Assessment of Hydrocarbons (C₁₀-C₅₀), Polycyclic Aromatic Hydrocarbons (PAHs), and Trace Metals (TMs) Contamination in the Riverbanks of the Chaudière River Three Years after the Lac-Mégantic Railway Disaster (Southern Québec, Canada)

Bioremediation of Unconventional Oil Contaminated Ecosystems under Natural and Assisted Conditions: A Review

“…Moreover, there is no good understanding of the fate of toxic and recalcitrant fractions in an environment following oil spills. Saint et al demonstrated that the most toxic components in Bakken oil (e.g., the trace metals and alkylated PAHs) were very low in the river sediments due to the river currents that prevented the accumulation of contaminated sediments during spring floods . But, Hossain et.al reported that gravel sediments with large pore spaces can trap oil for a longer period of time and are considered as a source of contamination …”

“…Still no single remediation practice is considered the best option for removal of two main classes of the major constituents of unconventional oils including polar nonhydrocarbons (heavy nonvolatile compounds) and PAH from the environment. , SI Figure S1 shows a three-component research project that will be required to make a decision concerning the technologies to remediate the unconventional oil-contaminated site. In fact, a multiple lines of evidence approach is needed to study (a) advanced physical and chemical characterization of unconventional oil (i.e., Dilbit and Bakken oils); (b) development of innovative efficient oxidants and nonchemical oil adsorbents; and finally, (c) evaluation of in situ toxicity (eco-toxicity bioassay); natural degradation; and improvement of assisted oil-biodegradation. The assessment of the contamination characterization, ecotoxicity, and the impact of unconventional oil on the indigenous microbial community is required to determine whether unconventional oil spills could be the worst-case scenario of all oil spills .…”

“…Moreover, bioremediation is not applicable in sites where a high concentration of inorganic salts, and organic compounds hinder microbial growth and Bakken oil spill. Thus, bioremediation should be applied with a thorough understanding of the metabolic pathways and the microbial processes involved to prevent the production of more toxic substances . Santiago et al mentioned unresolved issues and requirements that may lead to higher initial costs for site characterization and feasibility evaluation for bioremediation .…”

“…al studied the behavior of toxic and recalcitrant fractions of Bakken oil to address the above-mentioned issues. They carried out a full characterization of riverbed sediments and river-bank soils in the Chaudière River to measure the concentration of petroleum hydrocarbons (C 10 –C 50 ), PAHs, and trace metals (Cd, Cu, Ni, Pb, and Zn) . They mentioned new issues regarding the Bakken oil remediation monitoring including the threshold of certain pollutants (i.e., some derivatives of PAH).…”

“…With this rapid development of new supply sources, the other environmental problems associated with unconventional oils that have raised concerns over oil spills include waste generation and leakage from the streamer, underground tanks, and abandoned bitumen refinery sites. The aftermath of recent high impact oil spill incidents (e.g., spill of Bakken oil in Lac Megantic and Dilbit from Alberta’s oil in Kalamazoo) highlights the lack of preparedness of governments to deal with unconventional oil emergencies . The inability to timely control the hazards; to constrain the spread of oil, and to efficiently protect polluted zones has been attributed to the differences between unconventional oil and traditional petroleum characteristics and their behavior in the environment.…”