caused by the lack of understanding of the effects of biological covariables on metal concentrations which may explain part of the variance observed in samples, and also of the physical and biogeochemical processes, which may cause changes in the bioavailability of metals and levels of contamination. [ABSTRACT FROM PUBLISHER]

Marine debris is known for its ubiquitousness and harmful effects on marine life. This study is the first analysis to provide information on the distribution of floating marine debris in German waters using aerial survey data collected between 2002 and 2016. During regular harbour porpoise monitoring flights, 191,167 km were covered and 26,512 floating debris items recorded (average encounter rate 0.1387 items/km). Debris was encountered more often in the North Sea than in the Baltic Sea (0.16 items/km; 0.08 items/km). The average encounter rate was higher in offshore waters than in coastal areas. Overlaps of marine debris distribution with 'Special Areas of Conservation' are a particular reason for concern. Moreover, the spring months (March-May) were identified to be the time of the year with the highest average encounter rates for marine debris. Fishing-related debris was shown to contribute up to 25% of the total number of all observed items. This study shows that opportunistically collected data on marine debris from aerial surveys are valuable for identifying distribution patterns of floating debris without additional survey effort and costs. These data can be used as baseline information to inform management schemes such as the Marine Strategy Framework Directive.

Petroleum waxes (PWs) are recognized as ubiquitously emerging marine pollutants. However, knowledge on their occurrence, particularly as persistent floaters of small size (<5 mm) in marine surface water, is scarce. For this study, 24 samples were collected in the North Sea by net-sampling (100 μm-mesh). Particles of wax-like appearance were detected at 14 stations. Similar appearing PWs from six stations with highest abundances were pooled per station and analyzed by ATR-FTIR (Attenuated total reflectance Fourier-transform infrared spectroscopy) and gas chromatography. Samples contained paraffin particles, being partly accompanied by substances like fatty acids and fatty alcohols. Using both analytical techniques provided a reliable detection of PWs and more details on their chemical composition. Furthermore, exemplarily the presence of PWs of 20-500 μm size was proven by μFTIR imaging. This study gives valuable insights into PW pollution in the North Sea, emphasizing the need for harmonized detection methods, ideally accompanying microplastics monitoring., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Oil spills in the marine environment can cause ecosystem-level impacts. Dispersant application as an oil spill response measure leads to the widespread distribution of hydrocarbons in the water column and marine sediments. The North Sea is an area of intense hydrocarbon production and is at risk of oil spills, which are of concern to its benthic ecosystem due to its sediments' high permeability. Here, entrainment of hydrocarbons via pore-water advection into permeable North Sea sands and the associated effect of Superdispersant-25, a commercial oil dispersant, were evaluated in a laboratory. Centrally stirred chambers that induce advective pore-water fluxes in sediments were filled with sediment, seawater and mixtures of oil and Superdispersant-25. Dispersant application had contrasting effects on hydrocarbon interactions with sediment: (1) it reduced accumulation of hydrocarbons in surface sediments and (2) facilitated the entrainment of hydrocarbons up to 8 cm deep into sediments by increasing hydrocarbon solubility in seawater and its subsequent washout or pumping into sediment by pore-water movement. Results here show that dispersant application can have counter-intuitive effects on hydrocarbon interactions with marine sediments and highlight the need for further research in this area to make better informed decision in an oil spill response scenario.

Discharges of contaminated drill cuttings have caused appreciable ecological change of the benthos adjacent to many oil and gas platformsin the North Sea. Many platforms have large piles of cuttings lying beneath them and these probably present the greatest potential hazardto the environment during platform decommissioning and removal. There is, however, a lack of consensus on which aspects of drill cuttingsare responsible for the adverse ecological effects. This hinders risk assessment of management options. Here we report data on the toxicity of sediments from around the North West Hutton platform to the amphipod Corophium volutator, the polychaeteArenicola marina and the Microtox(R) acute test system. Sediment was acutely toxic to Corophium out as far as 600 m from the platform. Sediment from 100 m from the platform remained acutely toxic to Corophium when 3% contaminated sediment was mixed with clean sediment. A 10% dilution of this sediment also inhibited Arenicola feeding almost completely. Sediment elutriatesdid not inhibit Microtox light output, but organics extracted by dichloromethane were very toxic. Fifteen minute EC50 values were as low as 0.25 mg ml-1 and were strongly correlated with hydrocarbon concentrations. Metal concentrations in whole sediments were correlated with their toxicity to Corophium but the relationship was much weaker when data on dilutions were included. Except at sites immediately adjacent to the platform, metal concentrations were well below ERL values from the literature, so were too low to explain sediment toxicity. Toxicity of sediments to Corophium was closely correlated with their hydrocarbon content, even when tests on dilutions were included in the analysis. We conclude that hydrocarbons are the most significant cause of toxicity in these sediments contaminated with oil based drill cuttings and that polar organics, sulphide, ammonia and other water soluble substances are of much lower significance. Appl [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate the charging systems for the use of port reception facilities for waste oil, and to examine the potential impact of the charging elements of the new (late 2000) EU Directive on port reception facilities for ship-generated waste and cargo residues. Experience to date with alternative models for charging is considered. Conclusions are drawn about the effectiveness of the EU Directive as a means of controlling pollution in the North Sea and producing a `level playing field' between ports. [ABSTRACT FROM AUTHOR]

Data collected by volunteers in a survey of imposex in the dogwhelk Nucella lapillus from North Sea coasts correlated closely with independent measures made by an experienced scientist. There had been significant recovery from imposex since an earlier survey in 1991, even inpopulations which had been classified as sterile at that time. The study has attracted media attention, and may therefore have had some impact on the current debate on the need to regulate further (or ban altogether) the use of TBT-based anti-fouling paints. [ABSTRACT FROM AUTHOR]

