Multiple contaminant ecological risk evaluation in small craft harbour sediments in Nova Scotia, Canada.

Small craft harbours are vital for the fishing industry and have high socioeconomic and cultural importance for surrounding communities. Presence of potential contaminants of concern in small craft harbour sediments can have significant impacts in biota and humans, including fishing activities and the local economy. While single contaminant sediment concentrations may be below sediment quality guidelines, the interaction of multiple contaminants in sediments may potentially exacerbate chemical ecological risk. An ecological risk evaluation for four classes of contaminants (i.e., petroleum hydrocarbons, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and metals) was conducted in 31 small craft harbours in Nova Scotia, Canada, using two approaches (i.e., mean probable effect level quotient and number and frequency of sediment quality guideline exceedances). Most small craft harbours showed a low ecological risk to marine biota, with only two small craft harbours suggesting high risk. While urgent action is not needed, monitoring is recommended for these small craft harbours to confirm that pollution is not increasing, and to potentially identify and control contamination sources.

Spatiotemporal characterization of petroleum hydrocarbons and polychlorinated biphenyls in small craft harbour sediments in Nova Scotia, Canada.

Previous characterization of polycyclic aromatic hydrocarbons (PAHs) and metals has been conducted in small craft harbour (SCH) sediments in Nova Scotia, Canada, but petroleum hydrocarbons (PHCs) and polychlorinated biphenyls (PCBs) have not been spatiotemporally assessed. This study characterized the distribution of over 500 PHCs and PCBs samples in 31 SCHs sediments between 2000 and 2017. Federal and regional sediment quality guidelines were used to determine exceedances. Results showed exceedances for diesel and oil resembling PHCs, expected given their longer permanence in sediments and lower volatility. However, only 7% of the samples exceeded 500 ppm, threshold where benthic impairment is observed, showing low risk. PCBs do not pose high risk to biota since only six samples exceeded the higher effect level and 25% of them exceeded the lower effect one. Monitoring is recommended for SCHs with significant exceedances, as well as collectively assessing all contaminants characterized in SCHs.

Structure-Based Design of a Bromodomain and Extraterminal Domain (BET) Inhibitor Selective for the N-Terminal Bromodomains That Retains an Anti-inflammatory and Antiproliferative Phenotype.

The bromodomain and extraterminal domain (BET) family of epigenetic regulators comprises four proteins (BRD2, BRD3, BRD4, BRDT), each containing tandem bromodomains. To date, small molecule inhibitors of these proteins typically bind all eight bromodomains of the family with similar affinity, resulting in a diverse range of biological effects. To enable further understanding of the broad phenotype characteristic of pan-BET inhibition, the development of inhibitors selective for individual, or sets of, bromodomains within the family is required. In this regard, we report the discovery of a potent probe molecule possessing up to 150-fold selectivity for the N-terminal bromodomains (BD1s) over the C-terminal bromodomains (BD2s) of the BETs. Guided by structural information, a specific amino acid difference between BD1 and BD2 domains was targeted for selective interaction with chemical functionality appended to the previously developed I-BET151 scaffold. Data presented herein demonstrate that selective inhibition of BD1 domains is sufficient to drive anti-inflammatory and antiproliferative effects.

Aquatic ecological risk assessment frameworks in Canada: a case study using a single framework in South Baymouth, Ontario, Canada.

Ecological risk assessment (ERA) is used to determine potential effect of human activities and industries on the natural environment. Numerous ERA management approaches exist and vary based on jurisdiction or ecological media. This ERA focused on contaminants within an aquatic ecosystem in sediments and surface water at South Baymouth port facility in Ontario, Canada. Contaminants were evaluated using the Canada-Ontario Decision-Making Framework for Assessment of Great Lakes Contaminated Sediments (COA). Following COA, this study (1) examined historical data from South Baymouth to determine contaminants of potential concern, (2) delineated potential contamination by comparing sediment and surface water concentration data to sediment quality guidelines and water quality guidelines from Canada and from different jurisdictions if Canadian guidelines were unavailable, (3) compared sediment concentrations to reference concentrations, and (4) developed an ERA decision matrix (used to inform management decisions at this aquatic site). Although sediments exhibited negligible potential for ecological risk and required no remedial management action, this case study highlights strengths of using COA for this ERA which included use of iterative and consistent approaches, but also highlights weaknesses which included unclear linkages between cause and effects of aquatic contaminants. Recommendations for future ERAs at contaminated aquatic sites include use of passive samplers and incorporating recent macroecology techniques.

Baseline characterization of sediments and marine biota near industrial effluent discharge in Northumberland Strait, Nova Scotia, Canada.

A bleached kraft pulp mill operating in Nova Scotia, Canada has discharged effluent into a former tidal estuary known as Boat Harbour since 1967. After treatment in Boat Harbour, effluent is discharged into Northumberland Strait. Contaminated sediments in Boat Harbour are slated for remediation following cessation of effluent discharge. A review of historical documents to identify contaminants in marine biota in Northumberland Strait found insufficient data to properly assess baseline conditions prior to remediation. This study measured metal, methylmercury, dioxin and furan concentrations in surficial sediments and American lobster (Homarus americanus), rock crabs (Cancer irroratus) and blue mussels (Mytilus edulis) in Northumberland Strait. When compared to Canadian Council of Ministers of the Environment sediment quality guidelines and Canadian Food Inspection Agency tissue guidelines results indicated limited contamination in sediments and biota, posing low risk to marine biota. Long-term monitoring is recommended to verify effectiveness of remediation.

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) in small craft harbor (SCH) surficial sediments in Nova Scotia, Canada.

Multiple source apportionment approaches were employed to investigate PAH sources which contribute to small craft harbor (SCH) sediments in Nova Scotia (NS), Canada. A total of 580 sediment samples were analyzed using PAH diagnostic ratios, Unmix Optimum receptor modeling, and by assessment of the composition of the PAH profile. PAH diagnostic ratios suggest PAHs are primarily of pyrogenic (thermal) origin, while UnmixO modeling identifies four individual sources which best describe surficial sediments and suggests contributions from both pyrogenic and petrogenic origins. These include coal combustion, automobile exhaust, and biomass incineration. PAH profile assessment determined an overwhelming contribution of high molecular weight PAHs, which exhibited a strong correlation with total PAH concentrations.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in small craft harbour (SCH) sediments in Nova Scotia, Canada.

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied in sediments due to their ubiquity and persistence in aquatic environments and potential for impairment to biota. Small craft harbour (SCH) sediments in Nova Scotia (NS), Canada, have yet to be studied comprehensively. SCHs are essential to the fishing industry, which is important for the Canadian economy. This spatiotemporal characterization study evaluated thirty-one SCHs across NS between 2001 and 2017 by analyzing sediment reports (secondary data). Sediment PAH concentrations varied widely across all SCHs. Few SCHs exhibited sediment PAH concentrations likely to impair biota based on comparison to sediment quality guidelines. Sediments in the Gulf region of NS were least impacted by PAHs, while the Southwest region was most impacted. Distribution of individual PAHs in sediments follows global trends, with high molecular weight PAHs dominating samples.