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In July 2013, a tragic incident occurred in Lac Mégantic (LM), Quebec, which led to crude oil contamination of regional surface water,soil and sediment in the LM Lake. The purpose of this study is to investigate spilled crude oil degradation potential by using the sediments from the LM Lake. In the present study, sediments collected from the spill site were used as a source of microorganisms. An aliquot of collected sediment was sterilized and used as the control of the study. Two oils having similar physicochemical properties, the LM spill source oil and Alberta Sweet Mix Blend oil (ASMB) as a reference oil, were tested for comparison purpose. This biodegradation study was performed at two different temperatures and incubation period: 22°C for 4 weeks, and 4°C for 8 weeks. The chemical composition, including total petroleum hydrocarbons (TPH), total saturate hydrocarbons (TSH), total aromatic hydrocarbons (TAH), unresolved complex mixture (UCM), polycyclic aromatic hydrocarbons (PAHs) and their alkylated congeners (APAHs), n-alkanes, and selected petroleum biomarkers, was analyzed and assessed to evaluate their potential degradation ability. Results show that there is no significant difference in degradation efficiency for the two oils used; while different incubation conditions had an impact on their biodegradation potential. For the two oils, the degradation rates followed the order of resolved components > TSH > UCM >TAH. The degradation of TPH in different carbon range followed the C10− C16 >the C16− C34 >the > C34 range. Higher temperature is favorable to the degradation of all petroleum hydrocarbons, despite that biomarker are far less biodegradable than other petroleum hydrocarbons. Specifically, almost 100% normal alkanes were degraded at 22 oC, but the degradation rates at 4 oC was less than at 22 oC, especially for pristine, phytane and some high molecular weight n-alkanes. For PAHs and APAHs, their degradation rates generally decreased with the increased number of aromatic rings and alkylated degree under the two incubation conditions, while their degradation was limited for the other 3−6 ring parent PAHs at 4 oC due to the limited bacteria activity. LM sediment can degrade contaminated petroleum hydrocarbons effectively if appropriate ambient temperature is supplied for the growth of the in-situ natural bacteria., 42nd Arctic and Marine Oilspill Program: Technical Seminar on Environmental Contamination and Response, AMOP 2019, June 4-6, 2019, Halifax, Canada

We investigated individual toxicities of the nitrogen-based energetic materials (EMs) 2,4-dinitrotoluene (2,4-DNT); 2-amino-4,6-dinitrotoluene (2-ADNT); 4-amino-2,6-dinitrotoluene (4-ADNT); and nitroglycerin (NG) on microbial activity in Sassafras sandy loam (SSL) soil, which has physicochemical characteristics that support very high qualitative relative bioavailability for organic chemicals. Batches of SSL soil for basal respiration (BR) and substrate-induced respiration (SIR) assays were separately amended with individual EMs or acetone carrier control. Total microbial biomass carbon (biomass C) was determined from CO2 production increases after addition of 2500 mg/kg of glucose–water slurry to the soil. Exposure concentrations of each EM in soil were determined using US Environmental Protection Agency method 8330A. Basal respiration was the most sensitive endpoint for assessing the effects of nitroaromatic EMs on microbial activity in SSL, whereas SIR and biomass C were more sensitive endpoints for assessing the effects of NG in soil. The orders of toxicity (from greatest to least) were 4-ADNT > 2,4-DNT = 2-ADNT > NG for BR; but for SIR and biomass C, the order of toxicity was NG > 2,4-DNT > 2-ADNT = 4-ADNT. No inhibition of SIR was found up to and including the greatest concentration of each ADNT tested in SSL. These ecotoxicological data will be helpful in identifying concentrations of contaminant EMs in soil that present acceptable ecological risks for biologically mediated processes in soil.