In previous surveys of North Sea sediments, arsenic has often been omitted from the range of metals analysed. In this study we analysed archived samples from these earlier surveys and combined the data withrecent results for the Dogger Bank, to examine the distribution of total arsenic in sediments from the western North Sea and Humber Estuary. Historically, the Humber has been subjected to a large point discharge of arsenic from an industrial source, and so there is interest in investigating the extent of contamination in the area. Normalization of arsenic concentrations to those of the clay analogues aluminiumor rubidium did not prove to be statistically appropriate for the whole of the surveyed area. However, normalization to iron (representing iron (oxy-)hydroxide coatings with which arsenate has a high affinity) did show strong relationships for sediments from the whole of theregion studied. This procedure showed elevated arsenic concentrations to be present in sediments from the outer Thames and off north eastNorfolk, while those from the Humber were close to their predicted value. The Humber receives a large amount of iron from industrial discharges, providing a possible source of material for iron (oxy-)hydroxides. Although arsenical waste disposal could explain the high arsenic concentrations in sediments from the outer Thames, the causes for those off north east Norfolk are as yet unclear. [ABSTRACT FROM AUTHOR]

A field study was carried out in the Norwegian sector of the North Sea during May and June 1997. The purpose was to measure the concentration of produced water originating polycyclic aromatic hydrocarbons (PAH) in seawater and to compare different sampling techniques for usein future monitoring programs. Three methods were used for direct water sampling: (1) in situ large volume sampling of particulate and dissolved hydrocarbons onto filters and XAD resins, (2) solid phase extraction (SPE) using polystyrene-divinylbenzene disks, (3) whole bulk water sampling. In addition, sampling by semi-permeable membrane devices (SPMDs) and blue mussels (Mytilus edulis) was used to obtain a 4 weeks average of the concentration of the target compounds in seawater. The samples were processed and analysed by GC-MS for determinationof PAH concentrations. The measured concentrations were generally found to be low, and in many cases below the limits of detection. The comparison of sampling techniques showed that blue mussels and SPMDs are suitable for measuring PAH in both near- and far-field seawater. In situ large volume water sampling was also suitable for a wide rangeof PAH concentrations, but this technique was limited by high break-through of the low-molecular weight compounds, such as naphthalenes. The small sampling volumes limited the SPE and whole water sampling techniques, resulting in potential detection limit problems. These grab-sampling techniques may, however, be suitable for monitoring in thenear-field areas around the platforms. [ABSTRACT FROM AUTHOR]

This paper gives an up-date of the scientific knowledge of changes that occurred in the flora of the North Sea since the Quality Status Report of the North Sea was published in 1994, and the Dobris Assessment (Europe's Environment) was published in 1995. It shows that, as anepi-continental semi-enclosed marine ecosystem, the North Sea conditions create complex interactions between the flora and the marine environment. Plankton distribution and succession are considered in the light of recent research, with a focus on ecosystem modelling. Changes in macrophyte biodiversity are reviewed in connection with pollution. Symptoms of eutrophication are believed to be responses to increases in primary production. Community changes in plankton, seaweeds, and eelgrass also influence lower and higher levels in the food web. The possible effects of predicted climate changes on the flora of the North Sea are investigated. The review demonstrates that, in the future, potential changes could affect the flora in relation to changes insolar radiation and temperature. Finally, attention is paid to crucial needs in related research, education, and conservation of species and habitats. [ABSTRACT FROM AUTHOR]

Concentrations of total mercury and methylmercury were analysed in muscle, kidney and liver samples from 57 harbour porpoises and three white-beaked dolphins, stranded or by-caught from the German waters ofthe North and Baltic Seas. Levels of total mercury ranged between 0.6 and 450 Mu g/g dry weight (dw) and of methylmercury between 0.2 and26 Mu g/gdw. No differences in concentrations of either total mercury or methylmercury were observed between stranded and by-caught animals nor between males and females. However, a difference in mercury content of cetaceans from the North and Baltic Seas was found. A significant correlation between animal age and total mercury as well as methylmercury in all examined organs could be demonstrated. Pathological, microbiological and parasitological studies were performed on the animals. The majority of pathological lesions were caused by helminths. Lesions characteristic of acute or chronic intoxication with mercury could not be found. However, there were significant associations between mercury levels and severity of lesions with respective to nutritional state of the cetaceans examined, demonstrated by means of polychotomous logistic regression for ordinal variables and adjusted for the effects of age and location. [ABSTRACT FROM AUTHOR]

Four decades of continual fly-ash disposal off Northumberland, U.K.,ended in December 1992. Quantitative sampling of the sediment and the macrobenthos was undertaken in the Summer 1993 over 27 km2 of seabed covering the Blyth Fly-ash Dumpsite and the surrounding area. The offshore portion of the region surveyed bore only traces offly-ash particles, waste being confined to the region shallower than45 m. There, disposals have changed local sedimentary conditions increasing the spatial patchiness of sediment types and altering silt-clay dynamics. Inshore of the dumpsite, substrata affected by long-termtipping have effectively become an artificial reef due to the cementation of the waste. The seabed within the designated dumpsite was still composed of pure fly ash, resulting in macrobenthic densities and species richness markedly lower than control areas, though higher than recorded in a previous survey in 1988. At the dumpsite, between 47 and 66% of the species had only one or two representatives and juveniles made up 47-88% of the individuals. Additional faunal impoverishment occurred where pebbly clinker and aggregates abounded. Nine monthsafter cessation of dumping recovery was essentially dependant on thedecrease in the concentration of the waste and will proceed as the gradual fertilization of the sediments occurs. [ABSTRACT FROM AUTHOR]