Varying temporal trends in the levels of six groups of legacy persistent organic pollutants (POPs) in liver of three gadoid species from the North Sea.

From 2005 to 2019, three gadoid species, Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and saithe (Pollachius virens), were sampled approximately every third year in the northeastern part of the North Sea. Liver samples were analyzed to investigate levels and temporal trends of six groups of persistent organic pollutants (POPs): polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its degradation products, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), trans-nonachlor (TNC), and polybrominated diphenyl ethers (PBDEs). Some of the highest average concentrations were found in cod, the levels otherwise being similar between the three species and mostly below established threshold values. The levels of all the contaminants except HCB and TNC were higher than previously reported for cod and haddock in the Barents Sea. Significantly decreasing levels were found for Σ7PCBs, ΣDDTs, ΣHCHs and Σ15PBDEs in all three species, and for TNC in haddock and saithe, while there was no significant trend for TNC in cod. HCB levels increased significantly in cod and haddock and showed only a minor decrease in saithe. The observed time trends of legacy POPs demonstrate the persistence of some of the studied pollutants despite efforts to eliminate them from the marine environment.

Co-occurrence of contaminants in marine fish from the North East Atlantic Ocean: Implications for human risk assessment.

Marine fish from the North East Atlantic Ocean (NEAO) are nutrient rich and considered a valuable economic resource. However, marine fish are also a major dietary source of several contaminants, including persistent organic pollutants (POPs) and heavy metals. Using one of the world's largest seafood datasets (n > 25,000 individuals), comprising 12 commercially important fish species collected during 2006-2019 in the NEAO, we assessed the co-occurrence of elements and POPs, and evaluated potential risks to human consumers. Several positive correlations between concentrations of mercury (Hg), dioxins, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were observed. Concentrations of Hg, dioxins, PCBs and PBDEs increased from North to South and associations between marine sediment contamination, sea temperature, and fish Hg and POPs concentrations were identified using multi-linear regression (MLR) models. In general, Hg concentrations in fillet and liver of fish were positively associated with increases in both sediment contamination and sea temperature. POPs concentrations in both fillet and liver were positively associated with increases in sediment contamination, and only POPs concentrations in the liver of benthopelagic and demersal species were found to be positively correlated with sea temperature. Using a probabilistic approach to estimate human contaminant exposure from seafood, we showed that intake of pelagic species posed the highest risk of dioxins and dioxin-like PCBs (DL-PCBs) exposure, while intake of benthopelagic and demersal species posed the highest risk of Hg exposure. This study can serve as a model to further understand the distribution, co-occurrence, and trends of contaminants in seafood harvested from the NEAO and their potential risks to human consumers.

Background concentrations of polycyclic aromatic hydrocarbons (PAHs) in deep core sediments from the Norwegian Sea and the Barents Sea: A proposed update of the OSPAR Commission background values for these sea areas.

Geochemical studies of 174 sediment cores collected by the MAREANO mapping program in Norwegian waters of the North Atlantic Ocean give new sets of values of background concentrations (BCs) for polycyclic aromatic hydrocarbons (PAHs) for the studied regions. The study is based on deep core sediment samples representing background levels of PAHs. The samples selected were only from the deeper parts of undisturbed sediment cores with low, stable concentrations of petrogenic and pyrogenic PAHs, with low variation for individual PAH compounds between the samples within the same core, and from below the parts of the cores dated with 210Pb to approximately the last 100-150 years. The results show that the main part of the studied area has BCs different from those previously established by OSPAR Commission (OSPAR) for the North-East Atlantic. Another area in central Barents Sea has a separate set of BCs of pyrogenic PAHs, apparently due to the influence from marginal ice zone mechanisms. A third area with its own set of BCs has been established for north-western Barents Sea off the coast of Svalbard, due to high natural contents of PAHs in this area. BCs for several PAHs not included in the present OSPAR list are also provided.

Levels and temporal trends of persistent organic pollutants (POPs) in Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) from the southern Barents Sea.