This study investigated the possibility that titanium dioxide nanoparticles (nano-TiO2) toxicity in Pseudokirchneriella subcapitata involves reactive oxygen species (ROS) production, using the dichlorodihydrofluorescein (DCF) assay. Algae were exposed to nano-TiO2 under laboratory fluorescent lamps supplemented with UV irradiation for 3 h, with or without a UV filter. Results showed that nano-TiO2 increased ROS production in UV-exposed cells, with or without a UV filter (LOEC values were 250 and 10 mg/L, respectively). Sublethal effects of nano-TiO2 on UV pre-exposed algae were also examined. Toxicity studies indicated that exposure to nano-TiO2 agglomerates decreased algal growth following 3 h pre-exposure to UV, with or without a UV filter (EC50s were 8.7 and 6.3 mg/L, respectively). The present study suggests that the growth inhibitory effects of nano-TiO2 in algae occurred at concentrations lower than those that can elevate DCF fluorescence, and that ROS generation is not directly involved with the sublethal effects of nano-TiO2 in algae.

The Defense Research and Development Canada (DRDC, Valcartier, QC) is developing new green explosive and propellant formulations, as part of a sustainable training strategy for the Canadian Army. The present research responds to the needs of DRDC by providing necessary physicochemical, chemical, and ecotoxicological data to help understand the environmental transport, fate and impact of new formulations developed within the RIGHTTRAC (Revolutionary Insensitive, Green and Healthier Training Technology with Reduced Adverse Contamination) project. The present study summarizes the dissolution, transport, transformation, and ecotoxicity of three propellant formulations, SP 7993, SP Unique, and CMR170, and their soluble components, NG, DPA, ATEC, MC, and EC. In addition, it gathers ecotoxicity data for an explosive formulation, GIM, which has been aged for periods varying from 6 to 24 months. Amongst the three propellant formulations tested, the single base formulation SP 7993 was found to be the most stable in terms of dissolution, even more stable than the formulation New Green M1 identified as the most stable of previously studied formulations. If scattered on soil surface and subjected to precipitations SP 7993 will give rise to low leakage of ATEC and the latter will not persist in soil. When comparing the two double base formulations, CRM170 appeared to be more stable than SP Unique. Although the MC/graphite coating present in CMR170 might have been responsible for the higher stability this could not be ascertained due to the concomitant higher NC content of CMR170, which also decreased its ability to dissolve.

Hexanitrohexaazaisowurtzitane (CL-20) is a polycyclic nitramine explosive and propellant, currently being considered as a potential replacement for existing cyclic nitramine explosives. Earlier studies have provided evidence suggestive of adverse liver effects in adult Coturnix spp. exposed to CL-20, yet analysis of tissue samples (plasma, liver, brain, heart, or spleen) indicated that CL-20 was not detectable in these treated animals. The present study was conducted to identify and purify the enzymes capable of CL-20 biotransformation. Results indicate that the hepatic biotransformation of CL-20 in vitro was inhibited by ethacrynic acid (93%) and by the glutathione (GSH) analogue S-octylglutathione (80%), suggesting the involvement of glutathione-S-transferase (GST). Partially purified cytosolic ?- and ?-type GST (requiring presence of GSH as a cofactor) from quail and rabbit liver was capable of CL-20 biotransformation. The degradation of CL-20 (0.30 � 0.05 and 0.40 � 0.02 nmol/min/mg protein for quail and rabbit, respectively) was accompanied with the formation of nitrite and consumption of GSH. Using liquid chromatography/mass spectrometry, we detected two intermediates, that is, open-ring, monodenitrated GSH�conjugated CL-20 biotransformation product with the same deprotonated molecular mass ion at 699 Da, suggesting isomeric forms of the intermediate metabolites. Identity of the conjugated metabolites was confirmed by using ring-labeled [15N]CL-20 and the nitro group�labeled [15NO2]CL-20. These data suggest that the in vitro biotransformation of CL-20 by GST under the conditions tested may be a key initial step in the in vivo degradation of CL-20 in the quail and resulted in the formation of more biologically reactive intermediates than the parent compound. These data will aid in our understanding of the biotransformation processes of CL-20 in vivo.