Comparative toxicity assessment of in situ burn residues to initial and dispersed heavy fuel oil using zebrafish embryos as test organisms

Sarah Johann,Bjørn Munro Jenssen,Valentina Selja,Leonie Mueller,Susse Wegeberg,Henner Hollert,Janne Fritt-Rasmussen,Mira Goßen,Kim Gustavson,Thomas-Benjamin Seiler,Tomasz Maciej Ciesielski

doi:10.1007/s11356-020-11729-5

Abstract

In situ burning (ISB) is discussed to be one of the most suitable response strategies to combat oil spills in extreme conditions. After burning, a highly viscous and sticky residue is left and may over time pose a risk of exposing aquatic biota to toxic oil compounds. Scientific information about the impact of burn residues on the environment is scarce. In this context, a comprehensive ISB field experiment with approx. 1000L IFO 180 was conducted in a fjord in Greenland. The present study investigated the toxicity of collected ISB residues to early life stages of zebrafish (Danio rerio) as a model for potentially exposed pelagic organisms. The toxicity of ISB residues on zebrafish embryos was compared with the toxicity of the initial (unweathered) IFO 180 and chemically dispersed IFO 180. Morphological malformations, hatching success, swimming behavior, and biomarkers for exposure (CYP1A activity, AChE inhibition) were evaluated in order to cover the toxic response on different biological organization levels. Across all endpoints, ISB residues did not induce greater toxicity in zebrafish embryos compared with the initial oil. The application of a chemical dispersant increased the acute toxicity most likely due to a higher bioavailability of dissolved and particulate oil components. The results provide insight into the adverse effects of ISB residues on sensitive life stages of fish in comparison with chemical dispersant application.

Highlights

In case of an oil spill, the most effective response technologies have to be selected to minimize direct or indirect adverse effects on the environment
Concentration-related increases in sublethal and lethal effects were observed for wateraccommodated fractions (WAFs) from initial IFO 180, in situ burning (ISB) residues of IFO 180, and chemically dispersed IFO 180
At the termination of the test (120 hpf), all zebrafish larvae exposed to 66.7 % of the initial IFO 180 low-energy water-accommodated fractions (LEWAFs) stock (1:50) were defined as dead according to the lethality criteria defined by the OECD guideline 236

Summary

Introduction

In case of an oil spill, the most effective response technologies have to be selected to minimize direct or indirect adverse effects on the environment. The selection of oil spill response measures, such as chemical dispersion, in situ burning (ISB), or oil recovery, strongly depends on operational parameters such as the physical-chemical properties of the spilled oil and the weather conditions on site (Ekperusi et al 2019). Unique oil characteristics such as viscosity, density, pour point, and weathering status influence the oil fate and behavior as a function of temperature, wind conditions, and ice coverage (Spaulding 2017). Even though the amount of residue is highly reduced compared with the initial volume of spilled oil, the residue may pose a risk for smothering seabirds or shorelines and might expose pelagic and benthic communities to toxic compounds (Fritt-Rasmussen et al 2015) As reviewed by Fritt-Rasmussen et al (2015) and Holmsen (2019), scientific information about the impact of ISB residues on the environment is scarce, and, in particular, research is needed on the aquatic toxicity of ISB residues

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Discussion

Conclusion