Occurrence, Levels and Spatial Distribution of Polybrominated Diphenyl Ethers: Case Study of Elemi River in Ado-Ekiti, Nigeria

Polybrominated diphenyl ethers (PBDEs) were seasonally determined in water and sediments of the Elemi River, Nigeria using gas chromatography analysis. Samples were collected in two consecutive seasons for six months, monitoring the program every month. Three BDEs congeners (28, 47 and 154) were only detected with the mean concentration of ND - 0.001 µg/L and ND - 0.143 µg/kg in water and sediments, respectively. BDEs (99, 100, 153, 183 and 209) were consistently absent in both seasons. The distribution of BDEs showed that BDE 28 was consistently found in the water samples throughout the months of sampling, while the sediments sparingly contained BDE 28 and 47. The study proposed the need for effective measures to reduce the deleterious contribution of these persistent compounds into the rivers.

Reviewing the UK’s Action Levels for the Management of Dredged Material

Action Levels (ALs) are thresholds which are used to determine whether dredged material is suitable for disposal at sea by providing a proxy risk assessment for potential impacts to biological features such as fish and benthos. This project tested proposed scenarios for changes to the UK Action Levels to determine the likely implications for navigational dredge licensing in England and Wales. Approximately 3000 sample data records from 2009 to 2018 were collated with varying numbers of concentrations for contaminant parameters including trace metals, organotins, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). Initially, these data were assessed using current ALs to determine the percentages of the samples with levels below AL1 (generally acceptable for disposal), between AL1 and AL2 and those showing levels above AL2 (generally unacceptable for disposal). These results were then used to compare with the results of the proposed new AL scenarios for each contaminant type derived from literature reviews and historic data. The results indicate that there are changes to the ALs which could be made such as updating the current ALs with the revised ALs, as well as the introduction of ALs where there are currently none set. The benefits of changing the ALs include reducing contaminant disposal to the marine environment and increased transparency in decision making. Any proposed scenarios will need to be phased in carefully in full liaison with stakeholders.