Liver samples of two gadoid species, Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus), sampled in the southern Barents Sea in the period 1992-2015, were studied for the levels of six types of persistent organic pollutants (POPs): polychlorinated biphenyls (PCBs), chlorinated organic pesticides (DDTs, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), trans-nonachlor (TNC)), and polybrominated diphenyl ethers (PBDEs). Higher average levels were found in cod than in haddock. Sampling approximately every third year allowed studies of temporal trends for all the compound groups except PBDEs. Time series are reported for 1992-2015 for Atlantic cod and for 1998-2015 for haddock. Decreasing temporal trends have been modeled in cod for the analyzed POPs for this time period. The decrease seems to be slowing down in the later years. HCB levels showed least decrease with time among all the contaminants, with the poorest fit to the proposed model. Similar time trends were found in haddock, but the decrease is less apparent due to shorter time series. The observed time trends of legacy POPs document the effectiveness of efforts during the 1990s to reduce the levels of these contaminants in the marine environment but question the possibility to eliminate them altogether from the marine environment in the foreseeable future.

Additive Models Reveal Sources of Metals and Organic Pollutants in Norwegian Marine Sediments.

We characterized spatial patterns of surface sediment concentrations of seven polychlorinated biphenyls (PCBs), seven polycyclic aromatic hydrocarbons (PAHs), three chlorinated pesticides, and five metals in Norwegian waters and Skagerrak. In total, we analyzed 5036 concentrations of 22 chemical substances that were measured between 1986 and 2014 at 333 sampling sites by means of generalized additive models (GAMs). We found that GAMs with organic carbon content of the sediment and latitude and longitude as co-variates explained as ca. 75% of the variability of the contaminant sediment concentrations. For metals, a predominantly hotspot-driven spatial pattern was found, i.e., we identified historical pollution hotspots (e.g., Sørfjord in western Norway) for mercury, zinc, cadmium, and lead. Highest concentrations of PAHs and PCBs were found close to densely populated and industrialized regions, i.e., in the North Sea and in the Kattegat and Skagerrak. The spatial pattern of the PCBs suggests the secondary and diffuse atmospheric nature of their sources. Atmospheric inputs are the main sources of pollution for most organic chemicals considered, but north of the Arctic circle, we found that concentrations of PAHs increased from south to north most likely related to a combination of coal-eroding bedrock and the biological pump. The knowledge acquired in the present research is essential for developing effective remediation strategies that are consistent with international conventions on pollution control.

Sources of polycyclic aromatic hydrocarbons in marine sediments from southern and northern areas of the Norwegian continental shelf.

Variability in levels and sources of polycyclic aromatic hydrocarbons (PAH) in sediments from one large sea area off the coast of northern Norway ("North area", NA) have been compared to similar data from another large area off the coast of southern Norway ("South area", SA). Samples from NA were collected at the Norwegian continental shelf in south-western Barents Sea and north-eastern Norwegian Sea. Samples from SA were from the Norwegian Trench and the Skagerrak. Sediment cores have been dated, characterised by grain size distribution (GS) and organic carbon content (TOC), and the composition of PAH and geochemical biomarkers (alkanes and triterpanes) studied to provide an insight into the different sources of PAH. Generally, PAH levels are higher in sediments from SA compared to NA. A mixture of pyrogenic and petrogenic sources contribute to PAH levels in SA, while the contents of petrogenic PAH is negligible in surface sediments in NA. At some locations in NA, petrogenic PAH levels are elevated in the deepest sediment layers from pre-industrial times, indicating a natural input of petroleum through seepage. Occurrence of elevated levels of microbial hopanoids (hopenes) in the deepest sediment layers at some locations both in the north and the south indicate the presence of petroleum.

Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea.

Subsurface sediments from a pockmark area in South-Western Barents Sea have been earlier found to contain elevated levels of petroleum-related polycyclic aromatic hydrocarbons. This work describes a comprehensive analysis of various biomarkers, including the highly source-specific hopanes, in a 4.5 m long gravity core from the same area, together with subsurface sediment samples from other areas in the region without pockmarks present ("background samples"). A clear difference between the pockmark gravity core and the background sediment cores was found, both with regard to genesis and the level of transformation of organic matter. A number of indicator parameters, such as methylphenanthrene index (MPI-1), point towards a significantly higher maturity of hydrocarbons in the pockmark core throughout its length as compared to the other sampled locations. Higher contents of microbial hopanoids (hopenes) may indicate the former presence of petroleum. These findings confirm the hypothesis of a natural hydrocarbon source in the deeper strata present in the studied location with pockmarks.

