No abstract

Concentrations of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined in sediment and biota (fish liver) from around Scotland. The concentrations were investigated using assessment criteria developed by OSPAR and ICES. Organic contaminant concentrations, PAHs, PCBs and PBDEs in sediment, and PCBs and PBDEs in fish liver, were significantly higher in the Clyde compared to all other sea areas. This is mainly due to historic industrial inputs. Highest PCB and PAH concentrations were found in the strata furthest up the Clyde estuary, with concentrations of POPs in these strata being at levels such that there is an unacceptable risk of chronic effects occurring in marine species. Furthermore, for PAHs in Clyde sediment there was a significant negative gradient going from north to south towards the open sea. PAH and PCB concentrations in sediment and biota in all other Scottish sea areas (except for PCBs in sediment from East Scotland) were unlikely to give rise to pollution effects, being below relevant assessment criteria. Although no assessment criteria are available for PBDEs, the concentrations observed in Scottish sediments were low with all congeners below the limit of detection (LoD; 0.03 µg kg(-1) dry weight) in 140 out of a total of 307 samples analysed. Where PBDEs were detected, the dominant congeners were BDE47 and BDE99. PBDEs were detected in fish livers, although concentrations were less than 150 µg kg(-1) lipid weight in all sea areas except the Clyde where concentrations ranged between 8.9 and 2202 µg kg(-1) lipid weight. Few trends were detected in contaminant concentrations in biota or sediment at any Scottish site with more than five years data. Downward trends were detected in PAHs in sediment from the Clyde, Irish Sea and Minches and Malin Sea and PCBs in fish liver from the Moray Firth. Rules were developed for the aggregation of the contaminant data across a sea area. An overall assessment for each sea area was then assigned, looking at the frequency of sites or strata within each sea area that were above or below the relevant assessment criteria. Overall the status of the various sea areas, with respect to the assessed POPs, can be considered to be acceptable in that they were below concentrations likely to result in chronic effects for all sea areas except the Clyde.

Sediments were collected from the 110 mile hole and along a transect from 58 degrees 58.32' N 1 degree 10.38' W to the UK National Marine Monitoring (NMMP) site in the inner Moray Firth, for determination of hydrocarbon concentration and composition. Total PAH concentrations (2- to 6-ring PAHs, parent and branched) were highest at NMMP site 95 and at the associated end of the transect in the inner Moray Firth. PAHs in this area were of predominately pyrolytic origin and could be attributed to urban and industrial activities. The majority of sediments collected in the middle section of the transect had low total PAH concentrations (< 100 ng g(-1) dry weight). The high proportion of naphthalenes and alkylated PAHs in this area suggested a predominately petrogenic input. The GC-FID aliphatic hydrocarbon profiles showed that the majority of sediments, including those in the inner Firth, had a limited petrogenic input. This was supported by the geochemical biomarker profiles, which contained triterpanes typical of Middle Eastern crude oil. Principal component analysis was used to investigate spatial trends in the PAH distributions and demonstrated that there were differences between areas. The NMMP site 95 and transect start and middle sediments were well separated. PCA further confirmed that sediments from the NMMP site 95, the 110 mile hole and the inner Moray Firth (south west) end of the transect contained PAHs from predominately pyrolytic sources, whereas sediments from the north east end (start) and the middle of the transect were typified by a greater petrogenic component.

Halogenated persistent organic pollutants (chlorobiphenyls (CBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol-A (TBBP-A)) and total lipid content were measured in the liver and muscle of three species of deep water fish (black scabbard, roundnose grenadier and black dogfish) collected from the Rockall Trough, to the west of Scotland, in 2006. CB concentrations (SigmaICES (International Council for the Exploration of the Seas)7 CBs) >500 microg kg(-1) lipid weight) were found in 9 of the 31 deep water fish liver samples. Non-ortho CBs were measured in samples with the highest ortho CB concentrations. Non-ortho CBs (CB81, 77, 126 and 169) were not detected in any of the fish muscle samples. In liver, CB81 was not detected in any of the samples while CB169 was detected in all but one sample. The total 'dioxin-like' CB concentration was calculated based on the 5 mono-ortho and 4 non-ortho CBs measured. The non-ortho CB concentration made a very small contribution to the total 'dioxin-like' CB concentrations (<1%). Concentrations for the individual ICES7 CBs in fish liver were above OSPAR Background Assessment Concentrations (BACs) in all three species, except for CB28 and 101 in black dogfish. Toxic Equivalent (TEQs) concentrations calculated for the five mono-ortho and four non-ortho CBs measured, and estimated TEQs calculated using published models in the fish muscle indicated that consumption of deep water fish muscle is unlikely to represent a risk to human health. However, dioxins and furans were not measured and the contribution to the calculated TEQs from these compounds was not taken into account. Calculated and estimated TEQs for some roundnose grenadier liver samples exceeded the 25 pg g(-1) wet weight limit for fish liver and, therefore, there may be a health risk if consumed. PBDEs were detected in both the liver and muscle of the deep water fish, whilst HBCD and TBBP-A were not detected in any of the deep water fish.

We describe seasonal and regional variability in carbonate chemistry around the northwest European shelf, from a large and unique 1.5 year dataset of biogeochemical sampling combined with underway pCO 2 data. The data has improved understanding of carbonate chemistry in relation to nutrient biogeochemistry, showing seasonal variations between the well-mixed inner shelf and seasonally stratified outer shelf regions.