Simulating a Spill of Diluted Bitumen: Environmental Weathering and Submergence in a Model Freshwater System.

The main petroleum product transported through pipelines in Canada is diluted bitumen (dilbit), a semiliquid form of heavy crude oil mixed with natural gas condensates to facilitate transport. The weathering, fate, behavior, and environmental effects of dilbit are crucial to consider when responding to a spill; however, few environmental studies on dilbit have been completed. We report on 11-d-long experimental spills of dilbit (Cold Lake Winter Blend) in outdoor microcosms meant to simulate a low-energy aquatic system containing natural lake water and sediments treated with low (1:8000 oil:water) and high (1:800 oil:water) volumes of dilbit. In the first 24 h of the experiment, volatile hydrocarbons quickly evaporated from the dilbit, resulting in increased dilbit density and viscosity. These changes in dilbit's physical and chemical properties ultimately led to its submergence after 8 d. We also detected rapid accumulation of polycyclic aromatic compounds in the water column of the treated microcosms following the spills. The present study provides new information on the environmental fate and behavior of dilbit in a freshwater environment that will be critical to environmental risk assessments of proposed pipeline projects. In particular, the study demonstrates the propensity for dilbit to sink under ambient environmental conditions in freshwaters typical of many boreal lakes. Environ Toxicol Chem 2019;38:2621-2628. © 2019 SETAC.

Determination of selected pharmaceutical residues in wastewater using an automated open bed solid phase microextraction system.

The detection of trace levels of pharmaceuticals in environmental matrices requires an analyte pre-concentration procedure to obtain the required sensitivity for quantitative determination. This research aims to develop a simple automated analytical method based on C(18) thin film solid phase microextraction (TF-SPME) for the simultaneous extraction of pharmaceutical compounds detected in surface waters. As a sample preparation method, solid phase microextraction, is a rapid, environmentally friendly, and a sensitive analytical technique which isolates and pre-concentrates trace organic pollutants from environmental water samples in a single step. High throughput analysis was achieved with the use of a robotic auto sampler which enabled parallel analyte extraction in a 96-well plate format. Application of the method was demonstrated using wastewater from pilot-scale municipal treatment plants and environmental water samples from wastewater-dominated reaches of the Grand River (adjacent Waterloo, ON) which were analysed using a liquid chromatography-mass spectrometry (LC-ESI-MS/MS) technique. The proposed method successfully determined concentrations of carbamazepine, fluoxetine, sertraline, and paroxetine in treated effluent at concentrations ranging from 240 to 3820 ng/L with a method detection limit of 2-13 ng/L with a relative standard deviation of less than 16%. Matrix effect was not observed with this method; therefore internal standards are not necessary for quantification of target compounds. The results suggest that this method is capable of detecting and quantifying many compounds present in both wastewater and wastewater-influenced surface water from multiple municipal sources. In this study, automated TF-SPME system is demonstrated as a simple and fast alternative method for high throughput analysis of pharmaceutical contaminants in environmental matrices.