Development of Atlantic cod (Gadus morhua) exposed to produced water during early life stages: Effects on embryos, larvae, and juvenile fish.

Produced water (PW) contains numerous toxic compounds of natural origin, such as dispersed oil, metals, alkylphenols (APs), and polycyclic aromatic hydrocarbons (PAHs). In addition, PW also contains many different chemicals which have been added during the oil production process. In the study described here, cod were exposed to real PW collected from an oil production platform in the North Sea. This was done in order to best recreate the most realistic field-exposure regime in which fish will be affected by a wide range of chemicals. The biological effects found in this study therefore cannot be assigned to one group of chemicals alone, but are the result of exposure to the complex chemical mixture found in real PW. Since APs are well known to cause endocrine disruption in marine organisms, we focused our chemical analysis on APs in an attempt to better understand the long-term effects of APs from PW on the biology of fish. In this study, cod were exposed to several concentrations of real PW and 17ß-oestradiol (E(2)), a natural oestrogen, at different developmental stages. Cod were exposed to PW either during the embryo and early larvae stage (up to 3 months of age) or during the early juvenile stage (from 3 to 6 months of age). Results showed that, in general, APs bioconcentrate in fish tissue in a dose and developmental stage dependent manner during PW exposure. However, juveniles appeared able to effectively metabolise the short chain APs. Importantly, PW exposure had no effect on embryo survival or hatching success. However, 1% PW clearly interfered with the development of normal larval pigmentation. After hatching most of the larvae exposed to 1% PW failed to begin feeding and died of starvation. This inability to feed may be linked to the increased incidence of jaw deformities seen in these larvae. In addition, cod exposed to 1% PW, had significantly higher levels of the biomarkers vitellogenin and CYP1A in plasma and liver, respectively. No similar effects were seen in cod exposed to either 0.1% or 0.01% PW.

Natural background and anthropogenic inputs of polycyclic aromatic hydrocarbons (PAH) in sediments of South-Western Barents Sea.

Polycyclic aromatic hydrocarbons (PAH) were measured in sediment cores from 13 locations in South-Western Barents Sea as part of a detailed study of the Norwegian seabed under the MAREANO program. The generally low PAH levels found, an average around 200 ng g(-1) dry weight for sum PAH, indicate low inputs of petroleum hydrocarbons to the marine environment in the area. Differences in PAH composition and various PAH ratios indicate a natural, mostly petrogenic origin of PAH in sediments from the open sea locations, while the fjord locations show higher pyrogenic PAH contents with an increase towards upper sediment layers, indicating low inputs from human activities. Petrogenic PAH levels increase in deeper sediments at open sea locations, also when normalised to total organic carbon (TOC) contents, suggesting natural leakages of oil-related hydrocarbons in the area.

Identification of estrogen-like alkylphenols in produced water from offshore oil installations.

Produced water released into the sea from oil installations contains a vast number of organic compounds. This work focuses on the analysis and identification of phenols in produced water, in particular long-chain para-substituted alkylphenols, which act as endocrine disruptors for marine biota. Some alkylphenol standards, unavailable commercially, have been synthesised and some compounds of interest identified. However, a complete identification is not possible since conventional GC techniques cannot achieve the desired degree of separation. An overview of the levels of the 52 known alkylphenols in produced water from nine oil installations in the North and Norwegian Seas has been made. The previously unidentified alkylphenols in produced water have been characterised by means of alkylphenol retention indices (APRI) and mass spectrometry, and their total amounts estimated for the same nine locations. Our results confirm the presence of naphthols and other as yet unidentified compounds in produced water, while thiophenols were not detected by the used technique.

Alkylphenol retention indices.

