10.6084/m9.figshare.11358350.v1 Sawyer Stoyanovich Sawyer Stoyanovich Zeyu Yang Zeyu Yang Mark Hanson Mark Hanson Bruce P Hollebone Bruce P Hollebone Diane M Orihel Diane M Orihel Vince Palace Vince Palace Jose R Rodriguez-Gil Jose R Rodriguez-Gil Robert Faragher Robert Faragher Fatemah S Mirnaghi Fatemah S Mirnaghi Keval Shah Keval Shah Jules Blais Jules Blais Dataset for: Simulating a spill of diluted bitumen: Environmental weathering and submergence in a model freshwater system Wiley 2019 oil spills fate and transport water quality diluted bitumen dilbit oil weathering Environmental Sciences not elsewhere classified Environmental Science Environmental Chemistry 2019-12-12 14:37:15 Dataset https://wiley.figshare.com/articles/dataset/Dataset_for_Simulating_a_spill_of_diluted_bitumen_Environmental_weathering_and_submergence_in_a_model_freshwater_system/11358350 The main petroleum product transported through pipelines in Canada is diluted bitumen (dilbit), a semi-liquid form of heavy crude oil mixed with natural gas condensates to facilitate transport. The weathering, fate, behaviour, and environmental effects of dilbit are crucial to consider when responding to a spill, however few environmental studies on dilbit have been completed. Here we report on 11-day long experimental spills of dilbit (Cold Lake Winter Blend) in outdoor micro-cosms meant to simulate a low-energy aquatic system containing natural lake water and sedi-ments treated with a low (1:8,000 oil:water) and high (1:800 oil:water) volume of dilbit. In the first 24 hours of the experiment, volatile hydrocarbons quickly evaporated from the dilbit, result-ing in increased dilbit density and viscosity. These changes in dilbit’s physical and chemical properties ultimately led to its submergence after 8 days. We also detected rapid accumulation of polycyclic aromatic compounds in the water column of the treated-microcosms following the spills. Our study provides new information on the environmental fate and behaviour of dilbit in a freshwater environment that will be critical to environmental risk assessments of proposed pipe-line projects. In particular, our study demonstrates the propensity for dilbit to sink under ambient environmental conditions in fresh waters typical of many boreal lakes.