Polycyclic aromatic hydrocarbons in sediments at dredged material disposal sites around England: concentrations in 2013 and time trend information at selected sites 2008-2013.

The maintenance of navigation channels to ports and the development of their facilities present a need to conduct dredging operations, and the subsequent disposal of dredged material at sea. Contaminant concentrations in candidate dredged material are determined and their possible impacts considered during the licensing process, which can result in the exclusion of some material from sea disposal. Monitoring of disposal sites is conducted in order to ensure that no undesirable impacts are occurring. In this study we consider the levels of polycyclic aromatic hydrocarbons (PAHs) in sediments at a number of disposal sites monitored in 2013 and variations in concentrations over time at three sites during the period 2008-2013. These were assessed using established sediment quality guidelines. Elevated PAH concentrations were generally observed only within the boundaries of the disposal sites studied.

Polycyclic aromatic hydrocarbons in fish from St Helena, South Atlantic, in relation to an historic wreck.

Concentrations of polycyclic aromatic hydrocarbons were determined in edible tissues of fish species consumed by the islanders of St Helena to assess any risk to human health posed by oil leaking from an historic wreck. Samples were collected from the vicinity of the wreck site and at two reference locations at which fishing activity occurs. Summed PAH concentrations ranged from 2.2 to 20 µg kg(-1) wet weight, and no PAHs with more than 4 fused rings were detected. All concentrations of the four PAH used as a basis for assessment in relation to health risks to human consumers of foods within the EU (benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene and chrysene) were<0.1 µg kg(-1) wet weight and raised no concerns. Additionally, concentrations were calculated as the benzo[a]pyrene toxic equivalency quotient and found to be well below the level of concern (0 to 0.05 µg kg(-1) wet weight benzo[a]pyrene equivalents).

Extraction of bioavailable contaminants from marine sediments: an approach to reducing toxicity using adsorbent parcels.

This paper demonstrates an approach to reducing acute toxicity in marine sediments using adsorbent parcels. Acute toxicity tests were carried using the marine amphipod Corophium volutator. Marine sediments were spiked with two know contaminants tributyltin and naphthalene and then treated with adsorbent parcels containing either amberlite XAD4 or activated carbon. Results showed that both types of adsorbent parcels were effective in reducing acute toxicity, not only within spiked sediments containing naphthalene and/or tributyltin, but also in an environmental field samples form an expected contaminated site. Adsorbent parcels such as these could provide a practical approach to remediate areas of contaminated sediment within marine environments. Furthermore adsorbents can be used as an identification tool for problematic contaminants using a toxicity identification evaluation approach.

Polycyclic aromatic hydrocarbons in commercial fish and lobsters from the coastal waters of Madagascar following an oil spill in August 2009.

Concentrations of polycyclic aromatic hydrocarbons were determined in species of commercial fish and lobsters following an oil-spill just off the protected Madagascan coastline. Samples were collected along the coastline within and outside the affected area. Summed PAH concentrations ranged from 1.9 µg kg(-1) to 63 µg kg(-1) wet weight, but with no higher molecular weight PAHs (>202 Da) being detected. All concentrations of benzo[a]pyrene, benz[a]anthracene and dibenz[a,h]anthracene were <0.1 µg kg(-1) wet weight, well within the EU and UK set limits for the protection of human health. Additionally, samples were calculated as the benzo[a]pyrene toxic equivalency quotient (TEQ) and found to be well below the level of concern in relation to health of human consumers. Evaluation of the biota PAH data indicated the origin of PAH was predominantly petrogenic with >80% arising from oil sources. Profile studies indicate a low-level multisource petrogenic contamination probably representing a pre-spill background for the area.

Towards a scheme of toxic equivalency factors (TEFs) for the acute toxicity of PAHs in sediment.

Toxic equivalency factors/quotients (TEF/TEQs) express the toxicity of complex mixtures. For PAHs, TEF values are available for assessing their carcinogenic potential and are expressed as benzo[a]pyrene equivalents. This study develops a similar approach for their acute toxicity in sediments. Acute toxicity (10 day EC50) values were generated using the marine amphipod Corophium volutator bioassay for twelve low molecular weight PAHs. The results ranged from 24 to > 1000 mg/Kg sediment dry weight for 4-methyldibenzothiophene and anthracene, respectively. Phenanthrene was used as the reference compound (TEF=1) and so the TEQ values derived are expressed as phenanthrene equivalents. In order to illustrate the applicability of this approach to the development of marine indicators we plotted TEQ values for acute toxicity to UK environmental monitoring data. Further work is required to validate the TEF values produced and to extend the TEQ approach to include a wider range of low molecular weight PAHs.