A novel type of retention indices for alkylphenols and related compounds are proposed. The alkylphenol retention indices (APRI) use para-substituted n-alkylphenols as reference series. APRI for para-n-alkylphenols are per definition equal to the number of carbon atoms in the alkyl substituent; the value for phenol is zero. Application of the APRI system with different types of derivatisation of the phenolic hydroxy group showed that the derivatisation has limited influence on these indices. Especially para-substituted alkylphenols gave APRI values that could be transferred with high accuracy from one type of derivative to another. By comparing results obtained with different gradients in temperature-programmed GC, it was also shown that APRI is less affected by chromatographic conditions than retention indices based on n-alkanes.

Gas chromatography-mass spectrometry analysis of alkylphenols in cod (Gadus morhua) tissues as pentafluorobenzoate derivatives.

A highly selective and sensitive method for the determination of 30 meta- and para-substituted alkylphenols from phenol (C0) to nonylphenol (C9) in biota is described. Dichloromethane extracts of spiked cod liver and muscle samples are cleaned up by gel permeation chromatography, derivatised with pentafluorobenzoyl chloride and analysed by gas chromatography-mass spectrometry with negative-ion chemical ionisation. Quantification is done with isotope dilution of five internal standards of different chain length. The detection limits were in the low microg/kg levels. There were encountered problems with background levels of 4-nonylphenol. 4-Nonylphenol isomers were found in a number of plastic and rubber products used in the laboratory.

Gas chromatography-mass spectrometry analysis of alkylphenols in produced water from offshore oil installations as pentafluorobenzoate derivatives.

A simple, highly selective and sensitive method for the determination of 14 representative alkylphenols from phenol (C0) to nonylphenol (C9) in produced water is described. Solid-phase extraction (SPE) by anion-exchange sorbent is used to extract alkylphenols from produced water. The samples are then derivatised by pentafluorobenzoyl chloride and analysed on GC-MS (negative ion chemical ionisation, NCI). The derivatisation procedure has been validated by means of two-level factorial design (2(7-4)) experiments. Quantification is done with isotope dilution of five internal standards of different alkyl chain length. The detection limits were at low ng/l levels. A comparison with GC-MS analysis of non-derivatised alkylphenol samples revealed the advantage of derivatisation as described in the method.

(n-Nitrophenyl)acetonitrile, with n = 2, 3 and 4.

The molecular structures of the three title nitro-substituted phenylacetonitriles, C(8)H(6)N(2)O(2), at 123 K show that the molecules are linked together very differently. In the 2- and 4-nitro compounds, there are both O...H and N(cyano)...H interactions, whereas the crystal lattice of the 3-nitro compound is essentially built up by O...H interactions. The O atoms seem to prefer the aromatic H atoms, while the cyano N atoms prefer the methylene H atoms. The phenyl-nitro torsion angles are -19.83 (13), -5.69 (12) and -2.88 (12) degrees, while the phenyl-cyanomethyl torsion angles are -62.27 (12), -147.99 (9) and -16.75 (14) degrees in the 2-, 3- and 4-NO(2)-substituted compounds, respectively.

[4-(Trifluoromethyl)phenyl]acetonitrile.

The crystal structure of the title compound, C(9)H(6)F(3)N, at 123 K contains molecules linked together via several C-H...F and C-H...N contacts, the strongest of which are 2.58 and 2.65 A, respectively. Apparently, an F atom in the CF(3) group is able to compete with a cyano N atom for aromatic H atoms but is less prone to interact with the more acidic methylene H atoms. The Ph-CH(2)CN torsion angle is -6.4 (2) and the planar phenyl ring exhibits a typical deformation of the endo angles at the ipso-C atoms, due to the difference in the electron-withdrawing power of the CF(3) and CH(2)CN substituents.

4-(Trifluoromethyl)benzonitrile.

4-(Trifluoromethyl)benzonitrile, C(8)H(4)F(3)N, at 123K contains molecules linked together through one C-H...F bond and two C-H...N hydrogen bonds into sheets that are further crosslinked to form a dense two-dimensional network without pi...pi ring interactions. The aromatic ring is slightly deformed due to the two para-related electronegative groups.